js0308

Im getting ready to tear off the plenum to do some vacuum line replacement and change the EGR valve. I am fairly new to dealing with gaskets and would like some opinions. I normally have been giving my gaskets a light coat of RTV silicone before installing them. Is this necessary or does it matter much. Your experiences and ideas would be appreciated. Thanks, :chevy

CorvetteZ51Racer

If you're referring to the runner-to-plenum gaskets on an L98, you do not want to use RTV. Just use the gaskets as they are. Make sure, however, to use a razor blade to clean the residue off of the gasket surfaces from the old gaskets.

Vic'89

Cleaning the old gasket material and preping the surfaces are the keys to a good install. I have never used any RTV on the plenum to runner gaskets.

Vic

Tolofou

Id say take your time. send me the pics on how you do your install... I did mine last week and have huge intake leaks..

But I was lazy cause of my back and used the bottom old seals and one new top seal with RTV and the other was an old but fairly new with the GM plastic holders made for the pleneum.

Install was a pain and removing things got my back to ache.. I am going to remove everything this week and start with new GM factory gaskets..

No RTV huh? How do those suckers stop moving? They seem to slide everytime I go to put the plenium in..

Cant I just install the runner on the plenium and install that way? Nope. Damn fuel rail..

I want pics man and I mean alot cause I spent a good day and a half undoing and puting back together..

Rob

js0308

Sorry, I wish I could help you on the pics, but I have no digital camera at this time. Even if I did have a camera I have already put it all back together except for attaching the TB. What I can do is tell you what I did. I removed the top runner bolts on the drivers side and completely removed the passengers side runner since you can pretty easily get to all the bolts. I did not replace the gaskets since they did not tear or anything when I removed the runners and plenum. All the gaskets looked great so I left them, I hope this does not come back to bite me. I did however take a razor blade to the sealing surfaces and cleaned them thoroughly. If you have any other ?s just let me know. I wanted to ask how do you know you have intake leaks? How can I check to make sure mine does not leak? :auto:

CorvetteZ51Racer

The danger in reusing the intake manifold gaskets is that they have raised bosses which are designed to compress in order to seal. If the bosses have already been compressed (i.e. used gaskets) the chances of them leaking go up astronomically.

As for how you get the gaskets to keep from moving, you have to correctly position the plastic tabs from the gaskets in their locating holes. You have to carefully position and work the plenum down into place, in order to keep them from moving. Once roughly resting in place, you will have to push down pretty hard on the plenum on both ends to work it down into place so you can start the bolts, because you are compressing the raised bosses in the gaskets to get the seal.

js0308

Thanks, since I have not put the car completly back together yet and since I have the gaskets already, I am going to pull the plenum back off and put the new gaskets on. Thanks for all the help everybody. :chevy

CentralCoaster

Where are you guys buying these tb/plenum/runner gasket sets?

All the parts stores seem to only have the entire TPI gasket set. I get sick of having all these extra intake base gaskets, it's a waste of money.

I just spent $26 for the set at NAPA, and the base gaskets are crappy, I'd never use them on my car (not that I planned to). :nonod: