Multiple problems with Yanmar shaft drive

[Palarran]

I'm looking for some advice with a few problems my port engine is experiencing. The engine is a 4JH4-TE with KM4A transmission. This is a shaft drive with Variprop feathering propellers.

My good friends are using Palarran right now and they have noticed 3 problems.

1 - The engine is vibrating when the rpm's are above 2200. It isn't a real bad vibration and only noticeable both visually and audibly when you have the engine cover open.

2 - There is a diesel film on the valve cover

3 - Most concerning - There is a slight movement in and out of the shaft to the transmission when shifting into and out of drive. This movement is so slight it takes a while to spot and probably isn't more than 1/4"

My friends had a Greek mechanic look at the motor today. His diagnosis is:

1 - The vibration is from a misalignment of the shaft and motor. I had new dripless shaft seals put on this winter and they needed to replace the coupling. I had specifically asked the technical director if the mechanic checked the alignment between the two and he said absolutely - so that means maybe. I can't imagine what else would be causing the vibration unless something caught the prop, but that is not likely.

2 - The oil is from a leak at the turbo. My friends can't see any leak and said the film is very slight, with no diesel accumulation anywhere. Is this a problem that can wait until I return?

3 - The Greek thinks the cone clutch is going bad on the transmission. The motor and transmission have 900 hours on them. The motor shifts in and out of gear very easily and to my knowledge doesn't make any noise at all. I've been replacing the transmission oil as recommended. Again, my friends say the movement is very slight. They are concerned that the transmission would break at the exact wrong moment like when docking. I don't have any knowledge of the inner workings of these transmissions to know if there's a problem here.

Any advice on these three problems would be greatly appreciated.

[Palarran]

I'm hoping someone has some suggestions on this. I told my friends there was no better place than the CF to get some ideas. If anyone has anything on the transmission especially it would be appreciated.

[four winds]

That's the angled output version, correct?

It has a compact output assembly driven by a helical cut gear off the intermediate assembly, but otherwise isolated from it. Any excessive play should be from wear or damage in the output assembly, not the cones and intermediate assembly. Though the helical cut will impart the force to cause the movement.

Maybe compare to the output of the other engine. If it shows no detectable movement, which I think it should, you may have a concern.

Notice how little room there is to allow a quarter inch of movement. Something's up if that is the case.

[MARINE ENGINNER]

[QUOTE=Palarran;2154966]I'm looking for some advice with a few problems my port engine is experiencing. The engine is a 4JH4-TE with KM4A transmission. This is a shaft drive with Variprop feathering propellers.

My good friends are using Palarran right now and they have noticed 3 problems.

1 - The engine is vibrating when the rpm's are above 2200. It isn't a real bad vibration and only noticeable both visually and audibly when you have the engine cover open.

2 - There is a diesel film on the valve cover

3 - Most concerning - There is a slight movement in and out of the shaft to the transmission when shifting into and out of drive. This movement is so slight it takes a while to spot and probably isn't more than 1/4"

My friends had a Greek mechanic look at the motor today. His diagnosis is:

1 - The vibration is from a misalignment of the shaft and motor. I had new dripless shaft seals put on this winter and they needed to replace the coupling. I had specifically asked the technical director if the mechanic checked the alignment between the two and he said absolutely - so that means maybe. I can't imagine what else would be causing the vibration unless something caught the prop, but that is not likely.

2 - The oil is from a leak at the turbo. My friends can't see any leak and said the film is very slight, with no diesel accumulation anywhere. Is this a problem that can wait until I return?

3 - The Greek thinks the cone clutch is going bad on the transmission. The motor and transmission have 900 hours on them. The motor shifts in and out of gear very easily and to my knowledge doesn't make any noise at all. I've been replacing the transmission oil as recommended. Again, my friends say the movement is very slight. They are concerned that the transmission would break at the exact wrong moment like when docking. I don't have any knowledge of the inner workings of these transmissions to know if there's a problem here.

Any advice on these three problems would be greatly appreciate


hi parallan

1- check the flexible mounts if they are tight and the bolts on the engine that are bolted common problem on yanmars

2- the turbo has a leak? or is it coming from the muffler , if it is coming from the muffler it is caused by low cruising rpm

3- cone clutch will not cause vibration if it is failing , the cone clutch starts to fail the time you engage then you understand a time delay that the transmission does not engage and suddenly it engages hard

M.E

[four winds]

I just realized something. Notice the use of shims and tapered roller bearings in the output assembly.

Tapered bearings require zero lash to function. In fact, often they are preloaded with negative lash or interference fit.

Can't find the shimming instructions for your trans. But for the KM3 behind my Yanmar the shims for the output are set to -.0039 inch. An interference fit of almost four thousandths. Which allows a "perfect" fit after coming up to temp. That's how tapered bearings work, no slack.

There are no thrust collars here. The bearing races are the thrust surfaces on the output assembly.

If your output shaft is moving in and out, at all, that's a problem.

And most likely the source of the vibration.

[MARINE ENGINNER]

Originally Posted by four winds

I just realized something. Notice the use of shims and tapered roller bearings in the output assembly.

Tapered bearings require zero lash to function. In fact, often they are preloaded with negative lash or interference fit.

Can't find the shimming instructions for your trans. But for the KM3 behind my Yanmar the shims for the output are set to -.0039 inch. An interference fit of almost four thousandths. Which allows a "perfect" it after coming up to temp. That's how tapered bearings work, no slack.

