1986 merc 260-heat exchanger

[samm835]

Can a bad heat exchanger make your motor overheat? Rather than buying a new one, can an average radiator shop fix/rebuild one? I heard you can by-pass and make my motor no longer closed cooled (50/50), is that true?

 

[nola mike]

Can a bad heat exchanger make your motor overheat? Rather than buying a new one, can an average radiator shop fix/rebuild one? I heard you can by-pass and make my motor no longer closed cooled (50/50), is that true?

1. Yes. You should inspect yours, flush it.
2. Yes, depending on the problem.
3. Probably, since plenty of 'em didn't have closed cooling. Not sure what parts you'd need though.
What specific problems are you having? Why do you think it's the HE?

 

[samm835]

It's an 86, and I have been going through the motor to find why its overheating. I am going to pull the tube that comes from the transom to check water flow tomorrow, but I'm thinking ahead. Btw, replaced foot impeller and water circulating pump recently.

 

[Scott Danforth]

you are pulling the end caps and inspecting every year like the manual states, correct?

if not, pull the end caps and clean the crud out of the tubes. simple 5 minute operation.

yes, any good industrial radiator shop can make the heat exchanger like new for very little money

you can remove the heat exchanger, remove the existing thermostat housing, get the thermostat housing for a raw-water cooled motor and replumb your motor to a raw water cooled version. will require a bunch of parts. I wouldnt do it, I would simply perform the maintenance required on your current system, which is an anual inspection of the heat exchanger for fouling (debris in the tubes). most likely the first section is plugged solid with sediment and rocks.

if you need to rod out the tubes, us a 3/16 diameter aluminum rod with the end rounded over