1987 Mercruiser 260 5.7L - purpose of thermostat sleeve

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Blueghost924

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After carefully rebuilding the top end of my 1986 Mercruiser 260, it purrs like a kitten. During rebuilding, I replaced the lower thermostat housing with a new one with all new internal parts and thermostat. The old lower housing (which was there from the previous owner) didn't have a solid metal thermostat sleeve (Mercruiser part # 23-47508T). Naturally, I ordered and put a new one inside my new lower housing.

Out of curiosity, what's the function of this solid metal sleeve (besides holding down the thermostat). I was initially worried that the metal ring, being solid, would block a couple of flow passages.
 

Bt Doctur

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The sleeve used depends on the thermostst housing being used. the brass sleeve does not have the cutaway for the water to go to the riser
 

Scott Danforth

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the sleeve, whether it is plastic or copper is to move the thermostat into the proper position so that the exhaust manifolds always get water flow and the engine temp is controlled by the thermostat.

it is designed with a notch to orient it in the correct location.

material depends on which company was supplying Mercruiser at that time.
 

Blueghost924

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Thanks for the replies. I have design #1, and I had the ring in there at first, but it being solid piece I removed it. I was worried about the fact that the ring is solid with no opening for flow. Would this be a concern? If so, I can modify (cut) appropriate sized flow areas into the ring before putting it in permanently. If there's no concern with blocking flow with it being solid (no cutout or notches), I'll put it in permanently.

thermostat 1.JPG thermostat 2.JPG
 

alldodge

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No issue, its designed to be solid. The square hole in your top pic is where small amount of water transfers until the thermostat opens.

Some old pic for flow design



GM 228 cooling.jpg
 

JoeRJGR

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All,

Last year my uncle gave me his 1984 CC Scorpion. Its powered by a 260 Mercrusier I/O. I ran it last season and it never got up to temperature, but otherwise ran fine. Long and short of it the thermostat was stuck open. Also, there was only about 3/4 of the copper sleeve left, the rest was gone. There was no gasket on top of the thermostat as in picture 1. I bought a new thermostat and copper sleeve, but the sleeve did not slip in easily. The housing was pitted, so I sanded it down until the sleeve would go in, but if I put the cork gasket on top of the thermostat and then the sleeve, the sleeve sits a tiny bit higher than the housing...(see attached). I actually put the old thermostat in to check its height, but it sits the same way.

So my questions are, 1.

1. Is the cork gasket really necessary?
2. Is it suppose to sit a little higher and will the top of the housing push it down once bolted in place?
3. Do I need to clean up the inside of the housing so the sleeve sits a little lower?

Thanks for your help!

(I know the sleeve is all buggered up....I originally tried to tap it into place and then couldn't get it out..)

Sorry, couldn't get the photo smaller than 2 mb...
 

jbcurt00

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So my questions are:
1. Is the cork gasket really necessary?
2. Is it suppose to sit a little higher and will the top of the housing push it down once bolted in place?
3. Do I need to clean up the inside of the housing so the sleeve sits a little lower?

Thanks for your help!
Start a topic about your 260 Mercruiser

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