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Discussion Starter #1 (Edited)
First of, thanks JColley for providing assistance when he has been able to. However, after the M5 sitting for a few months due to SMG issues, I really miss it and decided to use INPA to diagnose a little further. However, I need some expert advice on understanding my findings. First a little history:

2006 M5 with 110k miles.

  • Replaced original clutch at 87k miles with a SPEC Kit. All was well until about 8k miles ago. I started getting harsh 2-1 downshifts. When I inspected the Hydro Unit, i noticed the sensor strip harness from the actuator block was dry rotted and exposed wires. I tried repairing but that didn't seem to work.
  • Purchase a used Hydro unit with about 60k miles. Replaced mine with this unit at 300 miles ago. Since I purchased a brand new clutch slave at 87k miles, i replaced the one that came with the used unit. Along with that I replaced the release bearing, sleeve, fork, ball pin (brass one was worn flat and uneven). Bleed/Adaptations were run and car drove perfect until a WOT shifted into 2nd gear and a red gear light came on. Turned car off and cycled the ignition and light went away. Then a few mile after that it came back on.
  • Ever since then we have tried to bleed the entire system numerous times only to fail at the clutch teach in due to detection of layshaft speed. JColley remoted in an observed that the clutch was not closing and opening properly with the Engine on so an indication of possible clutch drag is present.
Tonight I decided to spend more time with it and found the following while in Neutral:

  • Ignition ON/ Engine OFF: Priming the pump took about 10 seconds to fully prime from 1.5bar to 85bar
  • Now I observed the Analogue Values 3 Current-Clutch sitting at roughly 21mA while the Position - Clutch Main Sensor was at 644 lnk with the Brake Pedal resting (1120mA / 224 lnk with the brake pedal depressed hopefully indicating clutch open)
  • While I was pressing the brake pedal, I was noticing the hydro pressure drop gradually after each pedal pump eventually going down to about 20bar before I manually primed it again. Is this normal?
  • After observing the pressure drop and priming the pump, I just sat there hoping that the motor would prime again but didn't. I'm wondering if there's a leak somewhere? I tend to wonder if the pressure accumulator has a leak or perhaps ran out of nitrogen to pressure the fluid.
  • I suspect the constant drop in pressure didn't allow the clutch bleed to finish successfully and resulted in error "minimum slave movement of clutch not reached". By the time the bleeding procedure failed, I observed the hydro pressure and it was really low.
  • Engine ON: the Current-Clutch was sitting around 1120mA, however I don't remember the Position-Clutch Main Sensor. I didn't see the SMG pump pressurize the system while Engine was on. The readings were roughly 40-50bar from what I recall.
My questions to the community are:

  • If anyone has done any logging with INPA on a working SMG, can you please share Analogue Values for comparison?
  • Does your pump try to prime on a cycle with the Ignition ON/Engine OFF?
  • Once primed, do you notice a connstant pressure drop while Engine OFF?
  • What about when engine is ON, does it hold operating pressure (~75bar)?
I need to get underneath and observe for any leaks but last time I looked I didn't see any. I couldn't find more information on how the SMG Hydro system maintains pressure (and if it does while Engine OFF/Ignition ON). I would have thought if the system gets primed upon driver door being opened, that it would maintain pressure but it doesn't appear so.

I'm suspecting a leaking slave or pressure accumulator. Thoughts? Oh I have a generic 4F67 code that will not go away.

Interested in your feedback and thanks!
 

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Discussion Starter #2
Attached is a TIS pdf outlining the SMG. It talks about a check valve:


  • Check valve
    The check valve at the outlet to the hydraulic pump prevents the hydraulic pressure from reducing when the
    hydraulic pump is inactive.


I'm seeing pressure drops while Ignition ON/Engine OFF. Could this be another thing to check? If so, I cannot locate this valve in any diagram I've searched in.
 

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Kevin,

The check valve is internal to the lower portion of the hydraulic pump casing, roughly in between the temp and pressure sensor. The discharge of the pump goes down through the temp sensor passage, through the check valve, and back up through the pressure sensor passage to the clutch valve supply port.

Hard to visualize all that, I'll post some pics of the block I tore apart soon. The hex bolt plug on the bottom of the block which is cracked open to prime the pump during replacement can be fully removed to access this check valve cartridge, but I wouldn't risk trying to pull the cartridge to check it without pushing it out from the top via the pump cavity.

Essentially, when the accumulator is charged to pressure, if you see leak-down when the clutch Is closed, there are only two potential leakage paths, either back-leakage through the check valve or leakage past the clutch valve. In my head, it seems straightforward to test for either, but requires a little ingenuity. Neither however could be done without removing the transmission from the car.

This seems a red herring though, as if the clutch is indicating open as it was when I was viewing it, and the layshaft is rolling, it would appear to be the cause of the adaptation failure for the slip point determination.
 

