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Mercuiser 3.7l 165 coolant leak issue

elcapitainnate

New member
Hello everyone,

I was wondering if anyone had any experience on bypassing the stock coolant pump on a 1987 mercuiser 3.7l. my waterpump is leaking through the weephole, and I have seen quite a bit online regarding these motors and that the dual cam seal can leak and cause issues.

has anyone had any luck installing a belt driven pump to replace this and just pulled the impeller off the stock unit to prevent damage?

thank you for any information you can provide!

Nate
 
Get it fixed,
Remove the pump and replace the seals.

No side stepping the repair with a work around
 
kghost, thats good and all, but as parts for these engines become more and more limited, I am not just trying to find a work around, but trying to re-engineer this large design flaw into something that will be more reliable and easier to service in the long run. I have a full service machine and fabrication shop at my disposal (as i run the shop) and know that they do not make the timing cover/waterpump assembly anymore and would rather replace with something modern, rather than putting band-aids on a poor design.

if no one here has done this, i will happily move forward with my own designs and will keep you all updated as to how it is done once functional.

Thank you!

Nate
 
The pump that you are referring to is your camshaft driven engine coolant circulating pump.
You cannot use a seawater water pump for circulating coolant!


Do as suggested, and tear into it and replace the seal.

.
 
I would suggest looking for a few dead 3.7's
There are thousands lying around and try to get a good cover and replace the seals and be done with it.
 
Thanks guys for all your answers. I guess I should say, I actually know a ton about this engine. I’m not asking how to fix the leak, as I know and can explain the whole process of how to uninstall and reinstall the cam mounted water pump from heart. What I am asking is if anyone else has gotten fed up with this poor design and re-designed this to work with a crank driven belt Water pump, similar to every other engine around. From a design stand point I see a lot of good in the engine, but this piece is a huge fail point, especially if pushing the engine harder than really designed for (currently getting the deck milled and will be rebuilding the motor from the ground up with all forged internals custom made at my shop.)

As I said in a previous post, just looking to know if anyone out there has done this before and has any tips or things I should be on the look out for.

again, thank you to all who answered.

Nate
 
To answer your question..... NO

Never heard or seen anything like you describe.

I guess I dont understand your issue with repair.
I have done a few of these and its not that difficult.
Some i did as preventitive maitanence while doing a timing chain replacement.
 
Not an issue with the repair, issue with design as a whole. Plus if I chose to get a custom cam made and run the engine at a higher rpm, I will want a higher flow pump than what that offers.

Well if anyone other than Kghost has any thoughts Id happy discuss this with anyone else wishing to do the same.
 
If you want more power/rpm and you are considering a different cam...

Good luck.

Sh!t can that piece of crap and move up ro the 20th century...
Not even the 21st.... ugh

A V6 is far superior in every way and dosent have much bigger foot print.

You may claim to know most everything thing to know about that engine but it is a waste of time.
If you over rev it you will most certainly loose a connecting rod either at the crank or pistion.

Anyway best of luck.....
 
Not an issue with the repair, issue with design as a whole. Plus if I chose to get a custom cam made and run the engine at a higher rpm, I will want a higher flow pump than what that offers.

Well if anyone other than Kghost has any thoughts I'd happy discuss this with anyone else wishing to do the same.
:)

All due respect...... perhaps you are not quite understanding the difference between the engine coolant circulating pump and the seawater pump. The circ pump is engine located, whereas the seawater pump is located in the lower gear unit.

And I agree....... you will not only gain very little by installing a more aggressive camshaft, this engine has it's limits.
This engine is similar to that of a slow fused stick of explosives.


But I digress....... using a more aggressive camshaft would not require any changes or modifications to the coolant circulating pump, nor would it require any changes to the seawater pump.


Short of the camshaft/circ pump oil/coolant seal doing double duty, and short of the front covers being prone to warpage, I would fix what you have and run it until the fuse reaches the explosive package!



.
 
Many years ago, when I was even dumber than I am now, I almost bought a boat with TWO of those losers in it!

Look for a V-6 or, if you can't find one, a 3.0 liter four cylinder. They aren't as powerful as the 3.7 (when they are running) but close enough--and they run great!

Jeff
 
I wonder where a new cam could be purchased.
This is a custom and unique block designed only be Mercruiser.

So even thinking of doing so may not be possible in the end.

To have one made...............I would rather fix the seal issue and be done with it.

This engine is a piece of crap and no amount of lipstick will make it any more reliable or powerful.
 
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