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low oil press, valve tap '99 4X4


NINFan
07-09-2007, 06:00 AM
Hi-

Need some advice. My son has a '99 4X4 that we bought used and later learned that the first owner didn't really take very good care of it. A while ago, he asked me "dad, what does it mean when the 'check gauges' light comes on?" :banghead: Turns out the oil press was low. I checked the sender, and it's fine. Now it's developed a valve tap. I naively bought an oil pan gasket, thinking I'd just replace the oil pump. Got under the car and realized it's not so simple on a 4X4. So I figure I've got 3 choices:

1)Do nothing and let it die a slow, painful death.
2)Adjust the valves and hope that takes care of the valve tap, just drive it with low oil press until it dies a slow, painful death.
3)Bite the bullet, pull the tranny and transfer case, replace the oil pump and let it live a long, happy life.

Option 1 is really not great.
For 2, I dug around a bit on the web and it seems that everyone is talking about adjusting lash with a feeler gauge. Back in the day, we used to adjust the valves with the engine running, valve covers off, just back off the nut on each rocker one by one until it taps, then turn it back down until it just stops tapping. Does that not work anymore? (I was a mechanic for a while, but haven't done major engine work in many years, so I'm a bit out of touch.) Also, I once made the mistake of starting the car with the air cleaner disconnected and had to take it to a shop to get rid of the dash light. How can I avoid that?

For 3, again, back in the day, in similar situations we had been known to fill the oil pan with solvent (like safe t kleen) and crank the engine (with the coil wire disconnected so it wouldn't start) and run that stuff through the pump and engine, then fill it with new oil, run it a while, change the oil again and it would clean out all the sludge that was in the screen of the pickup on the pump, which is what I suspect is happening here. Used to work like a charm, but I'm not sure I want to try that again. So if I don't do that, how bad is it to get to the oil pump? Can I get the transfer case and tranny out of the way enough to do it with the car on the floor? (I've got jack stands and a floor jack.)

Thanks in advance for your advice.
btw, I searched the forums and couldn't find a similar thread, so sorry if this has already been answered elsewhere.

MT-2500
07-09-2007, 10:00 AM
If your oil pressure is reading low on gauge you need to get a manual test oil pressure gauge on it and check actual oil pressure.
Are you using good clean oil and the AC Delco filters?
How many miles on it and has it had regular service?
Is the engine sludged up inside?
I would not use any engine cleaners or additives in it.
If you oil pressure is up to specs. with a manual test gauge pull the valve cover and have a look at the rocker arms and push rods and valve springs.


Most of your valves are not adjustable on the newer engines.
Post back what you find and the oil pressure readings.
MT

NINFan
07-09-2007, 02:39 PM
thanks for the quick reply.
If your oil pressure is reading low on gauge you need to get a manual test oil pressure gauge on it and check actual oil pressure.
had it checked at the dealer:
4psi @ 1K rpm spec is 6
11 @ 2K spec is 18
34 @ 4K spec is 24 (i suspect that's an error)

Are you using good clean oil and the AC Delco filters?
castrol, fram filters
How many miles on it and has it had regular service?120K. regular service since we've had it (~1.5 yr), but as i said above, the kid who had it before (from new) and racked up all the miles didn't do that much.
Is the engine sludged up inside?
with that many miles and the sketchy prior service history, i have to assume it is. haven't been inside it yet.
I would not use any engine cleaners or additives in it.
If you oil pressure is up to specs. with a manual test gauge pull the valve cover and have a look at the rocker arms and push rods and valve springs.


Most of your valves are not adjustable on the newer engines.
Post back what you find and the oil pressure readings.
MT
wait - you mean not adjustable while the engine is running, right?

MT-2500
07-09-2007, 06:46 PM
thanks for the quick reply.

had it checked at the dealer:
4psi @ 1K rpm spec is 6
11 @ 2K spec is 18
34 @ 4K spec is 24 (i suspect that's an error)


castrol, fram filters
120K. regular service since we've had it (~1.5 yr), but as i said above, the kid who had it before (from new) and racked up all the miles didn't do that much.

with that many miles and the sketchy prior service history, i have to assume it is. haven't been inside it yet.

[COLOR=black]wait - you mean not adjustable while the engine is running, right?


