Do transmission or oil coolers "wear out"?

[skipmac]

Spoke to a transmission shop and in the course of the discussion the owner cautioned me to replace the transmission cooler if it was more than a few years old. According to him, the brazing (solder?) that joins the cooling tubes to the body corrodes away over time in salt water which will allow the transmission fluid (it's a hydraulic transmission so the fluid is under pressure) to pump out into the cooling water and burn up the transmission.

I just removed and cleaned out all the coolers and on a cursory inspection they seemed OK but I confess I didn't star too closely at the joints. If this would happen with a transmission fluid cooler I would assume the oil cooler could have the same problem.

So is this nonsense, urban legend, scare stories or should I start thinking about replacing my 30 year old coolers?

[wayne.b]

Originally Posted by skipmac

Spoke to a transmission shop and in the course of the discussion the owner cautioned me to replace the transmission cooler if it was more than a few years old. According to him, the brazing (solder?) that joins the cooling tubes to the body corrodes away over time in salt water which will allow the transmission fluid (it's a hydraulic transmission so the fluid is under pressure) to pump out into the cooling water and burn up the transmission.

I just removed and cleaned out all the coolers and on a cursory inspection they seemed OK but I confess I didn't star too closely at the joints. If this would happen with a transmission fluid cooler I would assume the oil cooler could have the same problem.

So is this nonsense, urban legend, scare stories or should I start thinking about replacing my 30 year old coolers?

===

After 30 years there is certainly some risk. Three years ago I had a failure with a 31 year old fuel cooler that allowed salt water to mix with diesel fuel as it was being returned to the tank. It was quite a mess and cost many thousands to remediate.

One way you could test is to send some of your transmission fluid out for analysis similar to what you might do with an oil sample. If there's any trace of salt it will show up in the test results.

https://www.google.com/?gws_rd=ssl#q...e+oil+analysis

I've used Blackstone for my main engines and generators. They send you a very detailed report.

It's relatively inexpensive and will give you some peace of mind if negative.

[jimbunyard]

Well, the heat exchanger for the engine sees the same salt water (and probably under higher temperature gradients than the transmission cooler) and I've never heard of replacing them because they were 'more than a few years old'. I'd keep mine until I saw an 'oily film' begin to show up in the exhaust water.


Did the shop owner also offer a replacement cooler...

[jimbunyard]

Originally Posted by wayne.b

===

After 30 years there is certainly some risk. Three years ago I had a failure with a 31 year old fuel cooler that allowed salt water to mix with diesel fuel as it was being returned to the tank. It was quite a mess and cost many thousands to remediate.

One way you could test is to send some of your transmission fluid out for analysis similar to what you might do with an oil sample. If there's any trace of salt it will show up in the test results.

https://www.google.com/?gws_rd=ssl#q...e+oil+analysis

I've used Blackstone for my main engines and generators. They send you a very detailed report.

It's relatively inexpensive and will give you some peace of mind if negative.

Well certainly there is some risk, as there is even from new.

Were you able to determine if the fuel cooler leak was from failed brazed/soldered joints, or from erosion through the tubes or housing, or vibration induced cracks or deterioration of other sealing materials, or ???, or was the solution more 'isolate problem, remove, replace and discard?

As has been brought up before here, oil analysis is a good, valuable tool, but is generally most valuable if used in an ongoing schedule of preventative maintenance, where a base line value is established and trends can be monitored to indicate potential problems.

In other words, without a previous record the 'peace of mind' one gets from a one-off test is likely illusory, because the problem can start immediately after the sample is taken so the results look 'normal', or the results can indicate a normal condition that has existed since day one, or anything in between...

Also, the transmission oil cooler is often on the suction side of the raw water circuit and the oil pressure is generally higher than the water pressure anyway, so the tendency is for the oil to get into the raw water, not the other way around.

[skipmac]

As Jim mentions, the transmission oil cooler is on the suction side of the raw water pump plus the transmission is a BW Velvet Drive which is hydraulic and the fluid inside also under pressure. So I would think finding water in the transmission unlikely and this is the point the mechanic was making. Essentially the fluid can all go out in the cooling water and burn out the transmission without warning.

As I think about it further, wouldn't checking the fluid in the transmission on a frequent basis and looking for oily sheen in the exhaust address the concern. My guess is a leak in the cooler would start small and grow so would be indicated initially by a slow loss of fluid from the transmission?

