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**DONOTDELETE** 11-18-2002 05:59 PM

2.5L Oil Pressure Problem
Have a 97 TJ 2.5L with 91K miles on it. After traveling short or long periods of time on highway (55+ mph), once I come off the highway to a complete stop, oil pressure gauge drops completely to 0 as if engine was off - CHECK GAUGES light comes on, once I hold the gas down for 2 or 3 sec, gauge goes up until I let off it.

Skellator 11-18-2002 06:03 PM

Re: 2.5L Oil Pressure Problem
Does the engine start making any noise when the pressure reads 0?

**DONOTDELETE** 11-18-2002 06:06 PM

Re: 2.5L Oil Pressure Problem
no the engine doesnt make any different noise once the gauge drops

**DONOTDELETE** 11-18-2002 07:03 PM

Re: 2.5L Oil Pressure Problem
I hate to ask, but have you checked your oil level? [img]images/graemlins/blush.gif[/img] Sounds like an old Toyota that I had. Ran pressure fine unless stopped - added oil then it was fine.

**DONOTDELETE** 11-18-2002 07:09 PM

Re: 2.5L Oil Pressure Problem
I have an 87 Wrangler with a oil gauge problem. I recently got all the gauges working; or at least reading something.

My oil pressure gauge is doing exactly what it had done for a while before I disconnected my gauge cluster; it jumps from low end to high end eratically, and then sometimes it just zeroes out or pegs high; then when I accellerate or decellerate it will go back to what would appear to be a normal reading.

I am about to troubleshoot the sending unit. Will let you know what I find out if you don't have an answer by then.


**DONOTDELETE** 11-18-2002 07:42 PM

Re: 2.5L Oil Pressure Problem
I pulled over and checked the oil the first 2 times it happened, also checked it the other night and have enough oil everytime. could it be the gauge itself and nothing under the hood?

**DONOTDELETE** 11-18-2002 07:44 PM

Re: 2.5L Oil Pressure Problem

Sorry about the following looong read; I have not figured out how to copy an old thread and forward the shortcut so all you have to do is click on the shortcut and go to the thread.

Following is a thread from September on the gauge topic.


Gauge Needle Jumping:

How can I test my sending unit? I think its bad, but I dont want to toss $20 at a new one if not. My guage sometimes works, othertimes it flings over to way beyond the guage lines. Sometimes it will do it when it revs, most of the time it just sits there. And some of the time it will work for a week w/o issue, like now. I've hooked up a manual guage, and the oil pressure is good, no issues. So I know there is no problem with the motor in that respect, just the guage or sending unit. Can I disconnect the guage and measure resistance across the terminals on the sending unit? If so, what are the ranges?


Re: Oil Pressure Sending Unit... [re: pr0ntab]
09/27/02 11:08 AM Edit Reply

Most probably wiring problem, I would say check all the wiring and clean harnesses.

Re: Oil Pressure Sending Unit... [re: alkan]
09/27/02 11:12 AM Edit Reply

The basics have been done. I've cleaned it, removed it reseated it... , continuity tests between the guage and sending unit plug, all good, no shorts. -

Re: Oil Pressure Sending Unit... [re: pr0ntab]
09/27/02 09:49 PM Edit Reply

Mine did the same for about a year. I checked, cleaned and basically did everything you did. Then finally replaced the sending unit. That fixed everything and guage works fine now.

Re: Oil Pressure Sending Unit... [re: kgound]
09/28/02 11:04 AM Edit Reply

Very easy to Test... first things first, is your guage always pinned? the needle to the far right?

1990 xj sport

Re: Oil Pressure Sending Unit... [re: binare]
09/28/02 02:23 PM Edit Reply

It is when its freaking out. It pins over to the right. Right now if I go out and start it, it is working fine. Some days it will be working fine, but when the needed moves because of pressure change, like if you rev it up, it will peg, then come back, peg then come back.. Right now today, its working as designed, tomarrow may be another story -

Re: Oil Pressure Sending Unit... [re: pr0ntab]
09/28/02 02:45 PM Edit Reply

Heres what I would do, Take the one wire and put it to ground (a good ground). This should make your guage read zero pressure al the time, leave it like this a for a day or two. If it stays at zero and doesnt move, replace the sender and put the wire back. If the guage still jumps around, look at the gauge or wiring as your problem. My initial bet is the wiring is your problem, when the sender is faulty or you have a short or cut in the sender wire, your gauge will be pinned to the right. Actually first check the connection, but you've probably already done that. If you get a new gauge specify that you have a guage NOT the dummy light. And do not be worried if the new sender looks different, they changed it over the years but works the same.

Re: Oil Pressure Sending Unit... [re: binare]
09/28/02 08:07 PM Edit Reply

Bin, good troubleshoot idea. The sending unit is basically a current sending unit. By grounding the wire, you are doing a safe check of wiring. This will not hurt the gauge. If in fact, it stays at 0, then it indicates the sending unit is going open. I had a simular problem. In my case, the nut that holds the terminal stud on sending unit was loose. Once I tightened it, it went steady.

If your a technogeek like me, put a current meter in series with the sending unit. If the reading stays steady while the needle bounces, then it is the guage. If the reading bounces around, the use the above step. Steady, and it is the sending unit.

84-CJ7, 89 Cherokee

FatBoyRob 11-19-2002 11:36 AM

Re: 2.5L Oil Pressure Problem
What weight oil are you running? When was your last oil change.

My gauges also drops, after high rpm driving, but it never pegs out at 0.


Skellator 11-19-2002 05:59 PM

Re: 2.5L Oil Pressure Problem
</font><blockquote><font class="small">In reply to:</font><hr />
could it be the gauge itself and nothing under the hood?

[/ QUOTE ]

Yes it could very well be the gauge.
My advise would be to get rid of the electrical gauge and put in a mechanical gauge. It's not that hard and it'll end all doubt as to whether or not you have oil pressure. [img]images/graemlins/grin.gif[/img]

BTW... My 2.5 has 190k and still holds 40# [img]images/graemlins/grin.gif[/img]

GeeAea 11-19-2002 10:31 PM

Re: 2.5L Oil Pressure Problem
Can you tell us what kind of pressure that you have otherwise? Cold start ....warm idle? .........and to answer the sorta answered but unasked questions for my fellow asteemed associates above......

Does the gauge fluctuate or bounce? Go to FSD (full scale deflection) .......or otherwise act funny?

I'd say that if the answer is no to the above question that you have one of two problems. Either the sensor (I believe everything on a TJ dash comes through the PCM) is faulty and is giving an incorrect input to the computer .........or you have need for a new oil pump. Perhaps the relief springs are shot .

Change the oil with an appropriate weigh oil for the season and see if the condition is still present. If so ..replace the oil sender/sensor. Beyond that, as was suggested, at least put a mechanical gauge (shop type pressure gauge) on it to see if the pressure is as indicated by the factory electronic gauge (I believe that you will have to retain the factory electronic sendor/sensor to keep your "check engine" light off). If all these actions leave you where you started ...plan on having the oil pump replaced.

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