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1982 Euro 500 SEC, 1985 300D Turbo Diesel (338,000 miles!), 1984 Euro BRABUS 190E
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So I read over the mercedes shop guide: MercedesShopWiki: Measuring Timing Chain Stretch

I don't have a dial indicator so I was just going to measure by the second method but I don't know what marks on the cam bearing tower and the sprocket thrust washer to align. I know what the camshaft is so I could probably guess what the bearing tower is, but I have no idea what the sprocket thrust washer is. I've done a valve adjustment before but still have no idea what marks I need to align to do it this method. Can anyone describe this procedure more thoroughly? Pictures would probably help if anyone has any.
 

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1959 220S cabriolet, 1983 240D original owner, 1999 E300 turbo diesel, 1988 560SL, 2003 SLK320
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So I read over the mercedes shop guide: MercedesShopWiki: Measuring Timing Chain Stretch

I don't have a dial indicator so I was just going to measure by the second method but I don't know what marks on the cam bearing tower and the sprocket thrust washer to align. I know what the camshaft is so I could probably guess what the bearing tower is, but I have no idea what the sprocket thrust washer is. I've done a valve adjustment before but still have no idea what marks I need to align to do it this method. Can anyone describe this procedure more thoroughly? Pictures would probably help if anyone has any.
I have a 1985 and it is a bit of a hassle compared to say my 1982 240D. Line up the cam marks on the drivers side cam tower. Clean everything with brake cleaner so you have a chance of seeing things. Mark the TDC line with white marker ink welders use. Make sure the cam marks are PERFECTLY aligned. It may take many attempts especially if you haven't decompressed the engine by taking out the glow plugs or the injectors. DO NOT turn the engine CCW(backwards)!! Once they are perfect, check the timing on the crank dampener(Clean well). You will see the TDC mark and if it is the original chain you will see that it is some amount past TDC. If it is more than 3 degrees, the chain is stretched.You could put in a replacement woodruff key to restore the cam timing but why bother with 300K?. Ive done the job with a dial indicator which you can buy from harbor freight for a few bucks but if you see you are 5 or 6 or more degrees out, forget it and put a new chain in before it breaks. These are interference engines and a broken chain will totally destroy the engine beyond repair. The other parts like the tensioner and the chain rail are part of the repair and usually come with the kit. While you're at it you'll have the chance to put in a new thermostat and maybe a short coolant hose and god knows what else. Or you could sell it while it's running. I wouldn't think about taking any trip any further than I could walk if I had an MB with 300K on the original chain. If you hear a timing chain clatter on start up, it is on death row!
 

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money pits of various forms
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Do not use the cam tower marks on the 85, it is not accurate at all. Do the 2mm lift method. The tools are a whole $30-40 and are needed to measure play on your disc brakes anyways. Also you should be aware this is NOT a measure of timing chain stretch, it is a measure of cam timing. In effect it shows the offset of the cam not how long your chain is. There is no recommended interval or description in the FSM about when to replace the chain. If there is no offset key I would start with that before replacing the chain. Poorly crimped chains fail. Sometimes your better off with what you know works than trying a new part.

Also do not use the Beasley/Easley method of IP timing on the 85, completely inaccurate. Works on 82-83 kind of. Its better to make your own drip tool and do it the right way. Of course the RIV light is the absolute best.
 
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