I am still trying to find my missing mpg on my 1980 240D.

I measured chain stretch using the cam tower hash mark method and the indicator was at about 8*.

Should I correct this much stretch with a woodruff key or buy a new timing chain?

I will take pictures and post them over the weekend. I am going to do the dial gage indicator method to compare the 2 results.

In the meantime, I am interested in thoughts on this......

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Current Mercedes
1979 maple yellow 240D 4-speed

Gone and fondly remembered:
1980 orient red 240D 4-speed

Gone and NOT fondly remembered:
1982 Chna Blue 300TD

Other car in the stable:
2013 VW Jetta Sportwagen TDI / 6-speed MT

I wouldn't fool around with a woodruff key, just roll in a new chain if in fact your stretch is 8 degrees.

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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"

Sounds like it's new chain time. Should help in many ways. Go over to Cervans rack damper pin thread and have a look. Part of the thread has to deal with low fuel milage as well. Especially on 240ds. One of my own interests actualy.

I could never get past the 5-6 miles milage difference between otherwise identical good running simular examples of them. The cause of it seemed very ellusive. Perhaps at last not now.

I amk w/ stevo.

reduce the error instead of adding error to a very critical part of your drivetrain.

"if in fact, your stretch IS 8*"

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Throw in a 4* offset key and set the injection timing.

+1

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Scott
1982 Mercedes 240D, 4 speed, 275,000
1988 Porsche 944 Turbo S (70,000)
1987 Porsche 911 Coupe 109,000 (sold)
1998 Mercedes E300 TurboDiesel 147,000 (sold)
1985 Mercedes 300D 227,000 (totaled by inattentive driver with no insurance!)
1997 Mercedes E300 Diesel 236,000 (sold)
1995 Ducati 900SS (sold)
1987 VW Jetta GLI 157,000 (sold)
1986 Camaro 125,000 (sold - P.O.S.)
1977 Corvette L82 125,000 (sold)
1965 Pontiac GTO 15,000 restored (sold)

Understanding the ease of this task is reasonable. It makes alot of sense and is a factory approved method.

The other side is the one that errs on the side of caution. If this is a car you pamper, you will not want to ruin the cam sprocket and crankshaft timing gears by wearing them down with an elongated chain.
These gears were made to be replaced w/o removng the engine ,But i would never wish that upon anyone. By practicing (overly) preventive maintenance, you save yourself some effort in other ways.

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Don't for get the timing chain guide rails too.
I have read a lot on the Forum concerning replacing the Chain and the Chain Tensioner but not about all of the other parts that also wear as until now no one has made much comment on them. I say good call.

I would think that the Crankshaft Drive Gear would have the most wear of all the gears on it as it has less teeth to spread the load over and has the full load of pulling everthing else.
Also, if a timing chain has 8 degrees of stretch and your Oil Pump is chain driven it could be a good idea to ceck that also and the Oil Pump Chain Tensioner.

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84 300D, 82 Volvo 244Gl Diesel

I am weighing the options of DIY versus indy.....

I can certainly save some money by buying my own parts and DIY, but the cost of the chain press might make up for those savings (as well as my time and tears).

How many hours would a specialized shop require to do this job?

__________________

Current Mercedes
1979 maple yellow 240D 4-speed

Gone and fondly remembered:
1980 orient red 240D 4-speed

Gone and NOT fondly remembered:
1982 Chna Blue 300TD

Other car in the stable:
2013 VW Jetta Sportwagen TDI / 6-speed MT

According to the factory service manuals, it is allowable to use a woodruff key up until the point you can no longer eliminate the stretch with one. Having said that, there is certainly no harm in installing a new chain. You can get a woodruff key for around $10, a chain is around $120. FWIW, I put a woodruff key in mine.