My repair info shows the 4.3 engine does not have adjustable valves.
But double check repair manual and have a look at them.
If the rocker arm nuts are screwed down tight/ or torqued down they are not adjustable.

But I would pull both valve covers and check push rods and rocker arms for being lose or bent or bad.
Also some have screw in rocker studs that sometimes back out.
And or press in studs that will some times come up or lose.
Also make sure the cam lobes are not worn off.
Make sure cam lobes are opening all valves good.
MT

Oil pressure is not good.

There is a 50-50 chance oil pump will help it.
Also a Fram filter is not good for good oil pressure.
Fram filters have gave GM engines oil pressure problems for 50 years
Use AC Delco oil filters.

To get the oil pan off most of them the front rear end has to be dropped or removed.
Good luck and let us know how it goes.
MT

NINFan
07-09-2007, 10:32 PM
roger. thanks for the info. also, i searched the forums a bit more and found a thread about 2 bypass valves in the housing for the oil filter adapter. could that be it?

MT-2500
07-09-2007, 11:28 PM
roger. thanks for the info. also, i searched the forums a bit more and found a thread about 2 bypass valves in the housing for the oil filter adapter. could that be it?

There is one I know of that could be stuck.
It is a pressure release valve in oil pump body.
Also oil pump screem may be plugged.
But if you get to the oil pump I would have a look at rods and mains to.
Good Luck.
And let us know how it goes.
MT

blazes9395
07-10-2007, 12:19 AM
For this, I'd open up the bottom, change the oil pump to a high volume pump for sure, check the bearings while your there (like MT mentioned), and go from there. Running it low pressure will destroy it, so if you want to give it a fighting chance, pull the pan and see what it looks like in there.

As for valve lash, these engines have zero lash, so you just tighten the rockers arms down to the specified torque and that it - no lash adjustment.

Is it knocking/ making any other noise while its running? When you realised it was having pressure problems, did it just happen right away? Did you change oil brands? Fram, like MT mentioned too, doesn't have the best filters on the market, in fact they are poor quality, so that would be another thing to think about too.

I had a similar problem with my monte carlo having low oil pressure last winter. Turned out the oil pressure relief valve on the oil pump was stuck open, so at hot idle it would have low pressure. I changed the pump, and that was it.

NINFan
07-10-2007, 04:20 PM
Is it knocking/ making any other noise while its running? When you realised it was having pressure problems, did it just happen right away? Did you change oil brands? Fram, like MT mentioned too, doesn't have the best filters on the market, in fact they are poor quality, so that would be another thing to think about too.

no knock. just the valve tap. i don't really know how suddenly it happened cuz i don't drive the car. when i found out about it my son said the dash light had been on 'for a while.' no idea if there was a slow pressure drop or if it just started one day.
i started it on castrol when we got it. no clue what was in it before that.
so who makes the best filters?

thanks for all the great advice, folks.
btw, what about the air cleaner thing. is there a way to run the engine with the air cleaner off w/o tripping the check engine light?

NINFan
07-10-2007, 10:26 PM
so i got under the car again tonight - looks like i can do it, but it's a ton of work. need to take the front driveshaft out, the transfer case and the tie rod. but i think the pan will come off i can just undo the bottom bolts on the tranny - don't need to drop the tranny. looks like there are 3 bolts holding the transfer case to the frame. do you need to take the drive shafts out (remove the rotors) or will the whole thing just drop out? also, i now notice that the seals on the transfer case are leaking, so i'm assuming i should be able to just pop new ones in while i'm in there. anything to watch out for there?

muddog321
07-11-2007, 06:12 AM
I sure hope you have pressure tested the cooling system before doing the oil pump on this as the #1 cause of lifter tap is a leaking lower intake gasket that sprays a fine mist into the valley and presto startup lifter tap - you never see any water/Dex in the oil. As for low oil pressure go with a as stated - new filter and check the remote oil cooler lines for leaks at the crimps as they all do and if a major blow out they dump oil out.

