Kanzaki KH18 cluncking in drive

[pylotttt]

I've got a Kanzaki KH18 that is clunking while in drive. It seems to happen more at lower RPM and diminishes at 2800 RPM, but is still there. It sounds like something is misaligned or worn and is making an intermittent clunking sound that you can feel and hear throughout the boat. The transmission is about 30 years old but should have less than 2500 hrs on it. Does the drive engage with gears, plates, or interlocking splines or fingers? Other than the exterior mechanical engage arm is there any internal adjustments for the engagement of the clutch? I have made sure that the arm is fully extended in the engage position, but this did not reduce the problem.
Any feedback would be greatly appreciated.
Thanks,
Rob

[scotte]

While I don't have the answer to your question, a quick bit of searching shows that you've probably got this mated to a 3QM30H, and you may be able to find the info you need if you look for info on that Yanmar powerplant. My experience has been that even Yanmar dealers usually give a shrug when you mention Kanzaki, but have no trouble if you give the full Yanmar engine code.

[Alan Wheeler]

OK the first place to suspect... No I will come back to that. The second place to suspect is the flexable coupling between the box and the shaft.(if it has a flexable coupling) Make sure it is not coming apart and that there is not movement. It should be tight and solid feeling. You may even have to remove it, especially if you suspect something. While in position, take a good work light and look at the rubber and ensure it is not perished and cracked.
Now back to the first place Suspect. It is common for the flexplate to fail. This is a plate that is bolted to the back of the flywheel and usually has springs mounted around it, to take shock loading from the engine, through the gearbox. Without that plate, the box can simply rattle itself to death from what is called "injector shock". This plate will soundlike everything is coming apart below when you are idling or just above idle. Once you get a little rev on and the load comes on to hold it all in place, the rattle will go away. It is quiote possible that the rattle is a thump in your case. If you can not find anything obviouse elsewhere, that will be the place to look. If it is making the noise, it WILL fail eventually and you will have no drive at all.
The one other place is to ensure the prop is on tight. I know of one guy in these parts that had a strange thumping sound. He thoguht it was the gearbox. He stopped the boat, took a look, Put the boat into forward and the noise continued. He went into reverse and the noise stopped. But so did the boat. The prop was loose and screwed itself off the shaft.

[pylotttt]

Thanks for the feedback Scotte and Alan,
Do you know if this transmission has plates for the clutch or interlocking fingers. It sounds like there are fingers that have worn and are slipping out. Probably just my imagination but that is what it sounds like.

[Alan Wheeler]

No there are no fingers. That is a dog clutch if I understand you correctly. The box will most likely be manual clutch plates. That is, the plates are moved mechanicaly. Simple to a point. If something is clunking in there, it will not be just a clunk. There is nothing internal that can really do that without a major siezure of the box accuring, or compleate lack of drive. The only thing I can think of that would clunk would be a broken shaft, but that would stop fwd or rvs or both drives. Or a gear tooth, but that would more than likely go somewhere and cause a catatrophic failure.
To help isolate the noise, take a long shaft screw driver (or go to your autoparts shop and ask for an engine stethoscope) and place the end of either on variouse parts to locate the sound. IT works a treat. But do be very very careful of moving parts. Keep loose clothign and long hair well clear

[bruadair]

Rob,

We have a Yanmar 3QM30F coupled to a KH18. A few months ago we developed a knocking noise, more noticible at lower rpms. Since 2800 rmp is the max rpm for this engine we never revved it that high, but it noise went away at 1500 rpm and above, came back when we brought the throttle back down. The noise was absent in reverse, was only there in forward gear.

It ended up being our damper plate, aka flexplate.

Hope this helps,

Damon
s/v Bruadair
The Adventures of s/v Bruadair

[pylotttt]

Thanks guys, it's all great input. It gives me some things to think about.
Rob

[Celestialsailor]

Just a thought...Have you checked for a boken motor mount?

[Chief Engineer]

What Kind of oil are you using in it?

[Chief Engineer]

A dampner plat problem will sound like a can of rocks.

If it is clunking and then "going out of gear" it is most likely the drive cone.

I had a customer that had that problem....ended up the PO had put ATF in the trans and that "killed it daid"

Mack Boring does rebuilds....good turnaround time.

[Alan Wheeler]

If it is clunking and then "going out of gear" it is most likely the drive cone.

Ummm, did I miss something Chief? I can't find where he stated it was going out of gear. That would certainly be a different scenario.

[pylotttt]

Hi Guys,
The motor mounts have been changed. I don't know what type of lube is in the tranny.
It doesn't sound like a can of rocks, more like it is slipping out of gear and then grabbing back in, but I don't think it is actually going out of gear. We pulled the tranny back and are replacing the flex plate. The springs are loose while the new one is not. I don't think this will cause the noise I heard but it is the easiest and quickest thing to try.

Thanks for the input,
Rob

[Alan Wheeler]

The springs are loose while the new one is not. I don't think this will cause the noise I heard but it is the easiest and quickest thing to try.

Oh yes it will. Trust me.

[Chief Engineer]

when you get the gear in, scheck that you have a positive engagement of the lever. You can do this w/o hooking up the lever at the helm.
Forward should have a definite "feel" when it is engaged. The run the engine and see if the 'problem' goes away.

Keep us posted.

Originally Posted by pylotttt

Hi Guys,
The motor mounts have been changed. I don't know what type of lube is in the tranny.
It doesn't sound like a can of rocks, more like it is slipping out of gear and then grabbing back in, but I don't think it is actually going out of gear. We pulled the tranny back and are replacing the flex plate. The springs are loose while the new one is not. I don't think this will cause the noise I heard but it is the easiest and quickest thing to try.

Thanks for the input,
Rob

[BERN]

Originally Posted by Chief Engineer

What Kind of oil are you using in it?

Chief,
Would you take a moment to consider my problem,...please??.....sort of similar to the one you are dealing with in the KH18.

I have a 2GMF, with a Kanzaki KM2 transmission. I have had engine mounts, prop' shaft, cutlass bearing and stuffing box replaced new. The shaft was also realigned to the transmission.
So my problem is,...after the engine has been running for around 15 - 20 minutes and I use the forward gear,...when a accelerate above 1000 rpm the engine rocks horribly back and forth.(front to back) When I do this in reverse, the engine runs like a dream.
My thought is that the forward cone clutch face has some "chatter" or deformation and when under load, is slipping and grabbing, so causing this fairly violent vibration.
Do you have any thoughts on this??? What else could be a factor?
Thanks
Bernard