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1993 K1500 runs terrible when hot


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Thor1993
01-09-2014, 06:17 PM
Hi guys,
I am a new member here. I need a little help with my 1993 K1500 4.3L truck. Maybe one or more of you have been through this already. I have sent a few private messages to old_ master and I have put an Ac Delco cap & rotor on with dielectric grease as he recommends
I thought I would start a thread on this also.
Well here is the problem, my truck runs like a new truck for 3-4 miles (open loop maybe) then runs terrible after 3 miles (closed loop maybe) After 20 miles on freeway the pass side exhaust manifold is red hot. (I guess this is probably why I have a cracked exhuast manifold.) So until I fix it I am only using it for plowing. I am thinking about a new intake gasket. However, I spayed starting fluid all over the intake but speed never increased. The first time I did this I found a bad PVC line and discovered a bad throttle body gasket. This has been fixed. Here is a list of ideas I have already tried. Next I am onto the knock sensor.
Here is a little history
cc = carquest az = autozone
I made a spread sheet but it won't tranfer here so the date is way over on the right and the repair is on the left sorry for the confusion

11/9/2011


new batt cable
cc

3/3/2012


171,319

new plug wires, 5yr warranty,
cc

5/18/2012


171,600

new fuel pump & all gas lines
cc

5/18/2012


171,600

new fuel sending unit
cc

8/21/2012


new catalytic conv


9/22/2012


New coil
cc

10/1/2012


177,000

new new plugs, wires, cap & rotor
az

10/15/2012


new O2 & exhuast


12/23/2012


new coolant temp sensor & thermostat
az

11/1/2013


179,300

new plugs, wires, cap, throttle body gasket, belt tensioner, elbow for PVC line


12/22/2013


179,900

MAP - tested OK


12/22/2013


179,900

TPS - tested OK


12/22/2013


179,900

Temp sensor - tested OK


12/22/2013


179,900

new temp sending unit for gage


12/27/2013


179,900

new EGR valve & vac lines


12/24/2013


179,900

new O2 sensor


1/2/2014


179,900

new ECM


1/9/2014


179,900

new AC Delco cap & Rotor



This truck is driving me crazy. Any ideas are welcome.
Thanks very much,
Greg

j cAT
01-10-2014, 01:35 PM
the exhaust manifold crack my be the problem. with a crack the KS will retard timing.also the O2 will report a lean condition to the computer. this will be noticable after the open loop ends and the closed loop begins.

the ICM should be removed and call AZ to see if they can test it.

Thor1993
01-10-2014, 01:45 PM
Some more data on the issue in case some of you are thinking about this one….as I read other threads and see suggestions on other similar problems I will post the data on my truck here.
· It is probably not a tank of bad gas, I have been through several tanks of gas and added ISO heat and dry gas to get rid of water but there wasn’t any in the tank because I had to replace the o-ring on the tank and I was able to look inside.
· I have owned the truck for 5 years and it has been a good runner until a few months ago. Granted a 4.3L lacks power on a good day, but before, at least it would run 75 mph with no problem.
· The motor is bone stock no mods at all. No K & N filter, no disconnected emissions etc.
· Both injectors seem to spray a nice “cone” of gas mist.
· It idles perfect, it plows perfect(I live in Michigan and have been plowing my driveway), it starts right up. It just won’t hold 50 MPH on the freeway and struggles to get there after it drives 3-4 miles.
· The distributor shaft has no side to side play but does have a little up and down play. The distributor had a sticker that said something about voiding the warranty so perhaps the distributor is a replacement.
· The crack in the exhaust manifold closes up when the motor is hot.
· The exhaust does rattle on crossmember , I will fix this just to make sure not causing issue with knock sensor.
· Speaking of knock sensor, I will look for plug wires running to close to wiring harness to make sure we are not getting stray unwanted electricity to the ECM.
· The ground on the temp sensor checks OK

J cAT - The crack is huge but it closes up when the motor is hot, Do you still think that will cause issues with Knock sensor? and what is ICM?
Thanks, Greg

maxwedge
01-10-2014, 02:23 PM
Sounds like it could be running too lean, how about the fuel filter?

Thor1993
01-10-2014, 02:31 PM
Maxwedge,

Well it has been 1 1/2 year since I replaced it and it has about 8,000 miles on it so I will add this to the list ASAP since it is cheap. Should be easy I put in all new lines 1 1/2 ago.
Thanks, Greg

j cAT
01-10-2014, 03:58 PM
exhaust manifold leaks screws up the computer fuel mixture sensing / control. also the sound retards the timing because the KS picks up too much noise.

what this will do is dump more fuel into the engine then your converter will over heat.

melt.

fix the manifold then if it lacks power remove the upstream O2 sensor / LEAVE HOLE OPEN ... test run to see if power returns..if so then the exhaust is restricted converter or muffler ..

