Oil pressure gauge

[alex_and_sean]

Ok, I hereby confirm I am an idiot. Did the gauge cluster swap and finally got around to doing the sender unit change outs. Swapped in oil pressure send unit and gauge moved but was always less than 40 but moved about the right amount. Tried a different sending unit with the same result.

 

So, I decided that a gauge adjustment of some sort was needed. Took dash apart and was messing with the gauge and the dial broke off. So now I have two problems. Not sure I can fix this or not. Can I get a new oil pressure gauge? Maybe pull it from a cluster at the junk yard? Or do I need to do the gauge swap all over again? Did try a half-a$$ed attempt to super glue the dial back on which to me confirmed I was definitely in idiot country at which point I stopped and came in for some beer.

 

Got any ideas?

[Eagle]

The gauge is held into the cluster by two (or three?) screws. If you can find just a gauge, you can certainly swap just that, but in reality it's probably easier to find a complete cluster than to find a single gauge, and not much more expensive.

 

Why did you decide a gauge adjustment was needed? Unless you knew by checking with a calibrated mechanical gauge that your oil pressure is higher, 40 might have been the correct reading.

[alex_and_sean]

The gauge reading was always way below 40 (like between the 7 and 10 o'clock positions) and never got that high, though the range of motion vs engine speed seemed reasonable and the gauge moved the correct way during start up. Thus, silly me I was going to "adjust" it. Maybe the gauge is/was bad to begin with.

 

Guess I am in the hunt for a new gauge cluster.

 

Thanks Eagle

[Automan2164]

I think your still missing the point eagle is trying to make.

 

Have you checked the "actual" oil pressure with a mechanical gauge? Why do you assume it is the gauge, and not the truck?

Rob L.

[alex_and_sean]

I understood Eagle's point and will be checking. I think the truck is okay since it runs well and the idiot light version was not illuminated prior to the cluster change. My plan tonight is to do the actual check to see.

[Eagle]

The idiot light doesn't come on unless the oil pressure is below something like 7 psi. If your gauge is showing anywhere near 40, it wouldn't activate the idiot light. It would also be within spec. The factory spec is minimum 13 psi at idle, 37 to 75 psi above 1600 RPM. Most NEW XJ and MJ engines typically ran about 50 to 55 psi (warm) at highway speed. 40 psi would not be at all unusual for an older engine, and would not be cause for immediate panic.

[alex_and_sean]

Hooked up mechanical gauge and got between 25-35 psi at idle which jumped up to around 45 when I reved the engine. I guess I am working on a gauge fix or a cluster change out. At least I don't have an oil pressure problem.

[Automan2164]

Wasn't that what the cluster gauge was reading?

 

You do know that those gauges are supposed to be more of a "guideline" than gospel. If you want a dead accurate gauge, go aftermarket. A factory gauge just won't react like I think you want it to.

 

Rob L.

[alex_and_sean]

No the factory gauge was reading less than zero. It was hovering around the 7 o'clock position and occasionally going up to 9 o'clock when I reved. The range on the gauge that actually has numbers is from about 10 to 2.

 

So the gauge dial would move what I perceive to be the correct amount but was not pointing in the right place.

[Eagle]

No the factory gauge was reading less than zero. It was hovering around the 7 o'clock position and occasionally going up to 9 o'clock when I reved. The range on the gauge that actually has numbers is from about 10 to 2.

 

So the gauge dial would move what I perceive to be the correct amount but was not pointing in the right place.

Then the gauge is broken, because the actual physical range (in terms of a clock) only goes from approximately 10:00 o'clock to 2:00 o'clock. I've never seen a factory gauge on which the needle would fall not only below the "0" mark, but physically below the 9:30 or 10:00 o'clock position on the dial. It sounds like the needle was already messed up on the gauge before you started trying to calibrate it.

[alex_and_sean]

Yep. Wasn't sure if it was an adjustable thing, a pop the needle and reposition (which is what I did and broke it) thing, or something else.