Looking for Source of an Oil Leak

[wutanec]

Hello,

I have been experiencing a sudden oil leak - a serious enough to wet the pan and drips to the transmission and cat. So I lease a lift to check out the common areas mentioned on the forum. I cleaned the bottom of the car thoroughly with a can of brake cleaner to see where the leak is coming from.

1. Oil Pan: looked dry and no more oil was leaking - I tightened the bolts anyways to make sure.
2. Oil Pressure Regulating Valve Cover Plate - looked dry, tightened the bottom bolt only as the top one was impossible to see or reach.
3. Header Stud - was not leaking, looked like the oil on the CAT is from oil deposit on the pan.
4. Oil Pressure Switch - looked pretty wet and leaked a little bit after I cleaned it.

So I am narrowing it down to the Oil pressure switch but it seems like there is a bigger pool more toward the front of the car - and drips down to the front of the leaf spring structure (picture attached). Could this pool start from the switch? or is there something else I should look for? Also, with my limited mechanical skill, I could not see any way to access a tool to remove the switch. is there any trick to remove this thing?

Thank you.

[secondchance]

Have you checked crankshaft sensor? My leak comes from crankshaft sensor o ring. Just haven't had a chance to get her on a lift lately.

[wutanec]

I had to look up where the crankshaft position sensor was haha. It is the one close to O2 sensor correct? If that is, yes I checked and its not leaking from there. The pool seems to start in front of the motor.

[SLCKZR1]

It probably is the oil pressure switch. Seems like a common issue on our Z's. Great post on the subject if you use the search option. Just replaced mine using the suggestions on that post, but shortened the removal socket tool by cutting off a couple inches, then rewelding on the nut. I can send you a pic when I get back to my shop if you would like. With the modified removal socket, about a 20 minute job.

[secondchance]

I had to look up where the crankshaft position sensor was haha. It is the one close to O2 sensor correct? If that is, yes I checked and its not leaking from there. The pool seems to start in front of the motor.

Crankshaft sensor is on the passenger side, upper block tucked under in front of (I think) the motor mount. You have to look up from under to see it.

[billschroeder5842]

It probably is the oil pressure switch. Seems like a common issue on our Z's. Great post on the subject if you use the search option. Just replaced mine using the suggestions on that post, but shortened the removal socket tool by cutting off a couple inches, then rewelding on the nut. I can send you a pic when I get back to my shop if you would like. With the modified removal socket, about a 20 minute job.

This is the way to bet. I had a "mystery leak" that popped up out of no where. It was the oil pressure switch as the seal got brittle and cracked.

[wutanec]

I guess it wouldn't hurt to replace it since it looks like it is leaking. I will replace it and report back.
By the way, when it failed, how bad was the leak? enough to drip 1 or 2 drops per minute after driving?

This is the way to bet. I had a "mystery leak" that popped up out of no where. It was the oil pressure switch as the seal got brittle and cracked.

[SLCKZR1]

Mine leaked badly. probably a half quart per minute. It was real easy to diagnose. Huge puddle of oil under the car after just a few minutes running.

[wutanec]

Mine leaked badly. probably a half quart per minute. It was real easy to diagnose. Huge puddle of oil under the car after just a few minutes running.

I see. Thanks for that, mine is leaking bad (although not half a quart per minute!). Maybe one or two drops per minute. I was wondering if leak that bad would come from a little switch but it seems to be the case.

[rossgn49u]

My 7k mile 91 had oil pressure sensor leak a couple years ago...similar symptoms.

[wutanec]

So I just replaced the swtich. What a pain! but it has been replaced so we will see if that fixed the problem.

For tightening down the switch, I just tightened it until the seal was bunched up and felt firm through the ratchet. you don't tighten all the way through the thread with this one as you would with bolts correct?

[A26B]

That is correct. It is threaded NPT which is a tapered pipe thread. over-tightening can crack aluminum. You done good!

[wutanec]

That is correct. It is threaded NPT which is a tapered pipe thread. over-tightening can crack aluminum. You done good!

Thanks Jerry,

So yes I am happy to report that it was indeed the switch it was leaking from. I went for a few drives short and long and the bottom end of the car is completely dry! For now at least lol. Thanks so much for all the support you guys as always. I am glad I did not go for a 20k full rebuild that a reputable Corvette shop near I live quoted me to remedy this issue!