Heat exchanger

[Deadline]

Is there anything complicated about unleashing the heat exchanger on a Yanmar 18? I need to clean the rods and get any debris out. My understanding is that I drain the block of coolant and dismantle the caps at each end. Questions...

Anything else need to be disassembled?
Do I need to mark the track of the rods?
Will the gaskets still work or should I order new ones ahead of time?

Thanks.

 

[syoun10]

I'm not familiar with the Yanmar 18, but had the same situation on my Yanmar 3YM30. Theoretically, it should have been as simple as you indicate, but there turned out not to be enough room to get the core out, so had to take off the exhaust manifold as well. Maybe you're not planning on taking out the core, but cleaning it in place? Or maybe your H320 has more space round the engine than my H33? - so your experience may vary (as they say).

 

[Deadline]

I can get it out if it comes forward. If aft, may have to remove the manofold. Thanks

 

[Allan12210]

I have the 3GMF 22 which might be the 3 cylinder version of yours. Just to share what I did this weekend was to only pull the front cap after draining down the seawater and the antifreeze a bit. The 24 tubes are just a small amount over 1/4" in diameter. I used a 1/4" x 16" bit on my cordless drill and rodded each of them out. There was a bunch of crud that would fill the flutes, so I would push it in a ways, then pull it back and clean the bit. Keep advancing until you feel it go into the rear chamber. The big o-ring and divided gasket looked ok so I just put the cap back on. No leaks. I can't tell you yet how effective it was as I didn't get to take the boat out and run it up to operating temperature. With what I pulled out, it should be more efficient.

If you do pull the exchanger out it needs to be clocked in the correct orientation. The water doesn't just flow straight through. On mine seawater flows through 1/3 of the tubes then is directed off the back cap to return through a second 1/3 of the tubes where it turns again and flows through the last third and out. So the internal gaskets are clocked to make this happen. I can not remember if the entire exchanger is keyed so you can't rotate it. The tubes are press fit into the end pieces so it won't fall apart. If you do end up removing it, you probably will have to pull both caps as the gaskets can be hard to put back just from one side. Try the easiest way first.

Good luck.

Allan

 

[Ken13559]

I have a 10year old 2gm20f. what is the timeline or running hours before I need to clean the heat exchanger?

 

[jtm]

my 28.5 has a 2GMF. Maybe 10 years ago I drained the exchanger, removed the front side nuts& cap, and pulled out the "gatling gun" barrel exchanger assembly. Yes I'd mark the "top/front" - just to be sure it has minimal face contact change on the backside. You'll need 2 new gaskets to mate with the caps. I've not any overheating issues before or since. I don't recall anything special beyond that.

 

[Ken13559]

my 28.5 has a 2GMF. Maybe 10 years ago I drained the exchanger, removed the front side nuts& cap, and pulled out the "gatling gun" barrel exchanger assembly. Yes I'd mark the "top/front" - just to be sure it has minimal face contact change on the backside. You'll need 2 new gaskets to mate with the caps. I've not any overheating issues before or since. I don't recall anything special beyond that.

How bad was the curd?

 

[jtm]

Crud?! As I recall it was much cleaner than I ever expected. I soaked it in some vinegar or maybe light oxalic (FSR) and ran heavy duty pipe cleaners thru the tubes.and neutralized the acid with light detergent and rinsed thoroughly. I recall thinking why did I bother to do this.

 

[sea_casper]

Ditto

Crud?! As I recall it was much cleaner than I ever expected. I soaked it in some vinegar or maybe light oxalic (FSR) and ran heavy duty pipe cleaners thru the tubes.and neutralized the acid with light detergent and rinsed thoroughly. I recall thinking why did I bother to do this.

I used brushes from a gun cleaning kit, also could not remove it because I would have to cut aft plywood bulkhead to do so, or disconnect prop and rear mounts and jack up engine. It was really clean and I have ~ 1000 hrs on engine.

I also cleaned mixing elbow and replaced inlet water strainer, and have not had any overheating issues this year.