Diff lock overheating?

[Landy7]

I'm the proud owner of a 1988 Land Rover 110 with a 200tdi engine, LT77 gearbox and LT230 1.4 transferbox.

6 months ago, I've tested the diff lock by lifting one wheel and tried spinning it with diff lock engaged/disengaged, all went like it should, no problems there. Also the LT230 had been rebuilded, was a 1.6 before.

I've never needed the diff lock, but last weekend we went to a 4x4 parcours (was super fun!) with a lot of mud and steep hills. When we arrived at the track, I've engaged the diff lock but remained in high gear and first gear. After a minute or so on the parcours, the cabin started to fill with 'smoke' and it smelled like burned oil.. I've let it cool off for a few minutes and turned the diff lock off. The rest of the parcours went great, without diff lock engaged. I engaged it again and after a minute, the 'smoke' and smell was back.. Can't really trace it, but the smoke comes from the floor, first row, gearbox??

I drove around the parcours for hours, without diff lock engaged, no smoke, no smell, everything went fine.. If it became a bit tricky, I engaged diff lock just for that specific hill and turned it back off after, that worked perfect.

So, as an 4x4 amateur, I asked some other guy's if they had diff lock engaged and they all had diff lock engaged the whole time, never turned it off on the parcours.. But they were driving low gear, I drove high gear since I could easily do it all in first high gear.

Any idea what's wrong?

[Bowie69]

Difflock won't smoke, in fact there is likely less heat when you use it, as there are fewer moving parts.

Smoke from there is either fuelling and a leaky exhaust, or clutch smoke -much more likely.

[Landy7]

Well the gearbox and transfer box are a bit 'leaky', so I was thinking because they are hot, that's were the smoke/smell comes from, but it only happens when diff lock is engaged, that's a mystery for me.. I drove hours without diff lock, and no smell, all went perfect, and if I drive a few minutes with diff lock engaged, I get smoke in the cabin and burned oil smell..

[Bowie69]

Were you rocking it on the clutch?

[Landy7]

No, almost never touched the clutch!

EDIT: The only thing I guess that could have happened, is that I've forgot to disengage the parking brake.. When the parking brake is on, I cannot get the car to move, obviously..., but when diff lock is on, I can drive the car with the parking brake on, is that normal behaviour? (I'm not an expert, but the parking brake is on the LT230 in my case I think, transmission brake?)

Edited March 27, 2018 by Koen110

[Bowie69]

Yes it is a transmission brake.

No, not normal to be able to drive it while on, you were just overcoming the friction. 

If you left it on and it got hot enough to smoke you really need to disassemble it, change shoes if needed, and check everything else for melting. Also, pull off the backing plate, and inspect the transfer case output flange seal for leaks -they don't like getting hot.

[Landy7]

Ok thanks, will disassemble it and take a look. There was no friction in diff lock and handbrake on, could take a hill without any problem :/ Difflock off and handbrake on, I cannot move the car ..

[dailysleaze]

Could there be a short in the wiring that is only triggered when the diff lock light is on? I.e melting wires

[cackshifter]

Im wondering if difflock linkage and handbrake cable are somehow tangled, so applying difflock also applies the handbrake. Have a crawl underneath.

[Waldorf]

You should have asked us sunday, Koen. There were plenty of people who would have been more than happy to help you out. I was in the sand coloured military 110.