what does "flushing" fluids in the car mean?

Question

i have transmision problems with my mercedes so i was told i should "flush" the transmision fluid and the coolant, what does that mean? is it like changing the oil?

when going in higher speeds(40+) the car revs up but doesn't change gears could flushing help the problem? thanks

Answer 1

Flushing means the same thing worldwide no matter what the situation, whether it's your toilet, your colon, your radiator, your engine, or your transmission. Much like a toilet, when you flush a hydraulic system, you remove all the old fluid, use some method of removing almost all traces of the old fluid, and replace it with new fluid. Often times, the old fluid is contaminated with dirt, water, rust, or any number of undesireable contaminants, and over time, fluids like engine oil and transmission fluids break down, lose their viscosity, and actually undergo chemical changes due to heat and friction. They lose their ability to lubricate, and they also lose their ability to maintain pressure. They can also turn to sludge, which cannot be pumped through the system. If you don't get all the old fluid out, or at least as much as possible, the new fluid will be contaminated with some of whatever was there before, which is usually dirty, contaminated fluid. Sometimes, some kind of cleaning solvent is pumped through the system to clean out residual crap before new fluid is added. Changing the transmission fluid is more complicated than changing the engine oil, because it often requires removing the transmission oil pan, and in order to get all the fluid out, a special machine needs to be connected to the system in order to remove the transmission fluid from the torque convertor and any transmission coolers in the system. It is very possible that flushing the transmission will correct or improve your situation, but if you are going to get it drained and flushed, make sure they do it with machinery that will remove almost all the old fluid. Just draining what's in the pan isn't good enough.

Answer 2

It is like changing the oil. A flush clears out most of the old fluid (98% or so.) This may or may not help your shifting problem. As Trans fluid breaks down so does it's hydraulic properties. In isn't as strong as it used to be in other words. It will compress a little bit. That means is doesn't have enough power to shift your transmission.

However if you have a real transmission problem and you change the fluid, you could finish off the transmission. It was dying anyway and was about to do it will just die sooner with new fluid. The new fluid has detergents that "clean" the clutches inside the transmission. The clutches like that old dirty fluid for grip. New fluid cleans those clutches and their grip is gone. It's like wearing out sandpaper.

So clutches like old fluid and valve bodies like new fluid.

Rear wheel drive trannies are more durable and I've seen a fluid flush fix a bunch of them. I've also seen the car just sit there after a flush when the transmission had a real problem.

Answer 3

Out with the old and in with the new. In regards to the transmission, you can take the car into a shop and they will break into the transmission cooler lines and hook a machine to it that will pull out the old fluid, and then replace it with new fluid. You need to do it that way so that you can also get all of the old fluid out of the torque converter too.

You may have more problems than just the fluid if the transmission is slipping. good luck.

Answer 4

Usually this means draining the existing fluids, rinsing it out, changing the filters, and filling it up again with fresh fluid. Although in the case of the transmission, you dont want water in there, so you'd skip the rinse.

Answer 5

More or less, you are draining out the old fluids and replacing them with fresh fluids

Answer 6

Yes, like changing the oil!

Answer 7

Sounds like the transmission bands need to be adjusted or replaced.

Answer 8

It means you take all of the old out and put new in.