Transmission leaking... again (still?)

Justjeff1972

Justjeff1972

Member
 Nebraska
Good morning for the Midwestern US. The weather this week is unseasonably warm so I decided to pull the Z4 out of the garage from her winter nap and driver her to work. When I got the car out of the garage, there was a fresh transmission fluid stain. Prior to garaging her, I had the mechatronics gasket and the wiring harness seal replaced. The trans pan and filter had been done within the last year. The car was not leaking after bringing it back from the shop but now, a month later the leak has returned. I've already contacted the shop and I'm waiting to hear back from them. Other than the filter housing, pan gasket, harness seal and mechatronics cover seal, is there anyplace else the DCT leaks from. The car is a 2012 sDrive 35IS.

Subsequently, on the way to work this morning, the check engine light came on for fault code 29F4: Catalytic-converter conversion. One of the possible causes is an exhaust leak on bank 1. What is the liklihood that this is related to the prior transmission repair? If I remember correctly, to drop the transmission, they had to remove the exhaust but I'd imagine that they would only drop the exhaust from the end of the down tubes back. Any help is appreciated.

In unrelated news, when I checked the engine codes, I also had a code for DWA [DWA_63] | 9D12: Internal battery discharged. Does anyone know where this battery is? Is it a replacable battery or do I have to replace the entire module?

Thanks everyone.
 
I’d imagine the batteries in the alarm are serviceable..

Ref leaks on DCT..

There are 5 places that the DCT leak…sump, pressure filter, top gland and the 3 other covers..

I had an issue which took 2 years and over £1,500 to fix..in the end it was as simple as the o ring in the pressure filter cap was leaking…but..it made it look like it was coming from the sump..3 different sumps and over 50 litres of very expensive DCT fluid…

I assume the cat issue is due to oil contamination..

Here’s some bedtime reading


F80 M3 DCT Service - Redish Motorsport - Specialists for BMW M-Power Vehicles

Redish Motorsport are BMW Specialist in Bristol who offer the Ultimate BMW experience when it comes to specialist procedures for your BMW M-Power Vehicle, at our fully equipped workshop in Bristol.
www.redish-motorsport.com
 
My prior leak was on the right side and was diagnosed as the mechatronics cover. I had them replace the mechatronics sleeve gasket while the transmission was out. I don't know if the o-rings on the cooler pipes were replaced. Service at my local European vehicle expert was ~$1800.

Picture shows the old (pre-repair) and new oil stains. The new stain is from sitting for about 12 hours but could be exacerbated due to the car having been on a slight slope after having sat in the flat garage for several weeks. Oil may have pooled on the transmission underbody panel and then flowed off while sitting on the incline (~4 degrees). Men's size 11.5 (US) shoe for scale.

ATF Leak.jpeg
 
Today's the day... dropping the car off this afternoon for them to look at the continuing leak. Here's to hoping it is a warranty issue.
 
B21 said:
Hope the warranty covers leaks!
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Warranty would be on the transmission leak repair. I just had the mechatronics cover leak repaired and had them replace the sleeve gasket (~$1800 total). Pan was done by the previous owner and is still in the warranty period for the repair. Nothing else should be leaking on the transmission since they just had it out to replace the other two seals. If they have to pull the transmission again to repair a leak and they tell me it is not covered under the warranty for the previous two repairs, I'm probably going to lose my mind. Definitely will be looking for another shop.
 
Leak is the trans pan. All bolts were still torqued to spec so the new seal failed for some reason. Shop is warranting the repair even though it was done by the PO. I can’t complain about the outcome. Hopefully this will solve my leaks for a while. I’m getting the Mickey Mouse flange and upper coolant hose replaced while they have it. The plastic was starting to discolor so figured better safe than sorry.
 
Make sure they check the pressure filter house cap / o ring…

I wasted 2 years and £2k trying to fix a sump leak that wasn’t ..3 oil sumps, 50 litres of oil , 3 garages …found it myself in the end..
 
B21 said:
Make sure they check the pressure filter house cap / o ring…

I wasted 2 years and £2k trying to fix a sump leak that wasn’t ..3 oil sumps, 50 litres of oil , 3 garages …found it myself in the end..
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They did the filter when they attempted the first repair for the previous owner. I'll keep bringing it back if it keeps leaking. At this point, they've touched every seal on the transmission in the last year. I do appreciate that they warrantied the repair even though I wasn't the one that paid for it. PO had the transmission serviced for a leak before they sold it. Superior Euroworks in La Vista, Nebraska.
 
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I pulled the car out of the garage on Wednesday because Thursday was going to be almost 60F. Garage floor was dry. No new oil. I took my dog for a little ride to to get everything warm and parked the car in the driveway overnight. In the morning when I left, there was a small spot of oil under the car. I didn't panic because I figured it may just be residual oil in the belly pan from the last leak... nothing to worry about.

When I got out to the car after work, there was a small puddle of transmission fluid and a drip hanging from the belly pan... :(. I reached out to the shop again to see what the next steps are. This has been exhausting. Hopefully we'll be able to find this leak and fix it. Anyone have any experience with transmission leaks that were hard to resolve? I'm open to any and all suggestions. I know it probably looked like a lot more oil than it was but it makes it hard to trust the car for any sort of trip out of town. I know the thing holds like 10 quarts or fluid but there is no level indication and I don't want the first indication I get to be a transmission failure.
 
Well it’s obviously leaking from one of the filter housings or one of the gaskets on the various access plates..here’s a dissertation on the subject

E9x M3 DCT Gearbox/Clutch - Redish Motorsport - Specialists for BMW M-Power Vehicles

Redish Motorsport are BMW Specialist in Bristol who offer the Ultimate BMW experience when it comes to specialist procedures for your BMW M-Power Vehicle, at our fully equipped workshop in Bristol.
www.redish-motorsport.com
 
It's the filter housing. Not sure why they wouldn't have replaced that as part of the transmission service or when they had the transmission out for the mechatronics seal. They want $1000 to replace the filter, cover, and snap ring. Does anyone have experience with this?
 
Justjeff1972 said:
It's the filter housing. Not sure why they wouldn't have replaced that as part of the transmission service or when they had the transmission out for the mechatronics seal. They want $1000 to replace the filter, cover, and snap ring. Does anyone have experience with this?
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I did say right at the start that this was my problem!

Price seems v steep…the filter kit is about £50 ish…I guess it will need fresh oil £150..then purge say 2 hours labour total
 
TIS says the transmission and engine have to be lowered... I'm guessing that is most of the labor. Shop is covering half of the labor since their office manager agreed that they should have asked me if I wanted it replaced when the transmission was out. Said they didn't recommend it because it was not leaking at the time. Live and learn I guess. In your experience, did you have to lower the transmission to access the filter in the Z4? I'm assuming that the tunnel is too narrow to allow clearance, unlike the M3. I watched a few videos covering the replacement and none of them had to lower the trans but they also were not on Z4s.
 
If it’s the pressure filter which is the one with the circlip there’s no need to drop the gearbox ..it’s easily accessible…by bmw standards..
 
As said absolutely no need to drop the engine/gearbox. It is readily accessible from underneath once the splash shield is removed.
 
Messaged the shop and they said they were able to do it without lowering the transmission/engine. Adjusted shop hours based on the repair taking less time than book. Total price was ~$360. So far, no more leaks.
 
Justjeff1972 said:
Messaged the shop and they said they were able to do it without lowering the transmission/engine. Adjusted shop hours based on the repair taking less time than book. Total price was ~$360. So far, no more leaks.
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No need to thank us…🤣
 
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