Automatic Transmission Heat Exchanger Cleaning/Regulator Replacement (540iT)

[cgwebb]

I have a bit of a problem here as my Heat Exchanger needs to be replaced. The car has 130k miles on the clock and it seems as though the insides of the exchanger have corroded. Now the problem I have is in the removal of lines 5 and 6 in Diagram A. Over time the heat cycles have corroded the plastic clips on those lines.

The normal removal procedure is that on pulls the lines towards the exchanger and then one pushes the plastic clips in. This allows one to slide the hoses off the exchanger. The plastic clips have broken due to the corrosion and so now I have no idea how I am supposed to get those hoses off. Can anybody please assist me with this?

The clips are useless , there is a tool that slips down where the plastic clips go , its cool

google quick disconnect tool,they are like 10 euros

[bE34ST]

So glad I found this thread! My 03 M-Sport is doing the same thing. But it mainly only happens if I've been driving with the transmission is in sport "S". Which I would assume makes the transmission work a little harder, producing more heat. I'm going to try this as soon as I get a chance to. (*Fingers crossed!)

[AK_5eries]

lol never seen Randy so happy in a post before.

Anyway, this DIY does NOT apply to pre vanos 540i (97-98). Per realoem:



The early cars only have what seems to be an unregulated plain jane tranny fluid radiator type contraption.

Which begs the question: What if your pre vanos 540i is exhibiting these symptoms? Does anyone know what the normal operating temp of the transmission is? What are acceptable parameters for operation temp?

[jicaino]

The "normal" operating temperature is between 90°C and 120°C and should never climb up 130°C as per ZF instructions, but I wouldn't run it at that temp for long
Actually the earlier radiator is a better cooler than the later one. It's estimated for a lighter car or a lower power output engine or whatever. If you mash on your 540iA it will overheat the tranny (vanos cars are the worst)
I'm in the process of adding an auxiliary cooler like most of the X5 guys does, but I want to troubleshoot the original system first. Basically my sistem would consist on the stock coolant/ATF exchanger and the pre-vanos air/ATF radiator tapper into the return line after the coolant/ATF exchanger.
Will report as soon as I have conclusive results, that's if I don't swap in a manual or sell the car as is to a regular driver and move on to a manual

[jicaino]

Guys
Be aware that this clogged exchanger looked fine and had no visible crud inside.
If you are replacing the regulator might as well address everything and be cool (pun intended)
The rear half flows while the front half of the exchanger doesn't. It needs some pressure to marginally flow the coolant out.

[AquilaBMW]

J - How many miles on that exchanger?

[jicaino]

J - How many miles on that exchanger?

almost 150k miles. Actual 215000km. My bad for not having replaced it when I replaced the brittle and stupid regulator that I need to replace again now (break it during reinstall) In my defense I didn't have the "special tools" for the quick release hoses and I thought it would be a pain in the butt. It was the easiest part of any hose replacement I've ever done on the car, even easier than the quick coupling from the cooling system.

BTW, the exchanger I got was less than 100 bucks on eBay. ELFOTECHNO brand. IIRC 90 bucks. I've seen them go for over 200... more reasons to just replace the whole thing and be done with it.

[georgerobertlee]

Folks, I'm losing my mind on this one,

I replaced a damaged heat exchanger due to bottoming out without a skid plate. All that went well - but now I can't figure out for the life of me why there is a FLOWING leak between the voltage regulator and that metal water return pipe?

I mean FLOWING! I've pulled apart 5 times; where there is an O-ring in the groove towards the end of the metal pipe. I didn't even work on this area and don't have any left over parts. Doubting myself at this point, so is it possible that another O-ring goes on the very end of the metal water return pipe? What am I missing?

Please help!

This is for '01 E38

[jicaino]

Folks, I'm losing my mind on this one,

I replaced a damaged heat exchanger due to bottoming out without a skid plate. All that went well - but now I can't figure out for the life of me why there is a FLOWING leak between the voltage regulator and that metal water return pipe?

I mean FLOWING! I've pulled apart 5 times; where there is an O-ring in the groove towards the end of the metal pipe. I didn't even work on this area and don't have any left over parts. Doubting myself at this point, so is it possible that another O-ring goes on the very end of the metal water return pipe? What am I missing?

Please help!

