Ridgeback Posted January 12, 2010 Share Posted January 12, 2010 I got myself a Td5 defender 90 this summer and it came fitted with a GKN overdrive. The overdrive was fitted 2 years ago and has done about 14K. On the way to work (after about 50miles of motor way driving) I noticed that when I let go of the accelerator the engine braking was as normal, however when I pressed the accelerator again, the clutch felt like it was slipping for 10-15 sec before it took up drive. When I got to the car park at work it would not reverse. Again the clutch felt like it was slipping. It would try to move in reverse but did not have enough drive to move in the snow. After being left for the day (wait for the AA to come and get it) It would reverse but only just. I think this must be the overdrive because if it was the clutch, I would not be able to go foward. Any ideas what it could be and how much it will cost to fix? Devon 4x4 will do a recon for about £800 but this is the second GKN overdrive to be fitted to this defender.(the last owner gave me the old one for parts) I did find it very good when it was working but dont want to fit parts to my vehicle that could leave me stranded. The other option is I could fit Disco gears for less then the cost of a recon overdrive? Matt Quote Link to comment Share on other sites More sharing options...
reb78 Posted January 12, 2010 Share Posted January 12, 2010 I cant see how this is the overdrive. If you reverse with it engaged it will break as it has a one way gear system. If the OD is not functioning properly the gear setup is such that it should run as normal without the overdrive. Quote Link to comment Share on other sites More sharing options...
mmgemini Posted January 12, 2010 Share Posted January 12, 2010 Yep that's what mine was like. When did you last change the OD oil ? That is worth a try and clean the filter at the same time. Otherwise i's off with the OD. You did keep the standard gears didn't you ? Then away to Devon 4x4. I must say they made a very good job of rebuilding mine for me. Quote Link to comment Share on other sites More sharing options...
reb78 Posted January 12, 2010 Share Posted January 12, 2010 Yep that's what mine was like. When did you last change the OD oil ? That is worth a try and clean the filter at the same time. Otherwise i's off with the OD. You did keep the standard gears didn't you ? Then away to Devon 4x4. I must say they made a very good job of rebuilding mine for me. What was the cause Mike? Quote Link to comment Share on other sites More sharing options...
Ridgeback Posted January 12, 2010 Author Share Posted January 12, 2010 Yep that's what mine was like. When did you last change the OD oil ? That is worth a try and clean the filter at the same time. Otherwise i's off with the OD. You did keep the standard gears didn't you ? Then away to Devon 4x4. I must say they made a very good job of rebuilding mine for me. I have not changed the oil becuase it came with history showing the 1st oil change, its only done 14K so should not need another oil change? I cant see how the oil should make it fail like this and the problem now is that I dont trust it, even if it started working after an oil change. I did not get the standard input gear. The last owner did not have it. Think I will have a look at getting hold of an input gear and the plate/cover so I can drive it for now. Did Devon 4x4 do a full recon/rebuild on yours or just fix the problem. I dont want to spend our another £800+ on someing that cant last more then 14,000 miles. That level of reliability is bad even by Land Rover standards ! Matt Quote Link to comment Share on other sites More sharing options...
reb78 Posted January 12, 2010 Share Posted January 12, 2010 It is worth changing the oil - its only 700ml in there so changing it at the suggested intervals seems to low for me. The OD works through oil pressure so anything that blocks that flow may affect engagement/disengagement of the unit. Also, some of these units have problems with sucking oil from the transfer case. If it does this, the viscous ep90 can prevent the oil pump from working properly - best way to tell is emptying the oil and seeing if it is the right mount and if it smells like ep90. Quote Link to comment Share on other sites More sharing options...
mmgemini Posted January 12, 2010 Share Posted January 12, 2010 I don't really know the cause.I had a fair few problems, including the electronics box packing up in ZA. I then fitted a five pin relay to stop me reversing with the overdrive engaged. Before that I would have loss of drive. Just like has been described. A change of oil and a filter clean generally did the trick. Then I lost drive at various times. generally applying power in second gear. Then I lost reverse after a run. Don't even follow the GKN oil change instructions. Change the oil every service. Quote Link to comment Share on other sites More sharing options...
Ridgeback Posted January 12, 2010 Author Share Posted January 12, 2010 I cant see how this is the overdrive. If you reverse with it engaged it will break as it has a one way gear system. If the OD is not functioning properly the gear setup is such that it should run as normal without the overdrive. The overdrive was working fine and engaged/disengaged without any problem. The problems started when driving in 1st 2nd and 3rd. I then got to work and could not get reverse to work (unit was not/can not be engaged under 30mph) It would not be such a problem if it just stopped working but left you with use of the standard gears. It is worth changing the oil - its only 700ml in there so changing it at the suggested intervals seems to low for me. The OD works through oil pressure so anything that blocks that flow may affect engagement/disengagement of the unit. Also, some of these units have problems with sucking oil from the transfer case. If it does this, the viscous ep90 can prevent the oil pump from working properly - best way to tell is emptying the oil and seeing if it is the right mount and if it smells like ep90. If its down to oil pressure this could be why it would work when cold but would not reverse when hot? It did not really have an engagement problem, its was 99% loss of drive. I am not sure how the overdrive works inside but when you say engagement/disengagement do you mean the reduction in gearing when you turn the unit on, or should the unit also engage/disengage to allow you to still drive in normal gears including reverse I don't really know the cause.I had a fair few problems, including the electronics box packing up in ZA. I then fitted a five pin relay to stop me reversing with the overdrive engaged. Before that I would have loss of drive. Just like has been described. A change of oil and a filter clean generally did the trick. Then I lost drive at various times. generally applying power in second gear. Then I lost reverse after a run. Did devon 4x4 do a full rebuild or just fix one part of the overdrive. What was the cost to get it going again. If the cost it too high then I think the disco gears sound like a better option because as I said before, this is the second overdrive this landrover has had. I plan to get a stage 2 remap and IC fitted to bring power up to 180-200bhp so i need something that will last. Don't even follow the GKN oil change instructions. Change the oil every service. Quote Link to comment Share on other sites More sharing options...
