phughes69

When I just pulled the exhaust manifold on the 350 to pressure check the manifold, I did not find a exhaust manifold gasket. I scraped the head and the manifold thinking that it was stuck to it and believe me, its not there. On my BBC engine there were manifold gaskets. I never heard any exhaust leaks and I don't see any carbon tracking on the manifold or head. Can this be run like this still or should I put a gasket on it?

SB

iTrader: (1)

Put a gasket on it. Any exhaust leak, especially here, can cause exhaust water reversion.

Mr Maine

Now I'm curious if you have any head gaskets.....? Haha

BUP

iTrader: (9)

how about riser gaskets depending if your exhaust is 2 piece. You need exhaust manifold gaskets. plus any form of an exhaust leak inside the bilge area / engine compartment has harmful emissions.

COOPS

iTrader: (2)

This has nothing to do with boats....working for Dodge many years ago I thought the same thing when a tech told me that they never used exhuast manifold gaskets from the factory on the small blocks. Only after the manifold was removed would you install a gasket. I didnt believe it until I saw it myself.

dereknkathy

on the 350 there are only 4 bolts holding it on. u put manifold on 2 end bolts then drop gasket down between head and manifold. last guy just forgot that step. and with thru hull, it is hard to hear the inevitable leak at the flange.

motor

iTrader: (3)

They always use exhaust gaskets on marine engines...I do know on some cars ,they didn't ...This isn't a car

f_inscreenname

Like motor says, some cars came that way but for a boat motor they used gaskets.

BUP

iTrader: (9)

And I was told that a leaking exhaust manifold gasket can cost you about 15 hp. I will have to check in my notes as to why. I forgot. Again all marine engines have them. The best way to finally prove it to yourself is look up your motor on the parts catalog if it is an OEM marine engine with their manifolds.

Keep in mind the gasket is the seal between surfaces and on marine engines the heat cycling takes a lot longer time to cool down after shut down - not like a car engine where it has outside air helping cooling it down plus a lot more open space and air hitting it underside. On marine engines those longer and wider temps from running to shut down have a bit of metal expansion and contraction. My point is, I have no idea how those manifolds stayed sealed against the heads with out blowing exhaust across. If you ever heard a blown exhaust manifold gasket on a marine app it can be loud.

SB

iTrader: (1)

Leak at exhaust manifold to head can also 'eat' exhaust valves. More common back in the day with ****ty car headers and gaskets not staying sealed.