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Heat Exchanger

Rocinante33

Contributing Partner
Recently our heat exchanger has been showing some problem signs. Significant corrosion showing around the end caps, a very slight leak, and the last two times out, progressively more steam emanating from the exhaust, were all observed. The temp remained OK, though. So I crawled in and extracted the exchanger from the boat. I saw (Torresen Marine Diesel Direct) on line that a new exchanger for my M25 is ~$550, so I did all this with trepidation, to say the least.

I found that the corrosion is superficial.....great news. BUT, a severe case of arteriosclerosis from built up salt was found when I pulled the end caps off. I would estimate less than 10% flow through those tubes! That accounts for the leak- backed up pressure, I surmise.

This was reportedly a new heat exchanger when I bought the boat 4 years ago, so I am a bit surprised at how fast it got to be this bad.

Next steps; to a radiator shop for clean-out & a pressure test, new paint job, then re-install.

If you sail in salt water be aware that this problem can pop up quickly & with little warning!:tongue:

Keith
E-33
 

rwthomas1

Sustaining Partner
When I did an inspection of my heat exchanger in the search for a slight overheating problem I found the passages pretty clear but the zinc was non-existent. The metal was very "pink" which I have been told is a bad sign that the zinc has been missing for too long. The result of which is compromised strength and cooling? I ordered a new replacement from http://www.lencocoolers.com/ The price was very good, $325.00 for my Universal 5432. The new part is identical, appears of good quality, etc. I haven't used it yet but if there are issues I will report back. RT
 

Glyn Judson

Moderator
Moderator
Heat exchanger build up.

Keith, Rob and all, For what it might be worth, I devised a system of flushing my heat exchanger of all salt water after each use by means of a 3-way valve plumbed between the raw water intake, my onboard fresh water supply and the engine. At the end of a day sail or even a passage to or back from Catalina Island, I merely leave the engine running at idle while turning that valve. Salt water intake is shut off and fresh water begins to flow through the heat exchanger. In the case of my engine, a Yanmar 3GMF, 20 seconds of running time (30 to be safe) purges all salt water from the system and uses a mere 3 quarts of fresh water in doing so. The next step is to kill the engine, return the valve to salt water intake and the last but most important step, replace the engine key to its Velcroed spot inside the gally sink door adjacent to the 3-way valve so the next guy is forced to see that the valve has been returned to its salt water intake position. I checked this all out with Yanmar USA before proceeding and after they blessed the idea, went ahead with it. I might add that this works for any engine regardless of cooling design, raw or heat exchanger. A raw water cooled engine would simply use a slight bit more fresh water. My engine was originally raw water cooled when I had this system in place but I can't remember the consumption rate other than to say that it wasn't much more than now with the heat exchanger fitted. I wrote a little article about this including a plumbing schematic and parts list that appeared on page 55 of the July/August 2000 issue of Good Old Boat Magazine and can even send a scanned image to anyone who emails me back channel below. Regards, Glyn Judson, E31 hull #55, Marina del Rey, CA email: glynjudson@roadrunner.com
 

Geoff Johnson

Fellow Ericson Owner
The problem could also be a corroded exhaust elbow. One test, which my yard had me do while I was on a trip, is to run the engine, then pull the hose running from the heat exchanger off the exhaust elbow fitting. If everything is as it should be with the exchanger, you'll get a face full of salt water. If not, you need to pull the exchanger or start looking for hose problems (such as a balloning interior lining). As it turned out, my problem was a dislodged flapper valve in the exhaust line.
 

rwthomas1

Sustaining Partner
The raw water hose on my boat has a T and a ball valve fitted between the seacock and strainer. The ball valve has a screw fitting for a garden hose/washing machine hose. To flush the system I just close the seacock, fit an old washing machine hose to the open ball valve and drop it in a bucket. The PO did this to simplify winterizing the engine and it works well. It is a very simple thing to do so I will start flushing the raw water if I am leaving the boat for more than a week. There is also a "salt away" system that powerboats use if they are raw water cooled. I am wondering if that would be be beneficial to use in our cooling systems? RT
 

wheelerwbrian

Member III
You might also want to look at the rate of water flow through the heat exchanger. When seawater temperature exceeds 160 degrees Farenheit, crystals start to form. Typically the water temperature in a heat exchanger won't reach that level, even if the coolant is at or above 160 degrees, because of the water flow. But if its slow, then you could have a recurrance of the problem.
 

Rocinante33

Contributing Partner
Heat Exchanger follies

Thanks, guys. Several good suggestions to ponder. A rinse system must be helpful, whether direct plumbed or from a bucket.

Geoff, I am not too sure about pulling the hose while running to see if I get a face full of sea water! I own a boat, so I'm obviously a little bit masochistic, but that is too much for even me! I already have the heat exchanger out, though, so I will investigate downstream (hose & elbow) as you suggest.

Keith
 
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