I have a 1995 E300D and have a small oil leak that is spotting my driveway. I brought it into a local non-mercedes garage and they told me the leak is coming from the CAM Chain Tensioner O Ring. He said he would fix it but was very worried that if he did he might mess up the timing chain. He called around the local area and no one has ever changed one before.

My question is: what is the proper procedure for changing the O Ring or is it best left to the dealer. We've tried looking in a number of the typical aftermarket repair books but can't find any information about this.

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1995 E300D Black 170K miles

What I know about brand new 10 yr old Benz can fit on the head of a pin.... But it sounds like your mechanic is wisely worried about slacking the chain so it drops off the crankshaft sprocket below. If it was me replacing the chain tensioner O-ring, I'd think about removing the rocker arm cover and keeping the chain tight using bailing wire and/or bungie cords from above. Ask your mechanic about this approach to the situation.

I took the mechanics advise and relunctantly took it to the dealer to change the o-ring. After spraying the engine over with their white tracer paint and doing everything they could, they called me and told me they couldn't find a leak anywhere.

Seems that when my mechanic changed the oil with Mobil One 5-40W, the additives or the thickness of the oil sealed the small leak. The dealership said keep an eye on it.

I know it was leaking 'cause my driveway has a whole bunch of 50 cent piece size spots on it.

Thanks for the reply, I'll keep my fingers crossed.

Brian

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1995 E300D Black 170K miles

FWIW, I had the same problem with my 95 e300d in March of this year. Once the car warmed droplets of oil would drip from the chain tensioner. But wouldn't drip at idle. Revved the motor a bit and would get a drip every minute or so. Anyway I thought about replacing that o-ring as well. But before going through that trouble I gave the chain tensioner nut a 1/4 - 1/2 turn and it stopped dripping. Not a drop since. YMMV.

Found my old thread with pics....also, is the seal and o-ring or crush washer...I'm not sure...didn't end up pulling the tensioner.

OM606 oil leak (95 e300d)

FWIW, I had the same problem with my 95 e300d in March of this year. Once the car warmed droplets of oil would drip from the chain tensioner. But wouldn't drip at idle. Revved the motor a bit and would get a drip every minute or so. Anyway I thought about replacing that o-ring as well. But before going through that trouble I gave the chain tensioner nut a 1/4 - 1/2 turn and it stopped dripping. Not a drop since. YMMV.

Thanks for the previous thread information. I'll give it to my mechanic. I've driven it a few thousand miles since changing the oil and not a single drop has been seen on the white tracer paint.

But.....Murphy will be back from vacation so wi'll try torquing the chain tensioner to 80nm.

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1995 E300D Black 170K miles