hi i have a91 l98 that has the following mods added about a month ago 190 afr heads superram complete headers 58mm t.b roller rockers theb problem is thati have gotten aoil leak twice at the rear of the manifold where it meets the block oil will blow out at high rpms was cleaned and perfectlysiliconed and leaked again any help would be welcomed

 

Hmmm...

Several things to check. First, there is a couple of oil gallery passages there. One has a plug in it (almost covered by the driver's side cyl. head) and shouldn't be leaking. Then there's the oil pressure sender port, which is obvious. There should be a gasket under the distributor as well. When you apply silicone, put a healthy, liberal bead on the outside half of the intake/block mating surface, so it seals well. Use High-temp silicone RTV. Put this on the outside half so it doesn't bead up inside the motor, but squishes out to give a good seal. DONT wipe off excess, and let dry al least 3-4 hours. Torque intake bolts immediately to spec in order. This should take care of leaks, if not you have another problem like a leaking oil sender or rear main seal. Make sure it's not the intake before you pull it, though. Check the valve covers? Be sure to change the oil before starting it (AT ALL) because you'll drop coolant into the block, which eats bearings quickly. Good luck

 

Make sure that when you apply the silicon, you put it directly on the block AND the intake. By doing this you will assure that the entire mating surfaces of both the block and the intake will have silicon on them. This method also will remove the chance of any foreign object or substance preventing the silicon from bonding with the intake/block. I have done more SBC/4.3 intake gaskets than I care to remember and I have used this method along with GM RTV silicon (not sure of p/n but, the light grey stuff) on all of them with no comebacks.

Also, make sure your crankcase is venting properly - ie. PCV valve or breathers flow good and aren't plugged.

p.s. I would rather be stuck in the desert with a SBC intake than a canteen since the intake NEVER SEEMS TO RUN OUT OF COOLANT. Where the hell does all of that stuff hide in there????????????????? lol