Quick temperature fluctuation

[Darter]

There's a waxed paper gasket and rubber o ring. Both go on dry. Careful not to overtighten the cover bolts.

If you remove the old and it looks clean, just test it out in a pot of water with an instant read thermometer and put it back in if it is opening as expected.

If it falls apart in your hands like mine did, replace it.

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[flynnva]

Any idea what sealant I need to use?

Any of the auto stores will have Permatex RTV water pump/thermostat gasket silicone. I would always use a thin coating on the housing and intake and place the paper gasket in between.

[5:00]

There's a waxed paper gasket and rubber o ring. Both go on dry. Careful not to overtighten the cover bolts.

If you remove the old and it looks clean, just test it out in a pot of water with an instant read thermometer and put it back in if it is opening as expected.

If it falls apart in your hands like mine did, replace it.

I known I have the paper gasket but don't remember getting an o-ring. Of course it has been more than a few months so it is out of mind. I will take a look. I will see if I can find the torque specs on those bolts. Thanks!

[5:00]

Any of the auto stores will have Permatex RTV water pump/thermostat gasket silicone. I would always use a thin coating on the housing and intake and place the paper gasket in between.

Sold! I will go with that. I worry if there isn't a sealant used unless the gasket has it built in.

[Darter]

If you don't use the o ring, the rtv should be added around the outer face of the thermostat. That's where the ring would go.

There should be a slight channel on the thermostat that the ring lays in.

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[5:00]

If you don't use the o ring, the rtv should be added around the outer face of the thermostat. That's where the ring would go.
There should be a slight channel on the thermostat that the ring lays in.

Will do and adding extra characters.

[5:00]

Any of the auto stores will have Permatex RTV water pump/thermostat gasket silicone. I would always use a thin coating on the housing and intake and place the paper gasket in between.

I know these are milled parts but it always makes me nervous not using a sealant.

[JamesEvans]

Wish my temp gauge worked. Never moves. Think the guage is bad as I have grounded the sending unit wire and still no movement. New thermostat end of last year and impeller this year and haven't run it in the water yet, just in the hose.

Used a thin layer of rtv on mine.

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[5:00]

I’m too paranoid to run like that. I had a clogged sea strainer once. Since then I have eyes on that gague constantly.

[DOCDRS]

Change your tstat and impeller. If you just bought the boat you have no idea how old they may be. In cold water and running the tstat does not need to be open much to maintain temp. Then when you idle down with all the extra cold water flowing thru the tstat housing the tstat may remain barely open while the block can act as a heat sink sending the block and temp sensor upward. With low idle impeller flow it can take 10 or more secs depending on impeller flow to get enough water in to cool the block. If this is the case a new impeller and or tstat may be the first things to freshen up. If you find it creeps up after bringing the boat to idle after med to fast run, rev the engine in neutral and the temp should come back down in a couple of seconds.