There are no thrust collars here. The bearing races are the thrust surfaces on the output assembly.

If your output shaft is moving in and out, at all, that's a problem.

And most likely the source of the vibration.

four winds , all reversing gears are equipped with thrust collars astern and ahead and also shims as you mention and which gear you have KM3P or KM3A?

M.E

[four winds]

Originally Posted by MARINE ENGINNER

four winds , all reversing gears are equipped with thrust collars astern and ahead and also shims as you mention and which gear you have KM3P or KM3A?

M.E

Yes, of course I agree with these statements.

But this is not the forward or reverse gear thrust of the rest of the transmission.

This is an isolated output gear assembly. Driven by the helical cut gear on the intermediate shaft assembly. Which of course do impart some force fore and aft. But not like the forces absorbed by the thrust collars in the main body of the trans.

Look carefully at the section drawing pictured and I think you will agree that the bearing races are absorbing the longitudinal forces present via transfer of the helical cut on the gear.

Would you not agree that the output shaft should not be moving in and out a quarter of an inch?

[four winds]

Palarran, when the new coupling was installed, was it first installed on the shaft and put on a lathe to true the face of the coupling?

[four winds]

And my final post on this thread.

There should be zero fore and aft movement in your coupling.

The final two gears are angle cut and helical. Backlash is critical. Backlash is set by shim t5. Final fit is set by the output seal housing shim t6. This is done by carefully measuring the J and K dimension in the section drawing posted above.

The little formula there should be read as,

t6 equals J minus K, which should equal from 0.0mm to minus 0.1mm. (or 0 to -.0039in). As in no slack to about four thousandths interference fit.

If the coupling moves aft the gear drops down away from the gear driving it. Backlash increases. That's why it can't move.

I think an improperly prepped coupling or improper installation may have trashed your output gearing.

But ONLY IF there is play in and out at the coupling.

I could be wrong of course. But that's my story and I'm sticking to it.

[Palarran]

Thank you both for the suggestions. I think one test my friends could do is swim under the boat with the motors off and see if both shafts move forward and back the same way, or move at all. From four winds post, there should be zero movement of the shaft and if there is, they should have a Yanmar mechanic look at it.

How hard is it to have a mechanic change the cone clutch?

[tinkrman69]

Regardless of thrust washers or tapered bearings, there should be no noticeable -with the nakid eye - linear movement on the out put shaft. A 1/4 inch movement? I'm surprised it hasn't already locked up. And like most things, they do go out totally at the most inopportune times.

problem 1 and 3 are probably the same fix. as the force increases with the rpms the teeth on the helix gears mesh less causing grinding and hence vibration The gear problems may have been caused by misalignment of the shaft, during the dripless packing installation. I'd double check the alignment no the other engine to head off problems over there.

in todays world work mentality of do the least work to get the most money. Craftsmanship has gone out the window. Even tho, in the past as now, it's the owners responsibility to educate themselves to know the right questions to ask and know the appropriate answers, when they are given and pay attention to the work being done. if you don't want or can't take the time to be there. Hire someone who has "your" best interest in mind, to be your eyes.

Today there is such a high turn over of customers. Business' don't really care about "return" customers, who are mostly transient. They are overloaded with new ones.

[Palarran]

Originally Posted by tinkrman69

in todays world work mentality of do the least work to get the most money. Craftsmanship has gone out the window. Even tho, in the past as now, it's the owners responsibility to educate themselves to know the right questions to ask and know the appropriate answers, when they are given and pay attention to the work being done. if you don't want or can't take the time to be there. Hire someone who has "your" best interest in mind, to be your eyes.

Today there is such a high turn over of customers. Business' don't really care about "return" customers, who are mostly transient. They are overloaded with new ones.

Couldn't agree with you more tinkrman and I though I had. Here's a picture of the transmission dip stick for the starboard motor - after their mechanic serviced it.

[Vladis]

Originally Posted by Palarran

Couldn't agree with you more tinkrman and I though I had. Here's a picture of the transmission dip stick for the starboard motor - after their mechanic serviced it.

Hi,

The dip stick in this photo looks like mine! I tried to get one from Yanmar in Italy but it was longer than mine. I use some glue to hold the 2 yellow parts together and I inspect it carefully when I change the oil transmission! Good luck with your shaft problem.

Vladis

[Dockhead]

Originally Posted by Palarran

Couldn't agree with you more tinkrman and I though I had. Here's a picture of the transmission dip stick for the starboard motor - after their mechanic serviced it.

Ha, ha! Join the club of Kanzaki owners, Palarran! Mine looked just like that too.

Replaced it (and it was, surprisingly, not too expensive), and just remembered never to tighten it too hard, and no further problems.

These are basically good boxes. My advice would be not to guess yourself but to show it to an experienced Yanmar guy you trust. You are now running up against one of the great advantages of multihulls -- you've got a spare, unlike me!

Good luck!

[Palarran]

Thanks Guys,
I'm trying to get an appointment for Contract Yacht Services in Lefkas to look at the port motor. They did a 500 hour valve adjustment for me a few years ago and I was really impressed by the mechanic. They are the Yanmar service dealer for the Ionian's. Pisses me off though because the engines were running perfectly last year and I didn't notice anything this year when I launched her. Maybe it's nothing, or just misaligned.