Hurth hbw 50 gearbox overfilled.

[Gavlar1980]

Hi to all. I currently have a 33ft narrowboat fitted with a Nanni diesel 2.60 and a hurth hbw 50. I changed the gearbox oil last year shortly after purchase. It has been fine until last week when we were cruising the gearbox started to slip when under load. 
River canal rescue come out and said the gearbox needs replacing. 
when checking the oil I had overfilled roughly around the same distance from the min to max level. 
my question is if I drain this oil is there a chance this was causing the problem and the gearbox might be ok?  

[Gavlar1980]

Hi to all. I currently have a 33ft narrowboat fitted with a Nanni diesel 2.60 and a hurth hbw 50. I changed the gearbox oil last year shortly after purchase. It has been fine until last week when we were cruising the gearbox started to slip when under load. 
River canal rescue come out and said the gearbox needs replacing. 
when checking the oil I had overfilled roughly around the same distance from the min to max level. 
my question is if I drain this oil is there a chance this was causing the problem and the gearbox might be ok?  

[Bod]

Worth a try.

Do you have RCR parts cover?

 

Bod.

[Gavlar1980]

Good morning. No just basic cover unfortunately. It was just the case if I took it all out and sent off to be rebuilt and all the problem was is a little too much oil I’d be a little gutted. Thanks for your message 

[Tony Brooks]

50 minutes ago, Gavlar1980 said:

Hi to all. I currently have a 33ft narrowboat fitted with a Nanni diesel 2.60 and a hurth hbw 50. I changed the gearbox oil last year shortly after purchase. It has been fine until last week when we were cruising the gearbox started to slip when under load. 
River canal rescue come out and said the gearbox needs replacing. 
when checking the oil I had overfilled roughly around the same distance from the min to max level. 
my question is if I drain this oil is there a chance this was causing the problem and the gearbox might be ok? 

 

Its unlikely but definitely worth a try. Did you put ATF (Dexrom) in it, i not its the wrong oil so change to ATF and hope.

 

Regrettably Hurth boxes do not have the best reputation so if it comes to spending a lot of money see if tou can fit a PRM mechanical box.

[Gavlar1980]

Would any prm fit. I’m not really up on gearbox’s I understand it’s a mechanical gearbox and not hydraulic. But is the bolt pattern the same etc. Many thanks for your message 

[Tony Brooks]

11 minutes ago, Gavlar1980 said:

Would any prm fit. I’m not really up on gearbox’s I understand it’s a mechanical gearbox and not hydraulic. But is the bolt pattern the same etc. Many thanks for your message 

I think the mechanical PRMs that look a bit like a rectangular Hurth are all but a direct replacement. I doubt the hydraulic PRMs are but it may be possible to adjust the engine mounts and possibly shorten the shaft a little to allow one to fit. The dimensions are on the PRM website.

[Bee]

As Tony said, they are not the most long lived box but I'd hang on to it even if it has to be replaced and then dismantle it as a winter project. Could be fixable at not much cost and be a useful spare.

[Tracy D'arth]

The cost of clutches to overhaul Hursts is out of all proportion to the cost of a new box. Go the PRM route, much better reliable boxes. I think the PRM90 and PRM 120 are easy to substitute for the tiny Hurths.  Phone PRM, they are very helpful and freely give advice.

Excess oil is very unlikely to cause to box to slip, easy check, does it slip in reverse? If not then its just the forward clutch worn out as usual.

 

My advice and personal opinion, do not buy a recon box from RCR, it will come from KEY engineering and they have been known for poor standards of workmanship.  In fact I would get a second opinion anyway.

[bizzard]

Too much oil in it probably caused it to overheat. worth draining some out and trying it. Make sure it's Dexron though.

[Gavlar1980]

Thanks for your advice. That totally makes sense. It does not slip in reverse so I imagine that the forward gear is worn . I have seen a refurbished prm for around three hundred so I might take that route. Really appreciated thanks 

[Tony Brooks]

33 minutes ago, Gavlar1980 said:

Thanks for your advice. That totally makes sense. It does not slip in reverse so I imagine that the forward gear is worn . I have seen a refurbished prm for around three hundred so I might take that route. Really appreciated thanks 

 

So you don't sound an easy touch next time you talk to a mechanic the gear is almost certainly as good as new, it will be the forward clutch or     less likely a thrust washer that is worn. Stick with forward clutch.

[Gavlar1980]

I had found someone who will rebuild the hurth clutch for £300 but he did say if the gears are worn it wouldn’t be worth repairing. I dunno if this is a good idea or go for a refurbished prm. 

