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Noticed a slight weep from the upper transmission fluid pipe going to the top of the radiator, gave it a poke and its badly corroded , then whilst undoing it by its 10mm bolt , that snaps its head off, oh joy , got it disconnected at the bottom , so my question is , how vital do you reckon is the trans fluid cooler going through the side of the rad end caps is ? or , could i bypass it and connect to the bottom outlet hose with a custom made piece ,
busted part no is4b3317 819c , otherwise im not sure how succesful pulling the rad and trying to drill out the old thread , in a plastic housing?
any one with ideas or experience ,,
cheers

Better info may arise but my perspective is that it isn't wise for a street car. It's your transmission cooler, but also gets the gearbox oil up to required heat as quickly as possible. With the fragility of this gearbox, cold oil, or even overheated oil isn't where I would want to go. My RS4 (manual gearbox) also has the transmission oil cooler in the radiator. While I would like to get rid of that, the gearbox doesn't function that well until it is well and truly up to temperature, so it stays.

Maybe I need to look more closely, but I didn’t think the gearbox oil went through the radiator?

The oil cooler does both engine and transmission oil - but I also believe it’s a myth that the engine oil is used to heat the transmission oil. The flow paths through the cooler don’t allow the oils anywhere near each other aside from the end caps.

IMVHO, when my cooler gives up the ghost I’ll be switching to a pair of standard coolers. When you do a gearbox oil change, at idle, in park, with no engine oil temp, it’s a race to keep the transmission oil temp cold enough for the refill procedure. I truly don’t think getting the trans oil warm enough is an issue, it warms up fine, I totally do think keeping it cool enough is v. important.

Yep, got the twin cooler up front. I haven't had my radiator out yet (blessed by the fairies) but from what I can see it looks like this with the auto trans oil lines routed through the end tank of the radiator as well. No idea if this is common with all RS6 variants but it was a point of difference between the B5 RS4 and all other B5 manual gearbox models that I am aware of. Certainly the radiator is different and twice the cost in that model. All the pictures of the RS6 radiator that I can recall seeing have a tank on one end and a threaded boss top and bottom. Any idea what they would be for if not oil?

This is mine, only ran briefly (250miles) before I discovered the head gasket is less than perfect. The little cooler up on the right is transmission, the big one at the bottom is the new 2 pass engine oil cooler (setrab),and the pas loop is a pov spec A6 massaged at the ends to fit. Gearbox oil temp comes up fairly quick.

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Had mine redone completely as well - similar to puggie's one but I got two coolers side by side

Are you not worried about the reduced flow of air going through the water coolant rad?

ChrisA wrote:Are you not worried about the reduced flow of air going through the water coolant rad?

Not really, that trans cooler is a Goodridge (PWR I think) generic motorbike radiator. Its maybe 3/4" thick and not very restrictive to air. That heat would be going straight into the rad anyway, so I've taken thermal load off the water coolant system, it shouldn't have to work as hard.

My main drive for this was that when I dropped the engine i had the torque converter refurbed on MCRs reccomentadion (was told over 100k they are passed their best if you plan to remap). The company that refurbed it warned me I had coolant residue in the torque converter, so I had a leak from coolant to gearbox oil. That is not good for the torque convertor or the chocolate gearbox! So I moved to all separate coolers.

I also relocated the oil filter as its stupid to get to. I now have a big BMW V8 filter where the SAI pump was.

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ChrisA wrote: ↑

Wed Aug 26, 2020 7:51 am

Are you not worried about the reduced flow of air going through the water coolant rad?

I have an RS6 PLUS engine in mine as well - it comes with the additional radiators that were standard for RS6 in HOT Countries.

Puggie wrote: ↑

Wed Aug 26, 2020 8:20 am

...........................................
I also relocated the oil filter as its stupid to get to. I now have a big BMW V8 filter where the SAI pump was.

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This is something I'm looking at. Did you make up a custom setup or use an existing relocation kit.

IchBautAuto wrote:

Puggie wrote: ↑

Wed Aug 26, 2020 8:20 am

...........................................
I also relocated the oil filter as its stupid to get to. I now have a big BMW V8 filter where the SAI pump was.

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This is something I'm looking at. Did you make up a custom setup or use an existing relocation kit.

Custom setup. A Mocal 90 degree take off plate where the filter was. AN-10 lines through the wing into the engine bay, the filter was from an X5, but it looked like the one on my e34 540i so I think all bmw v8 filter housings are the same. Then I made up a simple bracket where the SAI pump was.

I'll do some piccies when I drop the engine.

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Thanks, will look forward to it.