Hurth / ZF M15A Transmission Failures

[Joe8621]

I have a Hurth HSW 800. It is stuck in forward. With the shift lever in neutral, when I start the engine it takes off right away. If I try to shift to reverse it kills right away. Any sugestions?

[jeff gillette]

Try disconnecting the linkage at the transmission and see if you can manually move the shifter into neutral. If so readjust the linkage.

[RBEmerson]

+1 - if you can move the arm without the Morse cable attached, there you are. OTOH, if you can't shift from the arm alone (you should be able to move the arm without resorting to any tools)... time to think "rebuild or replace".

FWIW, after we finally got the engine located in the correct place (bad engine mount lead to impossible alignment lead to two cooked trannies), the gear has been working like a charm for two trips from the Chesapeake to Abaco and back. In the ICW, we're all power boaters!

[kairoscruise]

Random, but when looking up something I found this thread from a bunch of years ago and felt compelled to follow up. I was one of the folks who in 2007 or whenever had a hurth go bad. Another poster went through 5 of these transmissions. Well after my original posts I went through two more myself, so that was three hurth transmissions in relatively short order. I believe the thrust washer wear was to blame and would never buy another hurth if my life depended on it (and it kind of does sometimes). My next one will be either a PRM or a twin disk. The PRM guy assures me that it is an exact replacement with only about a 1/4 inch difference in height that can be taken up easily with the engine mounts. The only other thing I could add is that maybe the stuffing boxes might have been cinched up too tight and that contributed to failures, but I really doubt it.

[Cheechako]

Originally Posted by kairoscruise

Random, but when looking up something I found this thread from a bunch of years ago and felt compelled to follow up. I was one of the folks who in 2007 or whenever had a hurth go bad. Another poster went through 5 of these transmissions. Well after my original posts I went through two more myself, so that was three hurth transmissions in relatively short order. I believe the thrust washer wear was to blame and would never buy another hurth if my life depended on it (and it kind of does sometimes). My next one will be either a PRM or a twin disk. The PRM guy assures me that it is an exact replacement with only about a 1/4 inch difference in height that can be taken up easily with the engine mounts. The only other thing I could add is that maybe the stuffing boxes might have been cinched up too tight and that contributed to failures, but I really doubt it.

So... these were the newer Hurths sold by... I think... ZF?

[Jetexas]

To be fair, one of the cruisers in this thread that went through four transmissions later found out the PO had put a left-hand prop on the right-hand drive motor, so he was essentially running them in reverse.

[Sailmonkey]

Originally Posted by Jetexas

To be fair, one of the cruisers in this thread that went through four transmissions later found out the PO had put a left-hand prop on the right-hand drive motor, so he was essentially running them in reverse.

And I still carry one of them as a spare......I just don't expect it to stop me quickly......


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[CaptWil]

Hi

MD2040 mated to ZF15 L-A

Had an interesting moment with a marine mechanic today, in Malaysia. He was not the guy that removed the engine initially for overhaul

He had an issue with finding the seawater intake to the gearbox oil cooler as he ran the hull seawater line after the strainer directly to the engine seawater intake pump, then had another seawater intake line to the gearbox oil cooler...

Guess what, he was then confused with the outlet seawater from the gearbox oil cooler to nowhere lol as I was, as I did not know the setup myself having bought the boat with the engine already half dismantled by the seller (overheated)

So after spending a few hours on the net and searching, I can see that the original seawater from the hull should go to the intake seawater gearbox oil cooler then take the outlet seawater to the intake seawater pump of the engine...

Am I correct?

Rgds
Will

[four winds]

I have a different transmission, but that is how it is plumbed.

Thru-hull, to strainer, to trans cooler, to seawater pump, to engine.

[tomj]

I added a 'bolt on' oil cooler provided by Hurth/ZF after several of my 150A failures. The cooler is actually simply a 'water cooled heat sink' which bolts onto the side of the trans opposite the shift lever. It received water from the raw water intake and passed it on to the raw water side of the engine. It DID NOT HELP!

We have had no problems with the Twin Disc 60A, and have about 1000 hours on it!!! (no oil cooler on the TD!) Trans oil stays nice and clear.

I believe the Hurth/ZF jobber and sales office in the Annapolis area that I dealt with is no longer in business - they were always helpful, but after I had my 5th failure, their office was closed. I talked with the next higher level of Hurth/ZF, but they would no longer respond, and 'washed their hands' of the 'whole mess'!

I have 2 Hurth/ZF 'boat anchors' in my shop at home - one has bad clutches, and the other has new clutches. I never installed the rebuilt trans.....

Tom - currently on Man O' War Cay, Abaco, Bahamas

[CHM]

The Hurth cooler should be plumbed as follows: seawater through hull to strainer to water pump">raw water pump y'd off to trans cooler input. Trans cooler output back to raw water circuit prior to entry to heat exchanger inlet. This is published in their manual on the Internet.


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[micknor51]

This thread reminds me of the many 'happy hours' I spent toiling away removing/installing my Hurth 100 and ZF 10M gearboxes. Replacing the cluth plates on the Hurth was a particular pleasure!
I would get 100 hours out of the beasts before the clutch plates wore out.
In the end I replaced my Nanni(Kubota) 27hp, Hurth/ZFgearbox, shaft and 2 blade fixed prop. It turned out that the shaft was bent and this must have killed the gearbox.
The Nanni was good, so the new motor was another Nanni (Kubota)29hp with a TMC 40P gearbox, new straight shaft and 3 blade fixed prop.
All is now good with 330 hours on the new engine and no gearbox problems.
I have come to terms with missing the happy times of gearbox fun and now am engaged in more sailing.
Happy sailing
Michael norwood

[svGenesis]

Well I have a kanzaki hurth KP21 I'm having trouble getting it into and out of forward and reverse and not able to get neutral. have not used it much at all (a few hours) when this began. (any suggestions?) I'm planning to change the oil with synthetic then adjusting the linkage.

[micknor51]

Change oil then if still a problem it could be worn clutch plates. If you can get a workshop manual and fix it yourself, big savings, if not it will cost nearly as much as new unit.
At least that was my experience with a Hurth HBW100. $1500 for a new ZF 10 unit and $600 for the clutch rebuild kit. I did both and kept a spare transmission.
Good luck
Michael

[CaptWil]

When sailing, the transmission makes a lot of noise if left in neutral. I remember reading somewhere that shifting the gearbox into reverse would stop the shaft free wheeling..
Is it safe to do so for the gearbox, of course remembering to have it back to Neutral before starting the engine again?
Rgds
Will