C250 W202 transmission problem.

[Diver]

While driving my otherwise super-reliable 1997 C250TD on Christmas Eve, I noticed a burning smell which was very obvious after I parked but I couldn't trace the source. The next morning the auto transmission wouldn't (and hasn't since) changed out of what I think is second gear (limp mode?)
I checked the auto gearbox oil and the level is fine but the colour is very dark and a bit greenish. I appreciate the obvious thing to do is to take it somewhere to be plugged into a diagnostic, but does anyone have any guesses as to what might have happened?

 

[Diver]

 

[mario andretti]

Check the ecu on the passenger floor as it could be full of gear oil.

 

[Diver]

On the passenger floor? Not sure exactly where you mean but how would gear oil get to the passenger floor?

 

[mario andretti]

Pull the carpet back and there is a panel you remove and it is there. The oil travels via the wiring loom as the plug at the gearbox leaks oil. If you are stuck for an ECU I have one from a 99 c250 here.

 

[Diver]

Ah, I'm with you many thanks. Would that make sense with these error codes?

 

[Diver]

Pull the carpet back and there is a panel you remove and it is there. The oil travels via the wiring loom as the plug at the gearbox leaks oil. If you are stuck for an ECU I have one from a 99 c250 here.

Probably being a bit thick, but this is the passenger footwell with the carpet removed, what am I looking for?

 

[guydewdney]

i thought it was under the angled bit of the footwell, like where the brake pedal is (nt)

those codes are for the abs sensors arnt they?

 

[Diver]

There was a metal plate there under where feet would be and attached underneath was an ECU, but the wires for it go off to the left under the left hand side trim so there would be no way that oil could travel to it from the gearbox.
Those codes do seem to be abs sensors, but it comes up under 'automatic gearbox' in the scanner and it's unlikely that they are all defective I'd have thought?
I guess if nobody has any other suggestions I'll just scrap it. Shame though, was a fantastic car up until this happened!

 

[neilrr]

Take it to a MB indy & find out WTF is wrong with it.

Duh.

 

[Flyinspanner]

There is a speed sensor on the gearbox conductor plate, I've just had mine changed, as like you gbox stuck in second, also couldn't select between W and S.
Was diagnosed properly on Star, requires dropping sump on box, remove valve box, replace conductor plate, reconnect all, fresh gaskets n fluid.
Done in a day.
Don't drive car far, keep speed low, otherwise box will run very hot.
Cost me £480 for my CL500 at an independent specialist.

 

[Diver]

Take it to a MB indy & find out WTF is wrong with it.

Duh.

Helpful, thanks. The whole point of asking for opinions is to weigh up whether an old car is worth fixing, not hiring a tow truck to take it two hours away to the nearest MB Indy to find out it's not worth fixing.

Perhaps instead of a forum where people discuss their cars, this URL should just lead to a message saying 'Take it to a MB Indy. Duh.' :fail

 

[neilrr]

I'm afraid nobody on a forum can tell you what's wrong with it, they can only guess. It could be anything from a cheap & simple £10 fix to needing a new tranny.

If you are happy to throw parts at it based on the guesses of people, the vast majority of whom are not MB techs, then carry on. You've heard the guesses so far & AFAIC see are no nearer to getting to the bottom of the problem.

If you want to find out definitively what the problem is & what is needed to fix it before resorting to scrapping it see post 10.

HTH.

 

[BlackC55]

What gearbox codes do you have?

 

[guydewdney]

i think the cable runs from the under the bonnet to the ecu. if its the same as my w140 that is the same age.

replacing the 'bushing' in the gearbox is easy on a ramp, and i think slows or stops the oil leak issue.

cut some of the wires insulation and see if oil comes out? if its scrap anyway. ......

 

[Diver]

For everyone who has tried to helpful, thank you. Often asking on a forum can throw up easy things to check first such as the multiplug on the gearbox which is a known fault with these. Sadly, it look like none of the potential simple known faults are the problem, but they were definitely worth checking. Cheers!

 

[Diver]

I'm afraid nobody on a forum can tell you what's wrong with it, they can only guess. It could be anything from a cheap & simple £10 fix to needing a new tranny.

If you are happy to throw parts at it based on the guesses of people, the vast majority of whom are not MB techs, then carry on. You've heard the guesses so far & AFAIC see are no nearer to getting to the bottom of the problem.

If you want to find out definitively what the problem is & what is needed to fix it before resorting to scrapping it see post 10.

HTH.

As said in my post above, sometimes there are easy known issues that experienced people are aware of whether they are 'techs' or not so yes, I asked for guesses. It's always worth a quick ask before committing to large sums of money to just find out what a problem is (not fix it, just find out what it is). When the vehicle is of low value, the equation of potential repair cost to just replacing the vehicle isn't the same as with a 20 grand motor that yes you would just immediately take to a specialist or dealer.

For instance, I didn't know that the gearbox multi plug socket is a known failure point that can cause this problem before I asked and had it been that I could have fixed the car for £25.

As things stand just the cost of getting the vehicle to a specialist and having a star diagnostic done is close to what this car is realistically worth, let alone repair costs once the problem is revealed.

If you bothered to read the last line of my first post you would know that, so I can only assume you went out of your way to make an unhelpful and pointless post for your own amusement. Feel better?