On my L98 TPI it seems that there is no gasket between the intake manifold and the center part of the block. It looks like the PO used some RTV however it wasn't thick enough as it looks like it never touched the manifold.

The place where the manifold touches the head inlet ports has proper gaskets which now I am also going to replace but this center part is not making sense to me. Picture below. You can see the black untouched RTV between the heads.

Can someone give me some information on this?

 

I think I am going to answer my own question. Browsing through the rockauto catalog I am seeing some kits with what looks to be gaskets for this location.

Pity I cannot find a single set complete with TPI plenum (upper and lower) gaskets, throttle body front and rear, inlet manifold and these two pieces. Will have to buy two sets and complete it that way.

I thought writing it here might help others with the same issue.

 

That's the way they are done. The intake gaskets are like header gaskets in a way...two separate composite gaskets.

I believe there are end seals you can buy, but they still have to have the corners sealed with RTV, as far as I know. So a lot of folks just use a bead of RTV.

 

Understood so RTV can also be used here. No oil pressure really in this place. I guess the bead that they did was not thick enough then.

 

Your missing your spider web / lifter retainer.

 

There are rubber seals made for the wall between the heads, but they have a pretty bad reputation for failure. RTV is what GM used and what comes with the Felpro TPI intake gasket sets.

 

Thanks guys. Much appreciate your valuable help. Re. The spider Web I think you are referring to that plate which holds down the tappets held down by the three bolts correct? If so, I removed that on purpose to confirm that it is a roller tappet engine.

 

You can buy the end gaskets. I think they were called something like end rail gaskets at autozone. I have done both RTV and gaskets with RTV and both worked well for me.

 

I only use rtv for those areas. I have never been able to get the rubber rail gaskets to seat correctly. They always moved on me. All the engine builders I've talked to do the same... toss them

 

That's what I will do

 

Never used the end seals, never had a problem. Very common for causing the leaks if you do use them.
PS flat tappet cams dont even have the spider web or the brackets around the lifters(see picture), so right there is your give away that you have a roller block.

 

Make sure to use a high quality RTV silicone. The stuff GM sells is a little more expensive but it is the best stuff I have ever used and I will always make a trip to the dealership to get it (I was also a GM tech for a lot of years so I am kind of bias as well).

The other thing you can do.....if you have any deep pitting around the coolant ports on either the head or the intake manifold, use permatex liquid pipe sealant (will be white in color). Do not use alot, just a little wipe to fill the void and a thin coat around the perimeter. It can be put on both sides of the gasket if necessary. It stays plyable and allows things to move when it gets hot and cold. Do not use RTV silicone around these ports. Torque it down properly and let everything cure before you fire it up.