andyjim Posted March 21, 2011 Share Posted March 21, 2011 I own a p38 diesel auto. The problem I have is when I get above 60mph it feels like there is a wheel out of balance or that one cylinder is missing. The vibration can be felt through the whole car and the passenger seat can be seen shaking. The engine is firing on all 6 cylinders but sometimes it seems to run super smooth which makes it quieter, more powerful and lessens the vibration from severe to mild/moderate. It has had new tyres, all wheels balanced, new front prop, new viscous coupling, the flex-plate has been ruled out, all steering joints and drag arms have been replaced, the gearbox pressures have been checked and are ok, the diff oil is like new so there is nothing happening in there. It has been in three different garages and no-one can find the problem. It is now driving me mad so if anyone can help you might just save my sanity. Quote Link to comment Share on other sites More sharing options...
Range Rover Blues Posted March 22, 2011 Share Posted March 22, 2011 Couple of things. Get it on a slight motorway hill, get up to 60 so it vibrates and kick it into neutral. Does it keep vibrating? Try the same and pull the shifter back into 3rd, again what happens. Does it do it worse on power, does it go away on overunn or engine braking? Do you know what has been checked? whilst I'd hope that 3 garages would between them be very thorough, I find I often have to instruct mechanics how to deal with my LR. Quote Link to comment Share on other sites More sharing options...
andyjim Posted March 23, 2011 Author Share Posted March 23, 2011 I haven't tried your first suggestion, but it does the same whether under power or on the overun. One of the garages is my local garage who I trust, but they had it for three days and coudn't find the problem. It was they who suspected a dif problem but on draining the oil found it like new so ruled that out. It is due to go into a fourth garage this weekend which will be my last attempt at diagnosis. But before then I will try your suggestion of putting in nuetral at 60mph and see what happens. One other thing I tried was putting the transfer box in nuetral and running the main box in D at 30000rpm engine speed and there was no vibration. I will post the results after the weekend in case anyone else gets the same problem. Quote Link to comment Share on other sites More sharing options...
SteveRK Posted March 24, 2011 Share Posted March 24, 2011 My vote goes for a defective tyre that starts to mishape at 60mph, or an out of balance wheel/loose wheel bearing/loose wheel nut Quote Link to comment Share on other sites More sharing options...
Range Rover Blues Posted March 24, 2011 Share Posted March 24, 2011 I'd suspect something after the gearbox. Other than duff tyres I'd be looking at propshafts and UJs, the rubber doughnut (it needs a new support bush inside the prop too) and failing Diff pinion bearing. Perhaps something as simple as a loose propshaft. Quote Link to comment Share on other sites More sharing options...
andyjim Posted March 25, 2011 Author Share Posted March 25, 2011 I'd suspect something after the gearbox. Other than duff tyres I'd be looking at propshafts and UJs, the rubber doughnut (it needs a new support bush inside the prop too) and failing Diff pinion bearing. Perhaps something as simple as a loose propshaft. Since it started, I have had new tyres and all wheels balanced. I check the torque on the wheelnuts every month, with them being alloys, I don't know whether I should do that or whether I am just being an anorak. The front propshaft has been replaced as there was slight play in one of the UJ's. The rear prop has been checked and there is no play in the UJ's and the doughnut is in good shape. As for the pinion bearing, I would have thought that there would be bits in the oil but there was none. I am greatful for you taking the time to help and any other suggestions are more than welcome. Hopefully after tomorrow all will be revealed as the garage I am going to is a Land Rover specialist. I will keep you posted. Quote Link to comment Share on other sites More sharing options...
SteveRK Posted March 25, 2011 Share Posted March 25, 2011 I have bought my own wheel balancing machine as i have always had balance problems after getting new tyres fitted at various tyre outlets for the past 20 years, except when the tyres were fitted by a Mercedes Benz dealer. They got them spot on. Quote Link to comment Share on other sites More sharing options...
Range Rover Blues Posted March 25, 2011 Share Posted March 25, 2011 I'll be interested to know what the outcome is too, it's very difficult to diagnose a problem that you can't experience fost hand but I suspect that the probelm is "downstream" of the gearbox from what you have said. the common causes are the parts you have check already but it is by no means the exhaustive list. Anyhoo I hope they can get it sorted for you and we may all learn something from your experience Quote Link to comment Share on other sites More sharing options...
andyjim Posted March 27, 2011 Author Share Posted March 27, 2011 Right,I went to the garage yesterday and here are the findings. To start with, the Airflow Meter is faulty and not fueling the engine properly. This is why it sometimes feels like it is missing even though it isn't. The AFM was disconnected so that the engine ran in default mode and there was a slight improvement in vibration so that is the first thing to be changed, although Land Rover want £430+vat, so I will be looking on ebay. With regards to the main vibration prob, the crankshaft front damper is suspected. I hope this is the case because other than that it could be a problem with the torque converter that did not show up when I put the transfer box in nuetral because it was not under load. I will be having a new radiator soon, (yes my problems are like buses, all come at the same time), so while the radiator is off the damper can be checked. If this cures the problem I will let you all know otherwise I might go back to a td5. Quote Link to comment Share on other sites More sharing options...
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