Problems with Fixed Props on Yanmar SD50's

[1paulg]

Have one gearbox started not going into gear the odd time (usually as I want to reverse into the Marina!) - has only done it a couple of times but obviously there is an issue...
Have heard that Cats with fixed props (our drive unit lowers and retracts) can have a problem with the cone in the gearbox caused by damage from when you surge under sail and before the drive have been retracted...
Anyone know anything on this ..just want to make sure I head in the right direction on this !!

[Tropic Cat]

First off, Yanmar engines are required to be put in neutral while sailing or raised out of the water. It's in the manual.

The Yanmar cone clutch is famous for glazing over. However, the transmission fluid should be checked first and you have to understand that the 'check' is to unscrew the dipstick, and have it rest on the threads ... then pull it and read the level.

The engine controls should be checked next by disconnecting the shift cable at the transmission and shifting the transmission by hand. If it slips then, it's probably the cone clutch , if it goes into gear it could be just a worn shift cable or a cable adjustment or someone put the shift cable on the wrong connecting hole on the transmission shift lever.

Lastly, if the fluid level is good and no one put transmission fluid in it (It takes 30 weight oil) the fix is to dismantle the unit and rough the cone up with sandpaper.

Unless you have the service manual for the transmission and know how to break and reseal the case, you might need professional help at that point.

[ShaunJ]

I just went thru the shift cable not being adjusted correctly on my Yanmar. Easy to troubleshoot as Tropic cat pointed out.

[1paulg]

Thanks Tropic Cat... have checked the cables and doesnt seem any play in them , checked the transmission oil levels and is ok - but will check it is the right oil as this is crucial and previous owner put it in but as he was fastidious is no reason to believe it is wrong...
The units are retracted when sailing ..however when we put the main up and bear off initially if the breeze is fresh we will acelerate poss up to 9-10 knots before they are retracted and although they are put in neutral as soon as poss maybe there is a need to make sure that happens sooner..? so there is no load on the props/gearbox....
Maybe a folding prop would help?
Back to the problem ...guess the cones need a look is my current thinking....the units have only done approx 100 hrs since new - disappointing to have a disassembly job ahead....

[Tropic Cat]

Originally Posted by 1paulg

....the units have only done approx 100 hrs since new - disappointing to have a disassembly job ahead....

Wait.... the units only have 100 hours? There's no way cone clutches wear out in 100 hours. I'm reasonably certain you have an adjustment or maintenance issue.

[1paulg]

well have had someone look at the adjustments and all seems ok ...will talk to the local agents but the warranty has just expired by 4 months- the previous owner didnt use the boat for a while due to health issues ...after double checking it is the right oil dont see what else it can be...

[Cotemar]

1paulg,

You are missing the most important part of what Tropic Cat said to check.

The engine controls should be checked next by disconnecting the shift cable at the transmission and shifting the transmission by hand with the engine running. If it slips then, it's probably the cone clutch , if it goes into gear it could be just a worn shift cable or a cable adjustment or someone put the shift cable on the wrong connecting hole on the transmission shift lever.

[1paulg]

Ok..will do..did disconnect the shift cable at transmission but did not try and shift with engine running (just checked for play) ...the leg was checked by a Yanmar service person when originally put in (110 hrs ago) so seems unlikely wrong cable and there didnt seem any play in the shift cable..would be surprised if it is on wrong hole on shift lever as why is it all of a sudden becoming a problem after being perfect until recently...

[Cotemar]

1paulg,

The reason I said to follow those direction is because I had the same problem.

With the shift cable off and the engine running then you shift it with your hand to see where the rev < neu > forward is really located. After I found it off a bit I made a slight adjustment at the control end adjuster (shifter box)and all has been well for a year since then.

[delmarrey]

There are a lot of assumptions being taken here. First it's assumed it's a Kanzahi tranny. If so, then all info is OK. And they take a 30w HD fluid.
But for a Hurth tranny these need to be put in reverse while sailing and take an ATF fluid.

As for the cable. The tranny lever should be shifted into gear and then the cable shifter matched up to the throw.

On the Kanzahi trannys it's best to run a folding/feathering prop so it's not spinning and creating a drag on the boat.

This has all been discussed on the forum to length.

What model of motor and tranny do you have, just to keep the info straight???

[1paulg]

It is a Nanni 37hp motor -originally had SD40's which were upgraded (by previous owner) to SD 50's 120 hrs ago... will need to check what transmission it is...
The props are 17x13 3 bladed fixed aluminium
One of the difficulties has been it is an intermittent prob -has happened just a few times with prolonged periods of being ok inbetween which means when we have tested at the marina everything was working ok even tho on backing into the marina mins b4 it had slipped.

[delmarrey]

Ouch! You may want to goto this thread and read up.>>> http://www.cruisersforum.com/forums/...tch-19413.html

The last post was informative.