Diff problems resolved by oil change!
Jul 23, 2009, 03:25 AM
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Bad diff grind resolved by oil change!
Over the past few weeks I have had a problem with diffs in my Evo X and thought my experiences may be of interest to X owners on here, so here we go (Sorry if it’s a bit long winded but I thought a full account would cover most queries).
I have an Evo X FQ300 M/T (Reg in March 2008) which has done 10k miles, the car has never been on a track and is driven sensibly I normally average 24mpg. The car has stage one mods and pulls some 400 bhp with an ECUtek map, full exhaust decat, induction kit, fuel pump which were applied at 9.5k miles.
The symptoms!
On the day of mapping my tuner noticed whilst mapping on the road a scraping and knocking noise coming from the front of the car during hard right hand bends. When the car was driven in a straight line the car was fine and fine around bends at normal speed. Also no noise on hard left hand turns. Gearbox shifts were fine with no whine at all from the diffs.
When I went to pick up the car he mentioned this knock and I said I had never noticed anything and didn’t think more of it given I was excited and wanted to take my new 400bhp Evo for a drive. For two weeks I never noticed a thing until one Sunday afternoon I went for a burn and went harder than normal round a right hand bend and noticed this bad scrapping noise.
I had not noticed this before but then again I don’t drive the car very hard around corners, I am convinced the problem was there before the mapping day it just hadn’t been noticed. First impressions were that for some reason a diff is slipping or seized either in the gearbox or transfer box maybe when the S-AWC kicks in.
Given the ECU had been accessed before the car had left the garage for the ECUtek map the warranty was now out the window. So we had to try and solve the problem ourselves or face a huge bill in the region of maybe 3-4k from Mitsi for a new transfer or gearbox.
So I called my Tuner and he said bring the car over and we will have a look. So to try and diagnose the cause of the problem we have been through a couple of steps.
Initially we drained the transfer box oil which seemed to have the normal amount of oil in it. However the oil was heavy and black and full of very fine filings but no big pieces of metal were noticed comments from the experienced Evo mechanics were that amount of wear would be expected on a diff with 50- 60k not a diff which has done only 10k. We inspected (but did not change) the oil in the gearbox which looked normal.
New oil - Silkoline was added to the transfer box and the car tested – but the problem was still there.
A couple of weeks later we removed and opened the transfer box and transfer diff to have a closer look at the transfer diff.
There were no broken bits of metal but signs of wear on bearings and flanges with some metallic scratches present. There was also a small amount of black gundge present stuck around parts of the diff and transfer box casing indicating metallic wear. We cleaned the transfer diff up and put it back together and on the car. We had confirmed a lot of wear but no hard evidence to suggest the cause of failure.
We then drained the gearbox oil and this was cleaner but with some black gundge stuck to the magnetic bolt, no larger bits of metal were noticed. We did not take the gearbox apart given it was getting late and I had to use the car to get home.
We then used Silkoline to refill the gearbox and transfer box and took the car out for a spin.
Taking the car hard around a roundabout we initially noticed some scrapping noise but it was much less harsh and the hard knock had gone down to a rattle. We then pushed the car further and the more we pushed the car hard around the right handers the noise slowly disappeared. The next day I took the car out and pushed it almost sideways around a (quiet) roundabout and there was no noise at all. The diffs in the car now seem fine.
So the diagnosis seems to be that for some reason parts of the diff either in the gearbox or transfer box were sticking maybe from overheating caused by poor lubrication. This was then solved either by taking the transfer box and diff apart and cleaning it and/or the application of new oil.
I have an Evo X FQ300 M/T (Reg in March 2008) which has done 10k miles, the car has never been on a track and is driven sensibly I normally average 24mpg. The car has stage one mods and pulls some 400 bhp with an ECUtek map, full exhaust decat, induction kit, fuel pump which were applied at 9.5k miles.
The symptoms!
On the day of mapping my tuner noticed whilst mapping on the road a scraping and knocking noise coming from the front of the car during hard right hand bends. When the car was driven in a straight line the car was fine and fine around bends at normal speed. Also no noise on hard left hand turns. Gearbox shifts were fine with no whine at all from the diffs.
When I went to pick up the car he mentioned this knock and I said I had never noticed anything and didn’t think more of it given I was excited and wanted to take my new 400bhp Evo for a drive. For two weeks I never noticed a thing until one Sunday afternoon I went for a burn and went harder than normal round a right hand bend and noticed this bad scrapping noise.
I had not noticed this before but then again I don’t drive the car very hard around corners, I am convinced the problem was there before the mapping day it just hadn’t been noticed. First impressions were that for some reason a diff is slipping or seized either in the gearbox or transfer box maybe when the S-AWC kicks in.
Given the ECU had been accessed before the car had left the garage for the ECUtek map the warranty was now out the window. So we had to try and solve the problem ourselves or face a huge bill in the region of maybe 3-4k from Mitsi for a new transfer or gearbox.
So I called my Tuner and he said bring the car over and we will have a look. So to try and diagnose the cause of the problem we have been through a couple of steps.
Initially we drained the transfer box oil which seemed to have the normal amount of oil in it. However the oil was heavy and black and full of very fine filings but no big pieces of metal were noticed comments from the experienced Evo mechanics were that amount of wear would be expected on a diff with 50- 60k not a diff which has done only 10k. We inspected (but did not change) the oil in the gearbox which looked normal.
New oil - Silkoline was added to the transfer box and the car tested – but the problem was still there.
A couple of weeks later we removed and opened the transfer box and transfer diff to have a closer look at the transfer diff.
There were no broken bits of metal but signs of wear on bearings and flanges with some metallic scratches present. There was also a small amount of black gundge present stuck around parts of the diff and transfer box casing indicating metallic wear. We cleaned the transfer diff up and put it back together and on the car. We had confirmed a lot of wear but no hard evidence to suggest the cause of failure.
We then drained the gearbox oil and this was cleaner but with some black gundge stuck to the magnetic bolt, no larger bits of metal were noticed. We did not take the gearbox apart given it was getting late and I had to use the car to get home.
We then used Silkoline to refill the gearbox and transfer box and took the car out for a spin.
Taking the car hard around a roundabout we initially noticed some scrapping noise but it was much less harsh and the hard knock had gone down to a rattle. We then pushed the car further and the more we pushed the car hard around the right handers the noise slowly disappeared. The next day I took the car out and pushed it almost sideways around a (quiet) roundabout and there was no noise at all. The diffs in the car now seem fine.
So the diagnosis seems to be that for some reason parts of the diff either in the gearbox or transfer box were sticking maybe from overheating caused by poor lubrication. This was then solved either by taking the transfer box and diff apart and cleaning it and/or the application of new oil.
Last edited by Morgan Evo; Jul 25, 2009 at 08:06 AM.
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