thirdchildhood

iTrader: (6)

Is there any way to get out all the sand and mussel shell fragments that the water hose will not back flush out? Thanks.

Velocity Vector

iTrader: (4)

The more long-term problem with heat exchangers is the gradual slow build-up of dirt on both the inside and outside of the small tubes that form the heat transfer area. This will gradually build up as a layer of insulation and is compensated for in every good heat exchanger design by so called "fouling factor". This simply means the heat exchanger has excess capacity when new and clean so it still performs acceptably when old and dirty. However, this "fouling factor" can only go so far and eventually a thorough cleaning of the heat exchanger may be necessary. The most drastic solution is to remove the heat exchanger and bring it to a radiator shop for a complete cleaning.


Make sure that the radiator shop has experience with marine heat exchangers. Proper cleaning should be a two step operation. First clean the unit with a strong alkaline solution to remove organic dirt such as oil. Second, in order to remove scale, the unit should be cleaned in an acid solution.


If a less thorough cleaning is desirable the heat exchanger can be left in the system. The jacket waterside can be cleaned in the same way as an automobile cooling system using any of the better radiator cleaning solutions on the market. Using a small diameter long handle brush similar to what is used for cleaning a rifle barrel can clean the small tubes on the raw waterside. It is possible to acid clean the raw waterside of the heat exchanger without removing it from the boat, but it is messy and dangerous. The ports of the heat exchanger will have to be plugged and the unit filled with an inhibited muriatic acid. Since an operation like that necessitates special safety equipment and creates a disposal problem we do not recommend that you try it unless you really know what you are doing.

bustedbrick

I just got done stripping down four of them for cleaning. Both of mine were >50% clogged with impeller bits. Any idea what PSI I should use to pressure test after they get back from the radiator shop? Last time I used about 30PSI on the oil side and dunked the whole thing in water.

Thanks, Randy

thirdchildhood

iTrader: (6)

It's a 2007 vintage 525 so not many hours on it but I sucked up a bunch of crud last week in a grounding. I flushed everything out but I'm not real confident about the flow through the heat exchanger.

BustedBrick, I think 35-40 would be safe.

bustedbrick

Thanks, I didn't think it would take too much pressure to see bubbles. Good luck flushing..

thirdchildhood

iTrader: (6)

I got the boat out tonight and it is running nice and cool. I might be taking on water though. I will need to check all my connections and hopefully nothing is cracked. I couldn't see any leak out on the lake, hopefully it was just water from my flushing job.