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Discussion Starter #1
Hello all. I have a E46 M3 with an SMG transmission. I recently replaced the clutch along with several other parts. Parts include rear main seal, DM flywheel, pressure plate, clutch disc, shift fork, throwout bearing, pivot pin (brass), slave cylinder, and compression springs. I bled the actuator/clutch using INPA and did clutch adaptation. Everything was fine until today when it started making a loud buzzing sound coming from the shift actuator area whenever I shift from N to 1 or N to R and back. If I try to drive with it like that, the car throws itself into neutral. Has anyone experienced this before? Any ideas? It does it with the key on without the engine running too.
 

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Welcome to the forum. This question is more suited to the M3 section.
Seems you did a thorough job on the clutch. Presumably its all OE stuff.

Check the level of the CHF11 (know the level rises with the key off).

More concise information is needed. General questions can only get general answers.

How long was it fine for, 50,000?

It does it every time so the car cannot be driven at all now?

Does the engine always crank and start?

Does the 0 flash?

Does it shift? What else is going on?

Locate the actual source of the noise - actuator, pump, solenoids etc.

Try pulling the 40A fuse (to power down the pump motor) and see what happens.

Great you have INPA. Curious why you are getting no lights or codes.
Make sure the GPS survived the surgery (INPA) although this should show codes too.
Good luck!
 

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Discussion Starter #3 (Edited)
Commando, thank you for the reply! I had a little charging issue after the clutch job, so I didn't get to drive it for very long. Changed the alternator and fixed the charging issue and when I had the plenum off a little SMG fluid came up through the hose from the pump and leaked out. Not thinking it was enough to worry about, I took it for a little drive. While driving I noticed the yellow cog light coming on and going back off. So I got back to the house and that's when I noticed it making the sound. I got up this morning and checked the SMG fluid reservoir and it was really low on fluid. I filled it a little past MAX knowing that the level would go down as the pump ran. With the car not running and just the key on, I cycled between 0 and 1 and R for a few rounds and nothing changed. So I threw a charger on the car and ran the actuator, slave cylinder bleed procedure again using INPA. Got in and the noise was gone! Took it for a little spin and put about 10 miles on it with no shifting issues whatsoever. I got back to the house and turned off the car. Just to double check, I turned back on the car and the noise returned. Double checked the fluid after the pump ran and it was at the MAX line.

The car will start but it makes a strange buzzing noise and takes a second or two to fire up. The sound coming from the shifter isn't really any different with the car on or off. It will engage 1 and R but shortly after it will turn on the yellow cog light. If the car is running, it will throw it into 0. The sound I'm hearing I can also feel as a slight vibration in the shift lever and really seems like its coming from the shift actuator. I took a video of it making the noise. It sounds a lot worse in the video.

Is it possible that my pump isn't supplying enough pressure?

What are some of the symptoms of a failing GPS?


https://youtu.be/WGs2_4Xti5U

That's a short video of the noise
 

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Everything was fine until today when it started making a loud buzzing sound coming from the shift actuator area whenever I shift from N to 1 or N to R and back. If I try to drive with it like that, the car throws itself into neutral.
The gear postion sensor -- rear of the tranny -- going bad. It has two encoders inside: a linear and an angular encoders. I think the angular encoder is dirty and cannot recognize the 'gate' angles. Shifting into other gears has no noise?
 

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Discussion Starter #6
Not the expensive pump but the cheaper GPS.

QUOTE=jsin00;18525373]What are some of the symptoms of a failing GPS?[
Your problem is the symptom of bad GPS.[/QUOTE]


Sapote, thank you so much for the response. Did you have a chance to look at that video I added? I thought I might have edited my post with the video after your reply. I do have to say I might have been a little rough on the GPS doing the job on my back patio on jack stands so I was leaning towards that.
 

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Discussion Starter #7
Sapote, will a failing GPS make that sound while just sitting in neutral (0)? If you take a look at that video, you can hear it making the noise a little bit while in 1. Then I push the stick over into neutral and it gets louder. Sorry for all the questions, but I just want to make sure.
 

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Move to neutral requires the computer controller to know exactly the position of the shift rod (inline with the GPS) and so if the GPS reported bad position then the controller might not able move the shift rod to the neutral position, thus the hunting noise. Most of the time when the controller could not shift to the selected gear and jumped to neutral instead then the GPS is at fault.

I did see the video and sounds like GPS bad
 

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Discussion Starter #9
I'll take your word for it. I was a little skeptical because it would fully engage 1st or R and have the weird buzzing noise the whole time, just quieter. It's really loud when shifting between them. I appreciate all the help!!! Looks like I'll be tearing into it again. :censor:Doing all this work on jack stands is rough. I've seen a DIY on here and it involves removing the exhaust and all that stuff again, sucks. Maybe I can just cut a hole in the floor from the inside lol. Again, thanks for all your help!
 

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I agree with Saote the symptoms are like a failing GPS. The GPS is just 2 pots inside they eventually wear or get contaminated hence the good then bad deal.

