View Full Version : Can't engage forward gear - WE'RE STUCK!!!!!!

16-09-07, 10:39
We have an ongoing problem with engaging forward gear and our boat yard cannot sort it out. We have spent hundreds of euros getting the gear box stripped down, the clutch plate rebuilt, and so on, but the problem keeps re-occurring.

In a nutshell: when pushing the gear lever into forwards, nothing happens. There is no satisfactory 'clunk' which we get when putting into reverse. After 10 minutes or so of constantly trying this it occasionally engages. After motoring for half an hour or so, the gear appears to engage and disengage fairly satisfactorily. This morning, however, no matter how many times I put the lever into the forward position, nothing happened.

Two years ago the clutch plate was rebuilt as the first cause of the problem offered was that the plate was slipping. Fair enough.....after a repair job the problem appeared to go away for a while. Since then the problem started again and so we have had the gear box stripped and serviced. Twice. The mechanics SWEAR there is nothing wrong with the gear box and indeed claim it is in very good condition. They demonstrated this by manually engaging the clutch lever (the one on the side of the gear box) into both forward and reverse with satisfactory clunks in both directions.

So, because the clutch plate has been repaired and because the gear box is seemingly in good order we were then told that the gear lever on the binnacle was wearing out and was not moving the morse cable far enough. A couple of sprays of WD40 later we were told that before starting the engine we spend 10 minutes moving the gear lever forwards and backwards to ensure that any salt or dirt trapped in the gear lever teeth would be freed up. This dirt, we were told, was the cause of the problem. Well, if this is the problem this isn't exactly a practical work-around. We were told we would eventually have to replace the gear lever. However we have thoroughly investigated the point at which the clutch lever engages and disengages and there is absolutely nothing wrong with the cable. The cable pulls the clutch lever arm far enough back to engage forwards gear.

I appreciate this is a problem that can't really be solved without someone taking a look at this in situ, but I would be interested to know if (a) this sounds familiar to anyone and (b) if there are any simple checks I could do to help me tick off possible causes. It's driving Liz and myself mad!

It's a Perkins Prima M60 engine and Hurth gearbox dating back to 1989.

16-09-07, 10:51
Twice. The mechanics SWEAR there is nothing wrong with the gear box and indeed claim it is in very good condition. They demonstrated this by manually engaging the clutch lever (the one on the side of the gear box) into both forward and reverse with satisfactory clunks in both directions.

[/ QUOTE ]

There but for the grace of God I guess.

If you are securely tied up alongside, can you engage the clutch lever on the side of the gear box with the engine running - i.e. someone at the gearbox, rather than using the morse and cables?

If you can, this would eliminate the gearbox and tell you that it is something between the morse lever and the clutch lever on the gearbox.

One other thought - could the clutch lever be kind of out of line, or loose, such that the cables pull, or push it, but it doesnt engage - I cant explain that any better, so hope you get the gist.

16-09-07, 10:56
well, stating the obvious really..... but try engaging gear using just the lever on the gearbox- if that works every time, it's clearly the cable adjustment or a control head issue. If not, well, rather plainly a gearbox one.

Start from scratch - forget everything you've been told is perfect, and determine if it works without the control head & cable being used.

16-09-07, 10:56
Does the gearbox always engage properly when manually moved at the gearbox itself.

If yes the problem must be in the cable or the selector.

Using WD40 to free off a cable is a time honoured and incomplete procedure. The WD40 will free the old grease for a while, but this is only an interim stage as the WD40 will have removed the lubricant and will then itself dry out fairly quickly so needs to be replaced with a longer term lubricant - zx1 is a great solution for this.

I would also be suspicious that the cable was in the correct position on the lever. If your lever is like mine, it will have a number of different positions to fit the end of the outer cable. These different positions are designed to change the amount of cable moved by the gaerbox cable at each selection of gear. - get the position wrong, and the gears will not engage every time, especially when cold.

I am sure you have probably already looked at all these, but it is the only thing I can think of.

16-09-07, 11:05
can you engage the clutch lever on the side of the gear box with the engine running - i.e. someone at the gearbox, rather than using the morse and cables?

[/ QUOTE ]


well, stating the obvious really..... but try engaging gear using just the lever on the gearbox- if that works every time

[/ QUOTE ]


Does the gearbox always engage properly when manually moved at the gearbox itself.

[/ QUOTE ]

My apologies, I probably didn't make that very clear. When the mechanics first reinstalled the gear box they did exactly as you all describe and, sure enough, it worked ok. However over the space of a few weeks the problem has begun again.

