4.0 Oil Pressure / Check Gauges

[jay79cj7]

In the past week now, at random times, my "check gauges" light has popped on in my 00 XJ. The oil pressure gauge reads 0 psi. This lasts for a few seconds, maybe 15-20 the longest time, and then jumps back up to normal 45-50 psi. This has happened at different speeds, different times on different days, and usually happens only once per drive. All the other gauges still work when this is going on. When you turn the engine off, the oil pressure gauge drops below 0, so this is its "natural resting point" when its completely off. When this problem happens, the needle is pointing right at 0, so it seems like the gauge must be getting a signal and not be completely disconnected.

I am thinking that my sender must be going, but I wanted to see if any of you have had similar experiences. I can't imagine that my oil pressure would really be 45 psi one second, 0 the next, and 45 again a few seconds later. I have heard of senders going bad and gushing oil and I have not seen that happen yet, although I do have a little new dripping the past month or two coming from an unknown location.

By the way, its a 4.0L that runs great with 105k miles. There are no funny noises or anything else going on.

 

[TwistedCU]

In the past week now, at random times, my "check gauges" light has popped on in my 00 XJ. The oil pressure gauge reads 0 psi. This lasts for a few seconds, maybe 15-20 the longest time, and then jumps back up to normal 45-50 psi. This has happened at different speeds, different times on different days, and usually happens only once per drive. All the other gauges still work when this is going on. When you turn the engine off, the oil pressure gauge drops below 0, so this is its "natural resting point" when its completely off. When this problem happens, the needle is pointing right at 0, so it seems like the gauge must be getting a signal and not be completely disconnected.

I am thinking that my sender must be going, but I wanted to see if any of you have had similar experiences. I can't imagine that my oil pressure would really be 45 psi one second, 0 the next, and 45 again a few seconds later. I have heard of senders going bad and gushing oil and I have not seen that happen yet, although I do have a little new dripping the past month or two coming from an unknown location.

By the way, its a 4.0L that runs great with 105k miles. There are no funny noises or anything else going on.

That exact same thing happened with mine twice (it was also a 2000 XJ, 4.0L). Never had an issue, and it ran fine. It must be either the sending unit or gauge itself.

 

[Saurian]

I would suggest the sending unit, though mine has done the same thing a couple times, usually when I'm about due to do an oil change, so it might just be sludgy oil... Check your connection to the sender, if it keeps doing it, replace the sender.

*oh. and as for the dripping, check the rear main seal, it's where the engine meets the trans... It'll look like it's dripping almost from the drainplug because it seeps down... Quite common in the 4.0s, as I understand it.

 

[jay79cj7]

Thanks. I may replace the sender, but I don't like the "swap" method of repair if I don't have to. Too many good parts get thrown out! I had just been operating under the assumption that my leak was the rear main seal, but I'll have to check it out one of these days. Its in the right neighborhood.

I am sure I don't have sludgy oil; I have been very good with oil changes on this truck, although I suppose deposits are unavoidable. It certainly is not gunked up enough to cut off all oil pressure though!

Thanks for the replies guys. If anybody else has seen this and fixed it, let mek now!
Thanks again.

 

[TwistedCU]

Yeah, it's definitely not because of bad oil, I change mine meticulously.

 

[Saurian]

I change mine every 3000 faithfully, it never gets particularly sludgy, not the best choice of words... I just noticed, the 3 or 4 times mine did it, it was right before it was due for an oil change, therefore the theory...

 

[B192734]

I actually had the same thing happen to mine a little while back ('00 XJ). Mine did turn out to be the sender. It worries me when something like that happens, so I try to jump on it ASAP. That way I don't get stuck out somewhere with a part that you wouldn't carry normally. scares me.

 

[jay79cj7]

Thanks guys. It hasn't happened since the day I posted. Very strange since it was happening just about every day. I'll keep an eye on it and swap the sender when I get a chance.

 

[Jeepr]

I would guess if your oil pressure was dropping to zero, there would be other problems as well. If it's still running good and the oil level has remained constant, I would first clean the connection at the sending unit. If it did it again I would replace the sending unit.

 

[jay79cj7]

If the oil pressure really is dropping to zero, I certainly do have problems! I highly doubt that's the case though. Again, normal to zero back to normal again...

 

[Bounty__Hunter]

Next time it happens, give it a whack right on top of the dash above the guages and see if it comes back any sooner. Could be a bad connection behind the dash, but that generally affects all guages.

 

[jay79cj7]

Thanks Bounty. That was the first thing I tried. I swapped out the sender today; we'll see what happens.