Have I wrecked my ML320 W163?

J.Smith

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Hi guys, I am in quite a dilemma right now, and I hate driving my car since I was distracted whilst giving it an oil change. I was also not very well at the time.

As I was about to go underneath my 1998 ML320 to drain the oil, a neighbour came up and started chatting, as I realised they were not going to leave anytime soon, I carried on with the job in hand whilst talking to them, BIG mistake!

This is where it really all got confusing for me. Instead of draining the engine oil, I accidently drained the front diff, which when I realised my mistake, I thought it was the transmission drain plug!

So after I completed the engine oil change here is what I did next:

Anyway, thinking I had drained the Tranny oil, about a litre, I topped it up with a further 1ltr, but the wrong grade! Thinking this had got me out of trouble for the time being, I drove the car with the intention of changing the tranny oil/filter at the sump a few days later. (There was a dull whine whilst driving) You wouldnt believe the trouble I had finding out what oil to use, even MB just said "We just use the pink stuff!" Anyway, a few days later I was taking the car to a garage for some minor work, I got about 100yds from my house & I could hear this horrible crunching noise coming from underneath, I headed back home VERY slowly and the noise was getting worst, the car also seemed to start stalling.

When I got home I jacked the car up ready for the tranny oil change. I went and got Dextron III and drained the sump, changed the filter & added the oil. Upon doing this it was only then that I realised that it was the FRONT DIFF that I had drained, so I had been driving the car with no oil in the diff! I had therefore 'topped up' the tranny oil by mistake (very costly)!

After I changed the tranny oil I refilled the front diff with SAE/90 gear oil.

Now every time I drive the car there is a sound more noticeable at between 20-30mph, it is like a constant dull wind sound, as if you have bad sound insulation in the car. The noise is only noticeable when on the gas in motion, so I suspect it is the torque in the diff?

A friend loaned me a MB tranny dipstick, which showed the oil level to be too high.

So I am thinking it is one of three things, 1) The diff oil is too low or the wrong grade? 2) It is the tranny oil level too high? 3) It IS the tranny oil fullstop?!

Or worst ways, I have wrecked the front diff!

Please help as soon as possible, as driving is no longer a pleasure....:(
 

roadhog

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How far had you driven the car with the front diff empty? My guess would be that your noise is coming from there.
As for the ATF level being wrong, are you following the correct procedure/using the correct dipstick?
 
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J.Smith

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Hi Hogg, a friend who works at MB loaned me the correct dipstick, I checked the level whilst hot, it was too high, so I need to drain a little as I am informed it could foam-up if driven hard on motorways.

I must have driven at least 40 miles with an empty diff.......
 

roadhog

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That's fair enough and assuming you used the correct oil I would discount the gearbox as being the culprit. Back to the diff then. :(
 
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J.Smith

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So the fact that the trans oil level is too high it wouldnt cause unusual noises?
 

bigasotonuk

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Hi,
I would also check the grade of oil for the diff, if in doubt buy MB fluid, as I believe synthetic diff oil is useds in diffs of the road cars so yours may have synthetic too.
 

roadhog

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So the fact that the trans oil level is too high it wouldnt cause unusual noises?

In your scenario I would suspect the diff over the incorrect fluid level but yes, you do need to drain some to correct the ATF level. You never know, you might get lucky and the noise disappears. :)
 


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