Transmission noise & removal of same on a MkI /w M35B engine.

[SailDan]

We had to replace our M35B engine on our 1994 C34 last summer and decided to replace to the transmission (Hurth HBW-100-2R) at the same time.

(1) Problem & symptoms:
This summer I started to notice a slight "chatter" in the transmission and later a "high whine / squeal" when the engine was run for at high rpm (2500-2800) for some time. The whine becomes less noticeable at low rpm. Transmission fluid level was OK but the fluid was black.

Has anyone else experienced the same problem with transmission and have a possible diagnosis?
I telephoned Maryville Marine who supplied engine & transmission.  They had no idea of what was going on and suggested I remove of transmission and send it to them to inspect (2 year warranty).

(2) Removal Transmission:
I think I know the answer to this question but will ask anyway. Do you "have to" remove the engine to remove the transmission on the Mark I with a M35B engine?  I did a search on this site and found a ref. (Ron Hill) to C34's with M25XP engine which indicated you had to remove the engine. Another ref. (Dave DeAre) to a C34 with a M35B said you did not but could access it after removal of the "engine cover" assembly in the aft cabin. However, this referred to a 2002 C34, MKII.

[Stu Jackson]

Here's a third answer from Charles Holder who has, over the years, provided us with some very good input.  From a search on "removal":  http://c34.org/bbs/index.php?topic=293.0

Dan, sorry to hear about your issue.  When we first changed our transmission fluid (many years ago and altogether too many hours in between changes, but I was learning) it, too, was black, compared to the nice syrupy purple of the new Dexron.  With the "black" fluid, have you considered changing the fluid, filling the whole reservoir up as if winterizing, then draining and refilling to normal and trying that?  Seems absurd to have to take the transmission out for a two year warranty check.  Have they no local representative?  Like for Hurth, rather than Maryville Marine.  Sorry, too logical.

I searched the Knowledgebase also but found no input to answer your question.

[Bob K]

I too saw black transmission oil when we purchased our boat several years ago.  Flushed and replaced the oil, and have had no problems since.  And it is still the proper purple-red color! 

[Ken Juul]

Hi Dan, Sorry to hear about your problems.  According to the schematic attached below it appears you can remove the trans without removing the engine.  Can't tell if the Bell Housing has to come off or not.  You will probably have to slide the prop shaft back to give enough room, that may be where the problem is because your engine is longer than the original M25.

http://www.marinedieseldirect.com/catalogs/catalog_group.php?owner=mdd&page_ident=201021-52&model=M-25XPB%20M-35B%20M-40B&manufacturer=Universal&title=BELL%20HOUSING%20AND%20TRANSMISSION&quant_position=&catalog=201021&printparts=201021&printservice=&printoperators=&comment1=

The trans works by pressing friction plates together.  I would assume that a new trans will shed a lot of the friction material during initial use, then taper off to what most of us see as normal.  I would completely flush the trans first, maybe a couple times.  Then run it 10 hours or so.  If it continues to turn black then you have a do have a problem.

[Roc]

In the Mainsheet Tech notes a few issues ago, there was an article on the C36 page by someone that removed the transmission to change the damper plate.  It was complete with pictures every step of the way.  The directions and write up were done so well, the whole damper plate change project seemed very easy.  I don't remember how long ago, but if you check the Tech notes and keep going back about a year or so, you should find it.  The C36 MkII uses the same M35B engine and trans.

[Jack Hutteball]

When my transmission failed on my C34 MKll under warrenty it was removed and replaced without taking anything else apart in the boat.  I did't watch, but it was in and out of the boat easily while in the water.
Jack

[lazybone]

Black oil might mean the trans was slipping.  Are you sure it was fully engaged (cable adjusted correctly)?

[SailDan]

Thanks everyone for the information and suggestions.  I decided to bite the bullet and took Weal Sea to Torresen Marine (Muskegon, MI) where they pulled the new transmission and reinstalled the old one. Since the new transmission was still under warranty, we shipped it to Maryville Marine for inspection.


Concerning removal of the transmission, you CAN remove the transmission WITHOUT having to remove the M35B engine or loosening its motor mounts.
(Note: I have a new M35B engine which is slightly longer than the originals installed on the 1994 C-34.  Therefore, the procedure given below should also work on the original M35 engines.)

Procedure to remove Hurth HBW-100 transmission (recently renumbered "ZF-10" by ZF corporation).
Item numbers refer to the diagram included with Ken Juul's response to my initial inquiry (see above).
1. Disconnect the transmission shifting cable from the transmission.
2. Disconnect the 4 bolts on the coupler (Item #19 in diagram) joining the propeller shaft and transmission.
3. Slide the propeller shaft back slightly.
Next you'll remove the transmission and the "adapter" plate (Item #25) as a unit: The transmission itself is bolted to the adapter which in turn is bolted to the "bell housing".
4. Remove the 2 bolts holding the heat exchanger to the engine block so it heat exchanger can be shifted up & down (Do NOT disconnect the heat exchanger hoses.)
5. Remove the 6 bolts connecting the adapter (and the attached transmission) to the "bell housing".
6. Pull the entire adapter-transmission "unit" backwards to disengage the transmission shaft from the "damper" (Item #8). (Note- you may have to pry it backwards a bit to break it loose.)
7. To get clearance to remove the adapter-transmission unit, you will probably have to "lift" heat exchanger upward a few inches. Its awkward to hold it up, so we used a rope on each end to tie it up.
8. Continue to pull the adapter-transmission unit backward.  You may have to rotate the unit 180 degrees to clear the coupler on the propeller shaft.

(NOTE: You can now inspect the "damper" (item #8)  & adapter (damper plate mounting) (item #4) through the opening in the bell housing.)

9. Remove the 6 bolts holding the transmission to the transmission adapter plate (item #25).  These are accessed from the "bow" / bell housing side of the adapter. 

If your transmission is still under warranty, do NOT open it. This will VOID the warranty (good for 5 years). Telephone Maryville Marine: (810)-364-7653 (1551 Michigan Avenue, Maryville, MI 48040). Ask for John Dillon. 

[Bill Sedgwick]

The M35 rear motor mounts are on the bell housing rather than on the engine as on the M35B. The rear of the engine must be raised and the bell housing removed to access the transmission bolts. My C34 is a 1990 with the M35.

[Ron Hill]

Guys : What Bill is saying is that the M35 and M25XP engines have the Hurth transmission bolted to the bell housing from the INSIDE.

The M35BC (MKII) and M25XPB  have engines/transmissions that are bolted together from the OUTSIDE - so the engine can sit inplace while you change out the transmission. 

[Hawk]

Dan,
This thread goes back a few years but I have unfortunately a similar noise at higher rpms. Did you ever hear what the problem was after they took out the transmission?

Many thanks.
Tom