western Posted January 12, 2010 Share Posted January 12, 2010 I'd say as the Overdrive is working OK & you can't get the main gearbox into reverse the OD is not the problem, sounds more like a gearbox/selection fault. Quote Link to comment Share on other sites More sharing options...
mmgemini Posted January 12, 2010 Share Posted January 12, 2010 Ralph Read the first post carefully He's having exactly the same problems I had with my OD. For some reason when hot the OD disengages and doesn't let you reverse. I know. I've experienced it. I was told by GKN that if the OD failed then I would have drave all the time. That was not true. Quote Link to comment Share on other sites More sharing options...
SteveG Posted January 12, 2010 Share Posted January 12, 2010 Fit 33" tyres and you won't need the O/D anymore. Quote Link to comment Share on other sites More sharing options...
western Posted January 12, 2010 Share Posted January 12, 2010 Ok, as you have been through a similar problem, I've not had this with my GKN OD. Quote Link to comment Share on other sites More sharing options...
Kev Baldwin Posted January 12, 2010 Share Posted January 12, 2010 The GKN OD is a fragile beast hence the reason GKN stopped production of the unit. Remove OD and replace with Disco T-Case. Sell OD on eBay for silly figure and the T-Case upgrade will cost you very little. Quote Link to comment Share on other sites More sharing options...
Ridgeback Posted January 12, 2010 Author Share Posted January 12, 2010 I do have the other overdrive (was told the oil seals had failed and this is why it was replaced) I think its time to take this to bits and try and find what is inside that could stop it working in reverse. How hard can it be! The more I google GKN overdrive problems, the more I am thinking its not worth keeping it. I go on 3-4 long greenlane trips a year covering over 1000 miles per trip. I really dont want any parts fitted to my landy that could leave me without drive. Have any of you with GKN overdrives taken them into water? I went through a ford last week (about 500mm deep) . without taking one to bits, I dont know if water could bring on the problems I am having? Quote Link to comment Share on other sites More sharing options...
reb78 Posted January 12, 2010 Share Posted January 12, 2010 They are sealed providing your breathers are high enough and the tubes are attached tightly so i cant imagine water ingress is the problem - if it is, then again the advice to drain and change the oil will tell you it has got in and may solve the problem. They are not difficult to take apart and are really very simple things once in pieces - i replaced all gaskets on mine when it was last off of the vehicle - the only thing that had me stumped was that there is a circlip behind the oil pump cam which is not obvious with the cam in place. This needs to be removed - the cam slides out with the encouragement of a magnet to reveal the circlip. Have a search on here for GKN OD problems and see what comes up - they are not without their problems, but are pretty simple to fix. I would drain and re-fill yours before you spend time dismantling it or another unit. Personally i wouldnt sell it on ebay unless it was fixed. If you sell it as broken it wont make that much and if you pay to have it fixed you may as well use it. Quote Link to comment Share on other sites More sharing options...
mmgemini Posted January 13, 2010 Share Posted January 13, 2010 I do have the other overdrive (was told the oil seals had failed and this is why it was replaced) I think its time to take this to bits and try and find what is inside that could stop it working in reverse. How hard can it be! The more I google GKN overdrive problems, the more I am thinking its not worth keeping it. I go on 3-4 long greenlane trips a year covering over 1000 miles per trip. I really dont want any parts fitted to my landy that could leave me without drive. Have any of you with GKN overdrives taken them into water? I went through a ford last week (about 500mm deep) . without taking one to bits, I dont know if water could bring on the problems I am having? You worry about a few lanes in this country. Well at least you are only a couple of hours from help. From your comments you wouldn't like to be coming with me on a trip. Try at least two full days from ANY help. I've had water over the bonnet in the River Kwai The overdrive was playing up before that....... Quote Link to comment Share on other sites More sharing options...
Ridgeback Posted January 13, 2010 Author Share Posted January 13, 2010 You worry about a few lanes in this country. Well at least you are only a couple of hours from help. From your comments you wouldn't like to be coming with me on a trip. Try at least two full days from ANY help. I've had water over the bonnet in the River Kwai The overdrive was playing up before that....... I would love to have the time and money to go on a trip like that. I would just make sure my Land Rover was not fitted with such temperamental rubbish. Landrovers are temperamental enough to start with! Quote Link to comment Share on other sites More sharing options...
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