Thor1993
01-10-2014, 05:40 PM
j cAT Thanks I will shop for a manifold and get it installed. When I had a missing donut on the Y pipe it ran terrible but then it was a big leak.
Greg




also how does the "thanks" thing work that I see below a poster's name??? I am new here and don't know how this works and I certianly don't want to be rude!! I really appreciate the help you guys give from this site!

also, I sent a private message to member old_master but I get a page not found What am I doing wrong?

Schurkey
01-11-2014, 12:50 AM
1. Is there an O2 sensor in the cracked exhaust manifold? I'd have expected this truck to have a single O2 sensor, in the driver's side manifold.

2. When was the last time the ignition timing was verified? Initial advance is easy, but does the timing advance with RPM? How much? Glowing exhaust manifolds are typically due to retarded timing, although incorrect fuel mixture can do it, too. An outright misfire can load the exhaust with fuel and air, the hot exhaust from other cylinders ignites it.

3. Does the engine have an air pump? Does the air pump switch from upstream injection (into the exhaust manifold) to downstream (closer to the converter, or on some vehicles, into the air cleaner)? Injected air into the exhaust manifold once the engine has warmed-up, can overheat it.

4. If you remove the PCV from the valve cover, and spray aerosol carb cleaner or (unlit) propane from a small torch into the open grommet, does the engine RPM change? This could signal a blown intake manifold gasket, where the gasket leaks at the bottom of the port, pulling excess air into the cylinder.

Thor1993
01-11-2014, 05:34 AM
Schurkey - Thanks for the ideas, here are my answers.
1. The truck has one O2 sensor just before the cat.
2. The timing was checked last week, with engine at operating temperature with the wire on firewall unplugged. I set it to 0 as the sticker on shroud specifies. (actually I have never moved it, it has always been at 0) RPM drops when I unplug wire. I have not checked to see if balancer has spun on yet. When wire is plugged in, the timing advances maybe 20- 25 degrees as you rev up the motor as I recall. The timing mark is steady and does not float around. All the spark plugs looked good and consistent when I replaced them in November 2013. Another words no obvious miss firing or fouled plug.
3 No air pump.
4. I will try this; I was wondering how to check for this without pulling the intake off. Great idea.

Unfortunately, I have to leave on a business trip today and I will not be back until Friday to try the propane. I will try that next week end. I also bought an AC Delco fuel filter for it just to rule it out.

Thanks for all the ideas, they are greatly appreciated.
Greg

j cAT
01-11-2014, 09:56 AM
with the use of a small propane torch and placing a hose on the end probing for vacuum leaks is a better way than spraying carb cleaner on the engine because carb cleaner damages electrical/plastics etc...

Thor1993
01-21-2014, 05:18 PM
Hi Guys,

news flash!!

I am back from a businees trip and being sick so now unto the truck again. I pulled off the PCV valve at the valve cover and tried propane but no change in RPM so I tried propane in pcv valve and no change either. Hmmm.... that seems odd so I carefully sprayed starting fluid into pcv valve and immediatly the rpm changed. So I sprayed a little into the valve cover and no change. So maybe the intake gasket is OK underneath?? I am so disappointed. I thought this was going to be it!! My son said funny things happen when your intake gasket is bad and I thought this would confirm it. Well, I still need to put the new fuel filter on it.
any other ideas?? ( I have not done exhaust manifold yet.)
Greg

rhandwor
01-22-2014, 05:42 AM
Have you actually checked the fuel pressure. Their is a pressure regulator for this vehicle. They have a rebuild kit. These throttle bodies get dirty and have to be cleaned they sell a kit at the parts store. Get a loaner fuel pressure test kit at Auto Zone or Advanced Auto. I have an adapter for these remove the filter and it connects at this point.
http://www.rockauto.com/ Search for throttle body repair kit. The Standard had what I remember as the pressure regulator diaphragm. The Airtex didn't have this part. Napa sells Standard products.

Thor1993
01-22-2014, 05:59 AM
Actually no I have not checked fuel pressure. I have a fuel pressure tester I bought several years ago. I will put it in line and test when I replace the fuel filter this weekend and report back.
Thanks for suggestion.
Greg

Thor1993
01-25-2014, 09:00 PM
Latest update!!!

Well we can eliminate the fuel filter as the problem. I put a new ac delco fuel filter in today and no change.

Also today I ran a vacuum gage into the cab and went for a ride. I am getting steady 18 at idle. 0-2 when I stick my foot in it and when I let off I get 20-25 for a second and then back ro 18. At any reading the needle is as steady as a rock.

Then I went to the auto store and picked up the fittings and gas line to run a fuel pressure gage and see what is going on. That test is next but I ran out of time today.

It has been a blizzard here in Michigan so I have not gotten to the junk yard to look for a exhaust manifold yet.

