What does a vibrating oil pressure gauge needle mean?
 

It only happens when engine is warmed up. Recently changed oil but same thing. Vibrates maybe 1-2mm up and down fairly rapidly, not jumping all over the place. Still pegs at 3 when stepped on it but as it goes down the needle vibrates. This started early June this year when we went to the desert (400mi trip). Nothing significantly noticed just that needle vibrates. Your thoughts?

Btw this is for the 300D '83. Thanks.

Sounds like you need new O rings on the filter stem.

My TD sometimes does it too. Usually on a long trip. Almost never around town. New O-rings. Vibration is too fast to be actual fluctations in pressure (I think) I don't have any explanation. It happens when coming to an idle after a sustained high speed drive. Goes away as soon as I press on the accelerator.

There is a TSB on this subject. As I recall, it involves adding a restrictor of some sort in the oil line to the gauge. It will be sunday evening before I can access my TSB book, but I will try to remember to look up the part number. (Good chance the part is NLA though).

Thanks I'll look into the O-rings. I had the oil changed at the mechanic got lazy, I'll open it up when engine gets cold. If I replace them and it still does it, what else could it be?

Palangi if you could dig up the info I'd greatly appreciate it. No rush of course, look forward to hearing your reply. :) Thanks.

No problem. Remind me next week in case I forget.

Yup, it's just the gauge, not a real oil pressure fluctuation. Mine only did it if it had been running at highway speed for several hours with my old gauge. The current gauge doesn't seem to do it at all, maybe it has the correct restriction installed?

Yup it's after a good highway run. I'll check the gauge when I get at it.

Anything bad that might happen if I let it be? Will it start leaking?

Not that I know of, but it is annoying. My old gauge eventually started leaking, but I doubt it had anything to do with the vibration.

I have heard that with straight 30 weight oil will not do that, but I don't know for sure. I don't think I would run 30 weight in a 617 turbo anyway.

You're right it's definitely annoying! Thanks again. :)

edit: no I wouldn't put 30 weight oil in there!

I had the same exact thing happen to mine. I think it started end of may,
or June. (something about June) all of a sudden it started vibrating. speed
up engine, pegs to 3. I replaced the o rings on filter stem 6 mo ago, so
that can`t be the problem. also had a heating problem start just before
this. thought it might be related, was going to chk out both problems
when got back from a trip. then eng go bang.
If it still does it w/the new eng. then it is the gauge.

charlie

What do you mean engine go bang? That doesn't sound good! :eek:

The same symptoms showed on my 92 300D several months ago. I did notice some oil leakage on the side of the engine, but thought it was the valve cover gasket. Anyway, during a highway trip last month, the head gasket blew spewing oil throughout the engine bay and in the exhaust. All is ok now with a new head gasket, and the oil gage needle is steady all the time. Related? I don't know; there were no other signs of a leaking head gasket, and I wouldn't have changed a head gasket trying to stop the bouncing needle.

A mechanic once said that my front main seal (crankshaft) is leaking, that was probably two years ago. Do you guys think this has anything related to that?