NINFan
07-11-2007, 11:42 PM
got started tonight. i was gonna post some pics, but my wife has the cam.
1) there's a cable that goes into a plastic housing on the transfer case. can't get that off without breaking the plastic housing. ideas?
2) what's the easiest way to get the front axles out so i can drop the transfer case? do i need to break the steering knuckle at the upper ball joint?
3) i can get the nut and bolt out that holds the top of the transfer case onto the frame (it's the one where you have to put a wrench inside the frame). i'm worried about getting that nut back on. there must be a trick.

thanks.

blazes9395
07-12-2007, 12:09 AM
1)The cable your referring to (I am pretty sure) is the differential shift cable. Remove the bolt that holds the cable on the differential and the cable can be taken off. Also don't forget to pull the vent tube down and out, so removal of the front diff can be done.

2)You do have to in fact separate the ball joint and pull the axles off and right out. To remove the differential, you also have to separate the pitman arm off the steering box, and disconnect the idler arm from he truck, as this will give you enough space to pull the differential down and out.

3)Not really any trick, if you can get it off, then you'll eventually get it back on. What I usually do is put the nut on the wrench, and slowly slide it to the hole inside the frame and then I slide the bolt in.

The differential can be tricky to get out, as its tight in that area, but it eventually comes out. This is also a VERY good time to replace the oil lines that run from the block to the oil filter adapter. Also another good thing to replace are the gaskets on the oil line to block adapter(where the oil lines bolt into).

As for which oil filter I perfer, NAPA brand filters, made by WIX are very good filters. Frams are just poorly constructed filters, about the worst out there in my opinion. Also, I would honestly go with a high volume pump in this case too, this way your assured you'll get oil right to the top, even if your clearences are a little big.

Good Luck!

NINFan
07-12-2007, 12:52 PM
^^
sorry, i was saying trans case and meant front diff. ya, i figured i just need to take that bolt off, but it's really on there. i'm afraid i'm gonna break the plastic housing if i keep twisting. i sprayed some wd40 on it last night,so hopefully that will help, but it's not like i can put heat on it cuz of the plastic housing.
thanks for the tip about taking the steering assembly out that way - much easier than breaking the connections at the tie rod ends.

NINFan
07-12-2007, 10:39 PM
the saga continues...
this is turning out to be a lot bigger job than i thought!
so i undid the ball joints (turns out it needs brakes, too) but still don't know how to get the axles off. i'm guessing you have to take the boots off, but don't want to break the metal clamps off if there's another way. please tell me i don't have to take off the rotor, cuz i don't have a deep socket big enough to get that big ass nut off. who knows what size it is?

edit:
oh yeah, and i got the fitting off the plastic housing, but it doesn't spin around the cable. must be frozen. anyway, ultimately managed to get it out, but the cable itself won't come out. do you need to take the 3 bolts off that hold the actual housing onto the diff? won't the gear lube leak out?

ericn1300
07-12-2007, 11:08 PM
oil pan removal: 199899 4 Wheel Drive Models from: http://www.autozone.com/az/cds/en_us/0900823d/80/18/b2/c3/0900823d8018b2c3/repairInfoPages.htm



Remove the battery and battery tray.

Disconnect the shift cable at the actuator.

Raise the vehicle and support it with safety stands.

Remove the splash shields from the steering linkage and the oil pan.

Drain the engine oil and remove the starter motor.

Remove the oil cooler pipes.

Remove the front wheels.

Unplug the electrical connector at the shift cable housing.

Remove the wiring harness bracket from the shift cable housing.

Unfasten the shift cable housing bolts and disconnect the shift cable from the differential carrier.

Remove both drive axles and the differential.

Unfasten the oil pan retainers, then lower the oil pan and gasket from the vehicle.

muddog321
07-13-2007, 05:46 AM
Hub nut is 36mm and to get 99up CV axles off/out of the center diff they have an internal snap ring so you hit the inner CV metal can with a block wood and hammer as you gently use a pry bar to apply outward pressure to the CV between it and the diff (otherwise the snap ring won't unclip) then the CV axle comes right out after you pulled the hubs and knuckles!

NINFan
07-13-2007, 09:28 AM
you hit the inner CV metal can with a block wood and hammer

from the wheel side or the diff side? i'm guessing wheel side, since there's really no room to get a block of wood in there from the diff side.
are there needle bearings inside the spider or anywhere else inside the boot? when i dropped the steering knuckle, the axle pulled outward quite a bit and i thought i heard something drop.:frown:

muddog321
07-14-2007, 05:37 AM
Diff side - you are trying to remove that CV and at 45 degrees there is room. Look up a pic of a CV and it is a 4 + design inside with caps on each end that ride in the metal can.

