Funny metallic tappy noise S320cdi

mjc54321

Member
Joined
Aug 18, 2009
Messages
12
Reaction score
0
Your Mercedes
S320 CDI
.........actually not that funny but definatly tappy.

I am wondering if anyone has suggestions as my local garage are looking blank.

I have a tapping noise which can be heard clearly when windows are down and car is being driven around a multi storey car park, it's most noticable when ascending ramps ie when engine comes under load. It can also be heard when driving down narrow streets when the sound bounces back of buildings etc.

We have changed auxillary belt and 2 tensioners which were worn.

It tends to be worse when hot.

Cheers in advance for any advice.
 

television

Always remembered RIP
Joined
Mar 14, 2005
Messages
164,073
Reaction score
332
Age
86
Location
Daventry
Your Mercedes
2002 SL500, 216 CL500, all fully loaded
Is the noise within the rocker cover
 
OP
M

mjc54321

Member
Joined
Aug 18, 2009
Messages
12
Reaction score
0
Your Mercedes
S320 CDI
  • Thread Starter
  • Thread starter
  • #5
Is the noise within the rocker cover

hi, it's difficult to tell as it will only tap when stationary when you blip the accelerator and not always then. Initially I thought it sounded like a manifold leak(which has been checked and tightened as it was a little sooty around manifold) mechanic is now sure this is not leaking. He was thinking perhaps a cat but he really is stumped as he called me in to have a listen as he is reluctant to needlessly bolt bits on.
 

Alex Crow

Senior Member
Joined
Jul 9, 2009
Messages
10,677
Reaction score
40
Location
Super Suffolk
Your Mercedes
W169, W124, w202, W203, KTM 250 EXC, VW T25 camper and a Polo in a pear tree
i think colin may have it.

get your mechanic to have a look under the plastic covers on top of the engine to see if the injectors are leaking.
 

Alex Crow

Senior Member
Joined
Jul 9, 2009
Messages
10,677
Reaction score
40
Location
Super Suffolk
Your Mercedes
W169, W124, w202, W203, KTM 250 EXC, VW T25 camper and a Polo in a pear tree
not on a cdi JT.
 
OP
M

mjc54321

Member
Joined
Aug 18, 2009
Messages
12
Reaction score
0
Your Mercedes
S320 CDI
  • Thread Starter
  • Thread starter
  • #8
Had the covers off this morning and the injectors are all clean no soot or oil or diesel so presume they are ok.
 

BlackC55

Senior Member
Joined
Feb 23, 2007
Messages
2,488
Reaction score
0
Location
South coast
Your Mercedes
C43
The noise you are talking about is normal. Loads of them do it. According to MB there is no cure.
 

Alex Crow

Senior Member
Joined
Jul 9, 2009
Messages
10,677
Reaction score
40
Location
Super Suffolk
Your Mercedes
W169, W124, w202, W203, KTM 250 EXC, VW T25 camper and a Polo in a pear tree
The noise you are talking about is normal. Loads of them do it. According to MB there is no cure.

what makes the noise then blackc55?? tell us everything.
 

turbopete

Senior Member
Joined
Feb 4, 2009
Messages
14,204
Reaction score
328
Age
46
Location
Spennymoor
Your Mercedes
2010 '60' Ford Mondeo 2.0TDCi Zetec (sorry)
and there i was thinking that was on the older stuff, pre cdi. i was told that the cdi engines didnt make that rattle as they run at higher pressure so the injector couldnt rattle! then again, much of what ive been told in the past has been incorrect, and this may be another instance of duff info!
 

Xtractorfan

Senior Member
Joined
Nov 16, 2007
Messages
6,084
Reaction score
156
Your Mercedes
S class
You could try using some 2 stroke oil in your diesel, some people swear by it, stay away from supermarket diesel..or if using it deffo use the 2 stroke, the other thing you should make sure is to use the MB genuine fuel filter.. I have heard the noise you talk about but have dismissed it as being normal...
 

David Nock

Senior Member
Joined
Jun 1, 2007
Messages
654
Reaction score
1
Location
South Yorks
Your Mercedes
CLK/2009/320CDI
Is your noise like mine and does my update at the end help?
Mine is a new V6 320CDI.

See if this link works:
forums.mercedesclub.org.uk/showthread.php?t=42109&page=2

No, I can't make the link myself. Search under 'restricted', then look at page 2 of 'initial thoughts of driving a 320 cdi' (post by brandwooddixon).
 
Last edited:

malcolm210

Senior Member
Joined
Aug 21, 2005
Messages
5,067
Reaction score
1,920
Hi,
From memory, I think there is a known issue with the 320CDi IL6. Some engines have a tendency to knock on load from low revs. MB did some investigation on this symptom and concluded that it was a slight amount of piston slap on cylinder no.1. As you can imagine some owners with new cars were not very impressed and pushed for engine changes under warranty. MBs official line was that the engine would suffer no long term internal damage from this. I havn't heard of any engines suffering from collapsed pistons or serious internal damage so I guess their conclusion was right.

Hope this helps)

ps. I do remember some posts on this subject on the forum, so might be worth doing a search.
 

Peter Best Insurance is a leading specialist in Mercedes-Benz insurance. All MBO members are eligible for exclusive rates on all our classic car policies.
Call now for our 'BEST' quote. Tel: 01376 573033
Top Bottom