proemtpff

I've had one of the two oil pressure sensors blow out in my '86. One was last week and the other was five years ago. When they blow they dump, pump oil everywhere, all I saw in my rearview was smoke both times and my pressure was 7 PSI. Both are located on the block, one behind the distributer cap and the other near the oil filter. Anyone having problems with these? Anything I can do about this to keep it from happening? I think two blowing out in 5 years is unusual, not only that my car only has 8700 miles on it.

bogus

That sounds more like bad karma then anything else...

CFI-EFI

The sensor in the block near the oil filter is the oil temperature sensor. I haven't heard of anyone "blowing out" either the temp or the pressure sensor.

RACE ON!!!

bogus

how much pressure do you see before it blows?

proemtpff

The one that has blown both times is the pressure sensor behind the distributer cap. I've never noticed what the pressure was before it blows.....I can't watch it all the time. Both times I was driving "normal" not on the throttle hard at all. I just find this VERY strange. This time it blew ten miles after a fresh oil change but I'm sure that was just coincidence.

JAKE

What exactly happened? Did the fitting(s), itself, actually blow out of the block? Or did it/they just spring a leak?

Did you replace the fitting with new ones or reuse the ones that blew out?

Both are screwed into the block so assuming they are the correct size and thread, either they were not tightened enough or the threads are stripped, either in the block, on the fitting(s) or both.

It's tricky cleaning threads for the fittings that serve the oiling system. The trick is to prevent metal shavings/filings from entering the oiling system.

You can try using a thread chaser - not a tap which removes too much metal - on the block. You can put a heavy coat of grease on the chaser to catch any filings; and bump the engine with the fitting REMOVED to flush any filings that the grease may miss. Remember, BUMP, not fire or run the engine.

Even better would be to use a engine oil priming tool in the distributor opening in the intake to turn the oil pump.

When using the thread chaser/grease, turn it one revolution, then remove it and clean the grease and any filings. Re-grease it, re-install it and turn it two revolutions, then remove it, clean, etc.

Keep doing it it this way, adding one additional turn each time until all the threads are chased.

A few turns of teflon tape on the fitting threads may help too. Be sure to leave the first two threads on the fitting bare/no tape.

Since this has happened in two different locations, I suspect they were not tightened enough or stripped threads.

Without disassembling the engine entirely, that's all I can think of other than maybe a heli-coil.

Jake

proemtpff

The threads are not stripped and the sensor "sprung" a leak both times. Both sensors were replaced with new ones. The first one to blow was the OEM sensor that came with the car new in '86, the second one just blew this week and was put in the car five years ago by the local Chevy dealership. The new sensor JUST put in was done by a trusted exotic car shop. Mine was the cheapest car by far in the garage.

JAKE

So then, they didn't blow out, but started leaking. Okay now we've got more to work on.

If you kept the old "bad" one, can you tell from where it was leaking?

Was it from the body of the fitting or the threads?

Is there any sign of it being cracked, as if it was over-tightened during installation. This can happen with spark plugs too, so look carefully for any hair-line crack.

Even the best and most experienced techs can make a mistake; even the NASCAR guys blow off an oil or coolant line now and again because it wasn't tightened properly.

Jake

proemtpff

I don't have the sensor but I was told it leaked from the body and it had a plastic type cap on the end that "blew out". I'm going to try to get the sensor on Monday or get a better description of it. Also, I would'nt call it a leak......it was PUMPING the oil out at a VERY high rate. The mechanic said everything looked good except for the fact it was losing oil.

bogus

uh, sounds like you need to get GM pieces... if your tech is replacing with no-name, that could be the problem.

What is your "normal" oil pressure?

proemtpff

Uh, GM pieces might be the problem being that ALL of them are GM parts bought at my local dealer. Normal pressure at idle 17-20psi. full throttle 40+ and crusing around 25-35 psi.

bogus

that is odd... most very odd...

proemtpff

Yep it sure is. So, I'm getting the idea I'm the only one having this problem and there is no answer to help me?

rick lambert

Check with GM to see if there was a recall on this part-it really seems like I read something about it-BTW, if memory serves me correct someone said if it wasn't black-it was the old style. I could be wrong but I'm pretty sure I read something about it.