Cleaning heat exchangers

[Diesel]

Read the thread and ready to start. I have 6v92s and when looking at the expansion tank I see 2 hoses coming out of each side. The higher ones appear to be the freshwater and I assume lower ones with the zincs are the saltwater. One side also has a small hose running back to the dripless shaft seal so I assume thy is the output side. I assume I should cap that off to isolate the exchanger? Also, if I'm correct the input side has a larger diameter hose? I went to close the seacock to that engine and it was frozen. What's the best way to free up without breaking something....rubber mallet?

Thanks- Ralph

[Canuck Dennis]

5 LB hammer, tap to shock the valve body then it should free up, may take a bit of work but easy does it, if the body has a drain plug, suggest a st stl grease nipple then grease it annually to help keep the valve free, in Northen clime, drain the body .
Can't help on the cleaning thing, never have to do mine.

[MikeP]

I know it's a lot more work but I suggest that if this is the first time you have cleaned the HEs on your boat that you remove/dunk them rather than clean them in place. This will give you the opportunity to see what everything looks like and to be sure they are thoroughly cleaned. I don't know about the HE on a '92 but on a 71 it's a half day job to remove/clean/reinstall the two HEs.

From the first cleaning onward I would then be comfortable with in-place cleaning.... Actually, I'm not really - I pull them every time

[REBrueckner]

"What's the best way to free up without breaking something....rubber mallet?"

Likely that WILL work, but the BEST way is to loosen the inner assembly, especially if the tapered type shutoff insert, from the outher housing...some seacocks alow that. some don't....Then swing the handle and work it in place...add some grease....

If you then swing the handle once or twice a year it should remain workable for at least several years....greasing during haul out every few years should keep it good for a long time...I greased mine and they stayed ok, not perfect but workable, for ten years....

[REBrueckner]

"on a 71 it's a half day job to remove/clean/reinstall the two HEs...."

Only for an expert like Mike because has does it frequently!!!.

On a "first" removal you have to contend with stuck bolts. When I did mine, I replaced the steel cap bolts with SS and antiseize compound...a couple old studs on the bottom were moderately seized, but I was able to get them off without breaking any. And if you do disassemble the end plates, coat the new gaskets with your favorite goop...silicon, gease, whatever, to retard moisture penetration and "salt" buildup at the outer edges of the gaskets.

I also found that after running the engines a few hours and rechecking the studs, all were ready to be snugged up again...I don't know if that was me not making them tight enough initially or if that is typical.....