BMW E61 Turbo Replacement Project - Cleaning Intercooler, Radiator, Power Steering and Transmission Coolers

I made the decision to pull the engine and transmission out of the front of the car when doing the turbo replacement project. I was using quickjacks which give me about 24" of lift - and don't have a 2 or 4 post lift to be able to drop the engine and transmission out of the bottom of the car. One thing that really impressed me about this car was there are 7 heat exchangers / coolers around the front of the car: radiator, AC evaporator, power steering cooler, engine oil cooler, charge air intercooler, transmission fluid cooler and coolant / transmission fluid heat exchanger.

Charge air intercooler - lots of grit came out of the fins.
 It was pretty impressive the quantity of road grit that came out of virtually all the heat exhangers, particularly the intercooler, power steering cooler, and transmission fluid cooler. The AC evaporator, engine oil cooler and radiator protect themselves somewhat because they are stacked behind the transmission fluid cooler. The AC evaporator is quite exposed to grit and debris coming through the kidney grille at speed, blasting the paint and flattenning the fin material.

Halo of grit from flushing the intercooler. 
This car is winter driven daily - and exposed to road salt and grit all winter. The intercooler was about 30% blocked with grit, the power steering cooler about 50% blocked with grit, and the transmission cooler was the worst off - almost 100% blocked with grit.
Transmission cooler - almost completely blocked with road grit.
 Through trial and error - I found that the best method to clean all these aluminum parts was to initally flush with soap and water, and try to get as much grit removed using a high flow / low pressure water hose to avoid damaging the fin material. Once that was done, I used aluminum wheel cleaner - sprayed to soak into the fins as much as possible, and then flushed with water within the prescribed time (a few minutes of application only). This remove a good amount of grit. Then the third stage was to clean out grit using a dental pick set - I needed to do this with the worst heat exhangers only - and since these parts cost between $300 and $700 each - it was worth the time doing a few evenings of dental picking to rehabilitate these parts.
Front end during disassembly - note the sandblasting of the AC evaporator - leaving the kidney grille shape with two lines from a cross brace. 

The transmission cooler is the lowest cooler on the car - and the most packed with grit.

Transmission cooler - almost completely blocked with grit.
During the dental picking, I also straightened and lifted any folded fin material - it's time consuming, but for me it was worth it.

Radiator after cleaning with aluminum wheel cleaner. 

AC evaporator after cleaning with aluminum wheel cleaner. 

Intercooler during cleaning - all the metal and fins were in good condition without any pitting at the hose mating surfaces.
One final thing to note - I replaced all the o-rings / sealing rings at all the hose interfaces to help ensure I wouldn't have any leaks at startup. Now that the car is on the road, running, and AC system charged - I can state that it was worth the effort - no leaks at all from any of the systems - cooling, power steering, transmission cooling, engine oil cooling. All good.
Front end with all the coolers replaced. Shop dog hanging out the garage. Not easy keeping the dog clean....
I'll post some additional articles with lessons learned from this project, hopefully it can help others out when doing similar work.

Sources and Links

I hope you found this post useful. Feel free to ask questions in the comments section below. I answer all questions. If you're interested, you can help support this site by using the following links to in the United States. Turbo parts were supplied by Turner Motorsports. Other parts were supplied by Pelican, BMW Park Avenue in Brossard, and eEuroparts.


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