E36 ECU Water Leak Questions

[BMWJPO]

I saw the following in another member post and I didn't want to step on there posts. So thats the reason for the new thread.

" Evidently some E36 cars have a water drain near the ECU"

I just bought my BMW and love it, I would hate for this to happen to my 325. Can you tell me were on a 92 E36 I can find the ECU and check that there is no water in the compartment. And if so how do you plug it?

Thx

[Dave at Pelican Parts]

"Use the Search, Luke!"

This has been discussed here before, do a search and you should find what people have talked about as a solution.

--DD

[BMWJPO]

I'm burnt didn't even think. Thanks for showing me the light...
LOL

[Ad Hoc]

I have a '93 325i. A few months ago I deep-fried my DME coming out of a car wash. On early to mid '90s 3 series, the DME sits in the firewall on the passenger side - behind the glovebox if you looked at it from within the car (DME, ECU and ECM are all the same thing - the engine control computer; engine control module; and in German - whatever "DME" stands for) . If you have a Bentley manual, look under Engine Control Module in the index for instructions on how to access the ECM.

The problem is that your typical car wash dumps on average 45-50 gallons of water on the car, and the ability of the car to effectively drain water away from the DME is compromised - computer chips and water don't mix. The DME is easily removable to check for moisture and/or corrosion.

The drain that's provided is in the cowl under the winshield - some suggest creating a larger drain tube - I just removed the tube altogether.

I recently added a performance chip to my DME and took what I believe are appropriate steps to prevent the DME from future water damage. I covered the DME in plastic bags, sprayed the connections with a spray used by jet skiers for their engine electronics, and sealed it into its compartment with waterproof silicone caulk (there is a black plastic cover that fits over the DME compartment that you can seal to the firewall with caulk).

Most importantly, avoid car washes at all costs - wash your car by hand with a bucket and a hose (car washes are hell on the finish anyway).

[n.10.z]

After I was warned about the drainage problem in an earlier thread, I removed the drain spout that is near ECU/ECM/DME. The spout was horribly clogged and I doubt that much water, if any, was passing through it. I was glad to get it out of there before it caused any problems.

[Ad Hoc]

My suggestion (this, coming from a person who was stuck with a dead BMW due to a fried DME) is to remove the DME from its compartment (a relatively simple task) and check it for corrosion. I purchased my car used and when the DME died, I inspected it and revealed years of built-up corrosion.

Clean any corrosion, go to a bike store that sells jet skis and purchase a can of anti-corrosive spray. Spray the electronics and DO NOT put your car through a car wash

[BMWJPO]

Thanks guys for your posts. AD Hoc Thanks for all the great info. I have one question. Is this on the inside of the car fire wall or on the fire wall outside in the engine compartment (IE under the hood)? What I mean is do I have to remove to glove box to get to it? And what do I look for that marks the ECU/DME or whatever they love to call it. Black box?? What type of markings? If I cover in a plastic bag should I be worried about fire due to melting plastic? Or does this not get to hot. Also the best thing to do is remove the plastic drain tube? How will it drain then? Thanks for all the info.

[Ad Hoc]

The access to the DME is on the firewall under the windshield on the passenger side. The following link makes it clear.

http://www.logun.org/dme.htm

The DME actually sits back from the firewall in its own little compartment - I'm not worried about the plastic I encased it in melting.

[blkongry]

If you do seal up your DME (which I am all for), make sure you do a helluva job at it, for once you have it all shrouded, if water ever does get in there, then it becomes a trap and you can potentially escalate the corrosion concerns.

[Ad Hoc]

I agree with blkongry. If it's not sealed truly watertight, if water does get in it may make matters worse since you've cut off any drying capabilities. In a related issue, I read in one instance where a person got his '93 325 DME wet coming out of a car wash - the car died - but after removing the DME and drying it with a blow drier, it was brought back to life.

Bottom line for me is even with all the precautions I have in place to protect my DME, the simplest and most important one remains: I never put my car through a car wash.