I did a search and can't come up with anything that makes sence to me.

I am going through the 83 300SD I just purchased so that I don't wind up with nasty surprises. at TDC (as aligned by the cam and casting mark) I show about 6 degrees. Confused about 2mm valve lift and specs so I didn't use a dial indicator (which I don't have anyway). My questions follow.

1. Must a dial indicator be used?
2. Is 6 degrees either a black, white or grey result?

If I need to use a dial indicator, would someone please help me make sence of it all?

Thank you

Don

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1980 300TD-T (82 Turbo and Trans) 159,000 Miles "Jackie-O"
1983 300SD 272,000 Miles "Aristotle"
1987 Jeep Wagoneer Limited - keeps the MB's off the ice and out of the snow
1994 BMW 530it

6 degrees is fine, but when it reaches 8 it needs to be replaced.

The method using the dial indicator is more accurate, but for just chain stretch the align the mark and read crank pulley method works fine.

If you wanted to re-set the cam timing with offset keys, you must use the dial indicator method.

That method works by measuring the exact point in rotation the valve starts to open. The degree reading is corrected for cam lift, etc, so that the proper number isn't 0, it's some other value, determined as the point at which a certain amount of travel is accomplished at the #1 intake (I believe, could be wrong). Hence this spec is something like 55 degrees or some such. Corresponds to TDC on both cam and crank, just a different way of getting the number.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Using the mark in the cam tower casting is inadequate for determining cam chain elongation. Personally, I don't think you could differentiate between 6deg and 8deg using only the notch and casting mark.

I was also confused by the dial indicator procedure the way it is written in the MBZ documentation. It took a little while but I did evenutally figure it out.

By using the dial indicator method, you know precisely how much elongation is in the chain.

The theory is that you use a dial indicator to measure a prescribed amount of valve lift and then read the amount of crankshaft roatation it takes to achieve a that valve lift directly off of the degree marks at the crankshaft pulley. MBZ offset Woodruff keys permit incremental adjustment of the cam sprocket to crank sprocket relationship to accomodate for manufacturing tolerances and routine wear in the cam chain.

Dial indicators aren't particulalry expensive and are handy to have for a lot of other tasks as well.

You should review the following procedure for the comprehensive method of determining the amount of chain elongation in your engine.

:http://www.peachparts.com/shopforum/showthread.php?threadid=64896&highlight=cam+timing

Here are the specifications for the valve timing events:
http://www.peachparts.com/shopforum/showthread.php?threadid=64144

Good luck,
R Leo

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Never a dull moment at Berry Hill Farm.

I always thought that 4 degrees was the limit for the camshaft to be out of sync with the crankshaft. Your engine is ready for an offset woodruf key in the cam timing gear or a new timing chain.

R Leo is correct that it is elongation, not stretch. The elongation is caused by wear on the chain pins and holes. The holes get oval shaped and the pins get worn on one side so the overall length of the chain is increased and the pitch gets slightly larger.

P E H

Where would I find the factory spec on elongation limits?

__________________
1980 300TD-T (82 Turbo and Trans) 159,000 Miles "Jackie-O"
1983 300SD 272,000 Miles "Aristotle"
1987 Jeep Wagoneer Limited - keeps the MB's off the ice and out of the snow
1994 BMW 530it