[cqtiger]

A few weeks back I took my 2007 335 e92 to a local shop to have some work done. When I picked it up the mechanic and the owner were chatting to me and told me maybe to get my transmission heat exchanger replaced shortly.

They said that inside is a cardboard piece that could fail and damage the transmission. Apparently they replaced one on another BMW after it failed and it cost the owner $8k in repairs.

Apparently you can't replace the cardboard bit as its a sealed unit.

Anyone on here had this problem?

[Socket]

Originally Posted by cqtiger

A few weeks back I took my 2007 335 e92 to a local shop to have some work done. When I picked it up the mechanic and the owner were chatting to me and told me maybe to get my transmission heat exchanger replaced shortly.

They said that inside is a cardboard piece that could fail and damage the transmission. Apparently they replaced one on another BMW after it failed and it cost the owner $8k in repairs.

Apparently you can't replace the cardboard bit as its a sealed unit.

Anyone on here had this problem?

I would be looking for another shop

Anyone who is charging $8K for a transmission repair is a rip off
Cardboard in the heat exchanger? I don't think so

Maybe a seal, but even if this failed, I can't see how it would get through the transmission oil line and cause catastrophic failure of the transmission

There is a thread listing recommended workshops here on the Aussie Forum, check it out and if concerned take it to someone who knows the N54

[Finngo]

Originally Posted by Socket

I would be looking for another shop

Anyone who is charging $8K for a transmission repair is a rip off
Cardboard in the heat exchanger? I don't think so

Maybe a seal, but even if this failed, I can't see how it would get through the transmission oil line and cause catastrophic failure of the transmission

There is a thread listing recommended workshops here on the Aussie Forum, check it out and if concerned take it to someone who knows the N54

+1

[juld0zer]

There is no cardboard inside the transmission oil cooler/heat exchanger. The only way this part can ruin the transmission is if there was an internal leak and the two fluids mixed

[cqtiger]

Originally Posted by juld0zer

There is no cardboard inside the transmission oil cooler/heat exchanger. The only way this part can ruin the transmission is if there was an internal leak and the two fluids mixed

Has anyone had a leak where the two fluids mix?

More so, how often would the heat exchanger fail and what would be the early symptoms?

[Coupes33]

I know the heat exchanger on the Ford Falcon turbo sixes transmissions were always an issue with internal leaks and it was always recommended that if you were modifying the engine, to replace it with an after market item. However, with the BMW transmission heat exchanger, I have never heard of any issues. When I had my transmission upgraded by Nizpro, I asked Simon whether the heat exchanger needed replacing with an upgraded item and he said no, it didn't. With his experience with modifying both turbo Falcons and the company 335i at one stage, he should know what he is talking about.

[cqtiger]

Originally Posted by Coupes33

I know the heat exchanger on the Ford Falcon turbo sixes transmissions were always an issue with internal leaks and it was always recommended that if you were modifying the engine, to replace it with an after market item. However, with the BMW transmission heat exchanger, I have never heard of any issues. When I had my transmission upgraded by Nizpro, I asked Simon whether the heat exchanger needed replacing with an upgraded item and he said no, it didn't. With his experience with modifying both turbo Falcons and the company 335i at one stage, he should know what he is talking about.

Thanks Coupes

[juld0zer]

First thing you would notice is transmission slipping and other issues, milkshake in the coolant expansion tank. I've never had to replace one either.

[ptpending]

this heat exchanger help to heat up car after star and then to cool AT when it's hot
so you need to monitor AT oil temp and compare it
keep in mind that e46 and e9x do not have it's own AT oil radiator but use that heat exchanger for cooling
the problem is that nobody can sell thermostat which is installed on that heat exchanger as separate part and you have to buy whole assembly