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C6 2.7 vacuum with LIFE!!
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machsantos   
Thu Feb 15 2018, 10:00pm
Joined: Apr 17 2017
Member No: #3108
Location: Aveiro
 Hello,
Got a C6 some months ago.
Was pretty bad so I rebuilt all the engine (completely), after a lot of effort and many head pain killing pills I made it work just fine!!
But there is a problem: brake pedal is too hard. Every time I press the brake pedal I hear a knok below the gear shifter, and at the same time, if suspension is working, it just stops. If I release the brake pedal, suspension is back to work.
There are no error codes released besides the usual P1351!!
Seems to me that it must be a vacuum problem but I just don't know where to look any longer.
Any help??
MGmike   
Fri Feb 16 2018, 12:41pm
Joined: May 21 2017
Member No: #3151
Location: South Queensferry
 Assuming the gearbox is in the P position this is normal behaviour (except the hard brake pedal bit).
The shifter has an interlock solenoid which clicks off when you press the brake and the suspension pump also switches off.

The hard pedal could be a lack of vacuum or many other things! The Vacuum pipe is quite obvious on the Servo unit behind the master cyl. If you trace the route it should go to the inlet manifold somewhere near the fuel filter, have you reconnected it when putting the engine back in? It should also have an inline valve to check. After that you'll need to check the abs unit and ensure fluid will flow out of each brake caliper.

Please report back on your findings.
321dave   
Fri Feb 16 2018, 12:53pm
Joined: Sep 09 2011
Member No: #614
Location: Dublin
machsantos wrote ...

Hello,
Got a C6 some months ago.
Was pretty bad so I rebuilt all the engine (completely), after a lot of effort and many head pain killing pills I made it work just fine!!
But there is a problem: brake pedal is too hard. Every time I press the brake pedal I hear a knok below the gear shifter, and at the same time, if suspension is working, it just stops. If I release the brake pedal, suspension is back to work.
There are no error codes released besides the usual P1351!!
Seems to me that it must be a vacuum problem but I just don't know where to look any longer.
Any help??



Hi Mach,
I believe the sound below the gear lever is operated by a switch from the brake pedal to allow the auto box shift out of park mode. It's a sort of shutter click sound they all make when you press the brake pedal. Maybe there is a connection to the electrics and the suspension or maybe it's not connected.

There was a relief valve installed by garages as part of a early recall with the C6 I believe that fix was I the area or related to the brake servo circuit. I cant remember the full details but maybe a member of the forum remembers or indeed brought a car in at the time. I remember checking that was in place when I first got my C6. It had the little valve installed. It's just a pipe with a valve connected onto the side of the brake reservoir. Might be something to look at. Or it might be unfortunately the brake servo be the ABS unit gone. But you should have fault code showing for that as it's also electrical.

machsantos   
Fri Feb 16 2018, 06:00pm
Joined: Apr 17 2017
Member No: #3108
Location: Aveiro
MGmike wrote ...

Assuming the gearbox is in the P position this is normal behaviour (except the hard brake pedal bit).
The shifter has an interlock solenoid which clicks off when you press the brake and the suspension pump also switches off.

The hard pedal could be a lack of vacuum or many other things! The Vacuum pipe is quite obvious on the Servo unit behind the master cyl. If you trace the route it should go to the inlet manifold somewhere near the fuel filter, have you reconnected it when putting the engine back in? It should also have an inline valve to check. After that you'll need to check the abs unit and ensure fluid will flow out of each brake caliper.

Please report back on your findings.




So having the suspension work to stop when I press the brake pedal is normal?
machsantos   
Fri Feb 16 2018, 06:09pm
Joined: Apr 17 2017
Member No: #3108
Location: Aveiro
 I'll get some photos to put in here so you have better elements to help me out!
321dave   
Sat Feb 17 2018, 12:13pm
Joined: Sep 09 2011
Member No: #614
Location: Dublin
machsantos wrote ...

I'll get some photos to put in here so you have better elements to help me out!


I believe this is the valve.



machsantos   
Sun Feb 25 2018, 06:38pm
Joined: Apr 17 2017
Member No: #3108
Location: Aveiro
 Hi guys.
Still no news of the problem. All the same. All except an issue!!
Car was working well in my garage. Sudently it just went off. Could not start it so checked for errors. Code P1641 appeared.

"P1641 -> Injectors control fault : Power stage / Injector residual voltage too large"

Any idea how to solve this one?
 

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