tecra

New to C5s here. I know that people with Mercedes E class (W210) can change out virtually all fluid in the transmission by disconnecting the transmission oil hose that goes into the radiator, pumping old oil out by the engine and add new oil in at the same time. Can we do the similar procedure? I guess it'll be difficult/impossible, since we don't have trans dipstick, so nowhere to add new oil in, right?

WOWDee

as I am a little paranoid about the flush process. Lots of guys say it can cause problems. But then again lots swear by it ..... The only way I know to add fluid is thru the pan using a pump till it dribbles out at a certain temp as per the manual. That method doesn't change the fluid in the TC though. But I suppose they could actually pump fluid in thru the coolant lines while doing the flush ... it would be alot of bother it seems to me as you would probably have to put the front end in the service position to get easy access to the coolant lines where they fasten to the radiator (which requires removing the front bumper).

4Driver4

First, the torque converter and the transmission share the same fluid. The fluid can be drained through the plug in the bottom of the pan...or at least some of it can. A typical fluid change gets about 2/3 of the fluid.

The "coolant lines" are not really coolant. They transmission fluid that is cooled via a separate chamber in the radiator. Coolant and trans fluid should not mixed.

The correct procedure is to drain the trans, remove and clear the pan, replace the trans filter (more important than changing the fluid IMHO), and reinstall the pan with a new gasket. One that is done, the trans can be refulled via the procedure in the Bentley manual.

A trans flush is the worst thing you can do. You are better off doing nothing at all. A flush forces fluid at high pressure through the tranmission, removing particles that are trapped in the filter. Never ever flush.

tecra

The procedure they use is not the high pressure method I think.

The detailed steps are, IIRC, drain oil, remove pan, replace filter, put back the pan, refill the pan with new oil, then disconnect trans cooling line, start engine and let it idle, collect a quart of the old oil coming out of the line, stop engine, add a quart of new oil via dipstick tube, repeat last two steps until all old oil is out.

If they use the idle engine to pump out the old fluid, they are not putting too much pressure on the trans, right? They don't even put in gear, I remember.

4Driver4

Why is this necessary? Just change the oil and the filter and be done with it. Is there a contaminent or some other issue?

4Driver4

Please post in the correct location in the thread. This is confusing.

4Driver4

BTW, it is also critical that you use the correct fluid. Generic ATF does not cut it.

Jefflafleur

That is how we used to change the Volvo's transmission. Super simple and super fast. I wish there was a way to do this on the Audi. If you find a way let me know.

WOWDee

Here is a link to a fairly lively discussion on flushing ,,,,,,

http://www.toyotanation.com/forum/sh...ad.php?t=58209

You have to read down thru a lengthy discussion to get to the different methods of flushing FOR WHAT IT's WORTH.

I Myself DO NOT TRUST FLUSHING for many reasons not to mention what 4D4 has explained above. ANYTHING that complex and convoluted just to get a few remaining quarts of tranny fluid is unneeded unless of course you have some kind of contamination issue or known mechanical problem in the transmission ..... at that point you may as well pull the transmission and send it in for a $2000 rebuild or fork over the $6000 to Audi.

It's complicated enough just changing and adding fluid to these transmissions .....JUST LIKE BIG GOV ...... why make it any nmore complex???