SMG Overheating? Sup with it?

[Frank Ricard]

Hai gize, long time no talk.

I was playing with the idea of picking up the fourth best M3, aka an E46... and of course I want it in the best transmission, an SMG.

Since M3F decided it was too cool to pay its bills or whatever, I can no longer search its plethora of info. Can one of you bro's hook me up with the deal with SMG's and overheating and all that? I live in Phx, so I'm wondering what I'm potentially getting myself into out here.

I wont be tracking this vehicle.

[oceansize]

Motor, accumulator, internal pump seals, or a combination of all three have gone bad.

[Frank Ricard]

Motor, accumulator, internal pump seals, or a combination of all three have gone bad.

Is it mostly related to heat, or just time and usage make it inevitable?

[Rkymtnrider]

I think the heat part deals more with old fluid becoming thinner with heat then pump works harder and burns out. Thinner oil gets through seals and the cycle continues. Just my opinion.

[oceansize]

Is it mostly related to heat, or just time and usage make it inevitable?

Both heat and time. I, and many others, relocated the pump unit to the passenger side engine compartment next to the firewall (drug bin). I had no issues with my pump, motor, or seals at 100k miles but chose to do a pump refresh (seals and o-rings), motor replacement, and relocation as preventative maintenance. I also run a higher viscosity fluid, which is not recommended if the pump has been re-located due to longer hydraulic lines but I've had no issues. Others have (cog light comes on).

[maw1124]

oceansize which fluid? I would expect higher viscosity fluid to eliminate the need for relocation, although admittedly that's an empirical matter. My theory is that fluids, like computer power and tire rubber, have advanced so far since these cars were engineered that's the best place to improve weak spots -- oil, transmission fluid, hydraulic fluid, computer code -- all fair game and smart moves.

maw

[r4dr]

I think the heat part deals more with old fluid becoming thinner with heat then pump works harder and burns out. Thinner oil gets through seals and the cycle continues. Just my opinion.

Should I be changing my SMG fluid? Lol.

[maw1124]

Should I be changing my SMG fluid? Lol.

Yes. Seriously. Every 5yr/50k miles as far as I'm concerned.

This is no different than the notorious Mercedes ABC system, where US dealers specified NSI (No Service Interval) from the factory. Of course they all had problems. German dealers changed the fluid and filter every 3/30k, and of course they didn't have problems.

15-20 years later EVERYONE with a brain knows the fluid doesn't last forever. Google "evaporative loss"... the fluid turns to tar over time and people wonder why the pumps, lines and motors struggle.

Same for transmission fluid, which was also thought to be NSI "sealed for life" back then. No one believes that shit anymore either.

maw

[oceansize]

oceansize which fluid? I would expect higher viscosity fluid to eliminate the need for relocation, although admittedly that's an empirical matter. My theory is that fluids, like computer power and tire rubber, have advanced so far since these cars were engineered that's the best place to improve weak spots -- oil, transmission fluid, hydraulic fluid, computer code -- all fair game and smart moves.

maw

Burkhart sold here. The relocation was as much for ease of maintenance as it was for lower temps. Access is so simple now.

[maw1124]

Thanks. LiquiMoly has one that looks interesting too. Full synthetic just like CHF11s.

maw

[JokerElite]

The Burkhart Engineering repair kit fixed this issue for me. I also replaced the SMG accumulator. I found no need for the relocation, as mine has been working fine for a few years now.

https://burkhart-engineering.com/en/shop/bmw/bmw-m/bmw-m3/smg-2-hydraulic-unit-repair-kit/

[eacmen]

I have a can of CH11S and just extract the old fluid from the reservoir and fill it with new every year. Not as good as a full flush, but seems to be holding up.

[maw1124]

I have a can of CH11S and just extract the old fluid from the reservoir and fill it with new every year. Not as good as a full flush, but seems to be holding up.

You're probably running all new fluid by now. I don't recall how much fluid was used but it wasn't much (at least not compared to the amount used in the ABC system for MB). I want to say 3 or 4 liters here, IIRC which I'm sure I don't.

maw

[Arith2]

CHF 11S has a shelf life of 5 years. The bottles sometimes come with an expiration date sometimes. Dealer bottles may not however, I've noticed sellers don't care about that expiration date so caveat emptor. It's a really good idea to flush the reservoir every so often. Doing this with power steering fluid is also a great idea since it's just ATF for most of us.