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Discussion Starter · #1 · (Edited)
Hi. Please help.
When gearbox is cold, the pressure in the accumulator is 90-100 bar, the pump works quickly and rarely. After 40-60 min, when gearbox is hot, pressure in the accumulator 50-75 bar and pump works everyone 10 sec...40-60 min drive=>yellow gear 10min=>N
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Maybe i need to re-seal the valves and the pump?
Can the pressure sensor work incorrectly when heated?
ECU updated, adaptation is easy.
Sorry for my english.
 

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Like Flaco said likely cause is solenoid o-rings. Oil gets thinner once it warms up, and o-rings just don't hold it as well as when its cold.
 

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Discussion Starter · #4 ·
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The mechanic said to replace the hydraulics with a new....9k euro.
I'm not sure if he understands the whole system, because he never even disassembled the pump...
 

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Yes that is one way to do it. If you are at a shop most will just replace the whole unit.

The motor, pump and clutch solenoid can be done in the car and will have the greatest effect. All of the shifting solenoids require removal of the transmission. All the write ups are in the DIY but I doubt the shop will do it this way.
 

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From the first post description nothing unusual until the yellow cog and gear drop to N which indicate a leak.

The main fault is 4FA0= clutch deviated.
Now this could be caused obviously by hydraulic pressure supply/control because you listed handful of hydraulic pressure codes.
Now it either the clutch valve or slave is leaking. The clutch valve fault is not significant in this case as long as you have pressure faults, what happens is the SMG ECU command the clutch and there was no adequate pressure at the same time, so the fault triggered when the PLCD didn't register any/not ideal slave movement.
The clutch valve is first to access, you may start the repair by replacing its O'rings and test, the slave require transmission drop but in this case if the whole system is tired so best to drop the box and repair everything/replace shift solenoids O'rings, you don't need to replace the whole hydraulic unit for 9000$.
Maybe i need to re-seal the valves and the pump?
The solenoids O'rings yes, the pump building good pressure, it is your choice but the pump is not what causing this issue.
Can the pressure sensor work incorrectly when heated?
No, the pressure sensor is good.
ECU updated, adaptation is easy.
Did you perform the adaptation and passed, all of them?.
You may start by bleeding the clutch by the software multiple times and test, but if you already performed adaptation and passed most likely you have a leak as I mentioned above.


From the test you performed above:
37.1=System leak (This is the accumulator pressure).
94.1=Pump and motor is building good pressure.
pump works everyone 10 sec
I understand it is the hydraulic build up pressure which is OK which means the pump and motor is OK to keep up with the leak and lose of pressure.
 
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