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...Along with that I replaced the release bearing, sleeve, fork, ball pin (brass one was worn flat and uneven). Bleed/Adaptations were run and car drove perfect until a WOT shifted into 2nd gear...

Just reread this and something occurred to me.

For that brass pin to have been worn, there was some serious force on that release lever. You got harsh shifting and replaced it with the OEM plastic one.

Things ran fine and them didn't. I'm willing to bet the plastic release pin has failed. This is the other half of the clutch release lever fulcrum, so now even if the slave piston/PLCD travel to spec, the clutch disengagement won't be to spec, this the dragging.

I hate to say it, but I would drop it for a look.
 

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Discussion Starter #5
UPDATE: I FINALLY WAS ABLE TO PERFORM ALL ADAPTATIONS!!!!!!

I decided to jack the car up and inspect underneath for any leaks since I was having issues bleeding the clutch actuator(slave) due to "minimum" slave movement.

Visually inspected for leaks and nothing. Everything looked sealed. I proceeded to inspect the level of the SMG fluid reservoir by sticking my finger and it felt dry. Topped off with roughly 70mL of fluid!!!! Yikes. Continued bleeding and after each bleed, topping off reservoir. After about 15 bleed sessions or so, I actually started to see better numbers in the Analogue 1/2/3 screens with engine ON. Also, one time I was having trouble setting the gearbox adaptations due to errors with low SMG pressure. I look underneath and see a puddle of SMG fluid. I cracked open the SMG Reservoir Fill Plug and the fluid seemed a little pressurized. Any ideas anyone?

Before it wouldn't teach due to layshaft sensor speed. Each time I bled and inspected the layshaft sensor speed, it was getting close to 0 RPM. Once I got to that point, it fluctuated between 0-24RPMS that boom that was my ticket.

NOTE: WHEN YOU PERFORM THE ADAPATIONS IN INPA, BE PATIENT IT MAY TAKE A WHILE. THE LAST ADAPTATION IS THE CLUTCH SLIP POINT. INPA WILL PROMPT YOU TURN ON ENGINE AND HOLD BRAKE PEDAL. WHATEVER YOU DO, DO NOT RELEASE THAT BRAKE PEDAL UNTIL THE ADAPTATION HAS RAN AND PROMPTS YOU TO TURN ENGINE OFF/IGNITION ON.

Boy after 6 hours of poking around, I must admit I learned quite a bit. Now the real test comes with road testing the car tomorrow and this weekend. Eventually I plan to inspect the SMG Fluid again in case it is not topped off.

JColley, thank you for all your help. You're definitely an asset to this community and I am grateful for your expertise, wisdom and patience. We will be in touch!

Praying to the BMW Gods for a successful drive tomorrow. I miss this car!
 

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UPDATE: I FINALLY WAS ABLE TO PERFORM ALL ADAPTATIONS!!!!!!

I decided to jack the car up and inspect underneath for any leaks since I was having issues bleeding the clutch actuator(slave) due to "minimum" slave movement.

Visually inspected for leaks and nothing. Everything looked sealed. I proceeded to inspect the level of the SMG fluid reservoir by sticking my finger and it felt dry. Topped off with roughly 70mL of fluid!!!! Yikes. Continued bleeding and after each bleed, topping off reservoir. After about 15 bleed sessions or so, I actually started to see better numbers in the Analogue 1/2/3 screens with engine ON. Also, one time I was having trouble setting the gearbox adaptations due to errors with low SMG pressure. I look underneath and see a puddle of SMG fluid. I cracked open the SMG Reservoir Fill Plug and the fluid seemed a little pressurized. Any ideas anyone?

Before it wouldn't teach due to layshaft sensor speed. Each time I bled and inspected the layshaft sensor speed, it was getting close to 0 RPM. Once I got to that point, it fluctuated between 0-24RPMS that boom that was my ticket.

NOTE: WHEN YOU PERFORM THE ADAPATIONS IN INPA, BE PATIENT IT MAY TAKE A WHILE. THE LAST ADAPTATION IS THE CLUTCH SLIP POINT. INPA WILL PROMPT YOU TURN ON ENGINE AND HOLD BRAKE PEDAL. WHATEVER YOU DO, DO NOT RELEASE THAT BRAKE PEDAL UNTIL THE ADAPTATION HAS RAN AND PROMPTS YOU TO TURN ENGINE OFF/IGNITION ON.

Boy after 6 hours of poking around, I must admit I learned quite a bit. Now the real test comes with road testing the car tomorrow and this weekend. Eventually I plan to inspect the SMG Fluid again in case it is not topped off.

JColley, thank you for all your help. You're definitely an asset to this community and I am grateful for your expertise, wisdom and patience. We will be in touch!

Praying to the BMW Gods for a successful drive tomorrow. I miss this car!
I wonder what happend with that test drive - ?????
 

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LOL - ok - I was more referring to all the dead threads - people ask for help - get help - people provide detailed responses - and the OP's never provide findings or if they were able to solve problem - they just go ghost on the subject

Thanks for your input
 
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