Transmission Replacement??

[Vitesse473]

So after sailing south from San Francisco to La Paz, MX and then back to San Diego, I've just learned that my transmission may need to be replaced. Before committing to the $5,000 project, I thought I'd take a moment to gather some opinions.

Symptoms are interesting. When moving the throttle handle into forward, I can hear the clunking sound of the transmission engaging. However, upon throttling up, the boat doesn't move. I can grab the shaft as it spins in low rpm and it will stop. I go back to neutral and try again and voila, the transmission engages and off we go. We went all the way from La Paz to San Diego like this (1000 miles). Once engaged, the transmission does not slip out.

Does this sound like a shot transmission?

Volvo Penta TMD22-p with a Volvo transmission MS25L-A

[HoffaLives]

i'm not familiar with that tranny, but most are similar. unless you have major internal tranny damage it should be repaired rather than replaced at that high cost. there are a lot of possible reasons for the symptoms that you describe but my guess would be the clutch mechanism since it works okay (without any bad noises?) once it is engaged. it could be something in the clutch piston, the hydraulic pump, the shift mechanism, pressure valves etc. but it sounds like your gears/bearings are okay.

i would get a second opinion, and one given with the tranny opened up to find out what the problem actually is. suspect advice that suggests replacement without determining what the problem actually is. Re and Re costs would be the same regardless and it should only take an hour of labour or so to open it up and find out what is wrong.

[amarinesurveyor]

Did you check the fluid level? Low fluid could cause a problem like that.
Brian

[Vitesse473]

Originally Posted by HoffaLives

i would get a second opinion

I have another mechanic going down on Tuesday to give a second opinion. I will happily pay the hourly rate twice to make sure the problem is properly diagnosed.

amarinesurveyor - Yes, I checked fluid levels. I wish that were the issue.

[bwindrope]

I might also check the cable adjustment. That clunking sound you hear on engagement is reassuring, but I know with my Hurth transmission that they are pretty sensitive to the travel of the arm that engages the clutch. If the travel is not adjusted correctly, then the clutch isn't smashed together tightly enough for the tranny to work. The cable could be out of adjustment just enough to allow it to make a clunking sound like it is engaging, but not so much to fully smash the clutch plates together.

Just a thought. After eliminating fluid levels as the culprit, and if you eliminate the adjustment of the engagement arms, then I agree with the idea of seeing what a rebuild would cost. The problem is almost certainly a clutch problem if once it is in gear it runs fine. There is really not much more to a tranny than the gears and the clutch. If it ain't one, it's the other.

Good luck and keep us posted.

[Wayne25]

Can you disconnect the control cable from the transmission gear selection arm. If so, try putting it forward manually at the transmission lever. That would eliminate any problems with the cable.

[Vitesse473]

yes, we removed the cable entirely and were manually engaging with the lever. Still exhibited the same issue, so definitely ruled out the cabling.

I appreciate the cable and fluid suggestion. Goes to show members of this board start a diagnoses correctly. I'm beginning to think the first mechanic was looking for some economic stimulus of his own.

[HoffaLives]

Originally Posted by Vitesse473

I have another mechanic going down on Tuesday to give a second opinion. I will happily pay the hourly rate twice to make sure the problem is properly diagnosed.

amarinesurveyor - Yes, I checked fluid levels. I wish that were the issue.

i'm not sure if having another mechanic look at it and run it is going to help very much. almost certainly you're going to have to pull the unit to go any further. as has been mentioned here, there isn't much external to work with beyond fluid levels and shift adjustment. you could consider pulling it yourself and taking it to a shop for analysis. few mechanics will guarantee a repair cost without pulling it apart to see what parts are shot and what need replacing.
at the very least the tranny must come out. after that, what they find will determine whether it is better to replace or repair.

another thing - did you check fluid colour? is it dark? does it smell burnt?

[HoffaLives]

Originally Posted by Vitesse473

I have another mechanic going down on Tuesday to give a second opinion. I will happily pay the hourly rate twice to make sure the problem is properly diagnosed.

amarinesurveyor - Yes, I checked fluid levels. I wish that were the issue.

i'm not sure if having another mechanic look at it and run it is going to help very much. almost certainly you're going to have to pull the unit to go any further. as has been mentioned here, there isn't much external to work with beyond fluid levels and shift adjustment. you could consider pulling it yourself and taking it to a shop for analysis. few mechanics will guarantee a repair cost without pulling it apart to see what parts are shot and what need replacing. what they find will determine whether it is better to replace or repair.

another thing - did you check fluid colour? is it dark? does it smell burnt? is there any water in it from a heat exchanger? is there a filter that can be replaced? any external fittings that you can stick on a pressure gauge to check pump pressure?

also do you know the proper procedure for checking fluid levels? run engine to operating temps and shut down. immediately have someone check the fluid level.

[timebandit]

I know this might sound strange----It does to me.

Looking online for your transmission and it's ills I found this--

http://www.maritimsd.no/Customers/msm/documents/Dokumentasjon%20Volvo/D2_serie.pdf

Now I presuppose (ya-all know what is is to assume) that the term "reverse gear" means transmission, than

Page 31 kinna describes your problem and it may just be a normal operation of your "reverse gear".

I don't pretend to understand why the transmission operates this way or it's purpose or how to get into or out of this mode but you might want to check further.

Also on page 63 is a simple one page trouble shooting guide that everyone should have on board.

All in all this complete document is worth reading for the new or novice boat owner even if you don't own a Volvo.