I would run the bleed/adaptation routine again plus the accumulator check.

INPA will tell you your pump pressures. INPA will also give you the GPS readings and allow you to select each gear.

You should have codes with low hydraulic pressure or a failing GPS. I have not heard that sound from a failed GPS, it almost sounds like the exhaust is touching on something. Does it make the noise with the motor not running?
 

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Discussion Starter #13
I'll try shifting with INPA. I've never done it before so it might take me a minute to figure out. The only thing I have taught myself to do with INPA is the actuator and clutch bleed/adaptation. I'll will try to figure all that out and get back with you guys.

Commando, it makes that sound with the motor off or on.

I do have to say I ran the bleed/adaptation procedure and right after it drove and shifted perfect. After I get home and turn off the car, it will start making that noise again and not want to engage gears.
 

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Discussion Starter #14
I also bought a used (but working) SMG pump, shift actuator, and GPS yesterday. I plan on getting to the bottom of this, thankfully with the from you guys
 

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Discussion Starter #16
So I did what was suggested and used INPA to shift through the gears. All gears passed the test and were very close to nominal. I also ran the pressure test on the pump and it reached 85 bar and turned off the pump and the pressure slowly dropped to 65 after about 1 min, so I have to assume everything was ok with the pump and the accumulator. After running the test, I fired it up and cycled between 1st and reverse a few times and didn't experience anything abnormal. I then took it for drive with it shifting perfectly (video). Returned home after a short cruise and sat in the car and cycled between 1st and reverse a few times (video). Turned off the car and started to walk inside when i thought "let's try that again". Went out to the car and it's back to making horrible noises, kicking out of gear, and the yellow cog light coming on.

It seems like every time I hook up to it, afterwards it runs fine and then when I get home and everything goes to hell again.


https://youtu.be/jzAESwyS26Y

After tests

https://youtu.be/u-wQoLJ_g7Q

During the drive

https://youtu.be/pIGJGQQPlLE

After returning and turning off the car and turning back on
 

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Ok if it makes the sound motor off forget the exhaust idea.
Every SMG owner should run the gearbox adaptation routine about once a year or so to allow for wear in the SAC and sensors. No SAC then do it more. In your case there is no guarantee all the air was bled from the system so this is the first thing I would do. This and the GPS still seem the most probable causes.

Still no codes, cog lights or flashing gear indicators?




Unrelated to your current issue it's great you got some spare parts. In the SMG ihe 4 brush electric motor driving the hydraulic pump is working to deliver the 80Bar system pressure. Eventually it wears out just like wear in tyres, brakes, clutch linings etc. However unlike tyres and brakes etc. this component wears if you have the ignition on and don't drive anywhere. In my experience most SMG failures are caused by this wearing out. Should you replace your 'pump' consider how much wear is on your spare used hydraulic pump? It may be a pig in a poke. Not good for peace-of-mind. Possibly open your spare one up and inspect it. The wear on the commutator is clearly visible. A new Burkhardt replacement electric motor (or another new one if you can source one) is another option.
 

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Discussion Starter #19
Ok if it makes the sound motor off forget the exhaust idea.
Every SMG owner should run the gearbox adaptation routine about once a year or so to allow for wear in the SAC and sensors. No SAC then do it more. In your case there is no guarantee all the air was bled from the system so this is the first thing I would do. This and the GPS still seem the most probable causes.

Still no codes, cog lights or flashing gear indicators?




Unrelated to your current issue it's great you got some spare parts. In the SMG ihe 4 brush electric motor driving the hydraulic pump is working to deliver the 80Bar system pressure. Eventually it wears out just like wear in tyres, brakes, clutch linings etc. However unlike tyres and brakes etc. this component wears if you have the ignition on and don't drive anywhere. In my experience most SMG failures are caused by this wearing out. Should you replace your 'pump' consider how much wear is on your spare used hydraulic pump? It may be a pig in a poke. Not good for peace-of-mind. Possibly open your spare one up and inspect it. The wear on the commutator is clearly visible. A new Burkhardt replacement electric motor (or another new one if you can source one) is another option.


Yes! I hooked up to it after it gave me the cog light in the video and I got a:

23 solenoid valve clutch


I was also looking at those replacement motors from burkhart
 

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Discussion Starter #20
Guys! I possibly have an answer. I googled the 23 solenoid valve clutch fault and I came across this thread saying that "the connection on the bottom of the reservoir was not on enough-not loose enough to cause a leak but loose enough to not allow fluid down into the pump".

The reservoir has a check valve on it so you can unhook it without all of your SMG fluid coming out. When I had my plenum off the other day, I unhooked that hose. I bet it's just not seated well enough or the valve is messed up. Might be wishful thinking, but it's worth checking out since I did just have that hose off and then started experiencing problems. I'll check back in tomorrow evening after I try unhooking that hose and reinstalling it. I hope this works!
 
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