Heat exchanger corrosion?

[RT Firefly]

Greetings,
Mr, H. Atta boy! Keep that cursed RTV off your boat. Sorry Mr. r. A few too many really bad experiences with silicone in a past life.

 

[GB32Patience]

Fully agree with all the above but will also add what is probably a given if you have the two end caps off. Get down in there with a flashlight... you should be able to see end to end on all the internal "tubes" a hose with some pressure and some piano wire will flush out the "dark" ones. I had a slight overheating issue on my Lehman120 at sea trial that was cleared up this way.

 

[grahamdouglass]

Getting fresh water hoses off of the heat exchanger

I have a 1979 Lehman 2715-E. Time to clean my heat ex-changers. I last did it in Dec 2009. I don't remember any thing remarkable in taking the heat ex-changer out of the boat and pouring a Draino mixture into the heat ex-changer to clean out the heat ex-changer. I re&re'd the tranny and oil ex-changes.
This time I can't get the hose off of the engine side or heat ex-changer side with out destroying the hose. I guess I should have used pipe dope.
I'm thinking of leaving the heat ex-changer in place and using a wooden 1/8 th inch dowel to clean out the main exchanger. Has any one done this?

 

[catalinajack]

Why should the impellers tear apart? I always figured to replace the impellers long before they would start to fall apart. I think I am missing something again...

Nope, you are not missing anything. Impellers are not particularly expensive. Change them out as preventive maintenance and it will be highly unlikey, but not impossible, that you will experience a shredded impeller.

 

[lwarden]

Using Permatex or Rectorseal makes good sense, but any grease on these can lead to the gasket slipping out and causing a leak. Ask me how I know....

 

[Nick F]

I have a 1979 Lehman 2715-E. Time to clean my heat ex-changers. I last did it in Dec 2009. I don't remember any thing remarkable in taking the heat ex-changer out of the boat and pouring a Draino mixture into the heat ex-changer to clean out the heat ex-changer. I re&re'd the tranny and oil ex-changes.
This time I can't get the hose off of the engine side or heat ex-changer side with out destroying the hose. I guess I should have used pipe dope.
I'm thinking of leaving the heat ex-changer in place and using a wooden 1/8 th inch dowel to clean out the main exchanger. Has any one done this?

I am cleaning my heat exchangers this week. I bought a $20 online rifle cleaning kit - it has little bronze brushes and brass extension rods. It has various sizes, including .22 and worked very nicely for removing the major buildup. I intend to follow this with an acid (vinegar) flush.