[desmo01]

All,

I've had a red cog o'death error for some time at startup, clutch position deviation. If I run the slave bleed routine all is good for a couple of days, actuator bleed routine does not help. This has gone on for some time (haven't had time to get to it). The car is otherwise fine, slave cylinder is new (MLR rebuild), no issues with the clutch position sensor, clutch arm/throwout bearing/pivot all fresh. I have a spare trans/hydraulics set and am in the process of swapping the lower unit for one I have gone through (clean clutch solenoid/new o-rings) with an MLR pump motor on it as well.

So here's the kicker, after getting the actuator supply pressure banjo off, and moving to the clutch slave cylinder banjo (a MFer to be sure), the clutch slave cylinder banjo was not tight. Not loose, just really really light tight. Fluid level was fine and no leakage. I'm wondering if thermals were moving it around a bit and allowing air in?

Any thoughts from the hive?

Only concern with swapping the lower is if the clutch solenoid is not good, although one of the things I was thinking could be the cause of the problem is a sticking clutch solenoid in the car presently.

 

[flacoramos]

Was gonna say sounds like a leaking slave. So def possible.

 

[desmo01]

Leaking air in you mean? Didn't have fluid leak

 

[desmo01]

So changed out lower block, this means different clutch solenoid and assembly. Just had red cog (position deviation) 300mi from home. Must be slave cylinder I guess? This is getting old.

 

[flacoramos]

Or PLCD.

 

[desmo01]

Ran clutch bleed routine and now drives fine. Same problem as before, again seems to point to slave.

 

[desmo01]

Could be PLCD I suppose, but last one I had go on other car articulated that in error code. How strong are u on that?

 

[platii]

Any thoughts from the hive?

Yeah possible "Black Magic " spell!!, the issue is that the philosopher who suppose to resolve it acting dead. lol.

 

[platii]

Leaking air in you mean?

No, similar is accumulated fluid vapor (cavitation) caused by mechanical pump wear on the shafts against the thrust plates. This condition could cause bubble pockets.

What did you swap exactly between the two assemblies?. Since you installed another assembly I would say give it some time to bleed properly by driving, the issue may resolve, and to judge the other assembly.

Could be PLCD I suppose

Least likely for two reason at least, it could means the clutch valve has delayed when the car started up and caused the slave deviation, no PLCD error also support the idea but no fault 5506 could deny it, I would suggest to monitor the clutch valve current before start up to watch the clutch valve value when the valve in transit from clutch closed to open, at the same time monitor the PLCD main value to move from around 650 to lower values, there should be no delay, the clutch valve may move to open the clutch but the clutch slave has a delay, try to catch if there is any deviation. I doubt it is the clutch valve.
Seeing the fault values may help.
Does it also happens during normal driving?.

 

[desmo01]

Thanks platii, will look.

I have not found an ability to log SMG ecu values with testo, has anyone else??

 

[desmo01]

I'm about to parts cannon a new slave and plcd sensor, if that doesn't do it, its rag in gas cap and match time.....


Help me resist......

 

[///DeafM5]

First thought when you said MLR Slave, I do not trust that slave. I only trust BMW slave at this point and when you change them out, flip the thread so it can be changed from outside next time.

 

[dullcho]

Have you ruled out voltage drop due to battery or bad positive or negative connections? Have you had an intermittent no-crank when you try to start the vehicle (usually cold)?

 

[desmo01]

Voltage is good, don't think it's that. But no, I haven't measured voltage drop when cranking. No intermittent no-cranks. As soon as you step on brake (and clutch opens) it gets pissed off. Thread on slave cylinder is flipped, why is there distrust for the MLR slave?

I feel like I'm down to slave cylinder, clutch position sensor, or (less likely) hinkey clutch solenoid.

 

[///DeafM5]

Voltage is good, don't think it's that. But no, I haven't measured voltage drop when cranking. No intermittent no-cranks. As soon as you step on brake (and clutch opens) it gets pissed off. Thread on slave cylinder is flipped, why is there distrust for the MLR slave?

I feel like I'm down to slave cylinder, clutch position sensor, or (less likely) hinkey clutch solenoid.

typically, rebuilt slaves are never 100% built like OE slaves. I'd rather eat up that cost and not to worry about it again.