Yanmar 3GM30F Heat Exchanger

[dmksails]

I'm not sure when the last time the cooling system on my boat was serviced, but I'm imaging it's been awhile. I've owned the boat for over a year during which she's been ashore getting various things worked on. Now I' ready to tackle the engine.


Here's my question - Do I need to drain the coolant prior to working on the heat exchanger?

[jamhass]

Yes you do

[gamayun]

Here's another trick I found. Take off both ends of the heat exchanger and have someone bead blast them. They get gunky. A diesel shop in San Diego did this for me. I then sprayed them with "Yanmar Grey" paint.

[Sailmonkey]

If you don’t drain the coolant, it’ll drain pretty quickly on it’s own when you push out the tube bundle!

[BruceS]

That's why I loved the Perkin's heat exchanger that was on the 4108!!!
Both the coolant & the oil cooler were enclosed & separate.

[billgewater]

I'm not familiar with the Yanwar 3GM heat exchanger but if there are rubber seals at the ends it definitely pays to replace them. After rebuilding it is a good idea to ensure that the copper nickel tubes inside the heat exchanger are electrically isolated from the external body otherwise you can get rapid corrosion of the housing. Check the seating of the rubber O rings as well as corrosion under the seals is not uncommon. The corrosion can be fixed after removal with an appropriate epoxy filler.

I suspect that the 3GM heat exchanger may have two sets of rubber insulators but that will be apparent when you dissemble the exchanger.