Thanks Greg

Schurkey
01-26-2014, 12:39 AM
Then I went to the auto store and picked up the fittings and gas line to run a fuel pressure gage and see what is going on.
Huh? Photos?

rhandwor
01-26-2014, 07:29 AM
I am the idiot in this Topic.http://www.crazyki.com/13.jpg
I worked on one of these trucks with an after market EGR valve and these used to come with washers and the engine would shake on hills. I had some used washers and found one that worked to correct the problem.

ASJT3
01-27-2014, 10:34 AM
Did you ever check the ICM like j_cat said? The ignition control module (ICM) is in the distributor underneath the rotor, it's a brake pad-shaped plastic computer card held down by two screws underneath inside the dist cap (wires running to it). Maybe pick one (or two) up from the junkyard when you go to test out.

When the ICM in my '93 went the truck just died, but I've heard that it can cause erratic behavior as it starts to fail (electronics sensitive to heat).

Thor1993
01-29-2014, 01:10 PM
Hi Guys,
I am in Germany at the moment on a business trip so I apologize for not respnding sooner. I did replace the ignition control module a few weeks ago. I thought it was the issue because the distributor cap never really fit good and when I put the new ICM in I had to leave it loose and then fit the cap and then remove cap, tighten ICM. After that the distributor cap fit perfect. I thought I had found the problem but noooo... it did not make any improvement.

Please keep the ideas and suggestions coming!!
Greg

rhandwor
01-29-2014, 01:20 PM
Hi Guys,
I am in Germany at the moment on a business trip so I apologize for not respnding sooner. I did replace the ignition control module a few weeks ago. I thought it was the issue because the distributor cap never really fit good and when I put the new ICM in I had to leave it loose and then fit the cap and then remove cap, tighten ICM. After that the distributor cap fit perfect. I thought I had found the problem but noooo... it did not make any improvement.

Please keep the ideas and suggestions coming!!
Greg
http://www.rockauto.com/ Search distributor pick up coil these will definitely make your engine run bad.

Thor1993
01-29-2014, 01:35 PM
rhandwor
I saw that distributor pick up coil in the service manual. I will add that to the list of parts to order. It looks fairly cheap so maybe I should just do it to eliminate it. looks like distributor must come out to change it on the bench.
Thanks, Greg

rhandwor
01-29-2014, 05:27 PM
rhandwor
I saw that distributor pick up coil in the service manual. I will add that to the list of parts to order. It looks fairly cheap so maybe I should just do it to eliminate it. looks like distributor must come out to change it on the bench.
Thanks, Greg
Pull the distributor and on the bench vise drive the pin in the gear. I have a specialty puller for this purpose. I think the Ford distributors especially needed this tool.
Most Chevy's I didn't need it. Ask Auto Zone or Advanced auto for a loaner.

Thor1993
02-01-2014, 04:27 PM
Hi Guys,

Well I made it back from Germany despite all the cancelled flights. In Germany, I had a Black Audi A4 with a 6 speed that was fun to drive but to be honest I am just more comfortable driving my Chevy W/T pick up. Speaking of the W/T.... I had a few minutes today to check the fuel pressure as rhandwor suugested. I put a T in the line right after the fuel filter. I then went for a ride. The pressure was 12-13psi when the truck was running good, when the truck was running bad, at idle, at WOT and at cruising speed. So I think we can eliminate the fuel pump as the problem. Still could be a fuel pressure problem in the TBI but at least we know the pump is good.

Tommorow I hope to do the distributor coil pick up or the intake gasket.

Thanks for all your suggestions guys,

Greg

Thor1993
02-01-2014, 09:02 PM
News flash!!!

Hi Guys (and gals if there are any)

We may have had a break through tonight. We decided to replace the distributor pick up coil tonight. We picked one up at AutoZone until we get an AC Delco one. When we took the cap and rotor off we noticed the rotor is contacting the cap. See the dark spots in the photo. That is where it rubs on the cap. I do not understand this, there is no play in the shaft??
http://i1193.photobucket.com/albums/aa359/gregthor/100_6611_zps06ddab7f.jpg (http://s1193.photobucket.com/user/gregthor/media/100_6611_zps06ddab7f.jpg.html)

http://i1193.photobucket.com/albums/aa359/gregthor/100_6612_zpseb28f2c5.jpg (http://s1193.photobucket.com/user/gregthor/media/100_6612_zpseb28f2c5.jpg.html)

Then when we took the distributor apart the magnate came out in 2 pieces.

http://i1193.photobucket.com/albums/aa359/gregthor/100_6610_zps3fe1907c.jpg (http://s1193.photobucket.com/user/gregthor/media/100_6610_zps3fe1907c.jpg.html)

Next the old pick up coil had the pin filed off. See where the punch is pointing to. The new pick up would not fit unless we removed the pin. We decided not to use it.
http://i1193.photobucket.com/albums/aa359/gregthor/100_6609_zpsbc369606.jpg (http://s1193.photobucket.com/user/gregthor/media/100_6609_zpsbc369606.jpg.html)

In the distributor there was no hole for the pin in the pick up coil to engage. Also there was a roll pin sticking up that did not engage into the pick up coil. You could see in the old pick up coil that it had been smashed into the plastic.

http://i1193.photobucket.com/albums/aa359/gregthor/100_6613_zps0c02731c.jpg (http://s1193.photobucket.com/user/gregthor/media/100_6613_zps0c02731c.jpg.html)

So clearly there are some issues with the distributor!?!? Even when we tighten the cap, it rocks a little on the distributor. I am thinking to order a rebuilt AC Delco on line. I don't know if this is the final solution but now that I know it is all messed up I gotta replace it.

