SMG II - MLR Engineering Accumulator

[bmrdvr]

Hello,

Has anyone tried the MLR engineering SMG II accumulator they sell? I'm hesitant to buy a non-serviceable OE unit if what they sell works well (and it's serviceable). I've had reasonable luck with what they sell albeit not perfect.

Appreciate any insight on this. I see that SMG Society sell a reman one as well but that may be more of a hassle than it's worth as they're based in the UK (or the EU, I don't recall).

[oceansize]

For the price he is charging I'd give it a shot (unless your not DIYing, labor might eat you up if you have problems).

I'm assuming you're referencing the upgraded accumulator.

[bmrdvr]

Yes, was referencing their upgraded one, correct. I'm at the point where I would agree with you and it's worth a shot. I was hoping some people had ran them or perhaps had some other options. It seems like a reasonably safe bet.

[sapote]

Anyone know if the stock ACC is compressed Nitrogen or spring loaded?

[Irhase46m3]

Anyone know if the stock ACC is compressed Nitrogen or spring loaded?

Its supposed to be Nitrogen

[sapote]

Its supposed to be Nitrogen

Then this is a challenging design to have the moving piston (which separates the gas and oil) in a cylinder that provides almost no gas leak performance for many years consider it moved many cycles per trip. The vintage Citroen DS and SM used a rubber diaphragm to separate the oil and gas in their ACC, and every 3 to 5 years we have to charge up the Nitrogen gas as it leaked through diaphragm.

Citroen ACC:

[Irhase46m3]

Then this is a challenging design to have the moving piston (which separates the gas and oil) in a cylinder that provides almost no gas leak performance for many years consider it moved many cycles per trip. The vintage Citroen DS and SM used a rubber diaphragm to separate the oil and gas in their ACC, and every 3 to 5 years we have to charge up the Nitrogen gas as it leaked through diaphragm.

Citroen ACC:

I think it does a pretty good job in terms of longevity of the ACC, it is a serviceable item. I think what contributes to the leaks is the breakdown of the CHF11s oil that ultimately causes the system to work double. Its very rare to see someone flushout the oil as maintenance. BMW should have slapped-on one of those "life time oil" stickers on the SMG cap.

[bmrdvr]

I appreciate the responses. Interesting note on the Citroen accumulator. I'll give one of these MLR units a try and make sure I'm flushing the system at regular intervals. I've had incredibly good luck with my SMG system and it's only been preventative maintenance in the form of a Burkhart motor and doing the seals on the pump and solenoids. I did put the MLR seal kit into a shift actuator and it leaked afterward which was my only gripe about MLR stuff. I ended up going back to spare unit I have. At some point I want to source the seals directly. They change a ton for them and near as i can tell, they're bog-standard hydraulic seals.

[oceansize]

I did put the MLR seal kit into a shift actuator and it leaked afterward which was my only gripe about MLR stuff. I ended up going back to spare unit I have. At some point I want to source the seals directly. They change a ton for them and near as i can tell, they're bog-standard hydraulic seals.

Good info, keep us up to date on how things go.

[bmrdvr]

I got the accumulator from them the other day. The thing is a heavy beast. I was told it will fit in the factory location with the factory bracket so I guess we'll see. Perhaps I'm mis-remembering the OE one (didn't remember it being as big). Plan to install it this week/weekend.

[bmrdvr]

Alright, I got the unit installed in the car and seems to work well. I will say: the first one I got was pretty beat up in shipping and missing a part but MLR promptly took care of it - sent a new one right away and a return label for the old one which was nice. I did the entire process via email which was convenient as I don't care to waste time on the phone.