NINFan
07-17-2007, 04:36 AM
now that i have things half taken apart, i discovered 2 things:
1) as i was taking out the rt axle, i found really heavy grease on the brake caliper. turns out two of the ribs on the boot are split.
2) i went to put the oil that i had drained out and was sitting in the pan into a jug to recycle it. it had been in the pan for a few days, so enough time for things to settle. there was about 50 lbs of metal in the pan.

now i don't know whether i should just put things back together and get rid of it or continue. the car's not really worth more than $1K at most, so i don't really feel like putting mains or any other serious engine components in it. yuck.

thanks for all the guidance, though. couldn't have done it without your help.

NINFan
08-13-2007, 10:58 PM
i decided to go ahead and repair the thing. so i ended up doing

main bearings
rod bearings
oil pump
front timing cover
pitman arm
boot kit on rt front axle
serpentine belt
lower ball joints
brake pads

fired it up tonight and had 60# pressure. i'll post all the lessons learned when it's all done.

blazes9395
08-13-2007, 11:16 PM
you did the bearing job/lower end while the engine was in the truck? If you did, post on here what/how you did it....that must have been some serious back braking work. Don't forget to change your oil and filter at a couple hundred miles or so. Hopefully all goes well!

NINFan
08-13-2007, 11:22 PM
^^
i did. i'll post pics if i can. put the car up on jack stands behind the front wheels (on the frame under the front door posts). gave me plenty of room to work under there.

NINFan
10-07-2007, 11:03 AM
Just realized I never put the whole story on here.

So yeah, you need to get the car up on jack stands. I put them on the frame rails just at the front door posts. Remove the wheels, steering knuckle, (break the ball joints, strap up the calipers, etc. The nut on the hub is 36mm). Remove the front drive shaft and mark the u-joints to go back where they were. Remove the front axles - that wasn't as bad as I thought. Just bang on the cans and when the internal snap ring lets loose, youíll see them starting to move out of the front diff. Then you can just yank them out from the outboard sides. You need to drop the entire steering linkage. Donít bother trying to work around it Ė itís easier to just drop the whole thing (leave the tie rod ends on and you can just wiggle the whole thing down) and put it back later. At that point, there are only 3 bolts on the front diff. take them out (leave the top one in for last) and you can get that last bolt out and the bushings will hold it in place until you can wiggle it out. Itís kinda heavy, so be careful. Also be careful because itís full of gear lube (I drained it first cuz I knew I was gonna replace it, but I guess you donít need to if the car is lo miles). Oh, you need to take the shift cable out first. That was kinda a pain cuz thereís a metal collar nut on a plastic housing and itís easy to crack. I ended up taking the whole assembly off, which is probably better in the end. You can unbolt the 3 bolts that hold the plate against the diff and pull the whole thing back (itís on a spring) and work a needle nose in there and pull the Jesus clip out. Reverse to install, but you need to snap the cable end back into the actuator (easy). Also, thereís a vent tube on the top of the front diff thatís a pain to get to. Anyway, with all that out of the way, you can finally get to the oil pan. You need to remove the oil filter adapter first (replace the o-ring and gasket when you re-install) and I just pushed them out of the way. BTW, make sure you have pans all over, cuz everything will be leaking (Iím assuming youíve already drained the pan :rolleyes: ). Now pull the two rubber plugs out that are in the holes between the bell housing and the back of the pan. There are 2 pan bolts up in there (that one took me a while to figure out :loser: ). Youíre home free. Drop the pan, replace the pump (get a new plastic collar that keeps the 2 shafts together), any other inspections, and put everything back. Getting the front diff back in was a treat. You really need to work the top bushing back into itís fitting, and thatís tough. I had the neighbor help, but it took a lot of grunting and groaning. Donít start without re-connecting all the electrical connections or youíll get the annoying ďcheck gaugesĒ light. (you can eliminate it by disconnecting the battery for a while. I think about 5 mins does it.)

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