GM transmission adventures - sharing the experience

[gojozoom 6]

Hi guys,

 

I thought I'd share my little journey with my faulty GM auto transmission (in my 2007 BMW 130i LCI) so that anyone having similar issues might take away something from it.

The symptoms: a "phasing" vibration at lower RPM (below 2000) under load (uphill). It's to do with the torque converter delamination.

There are 3 stages to fixing it:

1) Glycol test to make sure the sealants and gaskets are fine and there is no water or antifreeze in your oil - this only costs only $100, so it's totally worth it. If you skip this and just go for a full service/rebuild your trans issues can come back in a year, as the electronic and mechanic components will keep getting corroded by water. I'm getting this done today - I hope it comes back  "negative".

2) Full transmission service (oil change, filter, and optionally anti-shudder additive). These GMs need this done every 80K kms or so, but most people don't even think about trans service when it comes to general maintenance. Mine has 127K in it and I'm sure it's never been done. In most cases this will sort out the vibration and the additive will create a nice protective layer on the components. This costs around $500.

3) Torque converter rebuild - well, obviously this is the most expensive, starting around $1500 but can easily end up in the upper 2K range. Luckily I still have warranty from the dealer and I also have 2 years mechanical warranty from Autosure, but still, fingers crossed that it won't come to that.

I'll see how the glycol test goes today and I'll update this post as I go.

As a side-note , as much as I love European cars, I've always had issues with auto transmissions (except my MK5  GTI I had was manual). I had an Audi A3 - mechatronic failed, then a Golf 1.4  TSI with the infamous DQ200 DSG - mechatronic and clutch pack failure, and now this. I'm pretty sure Autosure hates me now - they paid out about 7K in the last 3 years

 

Cheers

Dan

Edited September 3, 2020 by gojozoom

[Driftit 1940]

Hah.  Just done all that.
Service and additive solved it 100% for me.  Only took a few hours.
Mine was low on oil and had been done before.  I feel this made the issue worse.  Likely someone didn't fill it correctly.

 

[///M 22]

1 hour ago, Driftit said:

Hah.  Just done all that.
Service and additive solved it 100% for me.  Only took a few hours.
Mine was low on oil and had been done before.  I feel this made the issue worse.  Likely someone didn't fill it correctly.

 

Is it worth adding the anti-shudder fix when doing the fluids and filters? I don't have the shudder but need to change the transmission fluoid ASAP (over 130,000km)

[gojozoom 6]

That's good news, thanks for confirming that. Fingers crossed.

[Driftit 1940]

13 minutes ago, ///M said:

Is it worth adding the anti-shudder fix when doing the fluids and filters? I don't have the shudder but need to change the transmission fluoid ASAP (over 130,000km)

It's only $15 from Repco. It's the most common solution for the box in other brands that have the same box.

[gojozoom 6]

Well, they found glycol in the oil so this is gonna be a swap or a rebuild. That explains why this otherwise mint car was traded in... The dealer is setting things up, I'll update this thread as I go... 

[M3AN 4015]

That sucks, great you have warranty coverage.

How does glycol, presumably from your coolant, actually get into the transmission? 

Edited September 11, 2020 by M3AN

[aja540i 1896]

Leaky cooler?

[M3AN 4015]

3 hours ago, aja540i said:

Leaky cooler?

Do modern cars use the engine coolant to also cool the trans?

This may be my ignorance of modern vehicles but the only platform I know well enough is the e36 and there was no relationship between the engine coolant and the transmission back then. The auto cooler was a separate radiator up front that you pumped your transmission fluid through.

[KwS 2373]

They generally have a tube that runs inside the radiator tank to heat/cool the trans fluid. This is common for failing and mixing fluids.

In the case of the 130i it appears they have a heat exchanger mounted to the radiator and acts as its own little radiator with coolant and trans fluid flowing through it. I guess the internals of this heat exchanger must have failed.

[aja540i 1896]

8 hours ago, M3AN said:

Do modern cars use the engine coolant to also cool the trans?

This may be my ignorance of modern vehicles but the only platform I know well enough is the e36 and there was no relationship between the engine coolant and the transmission back then. The auto cooler was a separate radiator up front that you pumped your transmission fluid through.

I like how you consider 2007 to be a "modern car" !

[Driftit 1940]

Heat exchanger failing? First I have ever heard of that on a BMW. 

[B.M.W Ltd 950]

1 hour ago, Driftit said:

Heat exchanger failing? First I have ever heard of that on a BMW. 

Had this happen a few times

[Driftit 1940]

12 minutes ago, B.M.W Ltd said:

Had this happen a few times

Can't be that coomon though right Glenn. I would expect you to have seen it though. 

[gojozoom 6]

Still waiting for an update from the dealer but your comments make me think if a full service + heat exchanger replacement would sort this out?

[B.M.W Ltd 950]

Water/Glycol in a transmission usually always ends up terminal

https://www.mistertransmission.com/water-in-the-transmission/

Edited September 14, 2020 by B.M.W Ltd

[gojozoom 6]

Quick update on this; after months of waiting and liaising with the dealer the trans has been replaced and the torque-converter rebuilt... Thank god for the warranty - ended up around $4600... The culprit (as discussed before) that silly oil cooler that fails and lets water into the trans which corrodes everything... Kinda silly design if you ask me as the trans itself is pretty much bulletproof. 

[Kiwi_BMW 89]

Glad you got it sorted, but September to March seems a fairly long time to have this done, what was the hold-up?

 

BTW for those using shudder fix, it is a zinc additive, which eventually fails to work as the actual problem eventually gets that bad shudder fix becomes ineffective. Usually by that stage the only fix is to rebuild the transmission.

[gojozoom 6]

The holidays slowed things down + delay with coming to an agreement with the dealer + the transmission guy having a long line of cars to fix before mine = 5 months