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Juddering when applying power in 6th

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rwb   
Thu May 09 2019, 10:06am
Joined: Dec 22 2014
Member No: #1988
Location: Telford
Hi,

Bought a C6 this morning! 2.7 HDi.

Noticed that it judders when under power in 6th, e.g., up hill on the motorway.

Any suggestions?
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rwb   
Sun May 12 2019, 08:24am
Joined: Dec 22 2014
Member No: #1988
Location: Telford
Actually, I think it's in every gear, both when under load and when the car is pushing the engine, e.g., down hill. I.e., when there is torque in the drivetrain.

It doesn't happen under light load or when rolling, e.g., in neutral. Therefore it isn't an unbalanced wheel or bad tyre.

It's CV joints, isn't it?
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arconell3   
Mon May 13 2019, 10:53am
Joined: Jun 28 2012
Member No: #922
Location: Kalkar
Start with checking the lower ball joints first. Certainly if it is a pre 2008 car.
Regards, Robert
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rwb   
Mon May 13 2019, 07:34pm
Joined: Dec 22 2014
Member No: #1988
Location: Telford
Really? My 2007 407 has never been /that/ bad! But of course I don't know the history here.

Been to see my mechanic who is a former Citroen tech and has owned a C6.
Told him I'd bought a C6 and I don't think he was impressed!

Anyway, Phase 1 is to get it starting and driving, then we'll see about reproducing this.

Is the intermediate bearing on the long driveshaft a possibility?
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arconell3   
Mon May 13 2019, 11:45pm
Joined: Jun 28 2012
Member No: #922
Location: Kalkar
On the early C6'es the lower front ball joints will only last some 10-15K miles. Reason: sloppy fitting seals. On the later models this problem was solved, but the new ball joints didn't fit the old model pivots. So on many cars they kept changing the joints without ever solving the problem. Which of course is as easy as getting 2 new pivots with the new type of joints and enjoy a smooth ride for the rest of the cars life.

A judder is either caused by unbalanced wheels or too much play in front suspension parts. Drive shaft joints can cause grinding noises or a loud clatter at full lock.

Regards, Robert
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MGmike   
Tue May 14 2019, 11:41am
Joined: May 21 2017
Member No: #3151
Location: South Queensferry
Check all the easy stuff first but my money is on the Torque Converter. A gearbox oil flush might help if it's not been done (recently).
Hattershaun   
Tue May 14 2019, 06:05pm
Joined: Dec 19 2010
Member No: #320
Location: Bedfordshire, UK
I've experienced a torque converter failing, symptoms where a juddering some of the time (light throttle, when the drivetrain is under load) as if you were driving over rumble strips.
Several partial gearbox oil changes improved the situation for a while.
Gearbox and torque converter were replaced eventually to cure the problem.
rwb   
Thu May 16 2019, 07:28am
Joined: Dec 22 2014
Member No: #1988
Location: Telford
Torque converter?! That's going to be megabucks isn't it. Is it scrap?
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MGmike   
Thu May 16 2019, 11:55am
Joined: May 21 2017
Member No: #3151
Location: South Queensferry
rwb wrote ...

Torque converter?! That's going to be megabucks isn't it. Is it scrap?


That very much depends on who's doing the work (if it is in fact the TC).

DIY? You spend a few days swapping the gearbox for a secondhand one of known good condition (£500 with new belts and water pump while you're at it).

Paying someone else to refurbish the 'box and TC circa £2,500....

You pays your money and take the chances....
Given your posts to date it would appear the PO saw you coming....
Buyer beware comes to mind....
Jas16   
Thu May 16 2019, 08:09pm
Joined: Feb 07 2017
Member No: #2994
Location: West London
Can the car not be taken back to the seller, if it is a garage? This is a major failure within 30 days and the Sales of Goods Act may apply. If so then contacting the Omburdsman may help.

- Click Here -

Just read it today
rwb   
Thu May 16 2019, 08:53pm
Joined: Dec 22 2014
Member No: #1988
Location: Telford
Thanks for the replies.

Private sale.

Anyway, I think the plan is to get the new starter motor on it and get the hydraulic leak fixed then get some miles on it and see if I can narrow down and be more precise about when it judders...
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