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basssears · 17-03-2017, 13:56

Working on installing a raw water transmission cooler (really just a heat sink, but that's what's available for my Hurth HBW100-2R). This is the cooler: 3306107001 ZF Transmission/Gear Cooler

Two questions have come up for me:

1) The raw water in/out barbs on the cooler measure at 1 3/16" OD (which is an odd size but that's what my calipers said, possibly because of a slight imperfection in the casting of the barbs). Question here is should I use 1 1/4" ID hose and hope it clamps down tightly enough, or should I use 1 1/8" ID hose and hope I can get it onto the barb (maybe with help of a heat gun)? Was planning on using "soft" raw water hose (fabric reinforced but not wire reinforced) for this new run.

2) According to my engine manual I should be taking raw water off the circuit after the raw water pump and running it through the transmission cooler. This will involve two T's into 5/8" ID raw water hose (after raw water pump before heat exchanger)... those two T's are going to need to connect to hose that that will run to the 1 3/16" OD barbs on the cooler... so I am going to need to adapt up to larger hose in the run (i.e. T'ing 1 1/4" ID hose out of a 5/8" ID circuit). What is best practice for this? I see there are bushings for adapting DOWN in size but haven't seen an equivalent for moving up in size. Female to female adapter->bushing->male to male adapter? Hoping not to have 8 million connections in this system, being below the waterline and all...

As always, thanks in advance.

-- Bass

waterman46 · 04-04-2020, 18:10

I didn't see that anyone had an answer for your 2017 post about the transmission cooler plumbing. I just got a new ZF transmission and while I ran the previous one with no cooler just fine for many years, I did buy a cooler/heat sink this time. Have not plumbed it in yet, as I have the same questions as you did.

So I am wondering what you finally did, if you made the raw water connections to your cooler. It sounds like you wanted to put the cooler in parallel with the raw water connection to the engine, since you mentioned using tees. Wonder where the two hoses to the cooler would be teed into the existing raw water system.
Any advice based on your experience would be most welcome.

Doug

**a64pilot** · 04-04-2020, 18:21

I don’t have a transmission cooler but don’t understand what the T’s are for.
I would run it raw water pump to transmission cooler and then back to engine.
You might could silver solder different fittings onto the end of the cooler tubes, depending of course wha they are made from. Whatever the smallest hose in the system is will determine flow so I don’t think reducing the cooler down to that size hose would change flow.
There are adapters that are essentially male nipples with two different sized ends if you don’t want to or can’t change the fitting sizes on the cooler.

This is a 5/8 to 3/4 adapter just as an example, other sizes exist. Now many are brass, and of course do not buy a brass one
https://www.amazon.com/Splice-Couple...s%2C455&sr=8-2

On edit a machine shop should be able to turn some down out of bronze for you and those should last forever

basssears · 04-04-2020, 18:29

Doug,

I did end up installing a heat sink style transmission cooler (seemed all I could find for my transmission, sure would have liked something that increased the quantity of ATF fluid but couldn't find anything like that, not sure I could have fit it anyway).

I ended up creating a manifold that would, if there were a problem, allow me to turn three valves and I would have isolated the transmission cooler out of the cooling system, so I could continue to cool my engine without running cooling water through a potentially compromised transmission heat sink. Part of my concern with the heat sink is it's aluminum and has no capacity for a zinc, I guess I could have drilled and tapped a threaded hole for a zinc but that was a nervewracking concept (among other things, my heat sink wasn't very thick material).

Part of my solution to corrosion is now any time I leave the boat I put fresh water (and salt away) in the raw water circuit so hopefully the corrosion will be less.

I did a write up on it on our blog, if you check that out and have questions feels free to post here (for posterity) or just PM me.

Spring Work – All About the Power – Sailing Idaho, the Salish Sea and beyond

-- Bass

stormalong · 04-04-2020, 18:42

Just plumb from the intake strainer to the transmission cooler and then to the raw water pump. Works fine. Been doing it that way since 2003.

Keep in mind that these are made of aluminum. If you have any copper in your raw water cooling loop, as is done on Beta Marine engines it is a good idea to get rid of the copper. I replaced all of my copper pipes on the Beta with hose.

