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very high oil pressure out of no where (i searched)

D

DurbElites

NAXJA Forum User
Location
Simi Valley
95 xj 4.0 184000 on the clock. replaced the sending unit about ten times now because oil leaks through the unit to the connections about 5 mins after running, finally got one that works and my oil pressure has been creaping up to around 35-40 at idle over the last month from 20, now it jumped to 60 at idle and all through the rev range. sea foamed the motor and it dropped back down to about 40 at idle. any ideas as to what the problem might be?? i read something about a regulator in the oil pump that can get stuck? potential of being the problem????
 
mecompco said:
Have you tested the pressure with a mechanical gauge? I think I would do that prior to spending time and money investigating other possibilities.
Click to expand...

X2 I've seen a bunch of senders that were way off. The one in my 88 right now is 20 PSI low. In my 96 20 PSI high (sometimes).
Electrical conductivity also plays a roll, in some years the more resistance in the wiring the higher the oil pressure reading. Clean off the connector (both sides) at the sender with a good solvent and make sure it isn't oil coated.
I had an 88 with a partial blockage in the oil passage, between the crank and the cam. It eventually cleared itself, but it had me sweating for awhile as I contemplated all that work for for a BB sized glob of junk.
Possible the Bypass (or regulator) in the pump is acting up, mine was covered in solvent proof varnish (soaking in acetone didn't loosen this stuff) the last time I had the pump out. Though to tell you the truth I've never had one stick.
 
i rebuilt the oil pump and changed the sender cleaned the hell out of the connector and still sits at 60 on idle and now it goes clear to 80 when i hit the skinny pedal at all! im stressed as hell its my dd and no more money to fix it if something major happens help!!!!!!!!!!!!!!
 
Get ready to install your 11th oil pressure sending unit. It really is most suspect here. Where have you been purchasing your sending units from? I would recommend buying it directly from Jeep for best reliability/accuracy/mating with your factory gauge.

As mentioned, you can always hook up a mechanical gauge to confirm if you're ambition and want to know for sure....
 
bought mech gauge going to try and my xj died sputtered at idle and now its dead and wont start run anything fuel pressure is ok, i have spark to cylinders what could that be??? cps?
 
not to steal your thread but while we're on th subject, does anybody have a FSM to look up what they say the oil pressure is supposed to read. If i recall correctlly I think it said 75 psi at 1500 rpm and above for a '99. Seems high, can anybody else look at theirs?
 
wacho4 said:
not to steal your thread but while we're on th subject, does anybody have a FSM to look up what they say the oil pressure is supposed to read. If i recall correctlly I think it said 75 psi at 1500 rpm and above for a '99. Seems high, can anybody else look at theirs?
Click to expand...

From the 2000 FSM:

13 psi is the minimum at 600 rpm
25-35 psi is normal at 800 rpm
37-75 psi is the normal range above 1600 rpm
Pressure relief valve opens at 75psi.

Same for both the 2.5 and 4.0 engines
 
My son just went through this with his '96. Two weeks ago, all of a sudden, it spiked off the scale. Got a new one, about 12 bucks at Advance, same deal. Bought one at the boneyard, all is well! I guess I'll add the sender to the short list of things I'll get cleaned-out for at the dealer.
 
get a mech guage from the part store ($20)...When i rebuilt my engine i put a high volume pump in my and at idle it would hold 50psi and and 60psi when its cold both at idel, so if your seeing that from a stock point...the more mech guages the better!
 
Sherman_thetank said:
get a mech guage from the part store ($20)...When i rebuilt my engine i put a high volume pump in my and at idle it would hold 50psi and and 60psi when its cold both at idel, so if your seeing that from a stock point...the more mech guages the better!
Click to expand...

Who makes a high volume pump for the 4.0? Was just thinking about that the other day.
 
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