Carver Owners Forum

Hello All;

Has anyone used a circulating pump system to run de-scaling solution through their heat exchangers to improve efficiency?

I have a persistent overheat at high throttle on starboard that corrects after reducing throttle a bit. I have been suspecting the heat exchangers as being kinda gunked up.

Initially I was looking at this as a kit:
https://www.rydlymemarine.com/product/portable-flushing-kit/

But then they're out of stock and it doesn't look to terribly difficult or costly equipment to source myself. They're also available as 'tankless water heater de-scalers' on amazon for much much less.

Thinking this might be an easier solution than the whole dissassemble/boil with acid/reassemble bit.

Thoughts encouraged.

Before you decide on the solution may I suggest, take the hoses off and have a look in the exchanger. Then you can inspect for any small obstruction in the inlet. I have found small bits of plastic etc, easy clean with a shop vac.

Before descaling or anything else, are your strainers clean and your raw water impellers new?

I took mine apart with considerable effort. well, putting them back together was the effort as some i***t cut a part off and bodged it back together. Only to find that they were not very scaled. I could have seen that with my mini camera (usb cam into a phone). In the end the problem probably was a hose that was mounted in a too small turn, restricting airflow.
I started that project because I had found impeller pieces in the intake hose (dropped in and came up irregularly) and the strainer (that was not a tight fit so stuff may have gone passed).
End of season I could run full throttle without overheating, satisfying after all the work.

This year the sterndrives were off, today is mounting day and guess what: coldest day in weeks, even snow may come and visit the last days of March.

Thanks I will remove the hoses to inspect for miscellany inside first before using a circulating pump on the system to descale.

New impellers and no strainers on my boat (there will be though - found some 1-1/4 groco units on ebay a year or so ago - bloody huge!)

Try running some Trac Ecological “Barnacle Buster” through it, letting it set for 4-6 hours, and flushing it out again.

Something else just came to mind.......if this problem has been with you since you got the boat it wouldn't hurt to check your thru hull valve while the boat is on the hard, check to see if it is fully open and unrestricted.....now is the time to check that off the list. Take the hose off and/or look from under with a light to see full operation.

Might also check transmission oil coolers... They're much smaller versions of the big heat exchanger. On my Voyager370 with 454 crusaders, the raw water hose from the raw water pump goes directly to the transmission cooler, then to the heat exchanger.

I was having excessive exhaust steam issues and replaced elbows/risers and impellers (old impellers were intact but cracked) but still had steaming problems. I too was thinking of pulling the exchangers. Then I noticed how things were plumbed..... I removed the inlet hose to the transmission cooler and was amazed to find the inlet FULL of Impeller debris. The boat was new to us and hadn't been used for a couple years. Same issue on the other engine, but less debris.

BTW, best way to remove debris is with a small 90deg pick tool, shop vac, and a bore camera if you have one

Please let us know if you do this. I just took the one off my generator and cleaned it at home but I am going to rig a bypass next time to do it in place. I was actually thinking of doing the same thing on my engines and flushing them a couple times a year just to keep buildup down. I had them professionally serviced last year and it took forever and wasn't cheap.

I did my generator with "Barnacle Buster", runs perfect nowl