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E39 (1997 - 2003)
The BMW 5-Series (E39 chassis) was introduced in the United States as a 1997 model year car and lasted until the 2004 when the E60 chassis was released. The United States saw several variations including the 525i, 528i, 530i and 540i. -- View the E39 Wiki

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Old 01-21-2015, 05:12 PM
danniseize39 danniseize39 is offline
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Location: Burnaby
Join Date: Jan 2015
Posts: 2
Mein Auto: 1998 528i
E39 1998 How to access Auto trans Oil cooler

Hey guys, i am a new member.

I own a 1998 528i (e39)

I have sprung a leak i have been told is from the Auto trans oil cooler, i ordered the part and now have it. My question is how do i access this thing? I have been told two things, one mechanic told me i have to remove a lot of the stuff from the front bumper backwards and some one else told me i could just simply remove the radiator and i should be able to replace from engine bay? anybody know or has done this that could provide any tips before i journey onto doing this job?
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Old 01-21-2015, 05:40 PM
edjack edjack is offline
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Location: San Jose, CA
Join Date: May 2007
Posts: 10,131
Mein Auto: '97 540i 6 speed
It will be prudent for you to carefully examine the source of the leak to verify that the cooler has failed. Most common leak is due to hoses.

There have been no reports of failure for the trans cooler since I've been on this forum. Bentley's and the TIS do not specifically describe the removal, but I suspect the first mechanic is correct.

Ed in San Jose '97 540i 6 speed aspensilber over aubergine leather. Build date 3/97. Golden Gate Chapter BMW CCA Nr 62319.
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Old 01-22-2015, 02:32 AM
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dtadrian dtadrian is offline
BMW's are like women. $$$
Location: miami
Join Date: Jul 2012
Posts: 471
Mein Auto: 1994 540i
also something you may want to look into is the power steering hoses from the reservoir. the power steering fluid uses ATF, sometimes mechanics mistake the red stuff that leaks to be from the transmission but in reality its from the power steering. Also the power steering has a cooler in the same location as the transmission cooler. there are o-rings on the those cooler lines that leak. Check that before you replace the wrong parts.

Oh and I also suggest you carefully read about bleeding cooling systems in the bmw. once you remove radiator to replace cooler as you wish to do, you better make sure you correctly fill and bleed cooling system before you overheat that car and kiss it good bye. these engines are great but cannot stand to be overheated

Last edited by dtadrian; 01-22-2015 at 02:36 AM.
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Old 01-22-2015, 10:02 AM
danniseize39 danniseize39 is offline
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Location: Burnaby
Join Date: Jan 2015
Posts: 2
Mein Auto: 1998 528i
Well the reason we are convinced it is coming from the Auto trans cooling system is a few things, when first noticing this issue (the leak) we filled up the auto trans with oil, seemed low. Car continued to leak and once again auto trans oil became empty after a few days of leaking. we removed the shield under the car and it became apparent that the ATF fluid was coming from the radiator area. Power steering fluid still stays topped up but auto trans keeps flushing out empty.

Anyway anyone know how to access this area? the one mechanic insist that you can yank it from the front of the car but yet other insist on the easy way is from engine bay and removing the radiator, i even found some pics of this online.
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Old 01-22-2015, 11:34 AM
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bluebee bluebee is offline
Seek to understand,^Value
Location: San Jose, California
Join Date: Mar 2008
Posts: 22,679
Mein Auto: 02 BMW 525i M54 auto 130K
Following the advice in the first thread of this forum...
- How To Easily Find Information on Your E39 Topic Before Posting a New Thread

I first looked in the bestlinks for /transmission oil cooler, and didn't find hits (although the R&R may be buried in a transmission thread, of which there are many).

I then ran the obligatory e39-only title-only search for 'transmission oil cooler', which came up with the following, which may have information for the OP.

Given the paucity of responses in the threads above, I'm going to unilaterally declare this new thread to be the "canonical" thread on how to remove and replace the transmission oil cooler in the bestlinks:
- How to remove and replace the I6 transmission oil cooler (1)

So, we should put as much information as we can, in this thread, so that others stand on the shoulders of the OP.

To the OP: Please post pictures of the steps that you perform and what you find out, so that others have an easier time replacing the transmission oil cooler than you are having right now.


Of course, there is always google, for example, there's a DIY in the first link below (also attached as a PDF) which you will likely wish to improve upon, so that the next person has a bolt-by-bolt step by step DIY for the transmission oil cooler R&R...
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File Type: pdf e39 Automatic Transmission Flush DIY.pdf (1.86 MB, 12 views)
Please read the suggested threads, where the best always add value to those threads, either by pictures or by descriptions, so the next person with the same problem stands on your shoulders.
See also: E39 Bestlinks & How to easily find what you need

Last edited by bluebee; 01-22-2015 at 11:53 AM.
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