Hurth kbw10 gearbox noise advice needed

[bony]

Hello,
The Hurth KBW10 gearbox on my Yanmar 2qm15 is making a whining noise in forward gear. It does not make the noise in reverse.

When I first bought the boat the old oil in the gearbox was a light grey colour which suggests it was contaminated with water at some time. I flushed the box out several times with a mixture of auto fluid and kerosene and refilled/emptied several times with clean Dexron 111 fluid.

The ID plate on the side of my gearbox is very faded but I can just make out that is says use ATA-A. I've read the many posts regarding the confusion over which type of oil to use in this model gearbox and I opted to use Dexron 111 auto fluid which I think complies with the manufacturer's ATA-A fluid recommendation.

Some of the posts said that SAE 20-30 engine oil is also recommended and I am wondering if the whining noise I am getting is a result of the Dexron 111 being to thin for the job. Would SAE 20-30 oil help reduce the whining noise problem or would it be a bad move to use it in place of the auto fluid?

The Hurth lubrication topic has been discussed many times on the web but I would appreciate your advice regarding my particular case.

bony.

[LeaseOnLife]

Originally Posted by bony

Hello,
The Hurth KBW10 gearbox on my Yanmar 2qm15 is making a whining noise in forward gear. It does not make the noise in reverse.

When I first bought the boat the old oil in the gearbox was a light grey colour which suggests it was contaminated with water at some time. I flushed the box out several times with a mixture of auto fluid and kerosene and refilled/emptied several times with clean Dexron 111 fluid.

The ID plate on the side of my gearbox is very faded but I can just make out that is says use ATA-A. I've read the many posts regarding the confusion over which type of oil to use in this model gearbox and I opted to use Dexron 111 auto fluid which I think complies with the manufacturer's ATA-A fluid recommendation.

Some of the posts said that SAE 20-30 engine oil is also recommended and I am wondering if the whining noise I am getting is a result of the Dexron 111 being to thin for the job. Would SAE 20-30 oil help reduce the whining noise problem or would it be a bad move to use it in place of the auto fluid?

The Hurth lubrication topic has been discussed many times on the web but I would appreciate your advice regarding my particular case.

bony.

I suggest to stick with ATF:

Yanmar Transmissions Capacity Chart

Regarding the whining noise: Most likely a bearing is failing. Reverse gear is a lower ratio and puts on less load, less whine.

My KBW20 once looked like this:

[DeepFrz]

Nice bearing. SAE 120 would probably smooth that right out

[bony]

Originally Posted by LeaseOnLife

I suggest to stick with ATF:

My KBW20 once looked like this:

Jeez, that bearing even looks noisy! If mine is like that a rebuild might be on horizon. Who said boating was fun?

Thanks for the advice.

bony.

[Crew of Turning]

We have the same gearbox tied into a 2qm20 which was rebuilt in May 2014. I'd plate clearly states ATF to be used and volume .6 litre. As for the whine it could be a bearing as stated and it could also be a failing thrust washer. Either way you have to open it up and before you do you may also wish to drain the existing fluid from the bottom of the case and pour it through a coffee filter and look for residual metal filings which may help you to know what is occurring. Parts are available but the gearbox case itself is hard to replace.

[bony]

Hi Crew of Turning,

Thanks for the good advice, much appreciated.

bony.

[bony]

Gi I'm updating this thread because I need some further advice regarding the noise in my Kanzaki/Hurth KBW10.

I've checked the boat running gear thoroughly and have found the noise (a loud squealing, whining sound) is coming from the transmission. I've also noticed a lot of fine specks of gritty dust scattered all over the bilge. They seem like tiny flakes of rust and are all over the bilge walls and floating on the bilge water. At first I thought it was just surface rust flaking off the engine but there is not enough rusty areas on the engine to account for the amount of dust in the bilge. I am thinking now that this is related to the transmission noise and that the dust might be coming out of the slotted vent on the bellhousing.

If so, would it be an indication of some kind of problem with the damper plate? Bear in mind noise only appears when in forward gear.

Any thoughts?
bony.

[Crew of Turning]

Hi Bony,
If you have access to the back of your engine and I mean a good physical working area you can pull the bell housing with the gearbox still attached, it weighs out at about 70 pounds. If not you will have to pull the engine up and forward. If you have good access, back the shaft off the coupling, remove the morse linkage from the shifter and remove the 12-20mm bolts from the bell housing and back it off. Inspect your damper plate for seized springs. Hope it is that easy for you.

[bony]

Crew of Turning,

There's enough room to do as you suggest, I'll give it a go.

Thanks for the reply.

bony

[bony]

Greetings everyone,

I'm updating this thread again because I pulled my tranny out and would like to get your opinions on the results.

