W202 C250 TD Knock/Clatter - MBClub UK

rayso · 09-05-2012, 10:01 PM

Hi,

I bought my C250 last year and have been very happy with it so far.

However, since I've had it, it has always had a slight knock/clatter at idle and also at about 1200 RPM. It's not a big deal, and doesn't seem to get any worse, so I'm not overly worried, but it would be nice to fix if it didn't cost a load of money.

I've read stuff about injectors, fuel additives, advanced timing, blocked oil holes in timing cogs, etc, etc.

One thing I noticed that is quite interesting, is that the knocking is vastly reduced/unnoticeable just after starting - from cold or warm. I did some reading, and found out that the glow plugs stay on for a period of time after starting to aid the combustion process - 3 mins. Funnily enough, the clatter gets noticeable worse after 3 mins. Could a dribbling injector be causing the knock and be masked by the glow plugs heating the fuel?

Finally, the other day I noticed a small amount of oil building at the bottom of the intercooler pipe that drops down from the turbo. I wiped it clean and after a few hundred miles I noticed a fresh oil deposit. I can't see any obvious leaks on the turbo, but can't all of it. I suspect that the oil feed from the engine block (or return feed) is leaking onto the intercooler pipe and running down. There is no smoking or anything like that. Could it be something as simple as a couple of bolts that need to be tightened or a new gasket required?

Thanks!

Steven

Dieselman · 10-05-2012, 07:17 AM

The knock is probably a squiffy squirting injector, try a strong dose of injector cleaner.
the oil leak is just breather oil mist condensing in the intake pipe ten leaking out due to a slightly loose clip, check and tighten them up.

rayso · 10-05-2012, 03:31 PM

Thanks for coming back to me. I believe the guy who owned the car before had tried that (or a garage did). He mentioned something about them using too higher concentration and dissolving some seals?! I'm prepared to try it though, any product recommendations? I presume if it is done correctly, there is no risk.

Cheers,

Steven

09-05-2012, 10:01 PM	#1
rayso New Member Join Date: Dec 2009 Posts: 10	W202 C250 TD Knock/Clatter Hi, I bought my C250 last year and have been very happy with it so far. However, since I've had it, it has always had a slight knock/clatter at idle and also at about 1200 RPM. It's not a big deal, and doesn't seem to get any worse, so I'm not overly worried, but it would be nice to fix if it didn't cost a load of money. I've read stuff about injectors, fuel additives, advanced timing, blocked oil holes in timing cogs, etc, etc. One thing I noticed that is quite interesting, is that the knocking is vastly reduced/unnoticeable just after starting - from cold or warm. I did some reading, and found out that the glow plugs stay on for a period of time after starting to aid the combustion process - 3 mins. Funnily enough, the clatter gets noticeable worse after 3 mins. Could a dribbling injector be causing the knock and be masked by the glow plugs heating the fuel? Finally, the other day I noticed a small amount of oil building at the bottom of the intercooler pipe that drops down from the turbo. I wiped it clean and after a few hundred miles I noticed a fresh oil deposit. I can't see any obvious leaks on the turbo, but can't all of it. I suspect that the oil feed from the engine block (or return feed) is leaking onto the intercooler pipe and running down. There is no smoking or anything like that. Could it be something as simple as a couple of bolts that need to be tightened or a new gasket required? Thanks! Steven

10-05-2012, 07:17 AM	#2
Dieselman Hardcore MB Enthusiast Join Date: Jul 2003 Car: Peugeot 403 Convertible Posts: 28,787	The knock is probably a squiffy squirting injector, try a strong dose of injector cleaner. the oil leak is just breather oil mist condensing in the intake pipe ten leaking out due to a slightly loose clip, check and tighten them up.

10-05-2012, 03:31 PM	#3
rayso New Member Threadstarter Join Date: Dec 2009 Posts: 10	Thanks for coming back to me. I believe the guy who owned the car before had tried that (or a garage did). He mentioned something about them using too higher concentration and dissolving some seals?! I'm prepared to try it though, any product recommendations? I presume if it is done correctly, there is no risk. Cheers, Steven

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