I mentioned this some months ago while still planning the job, part of a major engine overhaul on a 24 litre Kelvin marine diesel. It's been up & running for a while now, & the vessel should be ready to go back into service carrying cargo in a couple of weeks after about 15 years' idleness.
I've been struggling with just an old laptop for a while, but finally got a decent computer back into service so using it to post this!
The engine cooling heat exchanger is a dual oil & water cooler, with two tube stacks contained in one cast aluminium alloy housing. Raw (salt) water passes through the tubes, and the housing contains water/antifreeze in the top and oil in the bottom. The bronze end caps seal to the stacks and the casing with O-rings. What's happened in the past is that poor maintenance has allowed salt water to pass the O-rings and attack the ali casing.
Note the profile at the end of the water section on the left should be the same, with O-ring chamfer, as on the oil section at the right! It had previously been 'repaired' with something such as Belzona but this had failed.
New casing unobtainable, replacement secondhand casing offered for around $1000 US.
My solution was to bore out the two ends and make top hatted sleeves from 316 stainless. It was suggested by someone here that 316 was unsuitable, because of the prescence of salt water, but my view was that it shouldn't come into contact with salt water anyway, and if there were to be slight leakage it would be unlikely to lead to the sort of unholy mess that the Ali had got into.
I tried to get some heavy tube but failed, had to make do with a bar end of 6" dia which was just long enough. The first piece I had to drill and bore, but the remaining piece I was able to bore from either end with a big Rotabroach cutter, at least it gave me a piece of 316 about 2" dia & 3.5" long which is more likely to come in handy one day than would a pile of nasty swarf!
Last pic in another message
I've been struggling with just an old laptop for a while, but finally got a decent computer back into service so using it to post this!
The engine cooling heat exchanger is a dual oil & water cooler, with two tube stacks contained in one cast aluminium alloy housing. Raw (salt) water passes through the tubes, and the housing contains water/antifreeze in the top and oil in the bottom. The bronze end caps seal to the stacks and the casing with O-rings. What's happened in the past is that poor maintenance has allowed salt water to pass the O-rings and attack the ali casing.
Note the profile at the end of the water section on the left should be the same, with O-ring chamfer, as on the oil section at the right! It had previously been 'repaired' with something such as Belzona but this had failed.
New casing unobtainable, replacement secondhand casing offered for around $1000 US.
My solution was to bore out the two ends and make top hatted sleeves from 316 stainless. It was suggested by someone here that 316 was unsuitable, because of the prescence of salt water, but my view was that it shouldn't come into contact with salt water anyway, and if there were to be slight leakage it would be unlikely to lead to the sort of unholy mess that the Ali had got into.
I tried to get some heavy tube but failed, had to make do with a bar end of 6" dia which was just long enough. The first piece I had to drill and bore, but the remaining piece I was able to bore from either end with a big Rotabroach cutter, at least it gave me a piece of 316 about 2" dia & 3.5" long which is more likely to come in handy one day than would a pile of nasty swarf!
Last pic in another message
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