Rear of intake RTV replacement...for the third time.

[HallenTi]

Twice before I have removed all the TB and intake parts to replace the gaskets and RTV on my 1990 L98. I have to do it again I am afraid... rear RTV seal leaks again! Actually, the first time was the rear seal, second time was a bad intake side gasket, and now the oil leak is back.

First time I used the black Permatex RTV I had around, had some O2 sensor trouble and assumed that MAYBE the non-sensor safe black RTV caused it, so used the medium-blue sensor-safe Permatex RTV the second time. I VERY carefully removed all the old gasket material and all traces of RTV from the block and intake, then cleaned everything with brake cleaner and a rag, then waited for the parts to dry before continuing. I put the blue RTV on it with a 1/4" bead as recommended, then immediately assembled it as the Corvette shop manual suggests ("assemble while the RTV is still wet" it told me). The manual recommends GM P/N 1052915 or equivalent, and while I wonder if it is just the "usual" RTV, even if I have to pay 10 times the price for a slightly better product, I will do just that, as this is a lengthy job and I'd just as soon do it JUST one more time.

With the old cork and neoprene gaskets years ago on my 1964, I know we'd "dimple" the head and intake with a punch to give some "grip" and keep the gasket from "squishing" out under tension, but I expect that's why they went to RTV so it was just a plain seal rather than gasket material.

Anyone have any tips or techniques for me, so I this third time will be the LAST time?!?!

Thanks, Tim

 

[Hrtbeat1]

Try "The Right Stuff" it is in a pressurized can and comes out sort of like the expanding foam stuff (it doesn't expand like the foam). Follow the directions on the can, I think it says to let it harden up some before assembly.

 

[Mart]

I used that stuff and never had a problem, just don't use any end gaskets just use the "Right stuff"

Make sure everything is really clean and oil free, I used brake cleaner to wipe everything down prior to assembly. Lay a thick bead of this stuff down then when done assembling everything I let the car sit for at least 24 hrs more like 36-48, never had a problem.

Mart

 

[rrubel]

Mart's got the right idea, using "The Right Stuff." Also, there's a thread floating around which suggests taking a hammer and awl and lightly dimpling the rear of the block and underside of the manifold so that the gasket material will have a rougher surface to adhere to. I didn't do that, but I did use "The Right Stuff" and it does work...
[RICHR]

 

[tntcorvette]

I take some sandpaper and gently scar the intake manifold and block area where the two mate and use ample blue RTV to seal it up. Never had a leak. Make sure none of the sandpaper residue or such gets into the motor!

 

[Moonunit 451]

PROVEN

 

[G Winter]

both surfaces must be CLEAN , no oil at all. Use brake cleaner just before putting the right stuff on. Wonder if you could use a 3/32 drill bit and drill a few holes about 1/8 in deep on the block surface.

 

[Mart]

I used a punch and dimpled the front and rear, just a light tap will put a small dimple in there about every 1/4 inch, and stay away from the edge get it right in the middle.

I did not like the metal shavings from the drill part.

Mart