Thermostat cork gasket

[Bignev2]

Hi guys,

I replaced my thermostat on my 5.0 tks, housing was heavily corroded
Had to soak it in penetrine and use some decent force to get the sleeve and thermostat out.

When I used the cork gasket he sleeve would not sit flush , I tried a fair bit even put it in a vice and used a block of wood to try and force it down.

So I left it out for now and just used the sleeve and housing gasket with the metal prongs.

Seems to run OK but the cork gasket essential for some reason?

 

[Bignev2]

There was no cork or gasket at the top of the thermostat so confused whether my motor needs one.

I replaced the thermostat because the previous owner did not install the gasket with the metal prongs so my temp sender was not grounding. It works now

 

[Fun Times]

In this video you ought to be able to just see the how the plastic sleeve sticks out just a bit to where it’s not sitting flush from new,

Thermostat and Housing

Thermostat and Housing

www.mercruiserparts.com

 

[j cat]

There was no cork or gasket at the top of the thermostat so confused whether my motor needs one.

I replaced the thermostat because the previous owner did not install the gasket with the metal prongs so my temp sender was not grounding. It works now

replace the t stat every year or inspect it ....... flush out the engine in the fall ..clean it interior coolant system..

 

[Bignev2]

replace the t stat every year or inspect it ....... flush out the engine in the fall ..clean it interior coolant system..

yeah will do only had the boat a year just done spark plugs and fuel filter.

Only reason i changed the thermostat is because the temp gauge stopped working and had the wrong gasket installed by the previous owner.

What's strange is there was no top cork oring on the top of the thermostat at all, hence why I'm asking should there be one.

I have an infrared gun and nothing seemed to get higher than 70c, the temp gauge goes to a quarter or just above when ran for awhile. Beforehand it didn't work at all.

 

[Bignev2]

In this video you ought to be able to just see the how the plastic sleeve sticks out just a bit to where it’s not sitting flush from new,

Thermostat and Housing

Thermostat and Housing

www.mercruiserparts.com

Thanks was just confused cause there was no cork gasket when i took the old one out, seems to run ok without it. i have a infrared gun and was checking thermostat housing, manifolds etc

I Will take it apart and try and fit it again.

 

[Drcoffee]

When I changed mine last summer, I put in the cork gasket and the plastic protruded from the housing. Almost looked like it bent the lid when I tightened it down. So I removed it. I just used the t-stat, plastic part, and seal under the lid. Runs fine

 

[Bignev2]

When I changed mine last summer, I put in the cork gasket and the plastic protruded from the housing. Almost looked like it bent the lid when I tightened it down. So I removed it. I just used the t-stat, plastic part, and seal under the lid. Runs fine

Yeah seems to be running fine and no leaks just wasn't sure.. don't
really want to take it apart again haha.

 

[tailwind 67]

Hi guys,

I replaced my thermostat on my 5.0 tks, housing was heavily corroded
Had to soak it in penetrine and use some decent force to get the sleeve and thermostat out.

When I used the cork gasket he sleeve would not sit flush , I tried a fair bit even put it in a vice and used a block of wood to try and force it down.

So I left it out for now and just used the sleeve and housing gasket with the metal prongs.

Seems to run OK but the cork gasket essential for some reason?

There seems to be a couple of different thermostat housings Mercruiser used, which each use a different sleeve and component build up order.
I was curious of the same issue. I just built up a 5.7 and was hoping to find a closed cooling system, but they seem to be impossible to find through every source I tried. I decided to go with the existing raw water cooled set up. The brass sleeve goes in to the housing first with the turned in lip at the top. Then the cork gasket goes on that, then the thermostat. The picture I seen, also called for a stainless steel separator plate, sandwiched between two gaskets between the thermostat housing and the thermostat cover. I don't have a ss seperator plate, and in the pic it appears to be the same shape and cut out as the gaskets. If you build it up this way, with the sleeve first, then gasket, then thermostat, you will find it fits.
My sleeve was originally upside down without the gasket, and on top of the thermostat. This build up conifig is for the plastic sleeve with the cut-out. (using the gasket under the thermostat).

 

[achris]

Unless you're winterising (and filling with AF through the T-stat housing), there is no need to annually inspect the t-stat. I've replace my thermostat about 10 years ago, and haven't looked at it since....

Chris...

 

[achris]

When I changed mine last summer, I put in the cork gasket and the plastic protruded from the housing. Almost looked like it bent the lid when I tightened it down. So I removed it. I just used the t-stat, plastic part, and seal under the lid. Runs fine

It's suppose to do that. As you tighten down the housing screws, it pushes the plastic part up and compresses the cork gasket, and seals it...

Chris....

 

[tailwind 67]

Unless you're winterising (and filling with AF through the T-stat housing), there is no need to annually inspect the t-stat. I've replace my thermostat about 10 years ago, and haven't looked at it since....

Chris...

You must be on fresh water. Salt water raw cooled engines have a tendency to seize the thermostats closed. After removing mine this last time, (it had been in several years) I will probably open it when winterizing, and clean it up.

 

[achris]

You must be on fresh water. Salt water raw cooled engines have a tendency to seize the thermostats closed. After removing mine this last time, (it had been in several years) I will probably open it when winterizing, and clean it up.

Nope, salt, always salt. We don't have any fresh water bodies large enough to run a boat on.

And Merc genuine thermostats fail open...

 

[tailwind 67]

Nope, salt, always salt. We don't have any fresh water bodies large enough to run a boat on.

And Merc genuine thermostats fail open...

Ok. Interesting to note. I believe mine are seized closed due to the long hibernation allowing rust to form as they are put away for the winter with the engine cold, thermostat closed