Leaking riser Gasket

[freelunch]

Well I found something that I think could be the source of some of my problems. It appears my riser gaskets has failed, is there any way water could be making it back to the cylinders causing my engine to run awful?

 

[Don S]

Re: Leaking riser Gasket

Water will get to the cylinders because there will be water in the exhaust manifold when the engine is NOT running, but it won't get into the cylinders with the engine running.......... The exhaust will push it out.
But it is possible for valves to get rusty and stick, rings to get rusty and stick from the water that gets in the cylinders.
Be sure the manifolds and risers are in good shape. Seldom does just a gasket fail.

 

[HT32BSX115]

Re: Leaking riser Gasket

Absolutely.

I had this very problem with my OMC 460. My riser gaskets had just started leaking due to corrosion where the gaskets contacted the risers and manifolds.

Water will leak back thru the riser gasket into the exhaust system and enter a cyl thru an open exhaust valve. If you're in the water it will happen right after shut down. The amount depends on how fast the water normally runs out of the engine and back into the lake after shut down. (presumably back thru the raw water pump and water pick-up)

If you're running on "muffs" however, the water will keep leaking thru the failed gasket into the exhaust port until you turn off the hose since the risers stay completely filled until you turn off the water.

The engine will seem to have a hydraulic lock when you go to start it later. Sometimes it'll almost seem to have a dead battery or a failing starter since the starter will have a problem getting the offending cyl all the way thru a compression cycle.


Mine did it every time I shut it down and was particularly bad within 30 min of shut down.

If I let it sit longer the water that ran into the engine would slowly leak past the rings and not cause a problem if I started it much later.

If I tried to start it from 20-30 min after shutdown It would crank and stop on the cyl that was filled with water. It usually took 3 or 4 tries to get it to start. It always started.

If it's not the riser gasket it will be either a cracked or rusted thru riser or manifold.

It's something you want to fix as soon as you discover it.



Regards,


Rick

 

[freelunch]

Re: Leaking riser Gasket

Hey thanks for the replies. Rick that makes alot of sence due to the fact i am running it on muffs and when i was trying to crank it over my battery seemed like it was dying or something.

 

[I/O WALDO]

Re: Leaking riser Gasket

Riser gaskets don't corrode.It's the cast iron on each side that goes south then the gasket fails.