alexands

Whenever I start my car the oil pressure gauge is at zero and the "Check Brake Fluid" idiot light stays on. This happens for about 20 seconds. The oil pressure guage just stays at zero, then pops to life and displays the correct (I hope) oil pressure.

I just rebuilt the engine 200 miles ago (#2 rod bearing) so I've developed a very special relationship with the oil pressure gauge . Imagine my heart rate when it just sits there.

Any ideas what this could be? The brake resevior is full and the car runs fine, so I'm assuming it's an electrical issue.

Thanks for any advice.
Scott

UK952

Sticky oil pressure sender?

Bad earths / connections on the guage pod cause strange results.

Think if it was mine I would plug a temporary mechanical guage into the sender hole just to check before running it again.

I have heard a loose crankshaft pulley bolt gives oil pressure issues but not experienced it myself.

You given up on the Flintstone power then? (avatar)

Tony

phlip

I'd bet you have a stuck oil pressure releif valve. Has happened to me twice, with the same exact symptoms. I am at a shop in addison tx, Stuttgart on midway rd. If I can be of any help call 972 392 7900 ask for Phil.

alexands

Phil, Thanks for the input. Would a stuck oil pressure valve make the Brake fluid light come on? I just built the motor and left the original valve in (the spring and piston).

I'm taking the car to Mayo's today for alignment and I'll run it by them. If they don't have any ideas I'll give you a shout.

Thanks again,
Scott

phlip

When mine was giving me trouble there were lots of lights on. Exclamation [!], oil pressure light, brake fluid, brake pad, maybe more. A friend of mine at the dealer said they did this on purpose so a problem with oil pressure would be very noticeable. You can ask mayo to check with external mechanical guage. There is a special tool to align filter housing on block exactly in right position.
I did not use tool either time I had problem, But I also fixed the problem without the tool both times.
You just have to be absolutely sure piston portion of valve will move freely. Or better yet replace entire valve with updated one piece version.

UK952

Should add that three out of four cases I know of the loose crankshaft bolt causing low oil pressure were just after rebuilds.
Tony

Keithr726

WOW old thread, but I'm having the exact same issue. Did anyone find out what in fact caused this problem?

fortysixandtwo

A loose connection (open circuit) will peg the needle at full pressure (5+bar). It could be the gauge sticking, the sending unit failing or actually having oiling problems. As one of the others suggested, just go buy a cheap mechanical gauge and verify the oiling system is functioning properly to avoid treating a symptom as the problem.

While the needle is sitting down at zero with the engine running, is the low oil pressure light on? If so, either the sending unit has failed or you actually have low oil pressure at start-up.

Keithr726

Yes the little red light was on. Normally it's not and when I start the car it starts a 0 and bounces up to 5 over a few seconds. Occasionally there is some lifter noise on start up but not this time so I have a feeling OP is just fine. The lights stayed on for about a minute then turned off and the gauge went up to 5. I'll take a look at the sending unit wiring on my next break.

fortysixandtwo

hmm, it could be the sending unit or actual oil pressure problems. The warning light and gauge are separate systems, but are both driven by the same sending unit. This should rule out an issue with the gauge and wiring leading up to it.

Easiest possible fix is to verify the front crank bolt it torqued to spec. From there, you have two options; pick up a cheap mechanical gauge ($10-$15) or get a new sending unit.
If the problem persists, you have an oiling problem. Possibly a leak in the pickup (crack, seal)

Keithr726

I changed the connector and it was fine for the last day. This morning it happened once again, I didn't wait to see if it all went away and just turned it off. Odd thing is that no oil is leaking that I can see. Guess I won't be going on the local PCA New Years run.

fortysixandtwo

If there is a leak in the pickup that's causing the pump to lose prime, it will be internal to the engine, no visible signs from outside.

The time you spent changing the connector, you could have installed a mechanical gauge. Since its just for trouble shooting, all you need to do is sit it on the engine where you can see it while cranking the engine.

Keithr726

Checked with gauge, no pressure. Swapped in release valve with know working, still no pressure. Checked crank bolt, good. Dropped pan after replacing gasket last month no problems with pick-up. Smoke test identified small leak coming from the pump.

fortysixandtwo

Haven't heard that one before. Where on the pump is the leak?