91 ZR1 - Latest Issue
 

See Pic - just developed an oil leak coming from the read end of the oil pan - leaves a decent size puddle of oil after it's done. Looking closely appears to be a pin hole developed? But possibly a bad gasket. See pic and let me know of any suggestions to look for. 62K miles. Thanks

Re: 91 ZR1 - Latest Issue
 

Pan bolts tend to loosen over time. Tighten all M8 pan bolts to 23ft-lbs. The remaining 3 M6 bolts in the very front are hard to get to without removing the K-members. Proper torque for them is 89 in-lbs.

Try tightening all of the M8 pan bolts first to see if that helps. If you still see any leaks at the front of the pan, then pursue the M6 bolt tightening process.

If leaks persist, it will require a new pan gasket.

Re: 91 ZR1 - Latest Issue
 

I feel your pain! One other source USED TO BE seepage from the breather box and hoses, under the plenum. New gaskets and blue Loctite and hoses eliminated that. No more oil collecting in the valley after that, so nothing going down the drain tube...

That leaves the rear main seal and the pan gasket, I guess. :censored:

Re: 91 ZR1 - Latest Issue
 

Thanks Paul and Jerry. And Jerry, I understand you're the gasket king which I may be a calling.
The car literally went one day with no drips of oil to last week a good size puddle larger than a hand every time I take it out for a drive. The leak is in the back of the oil pan. Could this be an issue with a bad gasket coming out of nowhere and going bad quickly? Thanks again

Re: 91 ZR1 - Latest Issue
 

Another possible source of that much oil is the rear crankshaft seal. Jerry has them.

Jim

Re: 91 ZR1 - Latest Issue
 

Clean that area really good with WD40 and then see where the leak is coming from. Mine went away after retightening the pan bolts, there is a torque sequence that needs to be followed.

Re: 91 ZR1 - Latest Issue
 

You really need to clean it up well, then drive it and check it. Critical that you find the source, then we can fix it. My '91 developed a leak at the oil pressure sending unit at the front/passenger side, which blew back across the pan and left a good puddle..

Sent from my XT1585 using ZR-1 Net Registry mobile app

Re: 91 ZR1 - Latest Issue
 

Thanks JSS, mine does develop a good size puddle that came out of nowhere three days ago. I cleaned it up well and the drip ends up at the passenger side rear oil pan. However, I do not have access to a lift and cannot see where it started. At this point a guess.but with this big of a puddle, it has to be worse than a bad gasket or loose bolt on the oil pan

Can I visually access the oil sending unit from above? About where do I start looking for this unit?Thanks in advance

Re: 91 ZR1 - Latest Issue Oil Leak
 

I am the original Poster - After getting the car up on the lift at the shop, appears the oil leak is coming from the "oil vent/drain tube" on the oil pan. Did I read that comes from somewhere/something under the plenum? The pic shows it could be there. Thanks
:salute:

Re: 91 ZR1 - Latest Issue Oil Leak
 

That Tube is what is called.....the Valley Drain.

You have to remove the Plenum, the Coils, and the Starter to get to the Valley Drain (to clean everything). Good to know your Valley Drain is not clogged. Under the Plenum could be Injector Housing gaskets (tighten Injector Housing Bolts), Crankcase Cover (tighten Crankcase Cover Bolts or new gaskets).

If any bolts appear loose when re-tightening......I just remove the bolts, clean the threads and apply blue Loctite before re-installing the bolts. If I replace the gaskets........I Clean the surfaces and use a bit of Permatex on the gaskets (both sides) for a good oil seal.

I also Block TB Coolant at the Injector Housings and use nothing on the Plenum Gasket since no oil or coolant is involved in that seal.

It is all in my signature ;)