Exhaust Riser Gasket Question

[BAproject]

I have placed a few posts about an engine that is running too hot. I am still puzzled and will be replacing the lower unit impeller this afternoon. I have also replace the t-stat, circ pump, hoses, and exhaust risers. Still can't figure out why running so hot (idle 175 with a 140 degree t-stat), creeps to 200 degrees under load. Did it once, shut it down and got towed back in so I didn't cause any major damage. Run off muffs int he driveway for diagnosis now

When I replace the exhaust risres there were 2 different styles of gaskets that can be used int his system (this is raw water cooled btw). The lady at the boat place gave me the gasket that has 1 large opening in the center, 2 openings (1 on port and 1 on starboard side) and then the holes that are front and back are just very small holes. She explained this is the gasket for a system that doesn't use 4" extensions off the manifold(I don't have these). I'm not sure I believe her.....

I'm really not sure why there are 2 different styles, but could this be the reason for an overheat? Are these wrong gaskets? I have the manual but it's not clear

Puzzled....still!

-BAproject

 

[Don S]

Re: Exhaust Riser Gasket Question

Here is the service bulletin on what gaskets to use.

I notice in your original post you never mentioned anything about replacing the raw water pump impeller in the outdrive, did you? That should have been the first thing you checked.

 

[BAproject]

Re: Exhaust Riser Gasket Question

Hey Don S,

Thanks for always chiming in and helping out, much appreciated!!!
I am replacing the impeller today, I'm just gonna replace the entire thing, housing etc....I thinkt here are more issues then that though.

The gaskets I used seem to be the correct ones, if I reading the bulletin correctly.

I had a friend (who is a part time boat mechanic) help install the risers. He actually cut the gasket so the forward hole was actually a slot slot, but the aft hole is still the 1/8" diameter hole. Anyone know what this will do to the cooling systems?

It seems the cooling system is pretty sensitive and wondering if this will have an adverse affect on cooling.

-BAproject

 

[Don S]

Re: Exhaust Riser Gasket Question

Change the impeller/raw water pump, and put in the correct gaskets, then see if you have problems.
When you do run it, take some temp readings at the temp sensor with one of those temp IR guns. Just to make sure you don't have a sender or gauge problem.

 

[BAproject]

Re: Exhaust Riser Gasket Question

Hey Don....

Yes I did this and the temp gauge is off by 5-10 degrees (when pointing the IR temp gauge at the temp sender), but more importantly the gauge steadily climbs....and even the with the 10 degree differential it is still too hot.

I also took some other readings around the engine to look for obvious points of concern.....

See link post #22

http://forums.iboats.com/showthread.php?t=428220

BAproject

 

[crazy charlie]

Re: Exhaust Riser Gasket Question

Always start at the impeller/water pump when there is a cooling issue.Always . Charlie

 

[BAproject]

Re: Exhaust Riser Gasket Question

yep....got that and did that!

It was actually way easier then anticipated!

Of course it didn't solve the problem though