I am on my second cooler since there was considerable damage to the first one due to nearby copper pipes on the engine.

Someone was offering these in bronze. If you can find one get it.

FPNC · 06-04-2020, 07:42

Plumb from the seacock directly to the cooler, or from the raw water pump to the cooler. Both will work.

I have never seen the ZF block cooler corrode out that was not associated with stray current corrosion. The cooler is bonded to the engine block as is any zinc in the cooling circuit.

All good quality heat exchangers are made with cupro-nickel bronze which is typically 70% copper. The same goes for water pumps which are bronze and stainless.

An engine cooling circuit of this type will contain Aluminum, Bronze (copper/nickel), stainless and sacrificial zinc. If you experience inordinately frequent depletion of the zinc, look for stray currents.

stormalong · 06-04-2020, 10:34

Quote:

Originally Posted by FPNC

Plumb from the seacock directly to the cooler, or from the raw water pump to the cooler. Both will work.

I have never seen the ZF block cooler corrode out that was not associated with stray current corrosion. The cooler is bonded to the engine block as is any zinc in the cooling circuit.

All good quality heat exchangers are made with cupro-nickel bronze which is typically 70% copper. The same goes for water pumps which are bronze and stainless.

An engine cooling circuit of this type will contain Aluminum, Bronze (copper/nickel), stainless and sacrificial zinc. If you experience inordinately frequent depletion of the zinc, look for stray currents.

With a copper pipe is within an inch of the aluminum in a saltwater environment you have electrolytic corrosion. Most saltwater cooling loops do not have any aluminum in them. The raw water pump and raw water strainer are a couple of feet of hose run away from the transmission cooler - that makes a difference. After seven years of use there was considerable aluminum loss from the hose connection of the cooler that was closest to the copper - The rest of the cooler was fine. At that time I chose to replace the cooler and remove the copper. No problem since.

FPNC: What is your "experience"? Are you an engine mechanic? Your profile says you don't have a boat.

Bill Seal · 06-04-2020, 11:02

Automobile transmissions use a loop in the radiator for a heat exchanger, maybe put the Hurth cooler in the fresh water loop to eliminate the saltwater problem.

stormalong · 06-04-2020, 11:15

Quote:

Originally Posted by Bill Seal

Automobile transmissions use a loop in the radiator for a heat exchanger, maybe put the Hurth cooler in the fresh water loop to eliminate the saltwater problem.

Interesting idea. However, the fresh water cooling loop operates at 180-190 degrees in comparison to 50 to 80 degree raw water so the temperature differential would not be as great for cooling the transmission. This is a contact cooler on the outside of the transmission case, not an oil cooler so I think that the greater temperature differential is important.

Journeyman · 28-07-2022, 09:17

Reviving this thread with a question.

I have a Yanmar 3JH5E engine, ZF MIV 15 transmission, and a ZF p/n 3306107001 aluminum transmission cooler. All new in 2011.

Does anyone know the source for the bronze version of the ZF transmission cooler (ZF p/n 3306107001) I read about somewhere?

I have to replace the cooler AND the long Yanmar JH specific engine hose every 1-2 years due to severe corrosion of the cooler’s output pipe in the direction of the raw water pump.

As the cooler output pipe corrodes, the aluminum oxide grows inside the end of the hose around the hose clamp mushrooming it out until the hose balloons out and splits.

Strange that ZF made this of aluminum.

Thanks for any help!

FPNC · 28-07-2022, 09:26

I've Been dealing with ZF for over 15 years and have never seen a bronze version of the ZF mechanical gear box cooler.

I have seen aftermarket coolers that are aluminum with brass or bronze fittings. But never in the USA.

**skipperpete** · 28-07-2022, 15:38

Here’s one. I’ve seen a couple but ONLY on ZF 30M gears fitted to higher HP engines. The “Maritimus” one is pretty nice ( and bloody expensive) . I have some pics of the same style of cooler but with large diam cooling hose on the side of a ZF30M driven by a Mitsubishi7 5hp engine.... same footprint but physically much larger for the 40mm cooling hose connections. Yes , strange indeed to have a grounded aluminium cooler between a bronze seacock and a bronze thru hull.