Valve Burning - any way to know before disaster strikes?

[Woodie83]

The upshift light is controlled by the PCM and includes a few different calculations. It's along the same lines as a vacuum gauge, but it figures throttle opening, rpm, vehicle speed, and load percentage, then goes to a lookup table to determine if you should be in a higher gear. If you can keep it from ever coming on, you'll get better mileage. Hint: lots of right pedal with low rpm, when in doubt, upshift.

[91Caprice9c1]

Originally Posted by DOCTORBILL

"Many guys actually do this - and it's cool to watch the gauge react to throttle position.
This is a good way to monitor for a leak.
You only need one direct, unimpeded source of "manifold" vacuum - its the same
no matter where you get it from.

Are you positive about that?
I thought I saw a difference...

I am ABSOLUTELY positive about that. The key words here Doc are DIRECT and UNIMPEDED. I do not know which barbs have what opstacles but a very good place to get an accurate manifold vacuum reading (and where I always get mine) is from the brake booster hose. Be sure to avoid any check valves inline to the booster that are sometimes used for backfire protection.

Originally Posted by DOCTORBILL

My "green arrow" lights up a lot when I stay in 4th going up hills. That is showing
that I am pulling a strong vacuum - isn't it?

Wood gave a very good explaination of the shift light.

Going up hills you actually have very little vacuum. Way back in the day, when accessories such as wind shield wiper motors were run with vacuum - they'd crap out going up hills, and break speed records descending the other side. Vacuum is created by the closed throttle resisting the intake stroke's breath for air - so it is highest when decelerating with the throttle closed, and loweset with the throttle open. BTW when looking for a source for accurate vacuum - if your reading drops to 0 when the throttle is wide open, you've probably got a good source.


-MechanicMatt

[DOCTORBILL]

The Phoenix is a '93 three cylinder one liter 5 speed manual transmission.

I don't believe that I have any vacuum assisted brake boost...

If I do, where do I look for this?

Been all thru that engine compartment doing the rebuild, cruise control, wiring, etc.
and I don't remember any hoses going to anything on the brakes.

If I am wrong, please educate me.

I have a disassembled TB and Intake Manifold in front of me now and I do see
that the front two barbs on the TB connect with the main large chamber in the Intake manifold
as does the rear barb that goes to the MAP Sensor.

I hate to go back and reconnect hoses to front then the back and drive with each
to see if they read the same, but I was sure I got different vacuum characteristics
from each.

That is why I connected BOTH hoses to my Cruise Control Vacuum Canister via two barbs,
each with a one way vacuum valve to keep the different vacuum levels separated.
Didn't want to confuse the MAP Sensor data to the ECM.

The front gave 26 PSI at deceleration while the back barb gave less and at different times.... (????)

Otherwise one could connect all three barbs together with vacuum hoses via
"T" connectors. They are hosed separately on my system - front versus back.

Front goes to the EGR system and Idle controller while the back goes to the MAP and that strange air bleeder valve.
The back side has an air bleed controlled by the engine temp also - wouldn't
that affect the vacuum at the back?

I'm not trying to be provocative - just need clarification.

This is a rather complex multi-valve interacting "system" controlled by temp, the EGR, the throttle, engine vacuum, etc....
and I am trying to visualize how it interacts at different times.

Is there a simple diagram such as a view of the TB - Intake Manifold cutaway
side view available somewhere? Like slicing the two down thru the middle lengthwise showing it from the side...?

DoctorBill

[91Caprice9c1]

Originally Posted by DOCTORBILL

The Phoenix is a '93 three cylinder one liter 5 speed manual transmission.

I don't believe that I have any vacuum assisted brake boost...

If I do, where do I look for this?

You do have vacuum assisted power brakes. The black drum that the master cylinder is bolted to is the "brake booster." It will have a relatively large vacuum hose attached to it. If you follow this hose, through some hard pipe (across the firewall) and to another hose, it will lead you to the intake manifold. T-off your gauge from this hose, as close to the manifold as possible and this will give you the most accurate vacuum reading you can get.

Originally Posted by DOCTORBILL

Otherwise one could connect all three barbs together with vacuum hoses via
"T" connectors. They are hosed separately on my system - front versus back.

Front goes to the EGR system and Idle controller while the back goes to the MAP and that strange air bleeder valve.
The back side has an air bleed controlled by the engine temp also - wouldn't
that affect the vacuum at the back?

