View Full Version : thermostat and gasket for 1973 350ci OMC

08-03-2009, 11:48 PM
I would sincerely appreciate any advice and/or leads you can give me to find the proper thermostat and gasket for my vintage Mastercraft.

This is my first posting - this seems to be the best MC forum on the web - thank you for putting this together!

I am a new Mastercraft owner. I purchased the boat that I have been lusting over for decades.

The first task at hand is the engine temprature, which according to the gage is hovering only about 100 degrees. The other postings on this web forum indicate that the temp should be more like 160 degrees.

I pulled the thermostat last night and I found that it was a Delco 143 degree thermostat - it looks just like one I would find in a car. This thermostat is open just a crack, hardly enough it seems to keep the engine from heating up.

The gasket also appears that it will be hard to find. It is large enough for both the thermostat and a large check/one way valve (about the same size as the thermostat) that I think is intended to keep the waterpump full when the engine is not running. If I did it correctly, I uploaded an attachment to this posting to show the outline of the gasket.

I am located near St. Paul, Minnesota. My local dealer, Midwest Watersports, could not help me.

Thanks, Rick

08-03-2009, 11:53 PM
Try www.skidim.com

They have a lot of parts for PCM engines. Plus you can call them for free technical advice or any problems you might have.