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Bingo, and a possible red flag!I think the engine was originally raw water cooled and they may have been in use then.
I don't know why the photo didn't post. I am going to have to get one of my kids to help me out with it.
Rick: my boat is a 1984. A couple of years ago I ran into the daughter of the former owner, who recognized the boat. She told me it was originally raw water cooled and that her father had installed the cooling system. So it operated with the modified system for over 20 years.
KAG, unless these have been professionally cleaned at one time, that represents a potential XX years of rust scale debris build up.
I'm not suggesting that this is ultimately your issue, but it is certainly a possibility.
This spring while it was all apart I flushed and backflushed the HX. When I pulled it a week or so ago and cleaned the tubes I put some vinegar in the coolant side, let it sit for a while and then flushed it again. I doubt there is any rust or whatever in there.
Well, I still suggest that you have the H/E's cleaned out professionally. Chemicals will not always adequately remove the rust scale, whereas disassembly and cleaning will.
I know that this represents yet one more cost, but you can then remove this from your P of E list, and move on to a few other items, if need be.
............. unless someone comes up with something else, I think my next step will have to be to exchange the exchangers, which will have to wait until the weekend.
As in swapping the Port side H/E to the Stbd side???
That's one of the beauties of having twins..... we can swap some parts as part of our P of E.
BTW, not that it should matter, but the raw water enters my HX at one end, travels down half the tubes, gets turned around and exits at the same end it entered. The coolant goes in one end and out the other.
That would mean that these are double pass on the sea water side....... this is good!
Thanks again for all the input and suggestions. I feel that I am making progress. (painfully slow, but any progress is way better than none)
Yes, it sure is!
1.... Anyway, I think you are right, the housing is a carryover from the old system, but seemed to work fine.
With those ports (your c & d) blocked wouldn't it function the same as the one you pictured? In your thumbnail two posts up you mention that the return to the pump from the H/E is usually from the lower port. Mine doesn't have a lower port. Coolant enters the top at one end and exits the top at the other end.
2.... everything has to be perfect, so if the tubes are a little dirty, or whatever, the engine runs hot. If so, I have to figure out what else isn't perfect, or redesign or replace the system.