Grasscutter
New Member
Grateful for some advice if someone can help. I have a S203 with the M271 engine in 180K guise on a 53 plate. It's covered a reasonably trouble-free 120K mostly motorway miles and up until now has been MB dealer serviced, but home fixed if anything has failed. I'm ex-motor trade, but these days not so keen on spending time under the bonnet. The car was well used by the first owner, a friend of mine, and I bought it at 2.5 years old with 80K already on the clock. Ever since I've owned it, there has been a noticeable rattle on start up until it got oil pressure - although it seems it was only ever me who could hear it as funnily enough, during the last of the warranty, the MB dealer never could.
I didn't take much notice and accepted this was a noise I had to live with, thinking hydraulic tappets etc. Naturally the rattle hasn't got any better and am now having sleepless nights after reading reports of worn timing chains, tensioners and chains skipping teeth. The car starts and runs fine, however, I'd like to do my best to keep it that way. I can't afford to replace it right now, so thought I should check the condition of the timing gear and carry out preventative maintenance in preference to leaving it and running into much more costly corrective maintenance later.
Lining up the crank pulley to TDC, I thought a reasonable check of chain wear would be to see if the cam timing marks line up. Indeed the inlet is pretty well spot on. However the exhaust is retarded, but not by as much as a tooth on the sprocket. The attached pictures show the error on the exhaust cam relative to the inlet.
I believe the sprockets have a locating pin aligning them into the cam, so it is not possible to offset them. Is this kind of deviation normal on the 271 or is the adjuster built into the sprocket faulty? I can't find much information on the adjusters, except my research has lead me to the MB bulletin, AF05.20-P-1401AG, titled "Rattling noises after starting engine until oil pressure has built up" Apparently there have been at least 3 revisions of the cam adjusters to improve tolerances, minimise oil loss to stop rattling at start up until the adjusters have oil pressure. There is nothing to show what's inside the adjuster, how it works and if it is possible for wear in these to upset the static timing. Can anyone help me with this? Maybe I have found the cause of the start up rattle, but is it something I could safely go on living with?
I didn't take much notice and accepted this was a noise I had to live with, thinking hydraulic tappets etc. Naturally the rattle hasn't got any better and am now having sleepless nights after reading reports of worn timing chains, tensioners and chains skipping teeth. The car starts and runs fine, however, I'd like to do my best to keep it that way. I can't afford to replace it right now, so thought I should check the condition of the timing gear and carry out preventative maintenance in preference to leaving it and running into much more costly corrective maintenance later.
Lining up the crank pulley to TDC, I thought a reasonable check of chain wear would be to see if the cam timing marks line up. Indeed the inlet is pretty well spot on. However the exhaust is retarded, but not by as much as a tooth on the sprocket. The attached pictures show the error on the exhaust cam relative to the inlet.
I believe the sprockets have a locating pin aligning them into the cam, so it is not possible to offset them. Is this kind of deviation normal on the 271 or is the adjuster built into the sprocket faulty? I can't find much information on the adjusters, except my research has lead me to the MB bulletin, AF05.20-P-1401AG, titled "Rattling noises after starting engine until oil pressure has built up" Apparently there have been at least 3 revisions of the cam adjusters to improve tolerances, minimise oil loss to stop rattling at start up until the adjusters have oil pressure. There is nothing to show what's inside the adjuster, how it works and if it is possible for wear in these to upset the static timing. Can anyone help me with this? Maybe I have found the cause of the start up rattle, but is it something I could safely go on living with?