Flickering Oil Light on '87 Jeep

[Thorn]

I have a 1987 Jeep Comanche 4x4 with a 4.0L engine that I bought a few years ago. I drive the vehicle less than 2,000 miles per year, as I use it mainly for hunting/fishing and yardwork, etc.

The truck has ~104K miles on it, and it had about 99K of hard-looking miles on it when I bought it.

The oil light flickers on and off when the truck comes to a stop at idle (e.g. stop sign, red light). I took it to the local mechanic and he couldn't replicate the problem. Then I start thinking that it was probably because it doesn't happen until the engine is driven for several miles before the light starts to flicker.

The mechanic claims that he checked the oil pressure with a pressure guage, and that it was OK. I can't verify this 100% because I wasn't there.

I usually change the oil once or twice a year with 10w30 conventional.

Any thoughts?

 

[K-Man]

You probably have sludge built up. After driving for several miles, the oil gets trapped upstairs and barely enough gets down to the oil pan. Figure hard use = general maintenance neglect.

Another possibility is a bad oil pressure sender. Try this first. I had one go bad on an old Toyota years ago.

 

[Gary Allan]

Since you didn't mention indicated pressures, I'll assume that you only have an idiot light. If you don't hear too much valve clatter, I'd say that your pressure is okay. The reason that I say too much noise is that the 4.0 tends to be one of the noisiest engines that I've ever owned ..right out of the box ..add 100k of hard/less than ideal use .and you've probably got a pretty noisy engine ..even with nothing being truly wrong with it.

I'd swap out the sender and probably change the oil more often. If it continues -or happens no matter how new the oil is, I would consider jumping up a grade in oil. Naturally I'd also recommend buying a cheap aftermarket electrical oil pressure guage just so you can monitor any pressure related issues.