Any suggestions or ideas?

Greg

Thor1993
02-01-2014, 09:13 PM
Schurkey- Here are photos of the fuel pressure gage set up. A simple plastic T in the line after the fuel filter with enough hose to put gage where I could see it when I was driving.
http://i1193.photobucket.com/albums/aa359/gregthor/100_6607_zps21e66e52.jpg (http://s1193.photobucket.com/user/gregthor/media/100_6607_zps21e66e52.jpg.html)

j cAT
02-01-2014, 11:08 PM
if the distributor shaft wobbles even a little get a new one.

rhandwor
02-02-2014, 05:09 AM
I would order the rebuilt A C Delco distributor on line. I'm glad you found the problem.

Thor1993
02-02-2014, 06:55 AM
Rebuilt AC Delco is ordered. It would be great if this were the problem!!!

Rock Auto said it is at an outlaying warehouse and may take several days to get it. I put the truck back together with the old parts so it runs and I can plow if necessary.

Greg

j cAT
02-02-2014, 08:13 AM
Rebuilt AC Delco is ordered. It would be great if this were the problem!!!

Rock Auto said it is at an outlaying warehouse and may take several days to get it. I put the truck back together with the old parts so it runs and I can plow if necessary.

Greg

the distributor bearing worn is a problem that will cause these issues. timing is off and poor engine performance then no performance.

Schurkey
02-02-2014, 01:37 PM
my truck runs like a new truck for 3-4 miles (open loop maybe) then runs terrible after 3 miles (closed loop maybe) After 20 miles on freeway the pass side exhaust manifold is red hot.
Broken magnet in the pickup coil = problem
Wiped-out distributor mainshaft bushings = problem

I don't see either one of these causing a degradation of power/performance after 3-4 miles. They should be a consistent problem, not a heat- or time-related issue.

I don't see either one of these causing ONE manifold to glow, either.

Yes, you need distributor repairs/replacement; but I wouldn't count on the distributor fix taking care of the entire driveability problem. (We can hope...)






I can't figure out how you can attach that fuel pressure gauge to your fuel system. Isn't your fuel plumbing steel tubing and steel-braided hose? Where is the rubber hose that attaches to your "tee"? Has someone installed section(s) of rubber hose under the vehicle?

Thor1993
02-02-2014, 04:14 PM
Schurkey -There is a rubber line at the bottom of the firewall it connects the steel line from the TBI to the steel line that runs to the tank. I am not sure if the rubber line is factory or not. When the main fuel line rusted out a few years ago I went to GM and got all new replacement lines to the firewall. I don't remember cutting a steel line and putting a rubber line in. I usually don't cheat on fuel pressure stuff. Isn't rubber line Ok on a 13 psi fuel system?? Anyways, I sure hope you didn't think I was being a smart ass by posting the picture....but that is actually what I used.
Greg

Schurkey
02-02-2014, 04:49 PM
Schurkey -There is a rubber line at the bottom of the firewall it connects the steel line from the TBI to the steel line that runs to the tank. I am not sure if the rubber line is factory or not. When the main fuel line rusted out a few years ago I went to GM and got all new replacement lines to the firewall. I don't remember cutting a steel line and putting a rubber line in. I usually don't cheat on fuel pressure stuff. Isn't rubber line Ok on a 13 psi fuel system?? Anyways, I sure hope you didn't think I was being a smart ass by posting the picture....but that is actually what I used.
Greg
I wouldn't expect ordinary rubber hose on this vehicle. Mine ('88 K1500) has hard plastic tubing, steel tubing, or "steel-braided" hose. No plain rubber.

If the rubber hose and clamps are specified for fuel injection, you're likely OK. Plain "carburetor style" hose is not acceptable, neither are ordinary worm-clamps.

