reb78

Another gearbox issue or clutch?

26 posts in this topic

On my way back from Cornwall earlier, I had done about 210 pretty fast motorway miles in the 110. Slowing in traffic on the M4 near Reading, I went to change gear, but couldn't select anything at all. It was stiff to get out of 5th and wouldn't engage anything else (tried with and without the clutch) and I managed to roll from the outside lane to the hard shoulder on the A4 slip road!

Tried again to engage gear with the engine at idle, clutch down, felt like a good pedal but nothing would engage. You could hear the engine revs dip a tiny bit as I tried to push the lever into gear. I turned the engine off and the box would slip into gear. So I thought it must be a clutch issue. Checked the clutch fluid level and its a bit black, but full (its been pretty dark for years so I may well be at the end of some very borrowed time!).

Now, the weird bit. I jumped back in the cab and started in gear with the clutch pedal down. Slowly release the clutch and I could feel the bite point. Dip the clutch, pull it out of gear and again I couldn't re-engage anything. So how can it be a clutch issue.

Even more strange, I did the start in gear with the clutch down thing a few more times and normal service resumed. I drove on onto the A4 and stayed off of the motorway for a bit, but finished the last 35 miles of the journey without any drama or repeats.

Its an LT77 on a TD5 1.4:1 LT230 with a GKN overdrive. Clutch (plates, release bearing and arm) were replaced about 5k miles ago. The gearbox has had a lot of problems, but was reconditioned again last October when the clutch was done.

Any thoughts because I am stumped?

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Does sound like hydraulics, and the black fluid is the smoking gun.

Heat from fast driving can affect the operation of the hydraulics, and if marginal will worsen. I assume from air and/or water in the system, and seals that are just too floppy...

Experienced all the above recently on my Audi, eventual failure was the master, I had done the slave about a year ago.... :)

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This is what I'm thinking too. I have a new master ready to fit, just never got round to it. Perhaps the time on the hard shoulder was enough to let it cool. Weird though!

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I too would be suspect of heat on the fluid, either creating air / bubbles or thinning the fluid by warming it...

Can't remember your 110, does it have the heat shield on the down pipe?

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Heatsheild is gone as the pipe is a custom one and further from the slave and clutch pipework than the original. Strange that it did similar journeys in France last year in much hotter temps without issue. I will get onto the hydraulic system though and change the master and rubber pipe. The slave is not that old, although i may as well just do the lot i suppose.

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Ambient temperature may be cooler here but if you were travelling in the outside lane hammering the 110 today and comparing to another time, the temperature around the exhaust may have been a lot cooler with SWMBO next to you making you slow down and reminding you that you were on holiday and to take it easy....

As said above, it might be the heat just pushing the system too far..... Change master, refresh fluid and stop driving the 110 like you stole it...

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Quote

On my way back from Cornwall earlier,

what part of Kernow did you visit ? 

hopefully your not experiencing the same lack of drive as I had recently which turned out to be the overdrive internal clutch not gripping, I haven't stripped the OD yet. 

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My other half is working at Duchy College Ralph, so just over the border really up between Launceston and Liskeard. 

I hope it's not my OD, though I do need to do the gaskets on it at some point (got a set in the garage), so will check the clutch then. 

The other odd thing about this incident today is that I can usually drive this without a clutch if I match the revs. It absolutely wasn't having any of it today though! New master, slave and rubber pipe on their way now. 

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you were just over a hour from me, 

 

I did the clutch hyd's first as you've probably read my post, hope they get yours sorted. miss my overdrive on long runs.

 

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You could select gears though couldn't you Ralph? I recall yours was slipping/juddering? Mine wouldn't go in any gear for a brief period. 

I know exactly what you mean - I don't think I'd cope without the OD on these long runs now!!

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Yes I could select gears, slipping when clutch fully engaged, lets hope the new cylinders,hose,fluid gets it cured. 

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I'd be inclined to change the ATF in the gearbox and see if that improves anything and echo Uncle's advice about thrashing the nuts off it on the motorway, it's not a Mondeo !

Mo

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Well, just jumped in the 110 to take it to work this afternoon and cant engage any gears again. I need to get a friend to push the pedal whilst i look in the engine bay, but it must be hydraulic. All gears will select when the engine is off.

The box has been on and off so many times lately, the oil has been changed more than the engine!

As for thrashing it, with the OD working, 3000 rpm = just under 90 mph which is the same as a normal defender with the LT77 or R380 and a 1.4 ratio transfer box at 70mph (i.e. with my OD disengaged) so as long as I am under 90mph (which, of course, I was), I am probably thrashing it much less than someone travelling at 70!

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Stop trying to defend wreckless speeding :)

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This thread has just connected something in my mind which may be relevant. The other week while under my car changing the gearbox we discussed shielding of the slave cylinder from heat radiated by the exhaust downpipe. There was a shield fitted on 2.5TD models but it was not fitted to Tdi-on vehicles.

I have noticed on a few occasions when going to use the clutch after a long run at speed (i.e. doing a few hundred miles on the motorway at 60mph then coming off up to the roundabout on the slip road) that the pedal is a bit spongy. It then returns to normal after a few minutes. Perhaps this is the hydraulics being affected by the heat? I suspect it would be exacerbated if there was excessive contamination of the fluid - particularly with water?

I'm going to try and knock up a heat shield and see if it makes any difference to this. It may be the problem doesn't exist, hence why the heat shield was discontinued.

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Neil mentioned that too James. I used to have a heat shield on my standard exhaust. Mo has it now though because I had a custom system fitted and it wouldn't fit on that. The custom exhaust is routed further away from the slave and pipework though so should've needed the shield less (in theory). 

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I ditched that heatshield on my 110 [ex-td] years ago after the 200tdi & stainless steel exhaust was fitted, I haven't noticed any change in clutch feel.

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Used to get a peculiar symptom from the clutch pedal before changing the tubular exhaust manifolds on my 110. The previous manifold on the relevant side was practically touching the slave cylinder. I had it wrapped in several layers of heat wrap. When stooging around town in traffic, the pedal feel would get gradually worse, then the peculiar fault, depress the pedal, change gear, take foot off pedal and pedal stays on the floor. The gear would engage and the truck would drive fine. a tap on the pedal with a toe would bring it back up to the normal position. Since replacing the manifold for a cast item with a different down pipe I have not had a repetition of the problem

Edited by neil110

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1 hour ago, neil110 said:

depress the pedal, change gear, take foot off pedal and pedal stays on the floor. The gear would engage and the truck would drive fine. a tap on the pedal with a toe would bring it back up to the normal position.

You been driving my Audi? ;)

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All hydraulics changed and it's still playing up. Sometimes it engages gear perfectly, others, there are no gears to be had. 

 

Anymore ideas? I really don't want to drop these gearboxes again!

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Going over your other posts I would say start looking at the selector mechanism, the slight slowing in engine revs when trying to engage may be the synchro cones beginning to engage, but not getting enough  throw to actually select.

Not sure why heat would effect it, but certainly worth a look.

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is the cup on bottom of gear lever tight on the selector shaft ?

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Thanks chaps. I managed to take it for a drive last night and did 20 miles without a problem. The gearchange felt a little notchy at times, but i think thats pretty normal. Tried it again this morning and ok for now. I will restrict it to local trips for a couple of weeks and see how we go. Fingers crossed there was a little air left in the master cylinder and its worked its way out with use?!

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Oh well. I thought in for a penny in for a pound. It's just done 80 miles to my parents. It's kind of local compared to most of my current journeys! :)

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Good show Rich, glad to hear it may be sorted 👍

Mo

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