Iron filings on gear magnet plug

LostKiwi

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A much older car, but my 2004 w203 6 speed manual on a C320 V6 petrol was just the same when cold.
New gearbox oil made virually no difference.
Further reading suggested that when testing the gearbox during design, it worked fine in a factory (at 20°C), but alas, not when cold and outside. In the summer months it was fine.
I think it was an oil pressure relief channel to do with the 1st and 2nd gears. 1st was particularly bad when cold if moving at all. When all up to temperature it was fine.
There was an upgraded part issued for the gearbox that resolved the issue, but that would require a gearbox strip down to install, so not something I ever had done. I enquired about this part at my local Mercedes dealer, and they were surprised that the system showed they had sold hundreds of this part in the past year, and therefore concluded this was a common issue.

Thankfully with the torquey V6, I could get round this problem by setting off in 2nd gear if facing slightly downhill and by being gentle on the clutch, or if uphill, go from 1st up to e.g. 3-4k rpm, then change straight to 3rd. A bit of a pain, but not as painful as £1500 on a gearbox strip down and new clutch.

It sounds like a very similar issue, although I'm sure the gearboxes will be significantly different.
Unusual for a manual gearbox to have a pressurised oil feed. Only one I've hard of was used in Land Rovers (LT95 4 speed).
 

Botus

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years back in days gone by, the getrag box in rare Jag manuals circa 1988 - had vastly improved changes by moving to an approved wrong fluid.... for want of a decent recollection - I thought we did put auto trans fluid in them as a factory approved lighten the gear change mod

before going that route I'd check I'm not a mad old fool with a dodgy memory
here we go....


My old Jaguar manual recommends a SAE75 or 80, but goes on to say that if gear selection problems are encountered, it is permissible to drain and refill with Dexron II which is of course ATF. Other recommendations from BMW now say Dexron III or whatever its current name is
 
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I read on a forum that someone removed the gearbox and modified something solving the issue. But I don't remember what and even if I knew it, it would be such an enormous job that I'd rather sell the car :)

Living in a not too cold climate, if I could improve it just a little I'd be happy. In my opinion trying different oils could be the key :)
 

Mr Greedy

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Unusual for a manual gearbox to have a pressurised oil feed. Only one I've hard of was used in Land Rovers (LT95 4 speed).
It wasn't pressurised oil. I just meant a channel or design modification somewhere so that as 1st and 2nd gears engage, the small amount of 'trapped' thick, high viscosity fluid when colder was able to get out of the way quickly, from where ever it was stuck. At least, that was how it was explained to me.
 

Rockron

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Similar to Post #42.
Over the years I've quite often noted Mercedes specify alternative gearbox oils to those quoted in
the handbook.
My own vehicle gearbox supplied new, contained SAE 80 as per handbook. Cold English winters
produced crunchy baulking gear changes until warmed up......not ideal. I managed to source a workshop
manuaL. ATF Type A Suffix A given as an alternative (it didn't mention why). The lower viscosity of the
ATF did the trick. Now 130,000 miles on and there's no discernible deterioration in the changes.
 
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Hi, thank you. In fact I'm hoping that I could find some oil to make a further improvement. Putting the new Febi 75w oil made already a good improvement. If I could do a little better I could go on for many miles
 

sonic

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Back in the late 60's I used to ski instruct in the army in Bavaria, we had Land Rovers & 8 ton trucks. Daytime temps around -5 to -10C, night time as low a -30c on one occasion.
We used to change the engine oil to winter oil before driving down, & the gearbox oil to I think it was SAE70. The opinion of the vehicle workshops was the SAE70 was too thin for the long drive down.
I had a VW Beatle at the time I changed the engine oil to winter oil but left the summer oil in the gearbox. When parking the car up I would leave it in first gear facing out of the parking area. The following morning start up & drive the first 300 yards in first gear to thin the oil out. Even then it was not keen to go into second gear.
 
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Exact situation for me. First 300-400 yards in 1st gear but it's not enough when it's about 0 Celsius. I'll give a shot to the additive I think..:) all MB manuals I heard are quite rough in winter
 

sonic

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Exact situation for me. First 300-400 yards in 1st gear but it's not enough when it's about 0 Celsius. I'll give a shot to the additive I think..:) all MB manuals I heard are quite rough in winter
I have never had a manual MB, & never had problems with the auto box in cold temps. I am surprised the problem is still there with SAE70 in the gearbox.
I am assuming you are using SAE80 in the summer & changing to SAE70 in the winter?
 
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The old oil was the factory one. Now I put the Febi 75w GL-4 (MB 235.10). And it improved a lot. But still problematic when cold :)
 

Rockron

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When I drained the original MB first service SAE 80 gearbox oil after a few thousand
British cold winter miles, I noted the (not unexpectedly) bronze streaking in the oil.
And we all know what that means!

The handbook specified SAE 80 gear oil A bit of further investigation showed
ATF Suffix A Type A to be specified in the Workshop Manual, no alternative mentioned.
Somewhere else I read that use of ATF is permissable only if vehicle is not used in extreme
and arduous conditions?? Anyway ATF it was, and no more baulking, crunching or bronze
streaking.

However, in the workshop manual for the same gearbox but with differing ratios to suit the
turboed version of my engine, I noted that Gear Oil was specified, no grade stated. I can only
surmise with the higher stresses, that the gearbox requires the heavier duty properties of
gear oil, rather than the lighter duty ATF.

In my application I traded the probable superior wear characteristics of Gear Oil for the
practicality of the ATF. I mean who the hell wants to enter a fast traffic lane in first gear
for a 400m gearbox prewarmup!! More like 2 miles in my case.
 
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You are right and it's pretty absurd that cars of this level suffer from these issues. I'll make some attempts. I'd like to try the additive, and if it doesn't work, shift to a Fuchs 75w gear oil (even if it has not the MB 235.10 approval).
 


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