PeachParts Mercedes-Benz Forum - View Single Post

Grdenko · #2 09-02-2004, 01:54 PM

first, welcome to the forum. im sure youll learn alot here and soon youll be able to pretend to be an expert just like i do! Im assuming youre in Europe because of the km measurements, its good to have people on the forum over there, then again, maybe youre just a metric system enthusiast. and with a '91 300D 2.5 with only 45000 miles on it? i envy you.

1) thats interesting, thats the exact opposite of what everybody elses transmission problem is. most cars shift up too late. if youve never owned a diesel before, its possible that youre just not used to it. diesels run at a lower rpm range than gassers. cruising at 2000-2300 rpm is about right. as for the kickdown, its activated by a button on the floor directly under the throttle pedal, you can probably feel it when you push the pedal all the way down. the kickdown is the only way the tranny downshifts at speed (unless you use the shifter) so theres no way to kickdown without putting the pedal to the floor. the only way i can think to make it kickdown at a lower engine speed is if you adjusted the throttle linkage to reduce the amount of travel it gets when the pedal is on the floor, but the downsides of that are obvious. these engines and transmissions were designed to get maximum fuel milage, so they run at the lowest rpms possible. the kickdown was designed for merging and high speed passing (although i use mine all the time because my turbo doesnt work).
A good and easy way to check if youre transmission is tuned right is to start from a dead stop (with plenty of empty road in front of you) and punch the pedal all the way to the floor, including the kickdown button. there are 3 sets of orange dash marks on your spedometer, placed at approximately 30mph, 60mph, and 90mph (50, 95, and 145 kph) if my memory is right. these marks are where the transmission is supposed to shift to 2nd, 3rd, and 4th respectively. this is not affected by a lack of vacuum when the pedal is all the way down. if thats where it shift, then your tranny is fine.

2) i dont know what you mean by "flares a little bit...maybe 200 rpm", but maybe the answer above applies to this question as well.

3)its hard for me to get anxious about a diesel engine leaking/using oil, but since yours only has 45k miles on it, that is a little concerning. you said 1.5 liter after 12000km (appx 1.5 qt after 7500mi) that would be ALOT for such a young engine. mine only uses about .5qt after that, and ive got 4x as many miles. but you also said you only bought the car 8000km ago, which makes me assume that you dont know for sure what it was filled to at the last change. the manual calls for only 7.5qts or 7liters of oil i believe. this puts the oil level directly in between the max and min marks on the dipstick, about 1qt more than min and 1qt less than max. so if it was filled right at the last change, then it was filled 1-1.5 liters short of the max fill mark. if youre measuring that 1.5 liter loss from the max mark on the dipstick, then its probably just a .5 liter loss or less. or maybe you already though of that and you really do have a problem, what do i know. also you should probably change your oil more often than every 7500mi.

4)i dont really know anything about synthetic trans fluid, but if you used a trans fluid with more lubricity, it will make your trans shift sooner, and maybe you dont want that.

5)your vacuum lines, they dont have many miles on them, but theyre still old and will probably start falling apart soon since the car is being used more than it was under the previous owner.

gosh im sorry, i can be very long winded. hope i didnt waste too much of your time.

later