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Discussion Starter · #1 ·
Ok, So I've searched some of the forums here and am unable to find an exact answer to my problem. I realize on this first post I'm probably not going to provide enough information, but I'm going to throw this out there anyway.

I am driving a 1990 Jeep wrangler with 4 cylinder, 2.5L engine. I have noticed that I see my oil pressure spiking well above the 80 Psi that my gauge shows. It looks like it only does this when the engine reaches over 22-23,000 RPMS. At and above these rpms I can keep the oil pressure down by placing constant pressure on the gas pedal, and it goes down a bit. If I let off the gas pedal the pressure spikes well beyond what my gauge can handle. Any thoughts, advice, or tips on this would be appreciated. If anyone nees more info, let me know. Thanks in advance for any help.
 

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Welcome, and glad to see you posting here. My OP has always run high ( to me) on my 258 at 80+ lbs cold. I know that doesn't help you much, but wanted to say a "hi"..........
And.......
check your RPM figures before someone rips on you. /ubbthreads/images/graemlins/shocked.gif
 

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[ QUOTE ]

check your RPM figures before someone rips on you. /ubbthreads/images/graemlins/shocked.gif

[/ QUOTE ]

WHATS WRONG?? YOU DON'T RUN YOUR ENGINE AT 23000 rpm?
the guages suck.. hook up a mechanical guage and see what it says..
 

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The guage in my 88 YJ with the 4.2L does the same thing.
 

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[ QUOTE ]
[ QUOTE ]

check your RPM figures before someone rips on you. /ubbthreads/images/graemlins/shocked.gif

[/ QUOTE ]

WHATS WRONG?? YOU DON'T RUN YOUR ENGINE AT 23000 rpm?
the guages suck.. hook up a mechanical guage and see what it says..

[/ QUOTE ]

I was laughing at that RPM thing but it looks like a typo to me.

Don't know anything about those four bangers but the gauges do some funny things if there is a ground problem or sometimes even just a loose connection.

This looks like a hint to me:

[ QUOTE ]
At and above these rpms I can keep the oil pressure down by placing constant pressure on the gas pedal, and it goes down a bit. If I let off the gas pedal the pressure spikes well beyond what my gauge can handle.

[/ QUOTE ]

Would guess (and it's only a guess) that it's an electronic problem and not a motor problem. What do the other gauges do at that same point in time? Other strange things would be an indication of those silly electrons traveling places that they shouldn't be.

A mechanical oil pressure gauge is a good idea, it won't lie to you.

/ubbthreads/images/graemlins/40BEER.gif
Dale
 
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Discussion Starter · #6 ·
Ok, a couple things, first: Thanks to all for your responses.

Second: All my RPM numbers have an extra zero on them. I must have gotten zero happy (in other words, above 22-2300 RPMS).

There is no indication of any kind of electrical problem as no other gauges or electronics do anything funny at any point in time. They all give me fairly accurate (accurate meaning they are not off the wall) readings all the time.

There is certainly a problem, because until last week, when the pressure was getting high, the valve cover was leaking oil around the edges. Since then I have replaced the Gasket on the valve cover (the old one looking like it had never been replaced at all...it was solid as a rock and cracked all over the place).
Since I replaced it there are no oil leaks, but the pressure still goes way up. My real concern is not that the pressure is high, it's more, is the pressure high enough where it's going to negatively affect my engine??

Any more thoughts would be great. Thanks again to all who have already responded.
 

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[ QUOTE ]

Quote:
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..is the pressure high enough where it's going to negatively affect my engine??

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Huh??

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Actually that is a very valid question,,, If there is a blockage in the oil galley just after the sending unit part of the motor may not be getting lube.

BUT I doubt that as most all pumps have a psi relief or bypass at about 65PSI, so more than likely you are having a gage issue.
 

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[ QUOTE ]
[ QUOTE ]

Quote:
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..is the pressure high enough where it's going to negatively affect my engine??

--------------------------------------------------------------------------------

Huh??

[/ QUOTE ]

Actually that is a very valid question,,, If there is a blockage in the oil galley just after the sending unit part of the motor may not be getting lube.

BUT I doubt that as most all pumps have a psi relief or bypass at about 65PSI, so more than likely you are having a gage issue.

[/ QUOTE ]

True, but assuming there are no blockages or other malfunctions, would there be a point when high oil pressure would cause damage?
 

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The only time high oil might be a problem is: it might blow out o-rings or a gasket, or in a extreme case high pressure would increase the flow with the possibility of creating a cavitation point on a t-type oil passage junction.....as all other other's pointed out,,,get a mechanical guage and be sure.
 

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Some engines ARE very sensitive to high oil pressure. I read once that the Bristol engine used in many '50s British sports cars was that way. Until the oil was hot one had to keep the revs down and shift by the pressure gauge rather than the tach, or serious damage would result.

In the Jeep engine I could imagine excessive pressure in the main galley blowing out one or both crank seals. Don't know if that's a likely event or not.

In any case, a mechanical gauge is in order. You can get a cheapie and hook it up temporarily to see what's really going on.
 

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Probably the bigger risk with high oil pressure is the load on the cam gear to drive the pump.
 

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This may be stupid or not....

PCV?

You plugged up the leaks and the PCV is still plugged? The crankcase does need to be vented somewhere.

Just a thought...

But I'm still guessing the gauge and wiring.

When the crankcase needs to vent... it will blow a new leak.

Seems simple to run it with the oil fill (or something) open.

/ubbthreads/images/graemlins/40BEER.gif
Dale
 
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Discussion Starter · #14 ·
I had the same problem on my '88 YJ(a couple of times actually) and both times it turned out to be the oil pressure sending unit. Apparently these are these are prone to failure and they tend to read progressively higher as they fail. For such a piece of crap part the Jeep dealers sure are proud of them(about $35)! But for sure check with mechanical gauge before replacing. No problems since I swapped in the 4.O!
 

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You beat me to it...oil pressure sensor switch on these things are horrible. Should be mounted right by the oil filter, and usually gets bumped every time an oil change is done. The are known to crack and blow oil out of your motor and also for miss reading oil pressure as a whole. I start there check your connection maybe a little wd and some dielectic grease and see if the problem continues if it does replace the sensor...or check with a manual gauge.
John
 
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Discussion Starter · #16 ·
Thanks everyone for all the help. I'm definitely going to be checking the gauge. As far as the comment about it being pcv, I've already gone that avenue. Replaced some of the tubes and connecting valves. I did find a hose that was supposed to be connect to the Air intake that was just hanging, so that did help somewhat. At this point I'm going to take a look at the sending unit and go that avenue. It's not a horrible problem, as it's not affecting drving at all, but it's more an annoyance for me. Thanks again, and any additional comments/help are still appreciated. :)
 

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My '95 2.5l was doing the same a few years ago, soon as you got on the gas the oil pressure would peg. Replaced the sending unit and it took care of it. Good luck.
 
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