So the question becomes, how likely is it that there would be a sudden, total failure with loss of all fluid and immediate death of the transmission?

[rwidman]

I have never before heard of replacing a transmission oil cooler or engine heat exchanger based on years of service. Check the prices of these components and you will see why.


It certainly wouldn't hurt, except in the pocket book, but I'll wait until I see a stronger reason to replace them before I shell out the several thousand dollars to replace mine.


The real question is, are the aftermarket coolers the same quality as OEM?

[skipmac]

Originally Posted by jimbunyard

Did the shop owner also offer a replacement cooler...

Believe me this was the first thought I had. He didn't outright offer to sell me one but I'm pretty sure if I wanted one he would have one available.

[gjordan]

Install a transmission oil temperature gauge. It is a very good idea on any tranny, and if anything goes wrong inside, you will hopefully know it before major damage happens. They dont cost very much at truck outlets. ____Grant.

[lesterbutch]

I think there is a simple answer to this. EVERYTHING WEARS OUT! You must do periodic checks.

[Xthewater]

My first inclination is to have the cooler pressure tested just as one would do with a radiator. For a simple method block of one end, pressure the other and put in tub of water looking for air bubbles.
Heat exchangers are pretty robust. Thermal cycling over time may produce a crack on a solder/brazed joint but I would expect it to show earlier on rather than years later.
I cleaned out the exchanger for our M25xp last year during the rebuild, soaking in white vinegar for a couple hrs. With end caps off and turned out beautiful then neutralized in baking soda bath.

[JstaRebel]

Circumnavigating from DR back to St. Thomas, we were stopping off in Vieques under power, when I lost my gear. Upon opening the hatch to the engine room, I can hear a hissing noise. A quick look before shutting down the engine showed pink froth blowing from the overflow fitting on top of the velvet drive. Took me a day getting fluid, cleaning out the gear box, and coming up with a fix (Disconnected the cooler and bypassed the seawater flow) before limping home to St. Thomas where I ordered a new "Nickle Bronze" oil cooler. $256.00 that I would have been happy to spend if I knew the standard one was going to go out. EVERYTHING has a useful life time. Including Heat exchangers and oil coolers. Also, I highly suggest paying the extra $100 or so to go with the nickle plating. Last twice as long..

[S/V Alchemy]

Originally Posted by lesterbutch

I think there is a simple answer to this. EVERYTHING WEARS OUT! You must do periodic checks.

This, basically. If you are motoring in salt water and it's the salt water cooling circuit flowing past the dissimilar metals of either the heat exchanger or the oil cooler/transmission cooler, the potential for wear and catastrophic failure exists.

It's why we are leaving with spares sufficient to patch us over such failures, like a spare water pump, alternator and starter. We might have to rethink the cooling aspects as well. It's expensive and annoying, yes, but it's part of the game of proper boat management to cover off all reasonable bases. You wouldn't leave with one anchor. Well, I hope you wouldn't!

"Reasonable" in this context would mean carrying a spare head gasket, an injector or two and a full gasket kit, anode replacements and perhaps a few studs. It would not include carrying a spare head, or spare drivetrain pieces. What is reasonable to you, I would suggest, depends on how far you'll sail from easy access to parts and/or repair people.

[mickand]

In my humble experience, a sound transmission oil cooler is vital for a safe trip. The difficulty in most cases is you'll never know when it gives out. The pressurized fluid will leak out, mix with the raw water and exit the exhaust system probably undetected whilst underway.
I know of several first hand experiences including one where the transmission got stuck in forward causing a dock collision.
I have Lehmans and replace both every couple of years for peace of mind.

[sy_gilana]

Not a ruse. Ours corroded through and apart from the oil film on the water, there was water in the reduction too. Did 3x oil changes, and replaced the cooler. Cheap ones are copper and brass, expensive ones are CuNiFe (Cupro-Nickel-Ferrous alloy) Lifespan with regular anode changes is about 10 years for the former and 30 for the latter.

[Striker37]

If the pressure of the trans fluid is greater than the water pressure of the raw water and you have a leak from the trans cooler to the raw water side you will get trans fluid out your exhaust.No raw water will enter your tranny.