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trouble shooting oil leak.

V

vortex

NAXJA Forum User
Location
Chehalis, Wa
Some background info...'89 4.0 auto 178,000 on the clock...wheel it lots but only ran it really hard once....

oil is dripping off the bellhousing and tranny cover....cannot find anything to save my life...

Things i HAVE replaced:

Oil filter adapter O-rings (all 3)

Valve Cover Gasket

Things NOT replaced:

Rear Main

Oil pan gasket


ALSO since in talking about oil...My oil pressure guage is always bouncing around....the harder i accelerate the higher it goes when i let off it reads about 20....at randome times it spikes to a right angle and points to the right and sits perfectly level but then will randomly settle back around 45ish. Also the longer i go with this oil leak the LOWER my Oil Pressure Becomes.

Any ideas on what is going on here?

thanks'
-PJ-
 
Last edited:
I actually could be the valve cover loose. The back bolt is hard to reach, but when any are loose, oil runs down and into the bellhousing. Looks just like a rear main seal leak.

Tighten up everything, including the pan bolts, make sure the blowby from the valve cover isn't running down the back, then you can pinpoint the leak. You can dust the engine with talcum powder to spot check.

Don't jump into a rear main seal until you're sure - and at that point, you can use the '96 up silicone rubber gasket.
 
Things left to check at this point are oil pressure sending unit which is attached into the oil filter adapter, and the rear main seal. Both will cause oil to spray all the way back to the crossmember if leaking and driving at speed ( I know from experience). Easy way to check is take a rag and wipe down the oil pressure sending unit so it's clean and dry, then drive it for a day and check to see if there's any oil anywhere on it. If not then it's prolly the RMS which will also get the pan gasket replaced taking care of both of those possibilities.
 
I am betting on the RMS!!!
 
I very well could be the rear main, or pan gasket. Oil blowby will work its way back and down the bellhousing - it's taken me two years to burn the last of the oil off the exhaust under there.

Excessive crankcase pressure at higher rpms will force oil out seals, but in any case, clean the engine, dust it down, find all the sources, fix'em. I've done them all, it's unnaturally leak free for a Jeep.
 
So tonight i was coming back from the grocery store my oils pressure gauge pegged out on top of the little face plate screw...Which would probably read 120 psi....so now i am up in arms on what to do....being a student and having no source of incom i cant afford to do much...I am thinking about replacing the Oil Pressure Sending Unit...but thats just my opinion...

any help would be appriciated...

-PJ-
 
Sounds just like mine. Replaced the rear main seal and oil pan gasket and wala no more oil leak.
 
Yes-- IIRC- grounding the wire that's supposed to be attached to the sending unit will reduce resistance (to nothing) and cause gauge to read beyond it's intended limit-- pegged high. The unit or the wire could be grounding and causing the problem- as the sending units are known to fail often, I'd probably change it and inspect the wire as preventative maint. and repair all in one.
 
Shorty said:
Yes-- IIRC- grounding the wire that's supposed to be attached to the sending unit will reduce resistance (to nothing) and cause gauge to read beyond it's intended limit-- pegged high. The unit or the wire could be grounding and causing the problem- as the sending units are known to fail often, I'd probably change it and inspect the wire as preventative maint. and repair all in one.
Click to expand...


Sweet so should i just buy a new one or pull it at the junk yard?

-PJ-

-PS is this the same thing as the oil pressure sensor?

http://www.partsamerica.com/ProductDetail.aspx?MfrCode=BOR&MfrPartNumber=S4185&PartType=417&PTSet=A
 
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