The Stovebolt Site Forums The Shop Area Engine Shop 235 intake manifold gas leak

Have a gas leak from both intake manifold ports . Just took it out of storage and drove about 100 miles. Strange to see it coming out of both intake sides and down the block. Thanks for input.

A 235 would have three intake manifold ports. Sounds like your leaks on on the two side ports?

The manifolds might need to be planed by a machine shop, but I would first try new manifold gaskets. At that time see if the mating surfaces of the intake/exhaust manifolds are level to each other - place the mating surface on a flat table-top (or, against the head) and see if all surfaces mate properly.

There are alignment rings for the intake manifold. They are sometimes missing. They do not make a seal but if too much material has been taken off the manifold's mating surface, those rings can cause the manifold to leak (the rings would then need to be made thinner in depth).

If gas runs out the manifold when you shut it down you have a serious carb. flooding problem. A leaking intake gsaket will cause poor running & bad idle but there shouldn't be any gas there after shutdown.

Just to add to this discussion, a properly installed intake gasket will not stop liquid gasoline from running out. You must have a flooding problem and it could result in a nasty fire.

Have taken off the manifold and have a new set of gaskets.Ordered a set of alighment rings. Will check to see if the float is sticking. It seemed to idle fine and it actually ran quite well. Any additional input would be greatly appreciated.
Other than a stuck float what may cause flooding?Only leaked slowly when running.And the threat of fire made me lose sleep.

FYI- I used Marvel lubricating oil about 6-7 times , just cracked the bolts a touch, more Marvel yesterday and this morning and the manifold screws came out very easily. They didn't seem to tight.

When a needle valve is leaking a bit at idle, the engine is gulping the extra gas. When it is shut down, there is pressure there until is leaks off but there is nowhere for the gas to go since the engine is not running. It therefore runs down into the manifold.

Sometimes a small adjustment in the float height will do the trick. For slight flooding, moving the float level down a bit to lower the level may fix the problem.

Much thanks to all who gave input. New gasket, cleaned needlle valve, adjusted float from 1 1/2" drop to 1 3/4" as manual indicated as did some of you, drove about 20 miles today and no more gas leak, thanks again, truckernix,Wrenchbender Ret.,tclenderman and the Stovebolt site.