Re: [Amel] Maramu engine replacement

Chris Smither <yachtakwaaba@...>

    No, I did not do it myself - I had no repair manual, and I was told that the job is simpler with a couple of "special" tools that all ZF/Hurth agents have in their workshop.
   The symptoms that you notice are:- ( you can get some or all!!)

1. A longer than normal pause between selecting a gear and the drive engaging.
2. No reverse gear
3. Discoloured gearbox fluid - sometimes it smells "burnt"
4. A major leak from the oil seals.

The parts for the ZF25 are all included in what is called, I believe, a rebuild kit, which does not include a damper plate. 

On the Santorin, you have to remove the water and exhaust hoses at the front of the engine; "split" the drive train; remove the engine hold down bolts and slide the whole engine aft about 2-3". The gearbox can then be removed, and taken to a workshop.

If you have a ZF/Hurth agent near you they should have all the tools, and the manuals. However, there are plenty in Europe, so if you don't have a problem, and all is working well.......

What I would do is check the fluid in the gearbox by pumping it out into a clear container and then looking carefully for any specks of "dark matter" or cloudiness. If either is there, then I would get the gearbox off and get it rebuilt.

Hope this helps



From: Graham Johnston <>
To: "" <>
Sent: Saturday, February 11, 2012 5:44 PM
Subject: Re: [Amel] Maramu engine replacement

As we have a PerkinsM50, 4500hrs, with the Hurth gearbox and shaft alternator in our Sharki and so I guess a clucth disc replacement will be due at some time, possibly soon. Do you do the work yourself and if so are there any special tools needed?
The reason I ask is because if all goes well we hope to be leaving for the UK an exteneded cruise later this year and I would like to know what is involved and to have the necessary gear on board.
Do you happen to have a copy of the repair manual as I did have one for a previous boat but I let it go with the boat when she was sold. 

From: Chris Smither <>
To: "" <>
Sent: Saturday, 11 February 2012, 0:54
Subject: Re: [Amel] Maramu engine replacement

   If you have the Perkins M50 on your Maramu, then I believe the gearbox is now called the ZF25, (ZF acquired Hurth some time ago).
   I'm coming up to 9000 hrs on the Perkins fitted to my Santorin, and the only time I had an overheat problem was when the circular seal on the heat exchanger tube became misplaced. The only non standard fitting I have on the engine is the Australian 4M full flow oil and fuel filters. I think they are superb, and as the filter elements are toilet rolls, once installed the running costs are negligible. Coming through Indonesia, where the fuel was definitely suspect, I used 2 (yes two) rolls, when others were using 8 or 9 engine fuel filters.
   By the way, if you have the Hurth HBW250, (now the ZF25) with the shaft alternator, you should expect to get between 23-25000 sea miles out of a set of drive discs. At just over 70,000 sea miles, I'm just installing my 3rd rebuild kit. A little early, but we have done a lot of motor sailing in the last few years.
   Also, when you have the drive train split, consider changing the damper plate on the engine, the old ones had springs and after a while they "rattle" at idle - the new ones have a synthetic flex coupling

All the best

SN 027

From: Jim Dernehl <>
Sent: Saturday, February 11, 2012 1:28 AM
Subject: Re: [Amel] Maramu engine replacement

I successfully replaced my Perkins with a Westerbeke 85B several years ago
and used the standard Hurth transmission that came with it. At that time my
Perkins was overheating and I wanted to use a naturally aspirated diesel
engine for greater reliability.
Best Jim Dernehl
Pao-San #88

On 2/10/12 12:14 PM, "Bob Sarff" <> wrote:

I'm looking to replace my Perkins 4.154 engine with a Hurth HBW 250-3R trans
with a gear ratio of 2.74 soon and would like your opinion of a couple of
options. I know some of you have replaced your motors with the Yanmar
4JH4-TE. Did you replace the transmission at the same time or rebuild your
old one? If you purchases a new one, which model did you purchase. My
concern at this point is that the dealer I'm working with shows transmissions
that have a 7 degree down angle and the one I have has an offset rather then a
down angle.

Has anyone used the 75 hp Volvo instead of the Yanmar. Is there an
advandage/disadvantage either way?

Thanks for any advise you can provide.

S/V Chara
Hin 173

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