Yanmar 2gmf heat exchanger removal

[andyasj]

Hello,
does anyone have experience of removing a Yanmar 2gmf heat exchanger.
I have removed the endcaps and the heat exchanger tubes will not slide out. They move easily about 5mm but stop with a metallic clunk as if there is some other part to be removed before they can slide.
I have tried taps with a mallet but no further movement. I can't tap too hard!
I only wanted to check the condition as it is about 10 years since it was last looked at. I had the same problem then. The tubes are perfectly clear so I will just put it back together if no-one can help.
Cheers.

 

[sailoppopotamus]

I did this last year and there was no trick to it other than hammering the damn thing out. As a consequence I flattened/broke the pins that protrude and help align the heat exchanger with the end plates when reassembling, so I had to be careful when doing that. I also made the mistake of not realizing that the rusty blob of a heat exchanger was aluminium and put it in hydrochloric acid to clean it. Luckily I took it out before I lost too much material.

 

[andyasj]

No way am I going to hammer it hard. It is only soldered soft metal. A new one is about £1000!

 

[sailoppopotamus]

Yes, sorry, I had to be more specific, I had some wood between it and the hammer/mallet (not sure what I used) to protect it. But I understand the reluctance given the ridiculous cost of a replacement part.

 

[vas]

not ali iirc, some fancy casting with magnesium and whatno and apparently the reason there are no anodes on it.
did it 4-5yrs ago, wasn't v.hard (else I'd remember it!) there are o-rings on either side, maybe they are hardened and jamming?
take it easy and back and forth should come out in one piece!

 

[andyasj]

I made a softwood drift and used a lump hammer hard. It moved 2nd blow. Thanks for the help.

 

[vyv_cox]

not ali iirc, some fancy casting with magnesium and whatno and apparently the reason there are no anodes on it.
did it 4-5yrs ago, wasn't v.hard (else I'd remember it!) there are o-rings on either side, maybe they are hardened and jamming?
take it easy and back and forth should come out in one piece!

Sounds like 5083, 4.5 % magnesium plus some manganese and chromium. Many aluminium hulls are made from it, along with air-cooled VW crankcases. Very good seawater corrosion resistance.