I'm not trying to be provocative - just need clarification.

Snap a picture of your air bleeder valve if you can - I can't visualise what you are talking about off the top of my head. I'll study some throttle bodies and intake manifolds at work tomorrow and take some vacuum readings from various points to see if I get the same results and see if I can't offer some explaination for your difference in vacuum readings. No provocation taken =)

Originally Posted by DOCTORBILL

Is there a simple diagram such as a view of the TB - Intake Manifold cutaway
side view available somewhere? Like slicing the two down thru the middle lengthwise showing it from the side...?

Not that I am aware of. Although, I haven't looked.

-MechanicMatt

[Woodie83]

Trust me, you don't want a car with disk brakes without power assist. You can get away with it on drums, but it takes a ton of pressure to make disks work. Incidently, that hose going to the vacuum assist servo is prone to carbon fouling just like the EGR system. That's what did in my first Metro. The brakes work fine until you get in a stop and go situation where you hit the brakes multiple times in quick succession. Third or fourth time, you've got a brick beneath the pedal, the car just doesn't stop.

[Hugemoth]

Doctorbill,

Maybe the 3 cyl throttle body is different but the 4 cyl throttle body has a 1/4" vacuum port near the idle speed screw. It was just capped off with a rubber cap. That's the one I used to power the cruise control.

Q

[DOCTORBILL]

I will take some photos of my brake system and the hoses as they are in The Phoenix now.

BUT - am up to my neck in 56 students right now teaching two Chemistry courses with three labs sections,
so the pics etc will be a couple of days from now....

Thanks for the help folks!

I'll be baaaaack.....and get this sorted out.

DoctorBill

[pittbulljoe]

will a exhaust leak at the head burn exhaust valves?

[Twinkiedelight]

Hi my name is sondra. I currently was given a 94 geo metro 3 cyclnder. It was given to me because the lady that owened it blew it up over a divorce. I put a new engine it from a junk yard that sworn that it ran fine. It was put in three weeks ago and a week and a half ago i had a compression test done by muffler man and they said first cyclnder has 40 pds compression in and said i had a bad ring. But I don't have any blue smoke coming out of the tail pip and it was burning any oil. till today when it started to knock and i stopped at auto zone and found that there was no oil in it at all. what causes that can anyone help me. I was told these engines can't be rebuilt. CAn you or not?

[Twinkiedelight]

I'm not used to these engines. All I'm asking is for a little help please.

[DOCTORBILL]

First - the Metro's 3 cylinder engine is EASY to rebuild !

Whoever told that they are not rebuildable is a moron!

Second - if you had that low a cylinder pressure, the valve is burned.
Head job $250 and you can take it off and put it back on yourself.

Third - if you ran it w/o oil - ugh! Bad leak? Got to attend to THAT
immediately! Where is it going. Check it every day until you are
confident it doesn't leak out anymore!!!!!!

Fourth - being a woman...be very careful of what mechanics tell you!
Find one you can trust (hard to do - ask around) - a lot of buttholes out there
who try to con women. I know - they do it to my wife all the time!

Not nice to say, but unfortunately - it is true!


Do you know anything about auto's? Mechanical stuff? Sorry - not trying to be sexist....

If you have the patience to read thru all the stuff I wrote and see all the
photo's - have a look at how I rebuilt my '93 3 cyl Geo Metro...

I did a lot of stuff you may not have to do....but look at what I put in here.

Anyone out there reading this - give the lady some help!

First Page of ..................."That's the end of my '93 Metro....."
http://www.automotiveforums.com/vbul...d.php?t=611713

First Page of..................."NOT the end of my '93 metro...Life after death! RINGS"
http://www.automotiveforums.com/vbulletin/t613410.html

First Page of ..............."The Flight of the PHOENIX !"
http://www.automotiveforums.com/vbul...d.php?t=645309

First Page of ..............”A way to Clean the Carbon out of the IM Passageways !”
http://www.automotiveforums.com/vbulletin/t622536.html

You may very well have totally different problems than I had with my '93 Metro
3 cylinder - but then again maybe the same!

This little car is a breeze to fix.

And mine gets 49 mpg in the summer!

If I did it, a monkey with five fingers could do it!

DoctorBill

[idmetro]

Twinkie - start a new thread with the issues your car has, include year, mileage, engine, trans and anything else pertaining to its current condition. I think you'll be pleasantly surprised with the helpful responses you'll get.