SMG guys, Need help to identity SMG noise

[RazorM]

Hi Folks,

recently my 2001 SMG developed weird noise when shifting, mostly evident when coming to stop, or shifting to reverse, 1,2,3 maybe even higher gears, but I can’t hear it when the car is moving. The gearbox Shifts and works. Not sure, maybe the gearshift’s are a little bit slower when hearing this noise.
Link to video with the noise

https://youtube.com/shorts/lYkACR9GOXc?feature=share

thanks for insights

[eacmen]

Hi Folks,

recently my 2001 SMG developed weird noise when shifting, mostly evident when coming to stop, or shifting to reverse, 1,2,3 maybe even higher gears, but I can't hear it when the car is moving. The gearbox Shifts and works. Not sure, maybe the gearshift's are a little bit slower when hearing this noise.
Link to video with the noise

https://youtube.com/shorts/lYkACR9GOXc?feature=share

thanks for insights

I recently tore my hair out trying to fix this. At the end of the day it was the seals in the pump failing. You can try bleeding it to see if it goes away.

[RazorM]

I recently tore my hair out trying to fix this. At the end of the day it was the seals in the pump failing. You can try bleeding it to see if it goes away.

Great info thank you, So seals on pump failing were the whole problem? Did you change the seals or you only bled the system as you recommended?

[eacmen]

Great info thank you, So seals on pump failing were the whole problem? Did you change the seals or you only bled the system as you recommended?

I had the noise for a long time. In hindsight I now believe it is due to hydraulic cavitation in the actuator hydraulic lines that causes the shift linkage to vibrate. For about a year I would just bleed it before each track weekend. In recent weeks a bleed did not help the noise. This past weekend my car would drop into Neutral on track. I swapped in a spare pump I had and the noise went away and shifts perfect now.

The pump that failed was rebuilt using new seals, motor, and accumulator. I am sending the unit to MLR to investigate what actually failed.

For you I would bleed it and see what happens. If the noise returns then I would start planning to replace or rebuild the pump.

[RazorM]

I had the noise for a long time. In hindsight I now believe it is due to hydraulic cavitation in the actuator hydraulic lines that causes the shift linkage to vibrate. For about a year I would just bleed it before each track weekend. In recent weeks a bleed did not help the noise. This past weekend my car would drop into Neutral on track. I swapped in a spare pump I had and the noise went away and shifts perfect now.

The pump that failed was rebuilt using new seals, motor, and accumulator. I am sending the unit to MLR to investigate what actually failed.

For you I would bleed it and see what happens. If the noise returns then I would start planning to replace or rebuild the pump.

It would be interesting to know what failed. I have not bled the system yet as I don’t have INPA with me now, but I am thinking if just resealing all hydraulic unit would fix the problem, or also changing motor is necessary. Seals are 200 and motor is another 500.
Do you have your SMG unit relocated to drug bin?

[eacmen]

It would be interesting to know what failed. I have not bled the system yet as I don't have INPA with me now, but I am thinking if just resealing all hydraulic unit would fix the problem, or also changing motor is necessary. Seals are 200 and motor is another 500.
Do you have your SMG unit relocated to drug bin?

Get INPA asap. As an SMG owner it really is a requirement. Google Mike's Easy BMW tools and use that one to install.

I believe that air is coming in from somewhere. Could be smg pump or could be actuator. But my bet would be the pump seals failed. As long as you can build pressure the SMG pump motor is fine (again need inpa to check the pressures).

My pump is relocated. It makes it a pain to bleed but swapping pumps is so quick. I did it and bled it and adapted in the paddock in an hour. It was a messy one man job but better than going home early!

In your situation I would try bleeding it first. Maybe the fluid in the reservoir went low and air got in? Any recent work that required removal of the intake?

[RazorM]

Get INPA asap. As an SMG owner it really is a requirement. Google Mike's Easy BMW tools and use that one to install.

I believe that air is coming in from somewhere. Could be smg pump or could be actuator. But my bet would be the pump seals failed. As long as you can build pressure the SMG pump motor is fine (again need inpa to check the pressures).