Thor1993
02-08-2014, 04:22 PM
News Flash!!!!!
The new AC Delco distributor arrived today. I inspected it, lubed it and installed it. Then I set the timing and went for a test drive and……..drum roll please… It fixed it….well I went for a 10 mile ride and it ran better than it has in 2 months. I think t is 85% fixed. There is still something not perfect. But I am really pleased. The old distributor was a GM. It had same P/N as new one. The end play on the old one was about .062 and .052 on the new one.
http://i1193.photobucket.com/albums/aa359/gregthor/100_6617_zps61e0d67d.jpg (http://s1193.photobucket.com/user/gregthor/media/100_6617_zps61e0d67d.jpg.html)
http://i1193.photobucket.com/albums/aa359/gregthor/100_6618_zpse7d2aa7f.jpg (http://s1193.photobucket.com/user/gregthor/media/100_6618_zpse7d2aa7f.jpg.html)
Somebody is getting tired of me working on my truck all the time.
http://i1193.photobucket.com/albums/aa359/gregthor/100_6616_zps46537819.jpg (http://s1193.photobucket.com/user/gregthor/media/100_6616_zps46537819.jpg.html)
Anyways here is a picture of the truck. As you can see it has been earning its keep plowing. It plows fine and I use it all the time plowing. That pile of snow behind the truck is all over the edge of my driveway. The plowing has slowed my finding the problem because I need the truck every time it snows and here in Michigan that has been a lot lately.
http://i1193.photobucket.com/albums/aa359/gregthor/photo_zpsb59dc5cf.jpg (http://s1193.photobucket.com/user/gregthor/media/photo_zpsb59dc5cf.jpg.html)
Here is an update on other issues with the truck.
Correction on advance – I marked the line on the harmonic balancer white a white marker. The timing does not advance when I rev it up as I posted earlier.
Exhaust manifold – it has been too cold for me to go to the junk yard looking for a replacement manifold. The crack is big but closes up when the motor is hot. I want to replace it anyways. Here is a picture of the crack.
http://i1193.photobucket.com/albums/aa359/gregthor/100_6615_zps2fb521a4.jpg (http://s1193.photobucket.com/user/gregthor/media/100_6615_zps2fb521a4.jpg.html)
TBI- I think it is very dirty! I will get into that next, rebuild the regulator and send the injectors out for a rebuild/test.
Knock sensor – I found the knock sensor. On the V6 it is under the distributor. I was looking for it near starter but that is where it is on the 5.7 L engines. I will check that also.
Spark plugs – I think I will put new ones in. They have been through hell the past 2 months.
The vacuum gage says no problems but it just seems to me that it comes down too slow after you rev it up.
Anyway’s Thanks for all the great advice form you guys. I will keep doing updates as I go further.
Greg

Schurkey
02-08-2014, 05:27 PM
I think t is 85% fixed. There is still something not perfect...

...Correction on advance – I marked the line on the harmonic balancer white a white marker. The timing does not advance when I rev it up as I posted earlier.
Did you re-connect the single-wire connector?

Thor1993
02-08-2014, 05:56 PM
OK, I redid a timing advance check with the wire connected, it advances when I rev it up.

Thor1993
02-11-2014, 08:32 AM
Well I spoke too soon, I went to drive the truck to work today and after it warmed up it ran horrible again. I will start working my way down the list of more things to check.
It is so odd, we plowed with it for 2 hours straight over the weekend and it never missed a beat. But out in the highway no power, poping and missing....

rhandwor
02-11-2014, 09:06 AM
I had a Chevy and a valve guide got worn and it would run fine then the valve would twist and it would miss. With the valve cover off you could watch what was happening. When you do your exhaust manifold I would do a compression test. If you put some oil in a low cylinder and the compression doesn't change I would look at the valves sometimes a nut will come loose. They use lock nuts get a new one if loose.

j cAT
02-11-2014, 09:26 AM
Well I spoke too soon, I went to drive the truck to work today and after it warmed up it ran horrible again. I will start working my way down the list of more things to check.
It is so odd, we plowed with it for 2 hours straight over the weekend and it never missed a beat. But out in the highway no power, poping and missing....

I posted this on feb 10, 2014 " the exhaust manifold crack my be the problem. with a crack the KS will retard timing . also the O2 will report a lean condition to the computer. this will be noticeable after the open loop ends and the closed loop begins. "

having seen your crack you wasting time and money chasing ghosts !

Thor1993
02-11-2014, 10:25 AM
j cAT - I trust you! really! and I appreacoaite your help!!!

But it is at the moment 10F outside and the snow is 3 feet deep. I just don't have the motivation to get to the junk yard and get a manifold yet.....

You are totaly right about chasing ghosts and in general I don't do the shot gun approach by throwing money at it but the coil pick up in the distributor was cheap and then I found the bastard distruibutor so I bought a new one.

Maybe I should just give in and buy a new manifold because at the current rate of snow and cold it will be June before I get to the junk yard.
Greg

Thor1993
02-11-2014, 10:35 AM
rhandwor - Thanks for idea. I have the compression test on my list of things to check. I will look for valves also. (and a bad cam at the same time when I have the valve cover off.)

I am thinking hard about buying a new manifold and not waiting to get one at the junk yard also.

