Thermostat Plastic Sleeve Tab Broke - Where did it go?

SeaRay

Member
Sep 12, 2007
239
Iowa
Boat Info
1999 Sea Ray 210 BR
Monster Tower MT2
Engines
5.0L EFI
Bravo Three
I was changing my thermostat (Mercruiser 5.0L EFI) and noticed that the skinny tab on the plastic thermostat housing sleeve had broken off.

Not sure when or how it broke, but I think it was missing as soon as I opened it up. I looked and did not see anywhere.

Where could this have gone?

What if any damage might it do?

Can I get it back out?

Thanks in advance
 
Most likely it has begun its journey through the cooling system.
How far? Who knows.

You could try removing the large hose between the thermostat housing and water pump/drain manifold to see if it’s in there.
 
I looked a little bit closer at the plastic right where the tab broke off. It is dirty, so it has been broke for awhile. If I broke it off while taking it apart, I would expect that it would be a cleaner white.

I am not sure how the water pump(s) work on this engine. I have a Bravo 3 out drive, and I know I have a water pump at the lower front starboard side of the motor (sea water pump?? I have replaced that impeller several times). Is there another water pump that is part of the engine? And is the thermostat upstream or downstream of the water pumps?
 
The engine water pump (circulating pump) is just like you’d see on an automotive engine. It’s the pulley right above the crankshaft pulley.

Cooling water is pulled into it through the large rubber hose and pushed out to both sides of the block where the pump attaches to the engine block itself.
 
So, is it probably safe to assume that this little plastic tab is not going to do any harm???
I am assuming it broke off in the spring when I put the thermostat in the housing and it has ran fine all summer....??

I will replace the sea water pump in the spring, but I believe that is downstream of the the tab anyway - correct?
 
It probably won’t do any harm, but nothing is definite.

It could be pushed off into a harmless corner somewhere or possibly even make its way out through the exhaust someday.

The sea water pump is upstream from the thermostat, I would think it impossible for the tab to make its way against the flow and move toward the sea water pump.
 

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