This is for '01 E38

Yes, there's another o-ring in the end of the metal tube that fits in the middle of the regulator. Also probbly the regulator is cracked, since the exchanger pushed it up and the metal line is affixed to the front of the engine block. You may need a new regulator.
I ended up replacing the exchanger with a setrab oil cooler, now my transmission runs cooler and happier, and I replaced all of the hoses with manual transmission car hoses and the plug for the back of the alternator, so my transmission cooling is no longer tied up to my refrigeration system.

[dannyzabolotny]

This thread has been a really big help, and I've almost completed replacing the transmission heat regulator. The only trouble is that I can't seem to get the regulator onto the heat exchanger, no matter how hard I press on it. The new o-rings seem to be getting in the way. I lubed up the o-rings with some assembly oil but they're still not letting the regulator fully attach. I don't want to force it too hard because the regulator is plastic and will break if I do so. Any tips for getting the new regulator on?

[jicaino]

This thread has been a really big help, and I've almost completed replacing the transmission heat regulator. The only trouble is that I can't seem to get the regulator onto the heat exchanger, no matter how hard I press on it. The new o-rings seem to be getting in the way. I lubed up the o-rings with some assembly oil but they're still not letting the regulator fully attach. I don't want to force it too hard because the regulator is plastic and will break if I do so. Any tips for getting the new regulator on?

If you're getting the old regulator back on the new exchanger, are you sure you got a nice replacement? Some oriental ones have a slight dimentional iffyness. In any case you could lube up them o-rings with silicon grease (water base) and use a heat gun on a rather low/med temp setting over the regulator until you get it somewhat softened. Or immerse it in boining water for a couple of minutes (boil the water, turn off the heat source, dunk the regulator in)

[dannyzabolotny]

Ah, thanks for the tip. I ended up breaking the one I ordered so geargrinder just sent me the complete transmission heat exchanger as one piece. Problem solved.

[Redshift]

I've also got a spare auto trans heat exchanger from my 85k mile '03 540iT. Since the 6-speed swap I no longer need it.

[lalwong]

Can anyone explain how the Oil cooling pipes 5 and 6 are connected in a heat exchanger? E38 735i the previous owner mechanic cutted both ends and dont have any idea how to connect them. Pictures will be great. Thanks

[gmak]

YES. How do you get the hoses 5 and 6 off of the exchanger - the ones that come from the transmission. Those little plastic rings are damaged and gone. I've googled the "quick disconnect and it shows some rings that ( I guess) are supposed to push down on the plastic ring (that is broken and gone). I have some of those and it just doesn't seem to be working. Is there a trick to using these 'quick disconnect tools'? Thanks

EDIT: Nevermind. It's all good. I had to twist the quick disconnect tool around a bit until I heard a click and then I could pull the hose off. I guess it was just missing a piece of plastic that needed to be pushed in. Thanks all for this great thread.

About to "flush" (without pressure) the ATF.

[lalwong]

Anyone knows how lines 5 and 6 are connected to the heat exchanger unit.

[Tutti57]

With a quick disconnect tool you can get them off.

[lalwong]

hello people, I am attaching everything back to the original connection. Where lines 5 and 6 are connected to the heat exchanger. I have all the pieces apart and dont know which lines one goes to which plug? In and out, closer or further

[lalwong]

Here is the picture of my A/T cooler. and notice the attach joint that the previous genious mechanic did. Dumb
AT cooler.jpg

[Displaypro]

Sir just had to say Thank You for thread. Big Help!

[BMWTAG]

2003 540i wagon. I have to change the heat exchanger along with the cracked regulator valve. Any comments regarding removal of the transmission oil coolant lines at the heat exchanger ? There is no info anywhere about those oil line fittings.

Regarding installing the regulator valve onto the heat exchanger, if the O-rings are too thick the plastic regulator will crack.

[jonare]

Recommended procedure (continued):

Use the T30 torx allen wrench or socket to remove the three screws securing the Regulator to the Heat Exchanger. Pull up or pry the regulator up and off the Heat Exchanger.

Hello MLue1 or anyone else,

Great write-up - indeed! Thank you in advance...

Hopefully, someone will be to answer this quick question - before I tear things apart. Will be replacing the transmission cooling lines as they now leak and will replace the heat exchanger and thermostat. The new (Nissens) heat exchanger has three holes where the thermostat and heat exchanger mate - but the holes are not threaded, at all. Your first diagram - part 3 is described as a "screw", not a bolt. Is it meant to be a self threading screw?

Thermostat_HeatExchanger.jpg

Thanks!