Transmission fluid above max line very bad? 1985 300TDT - PeachParts Mercedes-Benz Forum

azitizz · #1 01-02-2011, 10:19 PM

I just did a top-up in my automatic transmission and I put a little too much in. Its probably 2 mm above th max mark. It was surprisingly low after not having checked it for a few months.

Is this a real no no? Filling above the MAX line on the dipstick? Ive been driving with it and thinking that it was obviously leaking some fluid over time that it would go down again.

Whats the works that could happen.

Its freezing cold here and I didnt want to have to syphon off any excess or deal with draingin off going under the car in sub zero weather on a gravel icy driveway. But If its the difference of life or death of the transmission, I may opt for a dirty cold climb under the car.

HuskyMan · #2 01-02-2011, 10:36 PM

It won't hurt anything. Mine's been slightly overfilled for a while and there have been no problems.

leathermang · #3 01-02-2011, 11:50 PM

HuskyMan, you need to delete that post so you don't look totally uninformed and possibly mislead some unsuspecting new person.

It is very bad to overfill either the engine or the trans... because it can cause foaming ...this causes extra fast oxidation which takes away that fluids ability to lubricate.
Lack of lubrication ability wears the clutches faster than they should wear.
Over heating of trans fluid can do the same thing.. for instance.. having to rock the trans from drive to reverse getting out of a hole.... there is a chart showing that above a certain temperature every 10 extra degrees of heat HALVES the effective life of that fluid..
It is easy to get it so hot within a few minutes that it would need to be changed as soon as you got home.

pawoSD · #4 01-02-2011, 11:53 PM

In Winnipeg Canada its going to be rather difficult to overheat anything!

Either way, its not good to have it overfilled. On level ground at operating temp with engine idling, trans in park, it should not exceed the upper notch on the stick. With it cold/turned off on level ground, it should be about 3/4" inch below the lower mark.

JimmyL · #5 01-03-2011, 01:15 AM

Quote:

Originally Posted by azitizz

Transmission fluid above max line very bad? 1985 300TDT

I'd take a look at that hatch a bit more closely next time!

layback40 · #6 01-03-2011, 01:30 AM

Quote:

Originally Posted by pawoSD

In Winnipeg Canada its going to be rather difficult to overheat anything!

Either way, its not good to have it overfilled. On level ground at operating temp with engine idling, trans in park, it should not exceed the upper notch on the stick. With it cold/turned off on level ground, it should be about 3/4" inch below the lower mark.

Just be careful doing the cold check, sometimes if left off for a while the fluid appears to empty out of the TC & you get a false high reading.
If you took the car for a light drive & then checked it, it may come up on the notch. 2mm isnt much. If I was going to worry about that amount, I would be using a spirit level to make sure the car was exactly level in both directions. If it was 10mm I would be doing something.

leathermang · #7 01-03-2011, 01:39 AM

I don't remember if they ' approve' of a ' cold ' check method.. whatever the instructions are for checking the trans fluid they need to be followed exactly.
What I am saying is that it is better to be 2mm below the max line rather than ANY over ( when checked correctly ).

pawoSD · #8 01-03-2011, 02:18 AM

I usually check it hot/running....but have come to the conclusion that the 3/4" down when cold is pretty accurate.....as it matches up on all of our 722.3 transmissions when checked hot for proper level and then cold later on. This is with Valvoline Dexron VI Full synthetic. Other fluids may behave differently.