MD22 heat exchanger removal

[Borealis]

Hi I was checking mine heatexchanger and it look open without any thing inside the pipes. So I just let it stay innside and since i didn`t know if it was going out in the back or the front and it seems stucked. I tried to take it out, but I didnt mange, so I let it stay there.  Should I have taken i out, and then foward or backwards?.
Regard
Leif Arne Andreassen.

[IslandAlchemy]

If the tube stack is stuck, I would say that there is a good chance that you have corrosion in the case, as the aluminium expands as it reacts with the salt water.

The pipe stacks were so jammed into mine that I had to hit them pretty hard with a hammer to get them out, which destroyed them.

If you get it out now and give everything a good clean up, I would recommend it, or you may find yourself in the same situation as me.

[Yngmar]

I left mine in and just took the end caps off and then poked each tube through with a welding rod. That was a tip from a Volvo engineer I chatted to in Portugal. Worked well, got the calcium deposits out and didn't have to remove the stack. It does require that you have sufficient access to both ends of the heat exchanger. O-Rings were fine and went back in.

[dawntreader]

I left mine in and just took the end caps off and then poked each tube through with a welding rod. That was a tip from a Volvo engineer I chatted to in Portugal. Worked well, got the calcium deposits out and didn't have to remove the stack. It does require that you have sufficient access to both ends of the heat exchanger. O-Rings were fine and went back in.

If standing in front of the engine does the exchanger come out towards you (over the pulleys) or backwards (over the gearbox)?

[Yngmar]

I left mine in and just took the end caps off and then poked each tube through with a welding rod. That was a tip from a Volvo engineer I chatted to in Portugal. Worked well, got the calcium deposits out and didn't have to remove the stack. It does require that you have sufficient access to both ends of the heat exchanger. O-Rings were fine and went back in.

If standing in front of the engine does the exchanger come out towards you (over the pulleys) or backwards (over the gearbox)?

Not sure, as I said, I cleaned mine without removing it. Removing both end caps gives you access to everything where seawater flows through, which should be the only parts that need cleaning.

The drawing clearly shows a flange on the gearbox end though, so it would presumably come out that way: https://www.marinepartseurope.com/en/volvo-penta-explodedview-7746710-25-2850.aspx

Picture of mine before cleaning:

[dawntreader]

I have cleaned both ends and the tubes of the exchanger 'in situ' recently but would like to remove it completely as I believe there could be silt build up on the inside casing - seem to remember this from an earlier post (by Salty?). Would be nice to know which end needs to be knocked on to remove it 

[Salty]

I have cleaned both ends and the tubes of the exchanger 'in situ' recently but would like to remove it completely as I believe there could be silt build up on the inside casing - seem to remember this from an earlier post (by Salty?). Would be nice to know which end needs to be knocked on to remove it 

I have removed the heat exchanger tube bundle in the past, unfortunately it was quite a while back and I can’t remember for sure from which end it was retrieved other than it came out without a struggle. Suggest you place a piece of soft wood, of slightly smaller diameter than that of the tube bundle, against one end and try gently tapping it with a mallet. Working each end alternately should hopefully reveal which way it will go. Just gentle tapping to ensure that the wood is not forced into any of the tubes, and gently again because you don’t want to disturb the way the tubes are fitted into the end plates. I think the tubes may only be secured into the end plates by expanding the ends of each tube once it has been located into each end plate, so anything more than gentle tapping and you might wish you had left it alone !!

[dawntreader]

I have removed the heat exchanger tube bundle in the past, unfortunately it was quite a while back and I can’t remember for sure from which end it was retrieved other than it came out without a struggle. Suggest you place a piece of soft wood, of slightly smaller diameter than that of the tube bundle, against one end and try gently tapping it with a mallet. Working each end alternately should hopefully reveal which way it will go. Just gentle tapping to ensure that the wood is not forced into any of the tubes, and gently again because you don’t want to disturb the way the tubes are fitted into the end plates. I think the tubes may only be secured into the end plates by expanding the ends of each tube once it has been located into each end plate, so anything more than gentle tapping and you might wish you had left it alone !!
[/quote]

Thanks for this information Salty - did you consider removing it worth the effort in the end (bearing in mind the risk of damage)?

[Salty]

I have removed the heat exchanger tube bundle in the past, unfortunately it was quite a while back and I can’t remember for sure from which end it was retrieved other than it came out without a struggle.
.
.

..........did you consider removing it worth the effort in the end (bearing in mind the risk of damage)?
[/quote]

I did find some sediment within the area around the outside (fresh water/antifreeze) side of the tubes, and at the time it had seemed worthwhile because I was able to wash that sediment away. However as I said, the tube nest came out without a struggle.

On the basis of your experience and that of Island Alchemy who was unfortunate enough to damage his tube nest to the point that it became financially more economic to replace his engine, I now feel that maybe I was very lucky that my tube nest came out so easily. If faced with the difficulties you and he have experienced and knowing first hand how little sediment I found on that occasion, I could be tempted to leave the tube nest alone. The only problem of course is that had I left it alone, I would not actually have known for sure how much sediment was there. It’s a bit of a catch 22 situation, you need to know that your cooling system is working efficiently, but you don’t want to wreck the tube nest and have to fork out for a new engine as a consequence. I think if the tube nest showed no signs of moving after a few gentle taps with a hammer onto a wooden drift, I could be tempted to leave it alone, but I would drain off the coolant and direct the business end of a pressure washer through the coolant filler cap on top of the engine.

[Borealis]

It was last winter i did it, and the stupid thing was that i had the engine out for changing the diagramh on the saildrive, and after I had the engine inplace again i start thinking of checking the exchanger. It seems like it was going out backwards and I gave it a small hit, but since it wouldn`t move I put everything together again. I came to the solution that I would`t manage to take it out backwards, since it is not enough space, so I stopped that project.I asked the question  because I still a little worried that next time I will have bigger problem and I would like to have the exchanger housing inspected, so there is no worries there. So maybee next winter I will try again, since after I had the engine out a small oil leak has started between the engine and gearbox
But if some of you says the exchanger is going out foward I may give it a try again.
Regards
Leif Arne.

[dawntreader]

I have removed the heat exchanger tube bundle in the past, unfortunately it was quite a while back and I can’t remember for sure from which end it was retrieved other than it came out without a struggle.
.
.

..........did you consider removing it worth the effort in the end (bearing in mind the risk of damage)?

....... I could be tempted to leave it alone, but I would drain off the coolant and direct the business end of a pressure washer through the coolant filler cap on top of the engine.
[/quote]

Thanks Salty. My current location and lack of serious chandler support is forcing me to keep all my remedial work to 'simple jobs only'. I don't have a problem with my cooling system but it has never been properly flushed. I will pressure wash it as you suggest once in a more 'commercial' marina and perhaps take off the coolant pump to facilitate the cleaning  . Thanks for the advice.