Merc 3.7 riser gasket leaking coolant

[gettin'even]

I found the coolant level on my 3.7 going down each time I ran her, and could smell "burning" coolant, and see some steam from the exhaust. I found coolant in the cylinders/exhaust ports due to a leaking riser gasket. This gasket was replaced by me when I first got the boat a couple months ago. The gasket I used was a Sierra replacement gasket, but is only made of what looks to be a standard gasket material. I have the riser and ex. manifold at the machine shop to be checked for flatness of the mating surfaces. ASSUMING the surfaces are flat, should I be looking for/using a different type of gasket (multi-layer steel?). Does a different type of gasket exist? Any help would be appreciated.


Thanks in advance,
Mark

 

[Bondo]

Re: Merc 3.7 riser gasket leaking coolant

Does a different type of gasket exist?

Ayuh,... Mercruiser's are of a graphite/ carbon composite....

 

[Don S]

Re: Merc 3.7 riser gasket leaking coolant

The gasket I used was a Sierra replacement gasket

Go to your local Mercruiser dealer and get the proper gasket for your engines SN. now that you saved a lot of time and money using the aftermarket stuff.

 

[gettin'even]

Re: Merc 3.7 riser gasket leaking coolant

Go to your local Mercruiser dealer and get the proper gasket for your engines SN. now that you saved a lot of time and money using the aftermarket stuff.

At least I used the OEM head gasket. Anything from here on out will be Merc brand.

 

[sdoomaha]

Re: Merc 3.7 riser gasket leaking coolant

Make sure you reinstall the gasket correctly. Not all 4 channels are open. Buddy reversed this gasket when reinstalling and it took hours of troubleshooting to figure out why it was overheating. Make a mental note or refer to the manual closely so you can avoid the frustration he experienced.

Take care,

 

[gettin'even]

Re: Merc 3.7 riser gasket leaking coolant

A quick update: The machinist @ the shop said the manifold was warped where it meets the riser. The riser surface was flat. He "milled" the manifold and hot-tanked the riser, as the riser is also the coolant tank, which was a little skanky on the inside. He also disassembled, cleaned and reassembled the head. I have the Merc brand gaskets on the way. Thanks for the replies/help.