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2.7 hdi engine knocking noise when warm
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rabenson   
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 -

Thanks
MGmike   
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.
C6Dave   
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.
Website
arconell3   
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
Website
Citrofix   
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
rabenson   
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.

Ron
2ilent8cho   
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.
Tjensen   
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 !)
rabenson   
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

Ron
2ilent8cho   
Thu Aug 16 2018, 12:30pm
Joined: May 11 2016
Member No: #2626
Location: Stoke on Trent
rabenson wrote ...

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.


Thanks again

Ron


I've only had mine since May , so just a couple of months like you. She is warm at the moment so i will see in the morning how it sounds cold. The 2.7 in this C6 is the noisiest of all my cars but i don't have anything to compare it to other than your video. I was just in my older 2007 C5 with the 2.2 (173bhp) engine that was also available in the C6 and i did really notice how much quieter the 2.2 is. My 3.0 HDI V6 C5 is also much quieter than the 2.7.

I do have this feeling at the back of my mind that something is not right with the engine, mine is still kicking out black smoke/soot from the exhaust when floored or stationary when first started even with a service just being done. It also sounded very tappy on the motorway a few days ago.

Just wish there were people near by with a 2.7 C6 so i could compare noise and feel.
FraserG   
Thu Aug 16 2018, 09:37pm
Joined: Jan 05 2015
Member No: #2011
Location: Auckland
 Your 2.7 C6 shouldn't be smokey at all. I've never seen black smoke/soot from my exhaust which presumably is because all the auto pollution gear is working as it is designed to do.

Perhaps yours has been deactivated or is malfunctioning?
2ilent8cho   
Fri Aug 17 2018, 11:11am
Joined: May 11 2016
Member No: #2626
Location: Stoke on Trent
FraserG wrote ...

Your 2.7 C6 shouldn't be smokey at all. I've never seen black smoke/soot from my exhaust which presumably is because all the auto pollution gear is working as it is designed to do.

Perhaps yours has been deactivated or is malfunctioning?


I will have to get the garage to investigate one my wallet recovers from its last visit.

Here is my C6 engine noise when cold - Click Here -
MGmike   
Fri Aug 17 2018, 11:28am
Joined: May 21 2017
Member No: #3151
Location: South Queensferry
2ilent8cho wrote ...


The 2.7 in this C6 is the noisiest of all my cars but i don't have anything to compare it to other than your video. I was just in my older 2007 C5 with the 2.2 (173bhp) engine that was also available in the C6 and i did really notice how much quieter the 2.2 is.


That's interesting! My 2007 2.2 C5 has a horribly noisy engine compared to both my 2.7 C6's and my 2.2 C5 from 2005! It's also waaaaaay less fuel efficient only averaging 34 mpg compared to the older cars 40 mpg. Perhaps my suspicion that something is not right is true although Lexia doesn't say there's anything amiss.
Out of interest what do you get out of yours?
2ilent8cho   
Fri Aug 17 2018, 01:08pm
Joined: May 11 2016
Member No: #2626
Location: Stoke on Trent
MGmike wrote ...

2ilent8cho wrote ...


The 2.7 in this C6 is the noisiest of all my cars but i don't have anything to compare it to other than your video. I was just in my older 2007 C5 with the 2.2 (173bhp) engine that was also available in the C6 and i did really notice how much quieter the 2.2 is.


That's interesting! My 2007 2.2 C5 has a horribly noisy engine compared to both my 2.7 C6's and my 2.2 C5 from 2005! It's also waaaaaay less fuel efficient only averaging 34 mpg compared to the older cars 40 mpg. Perhaps my suspicion that something is not right is true although Lexia doesn't say there's anything amiss.
Out of interest what do you get out of yours?





I get low end 30's on average for my 2.2, but if yours is a 2005 C5 i think it will be the older 136bhp 2.2 not the newer 173bhp that was also used on the C6 . My C6 for the last 1100 miles says 25mpg for the average. The most fuel efficient i have is the 3.0 V6 HDI C5 as that does mid 30's around town and high end 40s on motorways. If i reset the trip and hold steady to the speed limit on a motorway i can get 33/34mpg average out of my 2.7 C6.
Paulius   
Wed Oct 03 2018, 09:19pm
Joined: Aug 14 2014
Member No: #1821
Location: Vilnius
 Finally a thread concerning tbe 2,7HDI sounds!

Mine sounds nice when cold, but when it's warm, it sounds like this:
- Click Here -
I think that it is a top-end tick or something related to cams/compensators. Also, there is this lower-frequency sound, that could be a fuel pump or something (?). I have no idea actually, ant it's quite annoying. Mechanics don't hear nothing.

However, I would say that this is a better sound than the one OPs engine produces... I would bet that it has something to do with low end..
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