So, this morning I tried what you describe above and, sure enough, I can no longer manually engage the gear when moving the clutch lever at the gear box itself. As you say, I did this to ensure that the gear box is ok but if I can no longer engage in this way then it HAS to be something to do with the gear box and not the cable.

I'm wondering if the repair job they did a couple of years ago on the clutch plate has worn away again, but I can't see it. The repair job has only seen one season's action and of course the mechanics would have picked up on it since they are the same ones who did the repair.

Salty John
16-09-07, 11:24
If you have access to Nigel Calders book 'Boatowners Mechanical and Electrical Manual' you'll see he has some things to say about Hurth boxes:
'Hurth clutches in particular are very sensitive to improper cable adjustment'
And:'Hurth boxes do not have a distinct click when a gear is engaged. however, the lever must move through a minimum arc of 30 degrees in either direction'
There are some exploded views of a gearbox and instructions on clutch adjustment and cable adjustment. If you don't have the book and can't get hold of one PM me and I'll be happy to scan and send the appropriate pages.

16-09-07, 11:59
At this point I would be reaching for the cheque book and getting a replacement gearbox.

16-09-07, 12:05
So, this morning I tried what you describe above and, sure enough, I can no longer manually engage the gear when moving the clutch lever at the gear box itself. As you say, I did this to ensure that the gear box is ok but if I can no longer engage in this way then it HAS to be something to do with the gear box and not the cable.

[/ QUOTE ]

Yes, assuming that you disconnected the cable when testing as above - otherwise the vable/control may well prevent you from moving the lever sufficiently to engage gear.

16-09-07, 12:26
Many manuals are available free here (http://www.motoren.ath.cx/)

Which gearbox do you have?

16-09-07, 12:27
A couple of thoughts:

Does the cable move the lever OK?

Did you remove the cables when you were moving the lever manually?



16-09-07, 12:33
It's a Hurth and is probably the same age as the boat, 18 years. I don't know what model it is but it was made in West Germany, so it gives you some idea of how old it is!

Yes, I DID disconnect the cables when moving the lever at the gear box. I moved the lever through its entire arc, to no avail.

I have a copy of said manual...Liz is flicking through it now. Thank you for your kind offer of scanning it though.

How much is a new gear box? Do I want to spoil my Sunday afternoon with this knowledge?

16-09-07, 12:39
Another little fact: sometimes when leaving the gear in forward and it not engaging, I leave it forward. After about 2 minutes the gear will engage. Could this possibly mean something, somewhere is being affected by the vibration of the engine/gearbox? If so, what?

16-09-07, 13:04
Sounds a bit like a sticky spline.


16-09-07, 13:22

Sounds a bit like a sticky spline.

[/ QUOTE ]

Care to explain a bit further? If you are referring to the splined transmission I would have expected a half-decent mechanic to have picked up on this.

16-09-07, 13:28
Yes sounds like a selector hub in the box is sticking against its spring loading and not sliding along the shaft to engauge with the gear cone or blocking ring.
This could be caused by the indent pins/balls having worn their seats oval and wanting to spring out, jamming the selector hub.
Not knowing what engine size it is, but reading what you say about the lever having to move rearward to select forward gear, I would reckon its a Hurth HBW50 box, now known as the ZF5 as ZF have bought over Hurth.
Are you absolutaly sure that the lever on box side is tight on its spindle and not turning or slipping on it.
If you look at the rear face (output end) of the box, you should see the end of a shaft to the left side of the output drive flange, check if this shaft turns when the engine is idling in gear or neutral, and is it loosing any oil there, even the smallest weep.
This is a idler thrust shaft, which is fitted as an intereference fit and if it turns it will wear the alloy casing and allow axial movement in the idler shaft which would make gear selection difficult or impossible.
This shaft is just starting to leak oil on my boat and box is going to have to come out this winter to sort it.
I have a parts drawing, and manual some where on CD for the HBW 50- 2R.
Cheers, C_W

16-09-07, 14:29
Hey CW - you're blinding me with science here but I'm keen to understand more and, if this is the HBW50, to find a manual. I've taken a couple of shots of the gearbox, one from either side (plus a snap of the plate). One shows you the clutch lever with the cable taken off (you can just see it underneath). The other is a better one of the whole unit. Could you confirm that it is the model you suggest?




16-09-07, 14:30
Recognise this? http://www.marinegears.com/images/hurth/hm-15.gif

More information here (http://www.marinegears.com/catalog/cat-hm-15.html)

16-09-07, 14:33
That's the ticket, CW. Excellent work!

