phingoc

Hi.

my car recently started to get randomly spasms that lasts 1-2 sec each time.. It happends periodicly, maybe once or twice on one trip (20km).

I am just driving normal, 30-40km/h, and without pressing the throttle or anything, the car starts to shake/spasm. I am not sure, but i can feel it comming from the rear end of the car. I have not noticed if it appears while the trans is shifting gear..

I have a Star Diagnosis, and checked for fault codes.. No codes on any system.. Esp, engine, transmission etc, all of them are clear of codes.. So i dont have any leads to follow.

First i thought it was a ESP problem, but no indicatorlamp is flasshing when it happends so I am now thinking its the famous coolant in trans problem since my car is a 2003 with valeo radiator.. But no fault codes on transmission control unit. However, latley, i have noticed that it takes a tad longer time from i put it in R or D, for it to actualy shift into gear. This is most noticable when driving in R down a small hill, while my car is standing still on the hill, put it quickly into D and start off immediately, teh car will rev up and slam it into gear. If i wait 2-3 sec from the D is engaged to i give some gas, it would act normally. Again, no fault codes from the original Star Diagnosis system with 05/2013 software and all add-ons..

My car is going to the dealer on monday and change engine oil and transmission oil+filter. Can they see if the transmission oil has coolant in it? Will the coolant seperate out of the oil, or will it blend? Should i tell the mechanic to drain the transmission oil into a clear container to check for coolant?

This give some hard shackes.. Not some small rumbling or something, but my head gets thrown back and forth when this happen.

Again, no codes on Engine or transmission.. I dont think it is engine problems, but i may be wrong..

Rudeney

The easiest way to check for the Valeo radiator problem is to see if you have that part:

http://forums.mercedesclub.org.uk/sh...42&postcount=3

If you have it, it's almost certain to have leaked, and this could very well be your problem.

phingoc

i have the valeo.. The question is now, how can i be sure there is coolant in the trans oil when draining it of the transmission? will i see it if i drain it into a clear container?

Rudeney

I believe the official method is to do a glycol test on the transmission fluid, but my understanding is that the Valeo will always fail eventually and mix fluids. The symptoms you describe are typical of low or contaminated transmission fluid.

phingoc

Some more updates.. I have driven the car some more today, and the problem is at low rev range.. When im on the highway and drive in 5th, no problem.. Also with kickdown down to 3rd and change up to 4th and 5th is no problem.. But at lower speeds it will come.. Most likley when the car is changing gear.. either up or down...

ok, so i i will try to change oil and filter on the trans first to see if the problem is fixed, and i will also ask the mechanic to save a litre of the old fluid for glycol testing.

How is glycol testing done? Can my local dealer do it, or do i have send it away to a specialist?

VII

I don't think it is wise to do the service and then send oil for testing. You will probably end up having to do it twice.

If you have the valeo radiator probability of failure is high and if you are keeping the car for much longer you should probably replace it even if no failure has occurred.

VII

Also you can check for adaptation values if you have star, out of range values will indicate a transmission problem. Note resetting them will NOT solve the issue.

Glyn M Ruck

Check that the airbox is clipped down tightly over the MAF.