470 Mercruiser closed cooling system leak

[Travis Herrman]

I have a Mercruiser 470 with a closed cooling system. I went to fill it with anti freeze and it runs right out the exhaust on the out drive. I am guessing it has a hole in the heat exchanger. I run only in fresh water. Can you by pass that, and not run the closed system and just use the water from the out drive to cool the motor? Thank you in advance.

 

[kghost]

best to pressure check and find leak and fix it.
A standard radiator tester will work.

I have never seen one converted to raw water.

Why would not try to fix?

A lot of rerouting hoses and you would need to remove elbow and change gasket between exhaust manifold and elbow to different style. Its now a block off gasket...

If you can accomplish all the work required to go to raw water cooled, it may be easier to fix.

 

[Travis Herrman]

I was just thinking a new heat exchanger is $1000.

 

[Bt Doctur]

try thinking the riser/exspantion chamber where it bolts to the exaust manifold.That gasket will do the same thing, if it is bad mase sure you install it in the correct direction

 

[Bt Doctur]

 

[kghost]

I was just thinking a new heat exchanger is $1000.

You are assuming you know the cause.
You dont!!

Pressure check system and find leak first!

Then decide next actions.

 

[Travis Herrman]

I was pouring in anti freeze in the fill and it was running out the outdrive. I just figured it was getting to the raw water side in the exchanger.

 

[Bt Doctur]

thats not always the case, heat exchangers would be a slow leak. Go for the bad gasket first