Coolant leak into Transmission

[bgsquad]

Dears!

It's been a while indeed... not having much time with the kid now

My E53 01 recently popped up a low coolant message. I topped it up and went on, but the very next day, it gave the same message again. puzzled, i opened the coolant reservoir, to see a sludge of cream floating around. I took it to the shop immediately.

The total driven distance since the first warning message is roughly 20 miles.

I had the transmission cooling part replaced, the coolant system flushed many times, the transmission oil and oil filter flushed. The car is driving as usual, nothing weird in it... after another 2 weeks, i flushed the transmission fluid a second time, and the car is still driving as usual...

My question is: am i taking a high risk of having the transmission fail soon? should I sell the car to avoid expensive repairs? after how long can i safety say that "she made it"? what do you say?

Thanks guys

[LVP]

You've done everything I would have done in that situation. As long as you've done a complete transmission/transfer case flush and a new filter, I'd say you're clear. Twice was a good call too. I assume the coolant isn't changing color and is proper now too?

This is a good tip for others though. If losing coolant and it isn't on the ground or out the pipe, inspect the coolant for cross contamination/sludge.

[bgsquad]

Yes indeed, the coolant is clear. the second trans oil drain had still a little bit of white foam though.
Maybe during the next engine oil change, i will give it a third clean trans oil (if she makes it to the next engine oil change...)
I will be very attentive to any change in its behavior. if i notice any slight modification in the way she holds and changes the gears, she's sold.

[deepblonde]

Originally Posted by trader4

Inquiring minds want to know..... How does coolant get to the tranny?
I don't have the parts sitting here, don't know how exactly it's plumbed.
But fundamentally you have these heat transfers:

tranny ATF to air
engine coolant to air

I would think they would be separate heat exchangers.

The transmission uses a heat exchanger that uses coolant to maintain trans temps, there is a risk that the heat exchanger may corrode internally, allowing coolant and transmission fluid to mix, which may almost certainly eventually destroy the transmission.

[deepblonde]

It's a common way of maintaining transmission temps in modern cars, using coolant via a heat exchanger.

[g300d]

Yup, been that done there.

By luck came across a bit of mayo in the coolant tank that was getting worse.

Thought it was the head but as a last resort pulled the trans heat exchanger and pressure tested it.

There was a pinhole leak and replaced that first, flushed the cooling system, and leveled ATF.

Mine was different in that there was no mayo in the ATF though, only in the coolant.

Ive since done a pan drop filter and fluid change on the trans and coolant change part of a cooling system overhaul and no more mayo, so far so good. Been maybe 20k now since I replaced that heat exchanger.

I hope I'm not jinxing myself posting this lol.

[bgsquad]

Update: i noticed yesterday that the reverse lights were not going on when in reverse, and the gear indicator is not changing in the dashboard (prnd)... As i was wondering about this, i shortly got the failsafe warning.... Cold sweat...
The car kept driving normal (forward and reverse) but i noticed a kick when slowing down to a stop and rough 3-4 shift...
Today no warnings, the reverse lights and dash indicator r back to normal.... Behaving nice
Can it be a bad electrical connector after the last repair? Or elese what could it be?
Ps: it was raining heavily yesterday with big puddles
Ps2: no obd faults on the little bluetooth kit i have (even when warning was on)

[mam4.6]

If your getting both FAILSAFE and your indicator lights aren't changing the way they should, one thing to check is the wiring on the gear position indicator on the side of the tranny. Just recently discovered the wiring on mine is crumbling and corroding, and from what I researched, will throw fits like your X is having if it fails. If the wiring looks good, unplug the connector, clean and use some dialectric grease on the connections.