Curing L98 Tuned Port Intake Leaks - Stop The Seep

Up to 1988, the L98 used a cold-start injector to richen the fuel ratio, much like a choke on a carbureted engine would. This will have to be removed as well.

Now the fuel injector rails can come out.

Since the EGR valve is hidden under the plenum, this would be a great time to check it for proper operation with a vacuum gauge. If it will not hold vacuum or doesn't operate when vacuum is applied, replace the valve.

Clean up any coolant, crud, or foreign matter before you start loosening the bolts for the intake.

The intake bolts are T45s. Remove them and carefully pry the intake off the engine.

Put some clean shop rags in each of the intake runners in the heads, and lay down some rags in the valley area to prevent any debris from getting into the engine. Now you can safely clean the head and block mating surfaces in preparation for the new gasket. Once again, keeping foreign matter from entering the engine is essential. Also, this is a great time to clean up the intake and runners.

Tap all the holes and clean the threads on the bolts because all of the intake bolts will need to be coated with Teflon sealant; any old sealant left could result in an improper torque reading.

Make sure the sealing surfaces are clean. That includes the bottom side of the intake as well. Use a parts cleaner to remove any grease.

We used Fel-Pro gaskets (PN MS93318) for the intake. The kit does not come with a new EGR-valve gasket so be sure to get one. We used a silicone gasket from a tube for the intake/block mating surfaces. Be sure that hot oil does not affect the silicone. There is only a five-minute maximum window before the silicone skins over and will need to be redone, so don't put on the silicone until you have the intake ready to go back on.