16-09-07, 14:50
I am interested, do you sail with your gearbox engaged in reverse?

Is this a problem every time you want to engage forward, or is it ok when moving around under engine once you have successfully engaged forward for the first time?


16-09-07, 15:43
Hi demonboy.
Its not the HBW50 unless its an older model than mine, as my dipstick is right at the front of the casing close to bhe bell housing, but in the drawing that 2Tizwos has put on you will see the shaft I am talking about No 24.
These boxes are designed to be put in reverse gear when sailing or been towed to lock the shatf/prop.

16-09-07, 15:52
Its me again.
Sorry I must go now as I am starting the day skipper practical this eve and will be away for a week.
Will have a look for the pdf I have on Hurth when I get back
Cheers, C_W

Salty John
16-09-07, 16:05
The following company handles Hurth transmissions:
www.asapsupplies.com (http://www.asapsupplies.com)
The prices aren't too bad, but you could wait until tomorrow if you don't want to ruin your Sunday! I'm told these people are very helpful and clued up.

16-09-07, 16:08
Lancing Marine's site has this pdf which gives dimensions of the Hurth/ ZF gearboxes for identification (http://www.lancingmarine.com/Mechanical_gearboxes.pdf)

16-09-07, 16:42
FWIW I had an oil leak on my box ..I was the small seal on the gear selector shaft ( item 8) as shown in 2tizwos diagram

I dismantled the gear selector assembly and replaced the seal.

on re assembly I made a new gasket and all seemed ok ..but then I had trouble with gear selection as you describe.

I was concerned because I had no trouble prior to changing the oil seal.

I took it all apart again and although there was obvious ware on the selector due to age I felt it was to sudden for the box to fail because I disturbed the selector shaft.

on inspection I noticed that the new gasket I had made was very slightly thicker than the original (almost paper thin).

The original gasket was ok but was oil saturated.however I decided to put back the original gasket and get a new one when possible.

When reassembled all worked ok and I never had any re-occurrence

I feel sure that the tolerances in this assembly are very critical especially with age.

I did notice that a small amount of travel of the selector shaft (in and out) (Not Rotational) and I think my home made gasket allowed to much travel. (new gasket to thick)

Try pressing the selector leaver/shaft in as you rotate to select.

If by any chance or luck this is your problem DO NOT try to just tighten the assembly with the four bolts as this may strip the aluminum threads in the box

As said The above Is what I experienced

Good luck

16-09-07, 22:29

16-09-07, 23:06
I don't know this particular gearbox but if it is a hydraulic gearshift then perhaps there is a blockage in one of the oil feed lines to the forward clutch.

This is assuming that the oil level is correct.

17-09-07, 08:04

Firstly apologies for not responding to the previous replies sooner. Internet connection here is feeble on Sundays.

This morning I had a friend over who is an ex Naval mechanic. We had another look at the gear box and noticed something significant that immediately crosses off some of the causes suggested above:

When engaging the gear at the gear box and putting into astern, the gear engages no problem. This we know. When engaging into ahead, however, we noticed that the shaft was actually attempting to turn. It turned very slowly, then stopped, then turned a little more.

So, it is clear the gear IS engaging, but to what extent we're not sure. I'm not familiar with the mating system but perhaps it is not being pushed far enough in.

The symptom of the gear working ok after half an hour of motoring would suggest that after the whole box has heated up the mechanism works ok or the oil is viscous enough to operate the mating system correctly.

To answer the remaining questions above:

Paul: yes we do sail with the gear in reverse and yes, the gears are ok after half an hour of motoring, once we've finally engaged the forwards gear. I'm very interested to know why you ask this.

CW: Your first suggestion of the selector hub sticking against its spring loading could still be true, so says my mechanic friend. Perhaps after the oil has heated up this becomes less of a problem? The dipstick in the diagram (19) is exactly where mine is - it looks very similar so why could it not be the Hurth 50?

Billskip: no oil leaks as far as I can tell.

Mike: It's not hydraulic.

Tiswoz & John: thanks for those links and images. It's a good start (though I could do with knowing what the numbers refer to in the exploded diagram). I'm on GPRS internet connection here so the pdf is still loading up.

Finally it's worth noting that I am based in Turkey, a country full of tractors and boats, where finding a replacement gear box shouldn't be a problem. You'd have thought that, wouldn't you............

