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Thermostat Housing--Refurb?


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Attached are pics of the original 6-hole thermostat housing from a 1993 Comp Skier 350 5.7 mercruiser. The thermostat itself looks like the original since it's frozen in. Piping has typical saltwater inner blister rust. Sea boat with not enough maintenance.... I took one of those O'Reilly boroscopes and the internals are clear, not pretty but clear with no obvious flow blockages.

It is toast? Has anyone repaired such a critter? Refurbed by someone? Can you blast and dip into some magic coating(s)? It is one impressive part.

Having the water temp gage and alarm senders opposite sides right in front seems cool to me too. You sure know what part of the system you're measuriing temp on. Just toss, I mean?

I think this housing is NLA, and there is another design that can be hooked up close to the same way, I hope. I'm trying for aftermarket new parts.

If anyone knows the right substitution, please tell me.



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This guy's shop is up the street from my work.

Maybe he should get into marine T-stat housings? You could ask them.

Nice stuff! Thanks.

Actually I have one of those types of billet housing "outlets," for cars usually, on the other boat having a 305 chevy Indmar marinized engine. This was only made possible though after I installed a 1/2 cooling heat exchanger, which got rid of the oringinal housing, which IMO was a lot simpler/compact design than the oringinal mercruiser beast of a housing I'm dealing with now, which is probably more convoluted because the raw water pump is located so strangely...where everything needs to come off to simply inspect the impeller--haven't done that yet but considering PO's other stories will need to do so before splashing. I would love to mod that if anyone ever has and knows a good way...now's the time.....

Anyway, I contacted LighthouseMarine and ordered the compatible "new design" housing for about $210 (see link) requiring one specially molded hose that cost $30. Hard to fab a 6-hole "octo" housing for that price using any material...


I will try the Bradley T. vinegar rust removal method on the removed housing for the heck of it....and doubt it will with so much blistering etc.--will provide results afterwards--but WTH, I might just have an extra OEM housing that someone might want. But first to try....

Edited by malibuparadise
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