do we have a resident expert on Mercruiser 3.7 and a alpha 1 gen 1

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Dodgy Diver

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im fully aware that they are not the best things to have ,, but thats what I have got , if I could find a replacement then I would , but I cant find any options with out having to sell all 4 kidneys

so , I have got it running well after being stood for 2-3 years , carb clean and new plugs and its off

from there it all goes a little wrong , I need to re weld the manifold as I missed a bit and it has a tiny hole still

but the out drive has new impeller and housing fitted by me . with the water er muffs on and water running im not getting much coming out of where I assumed it would , ir prop or exhaust hole
but its leaking where the lower and middle part join

what if anything have I done wrong
also is there a tell tale like a outboard any where

many thanks for any help
 
ive pulled the lower part off again . I have checked the impeller is going the right way
also measured to check that the pie from the mum is a nice tight fit uo to the top part

thanks
 
So I’ve read installed the unit. I have water coming out of the prop centre when running.

A little from the 2 holes in the top swivel where the exhaust exits also.

I don’t think the small pipe was seated right from the pump.

A tiny drip from where I welded the manifold so need to deal with that today
 
It definitely has a circulation pump, its behind the top pulley at the front of the block, it circulates water until the thermostat opens then the hot water in the block moves out into the heat exchanger if you have one ( long cylinder low down on port side of block) if not fresh water cooled then the hot seawater goes out through the manifold and new seawater comes in. The temp should be around 80C if you have a heat exchanger and the exchanger should get warm as the coolant circulates.
 
spannerman said:
Yes it has
It definitely has a circulation pump, its behind the top pulley at the front of the block, it circulates water until the thermostat opens then the hot water in the block moves out into the heat exchanger if you have one ( long cylinder low down on port side of block) if not fresh water cooled then the hot seawater goes out through the manifold and new seawater comes in. The temp should be around 80C if you have a heat exchanger and the exchanger should get warm as the coolant circulates.
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Yeah it has the heat exchanger as you described.
But there is no top pulley. Only bottom pulley and a alternator.
That’s all the belt does.
I’m assuming it must be internally driven
But how do I check it’s working. Any thoughts please.
 
the water pump is apparently driven by the cam shaft and site behind the timing cover

I bet thats a arse to change

im beginning to wish that I hadn't brought this tub

but im to bloody stubborn to be defeated. ( I hope )
 
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