17-09-07, 09:24
The Hurth/ZF gearbox has two multiplate oil immersed clutches which are engaged to give either forward or reverse direction. You probably use forward more than reverse so that one will wear first. Whilst the parts may look fine as wear takes place some thickness will be lost from the metal plates and the clutch will no longer be sufficiently loaded to grip and transmit torque. If the plates warm up they may expand sufficiently to grip a little but none too well or reliably. Two years since an overhaul is not long but how extensive was the overhaul? The gearbox is rated for 'pleasure use' or a certain number of hours which you may be going through relatively rapidly. Do you use it a lot?
http://bpi.ebasicpower.com/mm5/graphics/00000001/ALT316901.jpg This is a picture of an overhaul kit for this gearbox showing the plates. $150 on ebay. The clearance is adjusted with shims. Do your mechanics have a manual giving the necessary clearances?

17-09-07, 09:55
Hi Tizwoz,

I'm afraid I don't know the answer to some of these questions, though of course you are right that we use forward a lot more and yes, as liveaboards, we are using it a lot. However this is a problem that has never really gone away. OK, the gearbox was working well after the lobe was rebuilt but I don't think this is the problem any more as they've taken it apart and looked at the clutch.

The problem I have here in Marmaris is that there are no real 'known' gearbox experts. The only people recommended are the same guys who worked on our unit. God only knows if they used the correct overhaul kit. I couldn't ask them as they do not speak a word of English.

17-09-07, 17:14
Good evening,
just one more question - what happens if you start the engine while reverse gear is selected, can you then select forward with minimal problems?


17-09-07, 20:08
Having had to have our Hurth 50 replaced, I was later told that the plates can be bought from Peugeot car dealers. Apparently they use the same plates as Hurth, and perhaps not surprisingly, they come cheaper.

18-09-07, 14:04
Paul - stop being cryptic! Tell me what you're getting at! I haven't tried starting the engine in reverse, except once when I forgot to put it into neutral. I'm not sure starting it in reverse is a good idea......is it? What could I expect to happen?

At the moment I can't try it out because yesterday, after my last post, the boat yard originally responsible for the failed repair job actually sent down a mechanic from Marmaris to take the box out and finally send it to a man in Izmir. They are paying for all expenses and any fixes that will solve the problem, so I can't complain at their fairness (even if I can complain about them not actually fixing it properly).

Obviously I will update you all as and when. In the meantime I just have to amuse myself in the marina for a few days. Bit weird after spending all summer at anchor. Not sure I like it. /forums/images/graemlins/frown.gif

18-09-07, 14:08
BTW - Tizwoz and Clyde - it's a Hurth 250. I confirmed this with Oyster who even had on record not just the engine and gearbox make and model, but their serial numbers too. I thought that was quite impressive!

18-09-07, 14:21
When I spoke with Cliff at winchservicing about my steering gear, he sent me a pdf of Moodys original job sheet for it ... equally impressive!

18-09-07, 19:21
Sorry I wasn't trying to be cryptic.
Its my engineering mind, I like to know as many of the facts as possible before committing to a solution.

It appears that you have it all under control as it could very possibly be a set of worn drive disc's.

My interest was aroused when I read that you had established that that was an improvement when the box warmed up.
I would have expected a different reaction as the normal thing for oil when warmed is for it to become more viscous (gets thinner), therefore gearboxes with multi-plate oil immersed clutches tend to loose rather than gain drive when warm or hot.
Another poster suggested that the plates could be expanding due to the heat, and while I have no evidence that this isn’t the case I personally would be surprised if it was this which led to the improvement in the performance of your gearbox. Of course we are all working on the theory that you have the correct grade of oil installed.

My questioning was trying to establish if you were suffering with worn drive splines, which could cause the gearbox to stay in neutral while selecting drive, this can sometimes also feel like you haven’t engaged gear as the box doesn’t seem to click or clunk into gear.

It is possible to lock up a gearbox by sailing with reverse engaged, this loads stress into the box, then when pushing it into neutral, starting the engine and selecting forward gear, the gearbox drive plates still haven’t fully engaged due to the splines binding together and the Belleville washers not being strong enough to close up the entire clutch pack. To get over this you can start the engine whilst still in reverse which unlocks the stress on the gearbox which causes the splines to bind on the drive plates, and so enables neutral and forward to be selected after with no problems.
In answer to your question starting in gear causes no mechanical problems as the prop is free to spin in water unlike a car which would move because of the physical rotation of the tyres on the tarmac.

Sorry for the long winded answer, but you did ask……………………

Again, its only my thoughts, and I am certainly not saying that anyone else’s advice or solutions are wrong.
I hope that upon your gearbox returning all your problems are cured.

Happy sailing.