Some things to note on this:

1. It is much larger than the OE unit. OD is about 5mm larger (60mm) and it's about 270mm long overall (~10.5"). I think the OE one is probably about 8" overall.
2. The OE rubber sleeve is not used - the unit comes with a new sleeve that is just a couple mm thick
3. The actual fit is perfect as far as I can tell and I'm picky. It uses the OE bracket and hardware, it's just longer. The additional length and diameter does not get in the way of any existing hoses or wiring so this is a non-issue.
4. The unit is torqued to the SMG pump body by the 27mm hex fitting on the pump side (the OE one is torqued on the opposite end) - just need to get it snug and it comes with a new o-ring installed.
5. The new unit has a large plastic hex cap on the end that covers up the nitrogen fill valve (which also has a cover) - it's important not not torque the unit on by this cap.

I did the SMG "ventilation" procedure using ISTA+ as I've always done. Per ISTA+, after replacing the accumulator, you need to run through the shift actuator bleed procedure as well as the slave cylinder bleed procedure. Combined this takes 20 minutes or so. After that I was good to go. I don't use a car charger or anything like that doing this procedure FWIW.

I only have 10 miles on the car with it but seems fine. I'll run the ISTA+ accumulator test on it and see how it reads. The accumulator I replaced was on the very low end of passing the test which is why I replaced it as a preventative thing. I wasn't getting any codes and the car was shifting fine. The only way we'll know how good these are is after a bunch of years and miles but I'm hopeful they last. MLR can rebuild them as well which is why I went this route. My guess is I could rebuild it too if I'm honest... These things are magical in operation but not construction.

[JokerElite]

Love that MLR, SMG Society, and Burkhart have these aftermarket options available. #SaveThe SMGs

[0-60motorsports]

Love that MLR, SMG Society, and Burkhart have these aftermarket options available. #SaveThe SMGs

100% 👍🏼

[nextelbuddy]

Alright, I got the unit installed in the car and seems to work well. I will say: the first one I got was pretty beat up in shipping and missing a part but MLR promptly took care of it - sent a new one right away and a return label for the old one which was nice. I did the entire process via email which was convenient as I don't care to waste time on the phone.

Some things to note on this:

1. It is much larger than the OE unit. OD is about 5mm larger (60mm) and it's about 270mm long overall (~10.5"). I think the OE one is probably about 8" overall.
2. The OE rubber sleeve is not used - the unit comes with a new sleeve that is just a couple mm thick
3. The actual fit is perfect as far as I can tell and I'm picky. It uses the OE bracket and hardware, it's just longer. The additional length and diameter does not get in the way of any existing hoses or wiring so this is a non-issue.
4. The unit is torqued to the SMG pump body by the 27mm hex fitting on the pump side (the OE one is torqued on the opposite end) - just need to get it snug and it comes with a new o-ring installed.
5. The new unit has a large plastic hex cap on the end that covers up the nitrogen fill valve (which also has a cover) - it's important not not torque the unit on by this cap.

I did the SMG "ventilation" procedure using ISTA+ as I've always done. Per ISTA+, after replacing the accumulator, you need to run through the shift actuator bleed procedure as well as the slave cylinder bleed procedure. Combined this takes 20 minutes or so. After that I was good to go. I don't use a car charger or anything like that doing this procedure FWIW.

I only have 10 miles on the car with it but seems fine. I'll run the ISTA+ accumulator test on it and see how it reads. The accumulator I replaced was on the very low end of passing the test which is why I replaced it as a preventative thing. I wasn't getting any codes and the car was shifting fine. The only way we'll know how good these are is after a bunch of years and miles but I'm hopeful they last. MLR can rebuild them as well which is why I went this route. My guess is I could rebuild it too if I'm honest... These things are magical in operation but not construction.

I've never seen a ventilation procedure before.

I use INPA and known about it the accumulator test but never seen a ventilation procedure.

Anyone know if INPA can even do this?

[oceansize]

I've never seen a ventilation procedure before.

I use INPA and known about it the accumulator test but never seen a ventilation procedure.

Anyone know if INPA can even do this?

He is calling the bleed "ventilation". I'm assuming that is how ISTA+ labels it hence the quotes.