CAT 3208 aftercooler flange corrosion

[thefatlady]

I have just come across another boat with this problem on both engines, so in case more owners are not aware, this is what it is about:

The CAT 3208 aftercooler seawater flanges are (were) made of aluminium. They rot. If they go, there is a very strong likelihood of getting sea water in the intake and wrecking the engine. The aluminium flanges have been superseded by bronze ones.

I am told that a lot of engines have been wrecked and that Caterpillar recognise the problem, They did a "recall" but could not contact many owners. I am also told that they have been known, under pressure, to replace the flanges free.

The first sign is tell-tale black streaking on the flange as below. A boatyard may tell you that the whole aftercooler must be removed to replace the flanges, but it can be done in-situ.

This is a good engine with a minor design fault which could become serious if left. You have been warned.

 

[compie1]

Thanks John,
my flanges are ok /forums/images/graemlins/wink.gif but i hear lots out there are not.

 

[oldgit]

This problem has been detailed on Not only Mercruiser make rubbish risers. With some nice pictures of Cat risers.Need to scroll down a bit.

 

[thefatlady]

Thanks for that, oldgit. The article is interesting, but it's not covering the same problem. This is not in the exhaust riser, but in the seawater feed from the pump to the aftercooler.

As the article says, the turbo version of the 3208 does not have the exhaust riser problem.

Once the aluminium flanges are replaced by bronze ones, this problem should go away.

 

[oldgit]

Oops sorry.Quite a bit on the site about unsuitable materials used to cut corners in marine engineering.Presume that using a bit of good old fashioned bronze in the first place would have added another fiver to the cost.Surely nothing to do with the weight.

 

[Deleted User YDKXO]

Yes this is a common problem on 3208 engines which, as you say, are otherwise good engines. I've had 3 boats with these engines and not had to replace the flanges on any of them but it certainly is well worth keeping an eye on them

 

[Whitestar]

I have just come across another boat with this problem on both engines, so in case more owners are not aware, this is what it is about:

The CAT 3208 aftercooler seawater flanges are (were) made of aluminium. They rot. If they go, there is a very strong likelihood of getting sea water in the intake and wrecking the engine. The aluminium flanges have been superseded by bronze ones.

I am told that a lot of engines have been wrecked and that Caterpillar recognise the problem, They did a "recall" but could not contact many owners. I am also told that they have been known, under pressure, to replace the flanges free.

The first sign is tell-tale black streaking on the flange as below. A boatyard may tell you that the whole aftercooler must be removed to replace the flanges, but it can be done in-situ.

This is a good engine with a minor design fault which could become serious if left. You have been warned.

Can you tell me exactly where the flanges are that need replaced with bronze? Is it the core itself with aluminum flanges welded to the core, or something separate.

 

[Whitestar]

Which parts on this parts list?

 

[Seastoke]

Which parts on this parts list?

It’s an old thread but old git is still on here and will be along to help you.
Week he was old git then but now he is Farther Time.

 

[thefatlady]

Can you tell me exactly where the flanges are that need replaced with bronze? Is it the core itself with aluminum flanges welded to the core, or something separate.

After 20 years, I am trying hard to remember! I think there were two separate flanges which bolted on to the outside of the aftercooler. They were definitely not welded to the core. This might be the one: https://parts.cat.com/en/catcorp/145-1822 but check, because after this time I cannot be sure.

Mine were 3208DITA engines. I think there are variants with different aftercoolers, so yours may not be the same.

These engines should have the flanges changed to bronze, whether they are blowing or not. Do not wait for signs of failure. I have seen several engines with evidence of this problem.
I changed the flanges on both my engines on a previous boat at about 400 hours. I had not been aware of the problem, but I noticed faint traces of sooty blow-out on both engines wondered what it was. On investigation, I found that the flanges were rotting.

They are not difficult to change (although a French mechanic tried to tell me it was a major job requiring removal of the aftercooler). It can be done in-situ. The pipes on mine were a tight fit and the hose couplings stiff and they needed a bit of heaving to get them clear of the flanges. The flanges have O-ring seals which should also be changed.

Good luck!
John