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Author Topic: Hurth Transmission Removal [and Rebuild?]  (Read 5708 times)

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Hurth Transmission Removal [and Rebuild?]
« on: October 23, 2001, 10:01:34 AM »

Has anyone removed the transmission on the M25xp and can provide some advice on how complicated a job this might be or where I can find some guidance?
 I lost forward during the season, had cable readjusted delaying the inevitable for a few months.  Now I am having intermittent success in getting reverse and forward and figure that it is time for a transmission rebuild over the winter.
 I am considering removing the transmission myself and either rebuilding it myself or taking it to someone else.


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Transmission Removal
« Reply #1 on: October 23, 2001, 10:34:02 PM »

Been there, done that with my C34, 1988.  The 25XP has to be moved out of the engine compartment into the galley area to remove the transmission and bell-housing, then separation of the Hurth transmission from the bell-housing.
 I can remove the engine in about 4 hours and replace it in under six, including realignment.
 To remove the engine:
 disconnect the transmission; exhaust; transmission, speed control and engine stop cables;
 remove the engine mount lag screws; alternator;
 disconnect the electrical harness;
 unscrew the cable ties holding the fuel and water lines from the port side of the engine to the engine compartment.
 You shouldn't need to disconnect the fuel and water lines.
 Using a beam across the hatch, arrange a pulley system and rope sling to lift the engine about 2/3 of the way back along the vale cover.  A little trial and adjustment will ge the right balance point.  I use a rope through the lifting ring near the rear of the engine and arond the raw water pump housing.  The engine weighs about 300 lbs so a six or eight to one pulley system is about right.
 Raise the engine off the bed, adjust the sling to get it Balanced if needed.  Move the lifting beanm forward by easing it along the hatch area.  Don't make the beam too long or you won't clear the jamb cleats.  Work slowly so you don't injure yourself of the boat.  Padding under the beam helps reduce damage to the teak.  Almost certainly you'll find some cable or hose that needs easing to allow the engine to move far enough forward.  When the rear of the transmisson is sufficiently far forward, rotate the transmission past the door into the head.  The engine will now be transverse to the boat axis with the shaft coupling towards the navigation table.  Lower the engine only blocks positioned under the forward engine mounts and the rear of the oil pan.  
 Disconnect the heat exchanger bracket from the bell-housing and tie the heat exchanger up out of the way.  disconnect the bell housing by removing the dozen or so bolts and nuts and bolts.  Ease the bell-housing and transmission back a few inches until the shaft separates from the damper plate.  Separate the transmission from the bell housing by removing four bolts located inside the bell-housing.  Curse the designer who put them inside the bell-housing so a half hour job took so long.
 My advice, have the transmission serviced by someone recommended by ZF Marine.  The Hurth transmissions seem simple but the mechanics needs some training to get it right first time.  I became expert at Re&Re on the engine because I didn't get the right mechanic the first time, even though I went to a good engine shop.  In Canada, the cost for bearings, thrust washer and the sintered bronze friction plates plus labour will be about $1500. This is about half the cost of a new transmission.
 Replacement is the reverse except you have the realign the engine.  Leaving the mounts on the engine means the vertical alignment should be correct so the main issue is to get the horizontal alignment correct.
 You'll need both metric and imperial tools for this job.  The engine is metric but most attachments are imperial sizes.
 Have fun.


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Hurth Transmission Removal [and Rebuild?]
« Reply #2 on: October 30, 2001, 08:06:51 AM »

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Charles Holder:
                                                   Been there, done that ....Have fun.<HR></BLOCKQUOTE>
 Thanks for your detailed message -  
 looks like I've got a difficult job that can be managed (you confirmed the bad news that the engine needed to be removed), probably should take advantage of the situation and do the motor mounts and anything else too.
 If anyone has some specific recommendations on service for the transmission in the South Amboy, NJ area feel free to e-mail me at or post a reply.


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Sorry to hear about the trans
« Reply #3 on: November 02, 2001, 09:04:07 AM »

Hey Skip!
 Sorry about the trans.  Otherwise, hope your summer was great.  The Chesapeake is fantastic!  Let me know if you will tackle the trans job, I'll give you a hand.  I'm sure an extra pair of hands will help in removing and installing.  Send me an email and let me know the schedule.
« Last Edit: May 10, 2010, 07:25:46 AM by Stu Jackson »
Roc - "Sea Life" 2000 MKII #1477.  Rock Hall, MD
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