Heat Riser gaskets

[Grant_West]

I took my boat into theWest Coat Correct Caft this week. Its a Air Nautique with 502 hrs on it. PCM 5.8 GT-40. The service tech (Mark R) noticed that the heat riser's look like they are starting to leak from the outside. He said that this is comon with this motor and that PCM has made 3 differnt versions of heat riser gaskets to try and fix this problem. He said my boat came with the 2nd version of the gaskets and he will install the very latest version. (not under warranty) :???: When he took the heat risers off he noticed that the inner gasket to the heat risers also has started to leak. This is not common and that when the inner gasket leaks it causes water to collect into the cylinder's. This can be very bad. He said when he removed the spark plugs he noticed that there was a bit of rust on one plugs and that told him that there was water in a cylinder at one time or another. They looked in the cylinder and everything is ok no damage but this could have been a much larger problem. if I was to have left the boat unfixed over the winter time, That rust could have built up in the cylinder along with not using the boat in the winter and cause a big problem come spring time when you would start to use the boat again. It was kind of by luck that we caught this problem take a look at you motor and see if the outer gasket is starting to fail. You will know if You can see some rust and water spots where the exhaust manafold meets the heat riser. Thats a good sighn somthing is fishy.

This along with some other things he found might be the cause of my mistrey Motor Quits problem?

[todda]

RE: Heat Riser gaskets

Yep, I had a buddy with another not-to-be named inboard that had his riser gasket fail, and BIG problems came of it. Water in the cylinder being the biggest problem, and not an inexpensive fix. A VERY worthwhile maintenance thing to pay attn too! I have the GT-40 in my 99 SNOB, and I too pay close attn to those little bugger gaskets.

Todd

[M3Fan]

RE: Heat Riser gaskets

I just installed the latest version in my 90 last year. They require no gasket sealant of any kind. They have not leaked one drop. Clearly an improved gasket design.

I'll also say this- I can't tell you how many times I see boats with riser gaskets dribbling rust and water stains down the manifolds. If the gasket is leaking on the outside, it is probably leaking on the inside (which is the part that takes the heat of the exhaust as well). The gaskets cost like 3.00 each and take a half hour to replace. If you are getting dribbles of water on the manifolds, change the gaskets ASAP.

[todda]

RE: Heat Riser gaskets

Hey M3, do you have the part information or number on the "latest version" of the gasket? Just curious, b/c I would like to do some research to see what version I have used for my GT. I just want to be sure that I am using the 3rd generation gasket rather than let a part's person sell me a 1st or 2nd version. Thanks.

Todd

[M3Fan]

RE: Heat Riser gaskets

SkiDim sold me the latest version. They are a graphite compisite of some sort. Quite thick and silvery. Give SkiDim a call and maybe they can help.

[EchoLodge]

RE: Heat Riser gaskets

http://www.skidim.com/prodinfo.asp?number=RM0002

Is this the right one? M3, my 90 has a small rust ring around the gasket but it does not drip. They are the original ones I think. I guess I should change them to be on the safe side!

[M3Fan]

RE: Heat Riser gaskets

That is it. Remember the closed off portion goes towards the back of the boat when you install them. 24lbs of torque. Tighten in a cross-pattern.

[EchoLodge]

RE: Heat Riser gaskets

Thanks for the advice!