TSB for Additional Under Plenum Drain?

[Erik]

I was given a link once to a TSB that was apparently for additional drainage under the plenum. However, the link was dead.

Any idea where I could find it?

[Dynomite]

I was given a link once to a TSB that was apparently for additional drainage under the plenum. However, the link was dead.

Any idea where I could find it?

3/8" diameter hole in the valley (https://www.zr1.net/forum/showthread.php?t=28320&highlight=valley+drain)

GM Service Bulletin #92-307-6

Service Bulletin #92-307-6 (https://www.corvetteactioncenter.com/tech/knowledgebase/article/1990-1992-corvette-zr-1-service-bulletin-no-start-condition-replace-starter-485.html)

[Corvette95]

You know a trick I have done a few time although my plenum never really gets dirty, it run a long hard vacuum line up the valley drain and spray electrical clean up the hose, can also use brake clean but thats second choice due to the DIS.

[Erik]

You know a trick I have done a few time although my plenum never really gets dirty, it run a long hard vacuum line up the valley drain and spray electrical clean up the hose, can also use brake clean but thats second choice due to the DIS.

Good to know. Thanks!

[Young1]

I use my rubber tip air blower on the pipe every time I do an oil change even though a dealer long ago drilled the hole.

[Corvette95]

Yep, air works too. I like to do the cleaner to keep oil from building up but it?s risky but been lucky for years with it !


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[Paul Workman]

Blue Loctite when torquing down the IH and the air breather dome does wonders too, far as preventing oil from leaking down into the valley in the first place. (Just sayin!)

[Corvette95]

Blue Loctite when torquing down the IH and the air breather dome does wonders too, far as preventing oil from leaking down into the valley in the first place. (Just sayin!)
I am glad YOU posted that Paul. I was going to but didn't want to take the heat for NO SEALANT ON PLENUM OR IH BOLTS REPLIES! After three additional torque sequences after install, yeah, next time, blue loc-tite for sure! Although dry as a bone after the third re--torque!

[Gsgnz]

Is it ill advised to drill this hole from the flywheel side?

[Paul Workman]

Is it ill advised to drill this hole from the flywheel side?

I have read where some have suggested such a hole drilled there. But, I think not having a tube to channel the oil clear of the FW might be an issue. OK, I've watched this FORUM for over 15 years and have yet to see any followup from anyone who did drill an aux drain hole. But, preventing oil leakage in the fist place and/or periodically cleaning out the drain pipe (as suggested) appears to be a better solution(?) Just sayin!:cheers:

[Flyman 27]

Is it ill advised to drill this hole from the flywheel side?

I would say ill-advised. Too easy to miss the intended target.
I drilled mine 4 years ago with no issues.
The hole is intended to drain water from driving in the rain and from cleaning under the hood.