With the snow we have had I can't take this truck out of service so I have to plan out working on it between plowing.
Greg

Thor1993
02-11-2014, 07:09 PM
Hi Guys,
Well I thought I better do some testing before I invest the time and money into a new exhaust manifold. So tonight I did a compression test. The motor was warm but not hot like the manual says but I ran one anyways. The results are cylinder #1, 2, 3, 5 & 6 were all 90-120psi on the first stroke with most about 110psi and 160-175psi on the 5th stroke. Cylinder # 4 was 75-80psi on the first stroke and 150-155psi on the fifth stroke. I put some oil in cylinder # 4 and re re-ran the test and it was 120 on the first stroke and 200psi on the fifth stroke. Spec is all psi readings within 20psi. So for a truck with 180,000 miles not too bad. I wish #4 was alittle better.
Next I am going to pull the valve covers and make sure the cam and valve train is working. If not I can do the exhaust manifold and other repair all at once.
Also, the plugs are AC Delco and the wires said "Standard 7mm". What do you guys think of Standard spark plug wires??
Take Care and THANKS FOR POSTING!!!,
Greg

rhandwor
02-12-2014, 06:56 AM
I've been retired for a few years but I've found aftermarket wires worked fine but weren't crimped properly on the spark plug end. If an engine was missing and a customer came in with a misfire and I noticed new plug wires I either used my scope or an ohm meter and checked the wires. They run around 1/2 scale depending on the length. Usually a wire on the plug end wasn't crimped properly.
I have a pair of plug wire pliers and cut off about 2 or 3 inches and used the same end but crimped it properly.
An independent can't get away with charging for new wires when they installed new wires them selves I charged shop time to check out and do the repair.
If you have a pair of plug wire pliers check and repair.

Thor1993
02-12-2014, 09:11 AM
Rhandwor – Actually I had one wire end stay on the spark plug so I re-crimped it with needle nose pliers. I checked ohms and I was getting 5 but I can’t remember what scale I was on. I probably should have cut an inch off the wire like you do. After the compression test I went for a test ride and as usual it ran great for a few miles than terrible so I think the plug wire was OK after I fixed it.

Schurkey
02-12-2014, 07:28 PM
We already know the exhaust manifold should be replaced. This is a priority.

First Guess: You're going to need a REAL scan tool to track down any remaining problem(s) after the manifold has been taken care of.

What will take weeks to discover by replacing parts will show up on the scan tool in ten minutes.








It is not possible to create a proper spark plug end crimp with a needle-nose pliers.

rhandwor
02-12-2014, 08:18 PM
Its next to impossible to do a plug wire crimp with needle nose pliers.
http://www.ebay.com/ Search 370320134406 I have a couple of pair that look like this. They do both 7mm and 8mm plug wire. As suggested a good scan will help you find the problem. From past experience if your timing chain hasn't been replaced its ready for replacement at this time. Remember if you cut a short piece from the wire you have to skin off about 1/2 inch so the carbon core can be doubled over the wire under the terminal.

Thor1993
02-13-2014, 05:55 AM
Hi Guys,
What does this scan tool look like?? Is it a hand held unit I can purchase or is it an expensive tool only a shop would have? In the old days in high school auto shop class we used to put problem cars on a big old Sun Scope and look at the screen to find problems but I haven't seen one of those in decades at a shop. Remember this truck is a 1993. All I have been doing is using a paper clip to read codes and now all I get is 12 12 12 which means no problems that the ECM can tell me. I should tell you I also have a 98 Astro Cargo van with a 4.3L. At the moment it is running fine but I believe for a 98 there are hand held scanners that can tell you a lot. If a scanner is something a home hobby mechanic can afford I would like to buy one that would work for both trucks.

I will order a new Dorman manifold today or tommorrow. I would like a GM one but I will freeze to death at the junk yard now.

Thanks for all the guidance, it is really appreciated.

Greg

Schurkey
02-13-2014, 06:38 AM
Used, PROFESSIONAL GRADE scan tools are available used on eBay or craigslist for < $400.

I sold a Snap-On brand MT2500 scan tool with half-a-dozen vehicle adapters, cables, and cartridges good until the '99 model year for GM, Ford, Chrysler, and Jeep for $300 about a year ago.

The price goes up LOTS as the model-year coverage gets newer; but anything 1999 or older should be inexpensive.

Used "professional grade" is a thousand times better than new "consumer grade" scan tools.

This is the tool body, without the adapters and cartridges.
http://hbassociates.us/Snap_On_MT2500_01.jpg




P.S., I have an old Snap-On diagnostic oscilloscope in my home garage. Yes, you don't see them in shops too much any more. A shame, they were (are) wonderful tools.

rhandwor
02-13-2014, 06:39 AM
Hi Guys,
What does this scan tool look like?? Is it a hand held unit I can purchase or is it an expensive tool only a shop would have? In the old days in high school auto shop class we used to put problem cars on a big old Sun Scope and look at the screen to find problems but I haven't seen one of those in decades at a shop. Remember this truck is a 1993. All I have been doing is using a paper clip to read codes and now all I get is 12 12 12 which means no problems that the ECM can tell me. I should tell you I also have a 98 Astro Cargo van with a 4.3L. At the moment it is running fine but I believe for a 98 there are hand held scanners that can tell you a lot. If a scanner is something a home hobby mechanic can afford I would like to buy one that would work for both trucks.
http://www.ebay.com/ Search 3108684499230 This is the only one I aware that will work work for both vehicles.

