potential engine death

[Bnjnz]

this might be what i am on the verge of. i posted some problems with acceleration and mpg. now looking arounf the engine i am finding oil coming out of somewhere. then in the carb housing there is a thin layer of oil in there as well. the oil pressure is down but the level is not to low. but it was a fair amount of oil in the carb housing(maybe 4oz or so.) what is wrong here? i am guessing the pump is going. should i look for anything before i jump the gun. thanks for any hepl
benjamin

1991 GW

[andy d]

dont junk the thing yet. oil in the air cleaner is condensed blow by. check the pcv make sure it rattles. the blow by is lost compression. the rig is 9 yrs old, figuring normal mileage it prolly has 120k+ on it. prolly got a few miles left in it. keep up on the fluids and dont try to break the fsj land speed record good luck.

[Bnjnz]

my rig has a remanufactured engine. about 15,000 miles on it. the compression was running a good 30 psi at normal driving speed. then after a trip the oil pressure went to 20 psi. it starts off at 40 psi then when i run to 40 mph it goes to 20 psi. it never used to do this. i will check the pcv system and see what the problem is first chance i get. i will keep you posted. thanks

1991 GW
benjamin

[nograin]

H'mm,
I'm only a shade tree mechanic, but I never hear of oil pumps going like that. They break, or they run. They are pretty simple devices. Sometimes the releif valves hang up, but that does not sound like what is going on.

If you are spraying oil around the engine while it is running, you've got an external leak in a pressurized part of the system. Most likely the oil filter, or the oil pressure sending unit. Not too many other places it can get out under pressure.

If you have excess internal leakage, it could be in the bearings. That is serious, or the heads, or head gasket. Also serious, but less labor to fix.

Your oil pressure should go up with enginer rpm. Unless one the low reading you gave was when the oil was much warmer than the high reading, you've got a leak in the pressure side of the system for sure.

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360 auto select
body by beer (PO)
carries wood inside
no "wood" outside

[reddog]

Check the PVC valve first. It connects to the base of the carb on the drivers side rear. With the engine running it should suck serious vacuum. After you ensure that the PVC is working good then clean up the oil on the motor and find out if it is coming from a faulty PVC system or somewhere else. With only 15K on a GOOD rebuild you should have better oil pressure. 30 lbs of oil pressure is ok but with a new motor is should really be higher. DON'T cook your new engine with bad oil pressure. Was the timing cover replaced with a new one when the engine was rebuilt?? The design of the AMC oiling system is very dependant on the timing cover which is also the housing for the oil pump. It has happened many times that somebody rebuilds a motor and does not check the oil pump "body" (housing) and a rebuilt oil pump (which is only the pump gears and the relief spring) will not fix a bad housing. Also the clearances when you setup the oil pump are critical. I don't know if this is what is happening with your situation but it is something to be aware of. Do a search on this site about "timing covers" or "oil pressure" and you should find some of the info on this subject. There are also some other AMC sites with some good info on oil pumps.

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87 GW - Stock (but it looks like RiverBeast when I'm sleeping)
TFI upgrade
360,727,NP229