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2.7 hdi engine knocking noise when warm

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Tue Aug 07 2018, 12:23pm
Joined: May 22 2016
Member No: #2632
Location: Northallerton N Yorks
Hi all

I have noticed an engine frequency knocking noise that can only be heard outside the car and when the engine is warm. I am worried that it might be a sign of impending crank failure!

I have taken it in to my local Citroën specialist and he doesn’t think that it’s anything to worry about. I thought I would appeal to the experience of you guys for an opinion. The car has 95k on the clock and I suppose that it could just be normal wear but not having had one of these glorious machines before, I really don’t know.

Any help would be greatly appreciated. I have taken a couple of short videos of the sound of the engine:

Engine cold
- Click Here -

Engine hot
- Click Here -

Tue Aug 07 2018, 05:08pm
Joined: May 21 2017
Member No: #3151
Location: South Queensferry
Hmmmm I think you're right to be a little concerned. There should be little or no noticeable difference hot or cold. If anything hot should be better!

I would be looking to see if I can get an oil pressure reading in both cases to compare. not sure if Lexia can show that but I'll check later on tonight and let you know.

It sounds like it could be a sticking hydraulic cam follower or crank issue caused by low oil pressure, possibly caused by an oil pump not doing it's thing properly.

One caveat if I'm way off, it's always difficult diagnosing from a couple of videos.

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 rabenson (Last Week)
Tue Aug 07 2018, 05:25pm

Joined: Oct 01 2009
Member No: #1
Location: Northumberland
Having had 2 2.7 Hdi's (current one is 102,000 miles)and a 3.0 Hdi I have not heard a knock like that from any of them so something is not right and warrants further investigation.
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 rabenson (Last Week)
Wed Aug 08 2018, 09:52am
Joined: Jun 28 2012
Member No: #922
Location: Kalkar
That sounds a bit like piston slap, rather than the beginning of big-end trouble. Also, it might be a diesel knock, when 1 of the 2 knock sensors are not functioning properly. I take it there are no warning messages displayed?

To be on the safe side:
1: Get an oil change before running the car any longer (if possible)
2: Get a diagbox readout, looking for problems with injectors, sensors, including the 2 knock sensors.

Once that is done (and corrected), check how the engine runs.

Regards, Robert
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 rabenson (6 Days ago) , cruiserphil (2 Days ago)
Fri Aug 10 2018, 09:25am
Joined: May 23 2014
Member No: #1722
Location: Krokstadelva
Hi, I also sometimes have this sound when warm, what is the pr number of your car? (Mine is from 4. January 2007). I change 5w-30 c2 liqui moly oil every 10.000 km as in the good old days, and do all repairs myself, so I know my car well, it rides perfect, except this annoying sound sometimes... Also have another C6 (230.000 km, one of the 11 sold new in Norway) that has a broken piston rod bearing, hopefully its not that (I'm repairing this engine now). Interesting to hear others opinions on this sound, and maybe can conclude what it is before its too late...

Regards, Christian
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 rabenson (4 Days ago) , cruiserphil (2 Days ago)
Fri Aug 10 2018, 02:42pm
Joined: May 22 2016
Member No: #2632
Location: Northallerton N Yorks
Thanks for your replies. I'm going to book the 6 in for further investigation starting with an oil change and check of the oil pressure. I'll get a full diagnostic done to see if there is anything flagged up re sensors as you suggest, Robert.

Christian, I'll check on the pr number and post it up. i know that our car was first registered in february 2008. Lets hope that we can get to the bottom of this noise - the car is perfect apart from this.

Thanks again, everyone - much appreciated.

Sat Aug 11 2018, 11:46am
Joined: May 11 2016
Member No: #2626
Location: Stoke on Trent
When warm your C6 sounds like my C6 i think, here is a video i took earlier . - Click Here - so either we both have the same issue or there is no issue.
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 rabenson (2 Days ago)
Sun Aug 12 2018, 12:33pm
Joined: Jul 17 2012
Member No: #954
Location: Bergen
Never had that sound on mine (3.0 Hdi)- To mee it sounds like old fashioned tappet/valve ticking. With our oil/hydraulic adjusted valves, oil change/oil pressure issues are candidates. This sound when warm could be low oil pressure and/or dirty oil channels. But I am very low in expertise here (compared to Citrofix !)
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 rabenson (2 Days ago)
Mon Aug 13 2018, 09:06am
Joined: May 22 2016
Member No: #2632
Location: Northallerton N Yorks
Thanks for your replies. 2ilent8cho, your engine does sound exactly like mine! Does it sound like this from cold or only when warm? Has it always sounded like this? Mine has sounded like this since I bought it a few months ago. It hasn’t changed in that time but obviously I don’t want to take any chances if there is a fault.

Tjensen, I’m going to cHeck the oil pressure etc and will report back.

Thanks again

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 321dave (Yesterday)

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