Sealing up the Plenum

[Bandit395]

I've been chasing high BLM's for a bit and used a home made leak tester (air compressor, soup can & rubber coupler) on the throttle body and found a good leak where the plenum meets the intake. I tried the following with no results.

1) tightened the bolts

2) took off the plenum and reassembled with new gaskets and used RTV gasket maker all around.

3) smeared RTV around the back of the plenum

It is an RJC 3" throttle body & plenum combo with a power plate

Is there a better sealant or gasket I can use to remedy this?

 

[toofastforyou]

Maybe RTV is good, but I would've used some "Right Stuff" by Permatex...Let it dry for a few days (the more the better) and trim the excess off with a razor blade for a nice finish...:wink: Hope this helps!

Claude. :smile:

 

[DailyDrifter]

I've been chasing high BLM's for a bit and used a home made leak tester (air compressor, soup can & rubber coupler) on the throttle body and found a good leak where the plenum meets the intake. I tried the following with no results.

1) tightened the bolts

2) took off the plenum and reassembled with new gaskets and used RTV gasket maker all around.

3) smeared RTV around the back of the plenum

It is an RJC 3" throttle body & plenum combo with a power plate

Is there a better sealant or gasket I can use to remedy this?

Can you take the plenum off and have it resurfaced (sanded) flat. And have the intake maifold resurfaced also? I would also use the "right stuff" to seal it up with.

 

[Bandit395]

I will pick up "the right stuff". Is the plenum gasket necessary (or two of them with the power plate), or is the right stuff enough?

I can resurface the plenum with a belt sander but not the intake.

 

[Razor]

So whats warped, the upper plenum or the intake? Fix the warpage.. a stock gasket is fine.. your done.

Fixing warped stuff with RTV is not the correct way. A belt sander may not be the correct way either. I would take it to a machine shop and have them resurface the upper plenum correctly.. if its warped.

 

[Bandit395]

I finally had some time to take it apart after trying to re-seal it all. I am looking for a machine shop to resurface the plenum as Razor suggested then I'll reassemble it all. I want to use studs in place of bolts in the intake /plenum holes this time.

 

[Bandit395]

I dropped the plenum off at the machine shop. He was able to see two low spots on the back and side surface of the plenum with his eye. It is an aftermarket 3" plenum from RJC. Not to knock RJC as they make and sell many fine procucts for our cars, but I was not happy with the plenum & throttle body I bought from them since day one. The throttle body & plenum alignment was way off and I had to dremel and smooth that myself, now to find that the bottom surface of the plenum has been the source of my vacuum leak for a while. Additionally the overall appearance of the plenum is too pourous and lacks a finished look. I would advise any one with an aftermarket plenum to do a pressure check on it so check for vacuum leaks as well. Hopefully machining the bottom surface of the plenum will resolve the issues. I'll let you know.