I will order a new Dorman manifold today or tommorrow. I would like a GM one but I will freeze to death at the junk yard now.

Thanks for all the guidance, it is really appreciated.

Greg
http://www.ebay.com/ this is the only one I'm aware of that will work for both vehicles. Check ebay and amazon and compare prices. Search 310868499230
Good scanners are around $3000 to$4000. I have one like this and it will check 25 functions.
Some junk yards will pull the part.

rhandwor
02-13-2014, 10:36 AM
You didn't say you have changed your timing chain. With the timing mark highlighted and on the bottom half of the pulley. Use a 1/2 inch long ratchet and deep socket on the crankshaft bolt turn counterclockwise until the mark is at TDC or Zero. Pull the distributor cap and highlight the rotor and mark the distributor. Watch the rotor as you turn the crankshaft clockwise when it just starts to move stop look at the timing mark. If it moved over 30 degrees your chain needs replaced.
As you drive the computer starts hunting and the engine won't run properly.
Start spraying your manifold bolts with PB Blaster daily until you do the job. use a hammer and tap the top of the bolts daily also. You may have to use a 12mm socket if your 1/2 inch is to loose on the bolt. Be careful and don't break as they are hard to remove. Use new grade 8 bolts
as they can break when being torqued.

Schurkey
02-13-2014, 11:15 AM
You didn't say you have changed your timing chain. With the timing mark highlighted and on the bottom half of the pulley. Use a 1/2 inch long ratchet and deep socket on the crankshaft bolt turn counterclockwise until the mark is at TDC or Zero. Pull the distributor cap and highlight the rotor and mark the distributor. Watch the rotor as you turn the crankshaft clockwise when it just starts to move stop look at the timing mark. If it moved over 30 degrees your chain needs replaced.
If you turn the crankshaft clockwise as seen from the front (normal rotation) first, then mark rotor position and turn crankshaft counter-clockwise, you can use the timing pointer scale to determine degrees of rotation.

I'd have said that more than TEN degrees of slack indicates the need for timing set replacement. Thirty degrees...woof.


Start spraying your manifold bolts with PB Blaster daily until you do the job. use a hammer and tap the top of the bolts daily also. You may have to use a 12mm socket if your 1/2 inch is to loose on the bolt. Be careful and don't break as they are hard to remove. Use new grade 8 bolts
as they can break when being torqued.
I have every expectation that penetrating oil will not get to the male and female threads, which is where it might do some good. Wetting the bolt head every day for a month is going to accomplish nothing useful.

Obviously, a six-point socket is required. A 12-point socket is asking for trouble.

Replace the bolts with new, and install them with anti-seize on the threads and under the bolt-head.

Thor1993
02-13-2014, 11:19 AM
rhandwor - I bought the Truck in 2009 with 153K miles on it from 2nd owner; the first owner was his father in law. Unfortunately, I did not get any service records with the truck. I have not changed the timing chain. I would assume it is original chain.
I will do the test you mention for timing chain.
I am 80% sure I had this exhaust manifold off 3-4 years ago because the y pipe donut studs rusted off. If I am right I would have put neversieze on the bolts. But Yes I will start PB blaster soon and hit the head straight on to shock it. The truck has no A/C so manifold is fairly accessable.
I will be careful to not break a bolt, but sometimes that happens. This is why I am checking other things like doing compression test and vacuum test, and maybe taking off valve cover to check cam and valve train. If the head has to come off to fix a broken bolt I don’t want to have to take it apart a week later to do a valve job.
About Scan tool – I need to start saving for one of these!!!! My cargo van is 5 years newer than this truck and I will need it for that too.
Thanks for all the advice!!!
Greg

Thor1993
02-13-2014, 11:22 AM
Yes, the PB blaster will not get to threads in the head but it will help the Y pipe threads right?

Schurkey
02-13-2014, 11:27 AM
Yes, the PB blaster will not get to threads in the head but it will help the Y pipe threads right?
Perhaps. Since he's scrapping the broken manifold, I'd consider the Y-pipe studs sacrificial. Hit the nuts with a 1/2" impact wrench, and if the studs break...who cares?

Be sure to install new studs in the new manifold if it doesn't already come with studs installed, and USE BRASS NUTS not steel to hold the Y-pipe in place. I get the studs/brass nuts in a blister-pack at NAPA, but any parts store will have them. Brass nuts don't seize to the steel studs.

As an example:
http://www.napaonline.com/Catalog/CatalogItemDetail.aspx/Exhaust-Manifold-Stud/_/R-NDP6001817_0412977908
http://s7d9.scene7.com/is/image/GenuinePartsCompany/NWMDC?$Product=GenuinePartsCompany/1472022

Thor1993
02-13-2014, 12:22 PM
News Flash.....
New Dorman manifold is on order from AutoZone. It was $111 but I get a $25 gift card. It should be on my doorstep early next week.
And yes I totally agree, I will put brass nuts on the Y pipe. and never sieze on bolts.

rhandwor
02-13-2014, 02:33 PM
Its not the chain that stretches that much its the plastic coated gear GM uses aftermarket gears are steel. A two piece set works 95% of the time.
If you have cast iron heads a torch will heat the bolts cherry red and any bad ones normally will come out.

j cAT
02-13-2014, 06:33 PM
the compression looks ok so that it should run good... the plug wires need be checked for damage and the ohms should all read about the same ...I believe 5,000 ohms is the resistance area... if you find one too high or open then get new wires that will fit into the wire plastic clips...

junk yard should be able to pull a manifold off for you ...they are cheap to have these removed..

I just do not like the location of the crack... looks like the manifold rapidly cooled , and the bolts prevented the metal from contracting creating the crack..

on some old engines like this the bolt heads pop off with repeated heat/cool cycles.. cool air could be entering the compression chamber at the higher RPM creating these run issues..as well as the lean/O2 being distorted by the lean mixture with the leak..

rhandwor
02-14-2014, 06:03 AM
As you live where its cold a heater is a big help.
http://www.globalindustrial.com/ Search TT360DG

Thor1993
02-14-2014, 07:16 AM
rhandwor - Great Idea - I have seen those heaters before, they seem to work well but the local junk yard does not allow propane torchs into the yard so I am sure they would not allow this heater either. My pole barn has heat so when I get the new manifold I will be working in comfort.

Thor1993
02-16-2014, 02:33 PM
Hi Guys,
The new manifold is due here from FedEx Monday so I tore apart the truck. I didn’t get a chance to check the cam because I had to do a sump pump job Saturday instead. It turns out I was right I had this manifold off before; I could still see never-size on the bolts. After I got the old manifold off I cleaned the heads with a wire wheel in a die grinder, then I ran a tap in each hole. I was happy all good threads and no issues with holes.
http://i1193.photobucket.com/albums/aa359/gregthor/100_6622_zpscf1f5991.jpg (http://s1193.photobucket.com/user/gregthor/media/100_6622_zpscf1f5991.jpg.html)

Nothing unusual in the manifold except the inside is white and I usually see black carbon. Is this a sign the motor is running lean and or hot???
http://i1193.photobucket.com/albums/aa359/gregthor/100_6623_zps55306ff8.jpg (http://s1193.photobucket.com/user/gregthor/media/100_6623_zps55306ff8.jpg.html)

You can see the witness mark on the sheet metal heat risor is black carbon.
http://i1193.photobucket.com/albums/aa359/gregthor/100_6624_zpsbe48c3df.jpg (http://s1193.photobucket.com/user/gregthor/media/100_6624_zpsbe48c3df.jpg.html)
I picked up some new bolts at the hardware store. They are grade 8 flanged bolts. The original bolts were slightly longer. But I still have enough thread engagement into head.
http://i1193.photobucket.com/albums/aa359/gregthor/100_6625_zps6fb35c6b.jpg (http://s1193.photobucket.com/user/gregthor/media/100_6625_zps6fb35c6b.jpg.html)

Well hopefully the fedEx truck shows up with the right manifold and then I should have the truck on the road tomorrow.
Greg

rhandwor
02-16-2014, 05:51 PM
Your lucky you used antiseeze it made your job a lot easier.

Thor1993
05-05-2014, 12:05 PM
Hi Guys,
I am back!! I finally got back to working on my truck. I was occupied with other stuff ( a death in the family, my wife had 2 eye surgeries, and I need to look for a new job..). Things are finally settling down and now I am back to my truck.
Well I installed the new exhaust manifold and I have been driving the truck lately and I must report the winner who properly diagnosed the main problem is ……drum roll please….j cAT who said all along it was the cracked manifold!!!! I bow to the master…j cAT you were right!!!! The new manifold has the truck running almost perfect. Actually I made a mistake when I put the manifold in. It had an extra plug on the top side of the manifold and I forgot to tighten it!?!. Well the truck ran perfect for 3 miles until the plug fell out. Then I went home and found a plug to put in it. It is not the right plug so I have to keep tightening it. I need to go to junk yard and find a plug. Other than that the truck has been running almost perfect. It still runs better cold than hot and surges a little bit sometimes when I accelerate and seems to have a small miss. Very small but still annoying. I should check timing chain and I still want to do intake gaskets.
Well thanks everyone, especially j cAT I really appreciate you sharing your knowledge
Greg

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