What is this (and where do I get a new one)?

[Mike OReilly]

My sea water cooling system has developed a leak. This piece that is held in place by the wooden bracket has a pinhole crack where the tape and putty is located on the right side of the image. There is also a leak at the hose nipple (possible a crack in the hose itself right there).





First off, what is this thing? It’s part of the cooling system, but beyond that, I’m over my head.

The large right hose connects to the heat exchanger and carries sea water. Then there are two smaller connecting hoses that seem to link down to the transmission. And finally there is a large exit hose on the left that joins the exhaust elbow that leads to the water muffler and final exhaust port.

Help!

[sailorchic34]

It's a transmission oil cooler. You can find it here. Hardin Marine - Tube & Box Style Oil Coolers

[hpeer]

What is this thing?

It's interesting it is!

My Volvo MD-7 draws its cooling water from the through hull, then a strainer, then through the transmission, then the engine, then to the exhaust elbow. The engine water pump sucks the water in through the transmission.

It APPEARS that in your setup the transmission has its own water pump. It draws water from the intake and passes SOME through the transmission on its way to the engine.

The second possibility is that "thing" has a valve that routs the water either straight to the engine OR to the engine through the transmission.

The third possibility, and my personal favorite, is that this is some hillbilly engineering. The PO put in this bypass for no good reason. It may be that your transmission is not getting the cooling it wants.

Engine make and model?

-----------

Sailor Chick, better answer than mine. Is the transmission pumping tranny fluid through the little hoses and through the cooler.

[Calif.Ted]

Transmission oil cooler
Hardin Marine - Tube & Box Style Oil Coolers

[DeepFrz]

Something like this?
Marine Oil Cooler: Inboard Engines & Components | eBay

[Mike OReilly]

Wow, thanks guys and gal. My engine is a Perkins 4108. I believe the transmission is a Velvet Drive.

[Cheechako]

Yeah, often the cooler is attached to the transmission with a bracket. That's a nice clean setup, maybe it was added aftermarket? At any rate, if the heat exchanger has a leak, I would imagine a radiator shop can rebraze it good as new.

[rwidman]

Here is another source:

Lenco Coolers - marine heat exchangers, marine oil coolers

Remember, if salt water is flowing through the cooler you want the tubes made out of something resistant to corrosion. Plain copper is not a good choice.

Also note, if this cooler develops an internal leak, it can mix water with your transmission oil and that can ruin it. Don't "cheap out" here.

[David M]

Replace it. If water gets in your tranny then it is toast.

[DougR]

Yep, it's the cooler for the BW gearbox. Best to replace it.

Borg Warner 71 series gearboxes require a relatively low pressure cooler, rated for about 75 psi, and as its on the saltwater circuit you should try to source a cooler with a replaceable zinc anode. That way you won't be having pinhole leaks again.

DougR

[Mike OReilly]

Thanks for all the wisdom and links folks. I know how to proceed now. Much appreciate the help.

[model 10]

I am puzzled by this. This example this is pretty simple, even the cruiser poster must have been able to figure it out. So why the question about what it is?

[skipmac]

Originally Posted by David M

Replace it. If water gets in your tranny then it is toast.

Also the transmission fluid can leak out.

I just replaced the cooler on my Velvet Drive. Purchased from Mr Cool. A few dollars more but the best service.

[scottydaum]

I am with David M.......regarding the issue of cooler water mixing with transmission.
Most large Tour Buses have "trans coolers" that are cooled by the radiator. In the event the inner core fails and mixes the coolant with trans fluid the damage can me catastrophic.
I would choose to play is on the very safe side and say if there is a failure on the outside, the possibility corrosion and possible failure on the inside where salt water is in play is very real.
I am a tightwad, and usually get every last bit of service out of all my boat gear but the engine and trans coolers are too critical to risk major systems just to get another half season or service.
Looking at the photo I will also say that those big loops of hose that are not supported, or otherwise secured make for a real source of vibration stress on the fittings they connected to.

[savoir]

Don't waste your time looking for a repair to the heat exchanger. Even though it is technically possible, nobody does that kind of work anymore, unless you know an old guy who is seriously old school. I tried three workshops last year without success.

Don't forget to replace the two black hoses.