Scott

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Scott
1982 Mercedes 240D, 4 speed, 275,000
1988 Porsche 944 Turbo S (70,000)
1987 Porsche 911 Coupe 109,000 (sold)
1998 Mercedes E300 TurboDiesel 147,000 (sold)
1985 Mercedes 300D 227,000 (totaled by inattentive driver with no insurance!)
1997 Mercedes E300 Diesel 236,000 (sold)
1995 Ducati 900SS (sold)
1987 VW Jetta GLI 157,000 (sold)
1986 Camaro 125,000 (sold - P.O.S.)
1977 Corvette L82 125,000 (sold)
1965 Pontiac GTO 15,000 restored (sold)

I just did the job this weekend with my wife helping me. I was 7-8 degrees retarded.If its over 3 you should think about a new chain.i bought the chain kit from mercedes source. i used a chain compression tool. and with the type of master link they sent me, it was ESSENTIAL to press on the end link plate and create the mushroom shape on the end pin.You then sell the tool for a slight loss to the next guy which is what I will do after I do my other MB, a 240 D. I will sell it on this forum. Some brands of chain do not require this tool. The tool works wonderfully(made in Germany of course!)You can hand peen the end with a punch but I decided the risk of doing that poorly and having the chain fly off was too great. I also discovered a broken chain rail which was ready to break loose and destroy the engine as well. Jeez! It's a big job so don't tackle it unless you do it right. It's necessary to pull off the thermostat housing as well ....with more gaskets and hoses. Often the housing is corroded so bad it's junk, so back to ebay or the junkyard for more parts. Then you need 2 gallons of MB coolant...don't use prestone....a new thermostat, new chain tensioner, of course the valves need adjustment etc etc. It gets a bit involved and somewhat pricey ...good luck! It went well and my car goes like a scalded cat but I'll admit I was a little nervous. If you make a mistake like dropping parts in the engine, you have to take the engine apart.......if you slip a few cogs on the cam....more work to get the timing right....you have to do the job by the book. If you do, it's not hard. To actually roll the new chain in took my wife and I less than an hour and that included the grinding and the swaging of the master link but it's a job that while easy requires great care and patience and 2 people! It's a job worth paying for if the guy doing it knows his stuff. I had estimates of $500 to $900. If the engine is great otherwise, you must do it to save the engine. If the compression is down, oil burning, smoking etc, forget it. Get a used engine and put it in. Do the chain out of the car..way easier job.

Well, it seems like if I go with a new chain, I am looking at a chain, tensioner, rails, press (maybe I can borrow one), and possibly new oil chain and oil chain tensioner (have no idea about THAT job!)

Seems like I am up in the $500-$1k range DIY, so I shudder at how much an indy would charge.

I will measure with the other method this weekend and think about my options and report back

Thanks for all your comments so far!

__________________

Current Mercedes
1979 maple yellow 240D 4-speed

Gone and fondly remembered:
1980 orient red 240D 4-speed

Gone and NOT fondly remembered:
1982 Chna Blue 300TD

Other car in the stable:
2013 VW Jetta Sportwagen TDI / 6-speed MT

No oil pump chain to worry about but it wouldn't hurt to pull the pump and check the bushings inside for ware.

__________________


1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"

Besides the stretch of 8 degrees. You probably have no proof the chain is not the original one. I noticed your overall indicated milage reading.

Even if it is accurate the chain might have been in service almost too long already. May be dangerous to exceed 300k on the original chain. Thinking fatigue. The gentleman that pointed out sprocket wear is correct as well. The other problem i feel occurs. As wear progresses it actually increases at a faster rate. This may be subject to some consideration . Some people do not believe that but I personally do.

Total agreement with worn parts continue to wear at a greater rate. I read the same in a Motorcycle Engineering book (that is lost in my house somewhere).
In the book they had a section on chain/sprocket wear.
As the sprocket wears the chain rides up higher on the gear teeth. In a sense the chain is trying to ride up over there top of the tooth of the gear but a machined part of the gear holds it in position. When that portion of the gear wears the chain moves up on the tooth stressing the chain and wearing the tooth in at a point it is not supposed to wear at.

It is sort of like the distance between the Chain Links and the Gear Teeth are timed to each other.
A new Gear with a stretched Chain is not timed well; a new Chain with an old Gear is not timed well either.
That is my opinion

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84 300D, 82 Volvo 244Gl Diesel