Hi there,

New to this forum, but in desperate need of some help or advise. I'm having some issues with my ML400 - I bought the car specifically for towing, but it turns out, it really doesn't do exactly that very well. Here's the symptoms:

1) After towing for a while, I'll suddenly "loose" 5th gear. It will out of nowhere shift down into 4th, and unwilling to go back into 5th, no matter up or downhill. Manual shifting (it's an auto) won't help either. It will let me shift down to 3rd, and back up, but not into 5th.
2) All other gears will eventually go as well, until stuck with 1st and 2nd. I can shift it manually if I let it rev higher and higher and use the manual shift mode.
3) This only (! - so far at least) happens when towing, but it happens regardless of towing 3,5 tons or my 1300 kg caravan.

At first I thought it was gearbox problems, but this last time I think it lost power as well. So now I'm thinking it could be engine related as well. It basically feels like the car thinks it is constantly towing something really heavy up a very steep hill.
I have had the gearbox oil and filter changed lately, made no difference.

Any ideas are welcome, before I start randomly throwing money and parts after the car.

 

If you don't know where to look, whether to search on the engine or the gearbox, then first find someone who has Star diagnostic.Dtc will be saved. When changing the oil in the AT, was the socket also changed? /see picture/

 

@simonpeter Sorry to hear. Please provide this information:

- what year is the vehicle?
- how many miles are on the vehicle?
- how long have you owned the vehicle and how many miles have you added?
- what maintenance and service has been done on the vehicle in the past 12 months?
- what weight are you towing?
- what road/state/region/country are you towing?
- what is your towing experience?

Thanks!

 

I have to write to you because I don't understand those questions. I specify - I understand them, but I do not understand what is their significance for the defect? That's why I'll be happy if you explain it to me. From my point of view, it doesn't matter if it is
1 / .2001 or 2005.
2 / .150.000km or 350.000 km.
I have it for a month and 3,000km or 5 months and
16,000km.
4 /. I have it for a month - no maintenance or I have it 5
months 1x service, front brake pads.
5 /. sometimes 1,300kg and sometimes 2,800kg.
6 /. Sometimes Germany, Holland, Belgium and back, sometimes
I'm just carrying wood from the forest on a trailer.
7 /. I had a trailer 8 times or I have a record of 16,200 km
per month with the previous car.
So I'm really curious how you can tell from the quiz if there's a problem with the engine or transmission. I like to learn.

 

Miles, miles...how many miles on the car!!!

 

How will it help you know how many miles it has? You can tell by the number of miles whether there is a problem with the engine or transmission? How?
​​​​​​​

 

@Mijanboy What are the specific answers to:

1. What year is the vehicle? Please give one year.
2. How many miles or kms are on the vehicle? Please give one number.

​​​​​​​Thank you.

 

Hello,

Thank you all for your contributions. I will happily answer the popquiz, even though answers to some of those questions should be readily at hand already.

1) What year is the vehicle?
It is a 2003 Mercedes ML400.
2) How many miles are on the vehicle?
I'm in Europe and I speak kilometers rather than miles. The vehicle has done 293.000 km, which should roughly translate to 182.000 miles.
3) How long have you owned the vehicle and how many miles have you added?
I have owned the car for about half a year and put around 5000 km (3000 miles) on the car during that period.
4) What maintenance and service has been done on the vehicle in the past 12 months?
Can't speak for the past 12 months, but as mentioned, I've had the gearbox flushed and replaced the filter a few months ago. This didn't help.
5) What weight are you towing?
Also mentioned in my original post. For work I'm towing up to 7500 lbs (3500 tons) which is the maximum this vehicle is allowed to tow in my country. For leisure I use it to tow our caravan, which is only around 2800-3000 lbs. Both situations results in same immediate symptoms.
6) What road/state/region/country are you towing?
Denmark, Europe. Very flat country. No steep hills.
7) What is your towing experience?
I do fail to see, how this might be relevant, unless trying to rule out the fact, that I might be towing my trailers with handbrakes pulled due to lack of experience. I have several years of towing experience in tractors, trucks, cars and military vehicles.

Thanks in advance for any further help. :-)

 

1. 2003
2. 340.000 KM

 

The best help for you is diagnosis. Otherwise, he'll answer the quiz questions by Christmas. After Christmas, the determination of the defect begins with a new trial-and-error method....

 

@simonpeter An 18 year old vehicle with 340k kms is near the end of its life, unfortunately. It sounds from your posts that you are using the vehicle as part of a business, is this correct?

Using an old vehicle with high mileage for a business seems like not the best idea.

What actions have you taken in the past month?

It sounds to me like the transmission needs to be overhauled or replaced. Or buy a newer vehicle. These are the alternatives I would investigate. There are no simple answers to your transmission questions. The car is old and has high mileage.