[Tony Brooks]

11 minutes ago, Gavlar1980 said:

I had found someone who will rebuild the hurth clutch for £300 but he did say if the gears are worn it wouldn’t be worth repairing. I dunno if this is a good idea or go for a refurbished prm. 

 

How long will he guarantee it for and is the guarantee insurance backed? It the answer is less than about 3 years and no ask yourself why.

 

Also ponder why three of us have indicated replacing a Hurth with a Hurth, especially an overhauled one, may not be the brightest idea. Either we are all on commission from PRM or our experience suggests fitting a Hurth is not a good idea.

 

Naturally it depends upon your finances but if you go for the £300 option it may be best to set aside another £300 for use in a few weeks, months, years time.

Edited July 13, 2020 by Tony Brooks

[Gavlar1980]

Your right I think a prm is the way to go. Really appreciate your advice. As for cables etc I take it they would need adapting to accommodate the prm box. 

[Tracy D'arth]

1 minute ago, Gavlar1980 said:

I had found someone who will rebuild the hurth clutch for £300 but he did say if the gears are worn it wouldn’t be worth repairing. I dunno if this is a good idea or go for a refurbished prm. 

Unless this box has done a terrific number or hours running it is very unlikely that the gears themselves are worn. If the oil is clean and free from silver metal debris then the bearings should be OK too. Anyone repairing Hurth boxes should know this, I'm dubious about the rebuilder.

Just to split the box and replace one clutch pack, the forward one, will leave you with an old gearbox with one new clutch. Is this what you want and can budget for? What if it fails soon after due to something else? These are not reliable gearboxes in many folks opinion.

Consider too that it may be prudent to replace the drive plate on the flywheel if it is rattly whilst the box is off.

Or would you be better off buying a brand new PRM90 box with its guarantee for around £660?  Try Midland Chandlers, lancing Marine,   only £518 from Calcutt Boats. Could be a bargain.

TD'

1 minute ago, Gavlar1980 said:

Your right I think a prm is the way to go. Really appreciate your advice. As for cables etc I take it they would need adapting to accommodate the prm box. 

Doubt it, they are fairly universal.

Go to the PRM web site, loads of pictures and info for free.

TD'

[Tony Brooks]

4 minutes ago, Gavlar1980 said:

Your right I think a prm is the way to go. Really appreciate your advice. As for cables etc I take it they would need adapting to accommodate the prm box. 

 

The worst it will require is a different cable anchor on the gearbox and just maybe a new cable end, the ends just screw on and off. I expect the Hurth end will be fine though and the cable anchor may come with the box, ask PRM.

[Gavlar1980]

Excellent much appreciated I’ll get onto prm today and ask all the right questions. Thanks to all . Always nice to hear advice and others views. 

[BEngo]

Suck it and see.  You will not do any more damage by taking the excess oil out.

I cannot see any reason though why it might have caused a problem, except by overheating things.  The Hurth box has no reputation for reliability in canal work or for being worth repairing when if goes wrong.  You are probably looking at replacement, and it would be worth looking at a better box, such as  a PRM, if there is room and the engine position is manageable.

You need a good margin of torque capacity and a box that is happy to have lots of gear changes every day.

 

N

[Flyboy]

I wonder if the op has put mineral oil in it instead of ATF at the last change.  I doubt if over filling has wrecked it.

[Tony Brooks]

I have asked the Mods if they will/can merge the two identical topics. I suggest that it may be best to stick with the other one that has more replies. Both replies here were covered earlier today in the other thread.

[Flyboy]

41 minutes ago, Tony Brooks said:

I have asked the Mods if they will/can merge the two identical topics. I suggest that it may be best to stick with the other one that has more replies. Both replies here were covered earlier today in the other thread.

Can you point me in the direction of the other thread please ? I can't find it in the maintenance section.

[Tony Brooks]

It seems to be in the sub forum Build Blogs, maybe best to move the merged topic into maintenance.

 

thanks

[ditchcrawler]

ASAP do boxes, don't know how their price compares https://www.asap-supplies.com/engine-spares-gearboxes/marine-gearboxes-and-spares/marine-gearboxes

[crosser]

i have 2 hurth 50 gearboxes sat in my shed with both failed clutches, parts are really expensive so there good door stops for now.. i did put another hurth 50 box in my boat as it doesnt do many hours and i managed to find a nos box for not alot of money otherwise i wa going to get a prm80 box as bolts straight on to bellhousing as same stud pattern.. good luck