Thermostat and exhaust cover

[grouper242]

Hi all,

Yamaha 4hp 2 stroke (4ac)

Ran it yesterday after 9 months storage and the tell tale was flowing but unusually hot.

I removed the thermostat and found it gunked up and stuck closed. Soaked it in vinager and it now opens in a pan of hot water.

As it is within the exhaust plate, do I need to use a gasket sealer with the new exhaust gaskets or fit them dry?

Thank You!

[grouper242]

One more thing, marine grease or permatex aviation sealer for the exhaust bolts?

[grouper242]

Anyone have any suggestions? Thanks

[Captn Dave]

I would replace the thermostat.
I always left the gaskets dry.
I like to use grease on the bolts.

[Jason2tpa]

I install gaskets dry, never had an issue. I grease every bolt secured to any part of the engine. All bolts secured in the block I use perametx anti seize lubricant.

Just a heads up....the corrosion you see in the stat housing is a very good indication of how the passages of the cooling system look.

[grouper242]

Alright thanks all. I was surprised at the corrosion as I flush the engine every time.

I have removed all the gasket I could with a plastic scraper and brake cleaner, can I use a razor blade to get the rest of the residue or leave it on there?

[panasonic]

Yes you can use a razor blade to remove the last bits of gasket material...But it needs to be done with care. Keep the blade at a very low angle and shave the bits of gasket off a little at time. If you use to high of an angle the blade will dig in and scrape the soft aluminum...Finish off with some green or red scotch Brite.

[panasonic]

As for the gaskets...I always think what will be the easiest thing to remove the gasket from if I have to remove the component again....which is usually the case or the cover...not the block.

This is how I go about it. I put a very very thin coating of gasket maker on the side off the gasket that I WANT it to stick to..the cover in this case. Put the gasket on the cover, housing...ect Then I put a small amount of oil on the dry side of the gasket...just enough to wet the paper slightly. Install the cover. If you need to remove the cover again in the future the gasket should come off with the cover and not stick to the block...A lot of times the gasket will be still in good condition and can be used again. Think thermostat covers which are removed frequently...