I just finished installing new Intake Manifold gaskets. The intake manfold kit by FelPro from Autozone. I also installed a new throttle body gasket kit and new M4 .7 pitch stainless allen bolts on the upper plate and coolant passage parts. The injectors have new O Rings as well. The EGR valve was also replaced as it would not hold vacuum, the replacement part was a new ACDelco unit.

It appears that my driver's side runner has one hell of a vacuum leak. There is a VERY loud sucking noise and the car runs like crap. When I spray carb cleaner on the lower front gasket and on the upper gasket, the idle is smooth and the loud sucking noise is gone.

All of the bolts are plenty tight, the cold start injector is in there good, the PCV pipe is good, the brake booster line is on and tight. I am going to pull the runner off again and see if the gasket was damaged in installation.

During reassembly should I use RTV on it? I didn't this first time because the original didn't have any of the sort.

Any tips so I won't f*** it up the second time? Any suggestions are great!

 

What engine are we talking about.

 

Sorry I forgot to post that.

The engine is a completely stock 87 L98.

 

Going back to the days when I was young and frisky, I use to have intake manifold leaks all the time. I tried different methods until I finally hit on one procedure that has been fool-proof.

I clean the heads and the intake mating surfaces extremely well to remove any grease, oil etc. I then apply thin layer of Sensor Safe Silicone Sealant on BOTH SIDES of the intake gaskets, around all 8 intake ports and ALL water ports.

I keep the silicone away from the port openings so that it doesn't get squished into the port openings which would interfere with flow.

Use the recommended torque sequence; you'll find it in you Corvette FSM and it differs somewhat from what you may use to doing. Pull the bolts down in several incremental steps, about 10 ft./lbs at a time until you hit 35 ft/lbs.

Let the intake sit for and hour or more, then re-check the torque on the bolts. You'll probably find that some will have lost torque and will need to be re-torqued to 35#.

Keep doing this; waiting and hour or more between each re-torque, until all the bolts will hold at 35#.

I also dimple BOTH China Walls and the corresponding areas on the underside of the intake manifold with a nail set. This gives the 3/8" bead of Sensor-Safe silicone sealant I apply something to "bite" into.

Bingo.

Jake

 

With Jake. Maybe you overtorqued and crushed the gasket? I feel your pain. I hate doing sh*t twice. Good Luck.

 

At least its the top runner. Are you sure you put the right bolts back in the right holes ? If the bolt is too long on that hole it won't tighten down and seat. Just a thought.