Q about thermostat housing seal

guy48065

guy48065

Chief Petty Officer
Joined
Aug 31, 2008
Messages
558
2000 4.3L Mercruiser.
I'm replacing the thermostat.
After scraping & cleaning the surfaces I installed a new O-ring, Tstat, oem plastic spacer, gasket (with metal rivets). I carefully centered the Tstat but when all stacked up the white plastic spacer sits proud of the gasket at least 1/16“.

Assuming the O-ring would squish down I tightened the housing in place. Nope. I can still wiggle the gasket up & down after tightened.
If I stack on another gasket I'll lose the rivet ground connection because the Quicksilver kit only came with 1 of those.

What an I doing wrong?

20251009_170907.jpg
 
Bondo

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
71,330
guy48065 said:
2000 4.3L Mercruiser.
I'm replacing the thermostat.
After scraping & cleaning the surfaces I installed a new O-ring, Tstat, oem plastic spacer, gasket (with metal rivets). I carefully centered the Tstat but when all stacked up the white plastic spacer sits proud of the gasket at least 1/16“.

Assuming the O-ring would squish down I tightened the housing in place. Nope. I can still wiggle the gasket up & down after tightened.
If I stack on another gasket I'll lose the rivet ground connection because the Quicksilver kit only came with 1 of those.

What an I doing wrong?
Click to expand...
Ayuh,...... Obviously, there's a problem with the white spacer, pull it apart, 'n see why it sits in the housing so tall,....
I'm guessing the problem is 'round the o-ring, or housing itself,.....
 
guy48065

guy48065

Chief Petty Officer
Joined
Aug 31, 2008
Messages
558
I got it sorted.
My service manual shows an O-ring under the Tstat. When i looked closer at the nasty flat thing that I took out I saw it was cork. My kit came with both so I put in the new cork ring and the spacer was the 'correct' height--just a few thousandths higher than the gasket so the cork will get squeezed.

20251009_163053.jpg
 
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