edan82

So it's been about 3 months since I rebuilt the transmission and gearbox kept slipping and transmission oil needed a replacement every aproxx 500 km as it was burned and full of metal scraps.

In search of the source we decided to cut open the torque converter and surprise surprise- we found the source.

The internal was completely burned, it received a purplish color as evidence to the extreme high temperature and it's plates were completely "shaved'.

I now purchase a 3000 stall converter but I want to understand what cause my oem TC to burn this way considering the car only had 55k KM and my car not heavy moded:
Eurocharged ECU tune+ H/E
Bosch 010 pump

I do drive the car hard from time to time inc high speed cruising from time to time (200-250 km/h range).
But than again, as far as I know the transmission can hold that torque, isn't it?

My garage suggested that maybe the aftermarket H/E causing a temperature increase of transmission oil as the Eurocharged H/E is thicker than stock and is about 2-3 cm closer to the radiator.
However, not much heat soak coming from the H/E (actually you can grab it while engine in working temp).

On the other hand another garage told me it can't be the oil temperature problem cause than the transmission itself was ruined, not only TC.
He suggested it's just a normal wear & tear.

Any suggestion?

SICAMG

Either a mechanical malfunction in the stator assembly in the t-converter, normally they will crack, or blocked cooler system for trans. Heat is the only reason you will have discoloration in any part of the trans. If the fluid keeps burning its because the temperatures are way to high. Make sure the cooler lines are not blocked/plugged and if need be put a external trans cooler on it.I have been rebuilding for 25 years and have seen this hundreds of times.

edan82

Thanks for the reply.

Do you think the fact that the heat exchanger is about 2-3cm closer to the radiator (which part of it is the transmission cooler) can cause a overheat of transmission oil?

Assuming oil lines and cooler aren't blocked, any other reasons for the TC overheating?
Maybe electronic problem that makes the transmission/TC "over working"?

I'm just trying to think anything that might cause the problem as I'm now ordering a new torque converter (not yet sure if OEM or STALL) but I want to find the real problem so I can fix it.

In some logs my garage had about 3 weeks ago the transmission temp was around 90c which I believe is ok but it was when outside temp was about 20c and not under extreme load.

Summer time here is about 30-33c.

What is the normal temp range for the transmission?

And again- thank you!

BmwBob335

Didn't some of the 55s have radiator problems where trans cooler would leak engine coolant into trans and take out the converter and sometimes trans? Something to look into.

Toadster

I believe '03 only

edan82

my car is 03' and has the well known Valeo radiator therefore I've checked already if any coolant leaking into the oil lines- there isn't.

2000UZJ

FWIW my 2004 has the Valeo radiator.

SICAMG

I personally like to see temps around 190 deg. on average. The trans can take more but fluid longevity is far greater at a lower temperature.This is a fact. My own tests on some of my own cars with a trans cooler over rated for the application will have transmission fluid for 80,000 miles or so and still look like the day I poured it in. Also its synthetic so dont forget that. Anyhow by all means if you possibly have a radiator that will cause a problem,especially with anti freeze mixing....put an external cooler on because you will NEVER catch it in time, and there is really no good time when they start to mix togather. Then its aalllllll done!!!

SICAMG

If you checked and it did ....99% of the time its done. The reason is and no one really knows why is this...the anti freeze removes the glue/bonding agent that adheres the clutch material to the clutch plates. The clutches will literally come disconnected from the steel part of the plates they are bonded to. For me a cooler on every car I own is step one in mods no matter what.

edan82

thanks for the tip!


assuming you have a similar car to mine, would you like to share info with me on your transmission cooler?
it will be great if you can post link to the parts your using.