My pump is relocated. It makes it a pain to bleed but swapping pumps is so quick. I did it and bled it and adapted in the paddock in an hour. It was a messy one man job but better than going home early!

In your situation I would try bleeding it first. Maybe the fluid in the reservoir went low and air got in? Any recent work that required removal of the intake?

Ok great Thank you, i have ordered OBD cable so i can make it work ASAP.

i checked the fluid level in reservoir and it is full. I did not do any airbox/ that area located jobs. I have not driven the car much this year to be honest.

Gonna bleed the system and see what happens. If air is still present I am wondering wether it would be viable just to reseal the whole pump as all seal kit cost less than 200 or also replace the pump “when in there”, which is another 300-400. Even though it may be working fine in good condition, it’s hard to know.

Relocating looks too much of a job to me to be honest. I would be hesitant to rebuild the car to manual in that kind of money to be spend, but I totally understand the benefits.

[eacmen]

Ok great Thank you, i have ordered OBD cable so i can make it work ASAP.

i checked the fluid level in reservoir and it is full. I did not do any airbox/ that area located jobs. I have not driven the car much this year to be honest.

Gonna bleed the system and see what happens. If air is still present I am wondering wether it would be viable just to reseal the whole pump as all seal kit cost less than 200 or also replace the pump “when in there”, which is another 300-400. Even though it may be working fine in good condition, it's hard to know.

Relocating looks too much of a job to me to be honest. I would be hesitant to rebuild the car to manual in that kind of money to be spend, but I totally understand the benefits.

If it ends up being the pump. I would just get a rebuilt pump from MLR and swap the whole unit and send your current unit back as core.

[oceansize]

If it ends up being the pump. I would just get a rebuilt pump from MLR and swap the whole unit and send your current unit back as core.

Did he get back with you on what failed on your prior SMG pump refurb?

[eacmen]

Did he get back with you on what failed on your prior SMG pump refurb?

Not yet. The refurb wasnt done by MLR though. The refurb was done by a fellow forum member and I bought his used unit.

[domibln]

I would be careful with such "rebuilds", no one can offer that with a clean conscience. Finally only about 60-70% of the components of the hydraulic unit are available at all - whether at MLR or SMG Society. Certain components like the solenoid valves or the gear pump are not available and can only be diagnosed to a limited extent. So if someone offers a "refurbished" unit, it's all more or less just a gamble. It is better to really investigate what is broken, carry out a proper troubleshooting and replace only the defective part.

Since the noise occurs when shifting gears, it seems to be a resonance triggered by a solenoid valve. The solenoid valves are controlled with a frequency (PWM) and a plunger is moved magnetically in the valves. If the valve is defective, either the valve itself or, for example, the hydraulic lines connected to the valve can make such noises.

I would look at the whole thing from close up, either from below at the gearbox or remove the intake manifold and check the hydraulic unit.

[eacmen]

I would be careful with such "rebuilds", no one can offer that with a clean conscience. Finally only about 60-70% of the components of the hydraulic unit are available at all - whether at MLR or SMG Society. Certain components like the solenoid valves or the gear pump are not available and can only be diagnosed to a limited extent. So if someone offers a "refurbished" unit, it's all more or less just a gamble. It is better to really investigate what is broken, carry out a proper troubleshooting and replace only the defective part.

Since the noise occurs when shifting gears, it seems to be a resonance triggered by a solenoid valve. The solenoid valves are controlled with a frequency (PWM) and a plunger is moved magnetically in the valves. If the valve is defective, either the valve itself or, for example, the hydraulic lines connected to the valve can make such noises.

I would look at the whole thing from close up, either from below at the gearbox or remove the intake manifold and check the hydraulic unit.

MLR actually offers new clutch and actuator solenoids. According to them they are able to bench test units and identify issues. I assume their rebuilt units go through a similar bench test procedure.

Failed gear pump should be fairly obvious to see visually.