L98 Intake Gasket Orientation
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L98 Intake Gasket Orientation
Looking in the 1989 FSM and it states: “Blocked openings in gaskets to be positioned at FRONT of engine.” This is interesting to me since all the posts I have read stated that the blocked openings face the rear ports. Is this a typo in the manual or is there some misinformation out there ? It honestly makes way more sense that the fronts would be blocked. I have never seen, nor serviced, nor heard of an engine with the rear coolant flow restricted. I mean the rear of the engine needs maximum coolant flow since it’s farthest from the water pump. I have been scratching my head all day trying to understand how severely restricting flow at the rear accomplishes anything except trapping coolant in the heads. This may explain why I read a post of someone replacing their intake gaskets and nine months later had a blown head gasket on Cyl. #7. Idk, I could be talking foolishness here, but regardless, it says blocked openings go to front of engine. EDIT: Ok, so after looking at many, many photos of TPI intake manifolds, it looks like iron head engines have no coolant crossover at the rear of the intake and aluminum head engines have a coolant crossover at the rear. Again, I could be totally wrong about all this, but the photos jive with having the rear ports open and the FSM stating so.
John
John
Last edited by jv_72_jv; Sep 6, 2018 at 01:49 AM.
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I've always thought, the blocked openings, or blocked/restrictive passage, are at the rear of the intake. if the FSM states the opposite, IMO, something's in error. one note - about 50% of the folks install manifold gaskets open on both ends - such as in 1985. when I did my 90's intake, I installed 1985 style fel-pro's and did not notice any cooling issues. seems to me, that most aluminum head L98's blow head gaskets around the #7 and #8 cylinders - right where the coolant is restricted. then there's the issue with the "steam" tube - "STEAM" - are you kidding me? if the engine running hot enough and needs to vent steam, IMO, something's not right. 
Last edited by Joe C; Sep 6, 2018 at 07:51 AM.
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I could see the open / original style gaskets working okay, but restrictor style installed backwards could be an issue. After looking at countless photos of L98 intake manifolds and L83 intake manifolds, it looks like some crossfire intakes had a crossover of sorts at the rear and some didn’t, just blind recesses, so idk what to think. I guess I’ll see when I pull the intake off. I have a receipt from the dealer from 1991 and they resealed the intake due to an oil leak with only 6,300 on the clock. EDIT: I just read a post about a TSB stating that the FSM was incorrect and that the blocked openings actually go towards the rear. After looking at a coolant flow picture of a SBC the water pump pushes the coolant towards the back of the block and then up through the heads, returning to the thermostat crossover area at the front, so the restrictions at the rear make sense now. I was totally wrong and now I know.
John
John
Last edited by jv_72_jv; Sep 6, 2018 at 12:33 PM.
