QSM11 leaking coolant

[Eric Manting]

Hello, I have a set of 2002 QSM11’s in my Tiara 41 open. I have a small loss of coolant in my starboard engine, about 1/5 of a gallon after a 3 hour cruise. This has been going on for about 4 years. I had my local Cummins mechanic come out last week and pressure test the system while in heated storage up here in Michigan. He said that the heat exchanger was leaking coolant into the seawater side and out the exhaust. I then received an 8k estimate to replace the heat exchanger.
The boat has been fresh water all of its life and is in heated storage during the winter, so I find it odd that the heat exchanger would fail It has never overheated and has never been hotter than 167 degrees operating temp, usually more like 164. Is there anything else to check before going down the path of replacement? I know any leak is not good, but is 1/5 of a gallon considered small or large? I did a quick search and someone said to use Alum-A Seal to maybe try and seal the leak…has anyone tried this with success?
Thanks in advance, Eric

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[Philip]

Heat exchangers rarely fail to the point of needing replacement however they do need service. It’s really a time and parts service item.

It takes some time to do it right but removing it from the engine and disassembling it, cleaning, pressure testing, assembling with new o-rings and grease should take care of it.

I wouldn’t add things to the coolant unless your looking for a very short term fix and then being faced with the same or worse problem at bad time (like middle of the summer when the mechanic is busy).

Problems don’t get better, just repaired.

Sorry to be the grim reaper.

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