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-   -   low oil pressure after highway driving (http://www.wranglerforum.com/f282/low-oil-pressure-after-highway-driving-84119.html)

cgd13 03-10-2011 10:40 PM

low oil pressure after highway driving
 
Oil pressure gets really low after driving my Jeep at high speeds for a while. While on the highway it's right in the center of the gauge (40). When I get off the highway, it gets pretty low but not low enough to trigger 'Check Gauges' warning. However, if I shut it off after highway driving (ex: get gas) and then start it up, the pressure is extremely low and 'Check Gauges' comes on. It looks like it's going to go up for a few seconds but then falls back down. So I shut it off, wait about five minutes, fire it back up and it slowly creeps into normal range. Usually takes about 30 secs to get into normal range on the second go around. On about 2 or 3 occasions while driving around town, the pressure got up towards the upper spectrum of the gauge when stopped at a light but would then go back to the normal range when I started driving again. I change the oil about every 3k miles and the oil level has never been low. Any idea what might be causing this? I would guess the gauge is faulty, but wanted some other opinions. I never hear any odd sounds or anything like that. Thanks in advance.

Black98 03-11-2011 01:25 AM

I have noticed this same thing on my 98 4.0L with about 95k miles on it. After driving for a long time the oil pressure will lower to about 20-25 on idle. I really wish I also had an oil temp guage to verify if this directly scales with oil temp and not just engine temp. Im pretty sure this is a normal thing from the oil just thinning with heat but if anyone else would like to chime in it would be apreciated.

2broke2gofast 03-11-2011 07:57 AM

I've noticed this with my 2000 TJ as well. My pressure will actually drop to 9-10psi at idle after an interstate drive. I verified this with a manual gauge. I had originally suspected my 0331 head may be cracked causing coolant to get in the oil and causing rod, main, and cam bearing wear, but I do not seem to be loosing any coolant, at least not enough to measure. I don't have any ticks or knocks and I'd hate to replace the motor and this one be ok. Again, if anyone else has more experience, please chime in.

modrodr 03-11-2011 08:10 AM

Check to make sure the oil pressure sending unit located next to the oil filter is not bad. It is a common occurence that these get bumped during the oil change and damaged. It would be a cheap and easy replacemen as a precaution. Hope this helps.

jeepers29 03-11-2011 10:38 AM

Quote:

Originally Posted by 2broke2gofast (Post 1110632)
I've noticed this with my 2000 TJ as well. My pressure will actually drop to 9-10psi at idle after an interstate drive. I verified this with a manual gauge. I had originally suspected my 0331 head may be cracked causing coolant to get in the oil and causing rod, main, and cam bearing wear, but I do not seem to be loosing any coolant, at least not enough to measure. I don't have any ticks or knocks and I'd hate to replace the motor and this one be ok. Again, if anyone else has more experience, please chime in.


I noticed this on my 98 as well. I called the mechanic the PO had been taking the jeep to for several years. The mechanic said this was very typical of this engine and not a problem. I do not have any ticks. knocks, ect. either. Any opinions would be appreciated.

offroadohio 03-11-2011 11:35 AM

15-20psi at idle is normal.

Mine doesnt hit above 20psi once im up to temp.

As the heat int he engine build sup the bear gaps and extra get bigger, cuasing oil pressur eloss. It happens in every engine out there.

vargassmooth 03-13-2011 01:49 PM

Is a common problem on tjs,,,, i think,I own a 97 and my brother a 99 and having the same problem,removing the instrument cluster and unscrew the lightbulb help me to stop looking at the evil Check Gauges warning light


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