Multiple problems with Yanmar shaft drive

[topmast]

Even if the coupling tests with a feeler to be aligned, if the weight of engine is not evenly spread out on all 4 mounts it may allow some nasty movement. and stress on the rear bearing.in the trannie.. unless something breaks first it will show up in failed rubber mounts or fractured bolts. (not specific to Yanmars)

[daletournier]

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.

These break regularly and are $70aud to replace. A friend just had two turned up in bali out of stainless steel for $5each.

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[RaymondR]

One of the things to check is whether it is the output shaft and coupling moving in and out of the gearbox or just the coupling moving on the shaft. Unless there is an awful lot of noise coming out of the gearbox I would suspect the coupling is moving on the shaft. If it's the latter the retaining nut is probably loose.


My Yanmar had a left hand thread on the output shaft coupling retainer although it was not the model you quote.

[spottsvillle]

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.

Palarran: I have a 4JH3-TE with the threaded half still in transmission. I need a good suggestion on how to remove the threaded piece without removing the transmission or losing the threaded piece into the transmission. Any great ideas out there?

Norm

[tinkrman69]

use a dermal to cut a slot in it and use a screw driver to turn it out. Or if the stick won't come out pull it up till it's tight and turn it. do it whilst its cool. the reason they stick is that plastic expands more than metal with heat.

bad design!!!!!!!

[Palarran]

Sorry, I missed your question Spottsville. After being a member for 3 years and only posting three times, you deserved quicker attention Sorry. Tinkerman's suggestion would probably work but I'd just try sticking a screwdriver in the hole and turning it out. It should come very easily.

As an FYI, the Yanmar mechanic will be working on the motor tomorrow so I'll let you know what he finds.

[spottsvillle]

Originally Posted by tinkrman69

use a dermal to cut a slot in it and use a screw driver to turn it out. Or if the stick won't come out pull it up till it's tight and turn it. do it whilst its cool. the reason they stick is that plastic expands more than metal with heat.

bad design!!!!!!!

That's an idea! I thought about using a small soldering iron to melt the slot in one part of the thread (say at 12 o'clock) in hopes the slot would release the tension on the threads that preventing it from turning. The dipstick is no longer connected to the thread like in the picture.

Norm
Quiet Company
Great Harbour GH 47

[tinkrman69]

if you try to melt it at the threads, you'll possibly make it stick harder. but if the dipstick is removed, then you have a hole in the center? use an EZ out and twist it out. yo might try heating the tube lower down -away from the plastic plug. As mentioned plastic expands more than metal, with heat...making it get tighter in the threads. But when the engine is at its coolest...early AM...using a heat gun, warm the dipstick tube down low...say at the point it enters the tranny housing. the metal will expand slightly and loosen around the plug. You could also use a flat thin piece of metal...like a butter knife...heat it and melt it into the hole in the center making slots on either side of the hole then turn it out like a screw.

Like I said, that was a pretty bad design flaw. When removing plastic plugs in warm/hot machines I usually cool the plug, by blowing on it, before reinstalling it, to keep from damaging the threads. If it's tight when screwing it in I stop and cool it some more. It will screw right in then. lubing the threads doesn't help. Besides after a while it thickens and bonds it to the hole, causing damage to the threads of the plastic.

I'll say it again BAD DESIGN!!! I don't think it was the idea of an engineer...unless they were on the board of directors and was trying to pinch a half cent.

[Palarran]

Originally Posted by Palarran

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.

After the Yanmar technician checked out the engine he found a sheered motor mount bolt. He is in the process of replacing and is confident that will eliminate the vibration. The diesel leak from the turbo took a few seconds to tighten up a clamp. He checked the shaft movement and doesn't feel this is an issue. So - All is fairly well :-)

Thank you for the input

[MARINE ENGINNER]

Originally Posted by Palarran

After the Yanmar technician checked out the engine he found a sheered motor mount bolt. He is in the process of replacing and is confident that will eliminate the vibration. The diesel leak from the turbo took a few seconds to tighten up a clamp. He checked the shaft movement and doesn't feel this is an issue. So - All is fairly well :-)

Thank you for the input

[tinkrman69]

that's good. but did the mechanic, specifically, address the linear end play on the output shaft of the reverse gear? A 1/4 inch is a lot of play and could cause some major problems down the line....no telling when near or far future.

I understand that you or whom ever observed it, might not be all that experienced, but it should be measured. It's not all that complicated to check. And the cost savings of early detection is well worth it.....think colission....not being able to stop.

[Palarran]

Tinkerman,
It was always questionable about the amount of play, with my friends basically saying they couldn't see anything to the mechanic. I'll look at it in three weeks and see if there's an issue to my untrained eye. Thanks.

[spottsvillle]

Originally Posted by tinkrman69

if you try to melt it at the threads, you'll possibly make it stick harder. but if the dipstick is removed, then you have a hole in the center? use an EZ out and twist it out. yo might try heating the tube lower down -away from the plastic plug. As mentioned plastic expands more than metal, with heat...making it get tighter in the threads. But when the engine is at its coolest...early AM...using a heat gun, warm the dipstick tube down low...say at the point it enters the tranny housing. the metal will expand slightly and loosen around the plug. You could also use a flat thin piece of metal...like a butter knife...heat it and melt it into the hole in the center making slots on either side of the hole then turn it out like a screw.

Like I said, that was a pretty bad design flaw. When removing plastic plugs in warm/hot machines I usually cool the plug, by blowing on it, before reinstalling it, to keep from damaging the threads. If it's tight when screwing it in I stop and cool it some more. It will screw right in then. lubing the threads doesn't help. Besides after a while it thickens and bonds it to the hole, causing damage to the threads of the plastic.

I'll say it again BAD DESIGN!!! I don't think it was the idea of an engineer...unless they were on the board of directors and was trying to pinch a half cent.

Tinkrman69
Thanks for your suggestions. Have already tried the easy out with no success. As the easy out started biting the plastic small scards of plastic were created so I stopped to avoid any plastic entering the transmission. Given your comment on plastic and heat, does plastic shrink when cold more than metal so if I freeze the plastic left in the tranny (see picture) you think it might loosen it? Thinking of spraying freon on it.

Bottom line is for me I can still reinsert the dipstick portion and it does not leak, but checking the true level of oil is a challenge. The oil is easy to change and suck out so I have changed it and I'm going to run it the balance of this season so I don't have to worry about "what will it damage" and "should I run it" if the removal doesn't go according to plan. We will winterize and layup the boat in the winter for 3 months so this repair and any attempt will go on the list for then

Thanks for your info!

Norm











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[Palarran]

How about taking a small paring knife and a torch. Heat up the knife and use it to melt two slots in the plastic which are about 1/4 of the circle. Use fishermans hook remover (roach clip :-) )to grab the 1/4 bit of plastic and remove, then unscrew the remainder.