Upon dismantling the box I found that water had entered it at some time. I found the oil was like cappucino coffee when I removed the transmission and drained it. This surprised me because before relaunching the boat I had flushed the transmission with kerosine and renewed the auto fluid! Perhaps there was still enough gunk in there to discolor the new atf.

Some of the internal parts are showing signs of rust but the bearings looked ok, no pitting or scoring on them, and there was no residual metal filings found in the box.

I have uploaded some pics of the bearings and also the 'output shaft coupling' which I'd like your opinion on. You will notice some deep grooves have been scored into the neck of the flange coupling, and the input shaft where they fit through the transmission's oil seals.

As the seals are made of rubber I am wondering how they would cause this deep scoring and I wonder also if this could have been the source of the squealing noise I'd been hearing?








Cheers,
bony

[MarkSF]

The best way to go is to install a reconditioned box, rebuilt by a respected firm. I put one in 5 years ago.

[DougR]

Couple of comments regarding your observations....

Seal surface wear: Yes the seals are only rubber, but they will still wear the shafts that they ride on. Remember the input shaft is spinning at maybe 2500 RPM...that's revs per MINUTE! And this goes on for hours and hours, so it's easy to see that this spring loaded rubber seal will eventually wear a grove in the shaft. That said, the shafts don't look too bad and may still give good service with new seals installed. Or, you could try to source a "speedy sleeve" to place on the shaft and restore the surface.

Rust flakes in the bilge: From the rusty condition of the input shaft splines I would say that the condition of the damper plate isn't much better, and that's where the rust is coming from.

Forward gear squeal: If you are sure the noise you hear is coming from the transmission, there might be a couple of places to check. You showed us two bearings, one on the input shaft and one on the output shaft, and they look OK. However, the forward bearing on the output shaft is the one that absorbs the propshaft thrust, and we didn't see that one. Check it, and also important is to check the condition of the outer race for that bearing and be sure it isn't spinning in the gear case. A bearing race spinning in the case will squeal.

Another bearing that could be suspect is the needle bearing located beneath the reverse gear on the output shaft. In reverse position this bearing is rotating along with the reverse gear, so there is no relative motion between the gear, bearing and output shaft. But in forward position the output shaft and the reverse gear on the output shaft are rotating in opposite direction and the higher the RPM the greater the relative motion between them and the needle bearing has to accomidate this relative motion......a fruitful source of noise.


Two other quick comments....is that a crack on the output flange seal surface? That could pose future problems. Also I see a little pitting on the gear teeth surfaces....what about the forward gear on the output shaft? Any significant pitting there? Rough pitted teeth could cause noise.

DougR

[Sailmonkey]

I hate to tell you this.....but you're better of replacing the gearbox. The cost of parts exceeds the cost of new. Replace either with a zf10m or a twin disc/techno drive mg340.


Sent from my iPhone using Cruisers Sailing Forum

[bony]

Hi SailMonkey and MarkSF,

I like to take your advice and either recondition my old gearbox or buy a new one but finances won't allow it at the moment. I did find a replacement box in very good condition though, got it for $400. It's the same model but was used on a later 3gm30 which had a different bell housing. It's all fitted into my boat now and seems to be running ok.

Hi DougR,
Thanks for the comments. You are right about the damper disc, it was knackered, rust was peeling off it in large flakes and it was rusted so solidly onto the input shaft splines I could not seperate the box from the engine. In the end I cut a hole through the bell housing vents so I could get a socket in there to undo the damper disc's bolts. Back home in my workshop I tried everything to get the disc off the shaft, all to no avail. As the disc was stuffed anyway I finally decided to cut it off with a 4" angle grinder, and took great care not to bite into the shaft in the process. I got a new damper disc sent down to me from Minards in Queensland at the cost of $366. (Ouch!)
When I swapped my 2qm15 bellhousing onto the 'new' gearbox I made sure I swapped the bellhousing bearing races over as well. To remove the old ones I had to heat the bellhousing to around 100C before I could pull the races out. They were very tight so I doubt they'd be spinning in their housings. I will check the old inner races though, as you suggest.

I think the "crack" that can be seen in the flange coupling photo is an opical illusion. I inspected the flange today with a magnifying glass a found no cracks in it.

The inner bearings both look the same as outer ones shown in the photos and the bearing races appear to be ok as well. I haven't pulled the gears off the shafts yet so don't know what the needle rollers are like. Pulling it apart further is on hold at the moment because I'm lacking a few of the specialised tools to do the job.

I'll post a few more pics when I've got it all pulled down.

Cheers,
bony.

[Innovator33]

Hi, I have started to get a noise from my KBW10 gearbox which appears to be like yours. Started shortly after an oil change. Only between 1500 and 2000 engine rpm. Sound like when you run a finger round the rim of a wine glass
Is this similar to your problem? Did the replacement gearbox fix it? When you opened the old box was there any apparent faults.
Cheers
Michael