Installing a 3JH4E *^%#! Yanmar (Rant)

[delmarrey]

Originally Posted by beneteau-500

just a silly question delmarry when you run engine at the doc 1/ is it in gear 2/ if not and the engine runs ok at 2700/3000 revs 3/then you may find that when you take boat out that when you get engine up to revs (2700) you may find you are getting prop shaft whip which is why your pss seal may have started leaking and this will happen still even if you think your prop shaft drive couplings are alinged and also you may find your propellor is out of balance which will also cause you probs when you run at higher speeds I had the same prob recently on my refit and had my prop shaft and propeller rebalanced and when they did the rebalance they ran the prop shaft and impeller together on the balancing machine at 3000 rpm tweakthe shaft and retweaked impeller blades so with all that done i fitted a new aqua drive shaft and tides seal and it worked a dream so it may be worth a check if all else fails

I was running it in gear at the dock and it was real smooth but obviously it's not a true environment. I believe the uneven pressure to the motor is causing it to dance around and that would come down to the motor mounts. I think it's time for a thrust bearing of some kind (Re: Rick).

The prop, shaft, strut, motor and coupling are all new. If the prop were out of balance I would think it would whip at the dock. And I was using this prop and shaft with the old motor for a year w/o a problem. But thanks I've considered having the prop spun just to be sure.

[DeepFrz]

del, are you getting any hull flex when you are moving? The engine beds don't seem to be connected to any stringers especially at the rear of the engine.

[delmarrey]

Originally Posted by DeepFrz

del, are you getting any hull flex when you are moving? The engine beds don't seem to be connected to any stringers especially at the rear of the engine.

Nope! The beds are solid as a rock.

Well, the latest. I talk to the Yanmar expert where I bought the thing and he tells me that one can not use a PSS with Yanmar's due the the shaking. It causes the seal to side shift especially at and idle. As well, stuffing boxes act as a center support for the prop shaft.

It makes since so I guess I'll be putting the old stuffing box back on and try it out. But I'm still taking her out this weekend and I'll deal with it afterwords. The spacer (solid coupler) seems to work better then anything for now so it stays.........................._/)

See my new buddy.


.

[knottybuoyz]

Originally Posted by delmarrey

Well, the latest. I talk to the Yanmar expert where I bought the thing and he tells me that one can not use a PSS with Yanmar's due the the shaking. It causes the seal to side shift especially at and idle. As well, stuffing boxes act as a center support for the prop shaft.

This may be totally off the wall Del but if the shaft needs more support couldn't you put another cutlass bearing at this end of the shaft tube? (see pic attached)

Originally Posted by delmarrey

See my new buddy. .

I think you should call him "Pistachio" (Pistachio, stach, mustache)

[DeepFrz]

Originally Posted by delmarrey

I talk to the Yanmar expert where I bought the thing and he tells me that one can not use a PSS with Yanmar's due the the shaking.

Wow, that is a surprise. I have never heard that before. Maybe Yanmar has softened up their motor mounts.

[GordMay]

Originally Posted by delmarrey

... Well, the latest. I talk to the Yanmar expert where I bought the thing and he tells me that one can not use a PSS with Yanmar's due the the shaking. It causes the seal to side shift especially at and idle ...

Mack Boring seems to think they're ok.
http://www.mackboring.com/CMFiles/Do...ngDampener.pdf

Oops, sorry - your tech was talking about the shaft seal, not the coupler.

[IdoraKeeper]

I admire your fortitude.. My Yanmar shakes and thrums at max rpm too. Hope to see you at Sucia and we can all kibitz in person.

Todd

[Chief Engineer]

Velly Interesting.....That had never occurred to me.....learn sumfin new every day, eh?

[SailPenelope]

This is a very familiar story for me. Had a minor variation of this problem when I bought the boat (CT41 ketch), and since then for various reasons, have gone through two engines, three shafts, and three propellers. Problem was sometimes worse, sometimes better, but always there.

After five years of this, did a sea trial with the yard staff, who said, yes, there's a problem, sounds like shaft is banging around in the tube. And yes, I have a PSS, but I had a bit of the problem when I had the stuffing box.

We did install a second bearing, just as Knottybouyz suggested, and in exactly the same place. Problem solved. I think it was just too long of a shaft run without support.....packing gland provides some support, PSS does not.

Our problem was a LOT better after balancing the shaft and propeller, and re-aligning the engine. First time no noise. But at higher rpms it came back, so we hauled again (no charge!) and they added the bearing. By the way, despite it being a cutlass bearing, the yard staff did not call it that.....apparently only the aft one is called that......kinda silly, 'cause it's the same thing.

Hope that helps!

Oh, and they didn't want to install the flexible coupling, even though the Yanmar intallation manual calls for it. And Ed Auck (Yanmar wizard from Bosun's Locker in So. Cal. agrees). So we'll see how it goes, can always install later. Yes, Yanmar engines like to "dance".

[DeepFrz]

Wow, green engines looking better all the time.

[olaf hart]

Would stiffer mounts help?

[delmarrey]

Originally Posted by olaf hart

Would stiffer mounts help?

Yanmar says they'll void the warrantee if one changes the mounts.

I put 22 hours on the thing this weekend using the solid coupler and the PSS didn't leak but I only brought it up to 2700 rpm's at max for running but ran it at 2400 rpm's 99% of the time to start it's 50 hour break in. I'll be installing a stuffing box here in the next day or so for more support and to finish out the summer then see if I can install a thrust/self aligning unit this winter.

The shaft is still slapping the stern tube above 1200 rpm's due to the motor jumping around. There is only about 1/8" on either side of the shaft in the tube but the motor jumps around a 1/2" at times.

Plus, I noticed the shaft pulsating in and out as the boat hit waves. The mounts are moving fore & aft as well as up/down/left/right. It's no wonder yanmar recommends replacing the mounts on it's maintenance schedule.

I did a video running the motor first at 1500 rpm's then 2000, 2400 & 2700. The fames per second are a bit slow but you can get the idea. I tried to shoot the mounts but it doesn't give a true view of the actual movement.

http://www.youtube.com/watch?v=zCaCw1tiBzs

[Laidback]

Del,
I have solved this type of problem using a Pillow Block :
McMaster Carr have in Stainless.

[delmarrey]

Originally Posted by Laidback

Del,
I have solved this type of problem using a Pillow Block :
McMaster Carr have in Stainless.

The problem with a pillow block is it would get torn right off it's mount as much as the yanmar shakes. Or it would fatigue the shaft or coupler so bad something else would break.

I would like to put in one of these (Pythondrive The ideal flexible and vibration-free drive unit) but the distance between the seal and the coupler is a couple inches short. I may have to move the motor forward about 3" to get this in.



In the mean time I've installed a stuffing box and it is more quiet now but is still banging a bit. It'll have to do for the rest of the season. I just don't like salt water dripping in my dry boat. I've cut out the end of a kitty-litter box and using it as a drip pan.

When I pulled out the PSS seal ring today there was carbon slung all over and you can see the uneven wear from all the vibration.

.

[Laidback]

Del,
Obviously I cannot see what you are seeing.
However, is it possible that one or more of the components on the shaft (excluding the engine and gearbox) has been weighted TOO much on one side causing centrifugal force to unbalance the shaft increasingly as RPM is increased and thereby vibrating the whole unit.
The blue arrows indicate possible problem sources :- (one suggestion would be to replace the locking bolt and its 'mousing wire' - with an Allan screw + washer+ anther locking Allan screw - which locks the first one. When both are inserted, they do not extend beyond the coupling's O/D)