So, I've moved back to New Mexico and "Trudy," my 1972 220D needs some serious refreshing. I know the timing chain is stretched 5-6 degrees just from using the timing mark on the camshaft and the mark on the crankshaft balancer. I'm hoping that 5deg is chain alone. If it already has a woodruff key installed, then we're talking serious stretch. The car runs great though so I'm thinking it's just the original chain.
Anyway, like the thread title says, should I woodruff key the gear and refresh a few things while I'm in there or should I just roll in a new timing chain from the top?
The former is way cheaper but takes marginally more work.
The latter is the better, longer term solution but way more expensive.

The car still has great compression on all four cylinders. Still has good pickup, even at 7000+ feet altitude (I've adjusted the IP and linkage to compensate for the lower air density here.) Still needs the IP to be timed better to the engine. I know my chain stretch and black smoke tells me that.

Opinions?

Thanks all.
Phil Forrest

__________________
1972 220D "Trudy," named by a friend.

"The 220D sounds good... I suspect it is the only car that you need a calendar for, rather than a stopwatch, when doing acceleration tests."
Tom Abrahamsson

Do the best that you can afford. You clearly know which is the better solution. And only you can decide if you can afford it.

__________________
1968 220D, w115, /8, OM615, Automatic transmission.
My 1987 300TD wagon was sold and my 2003 W210 E320 wagon was totaled (sheds tear).

Hey Phil, I'm not far from you in ABQ. North 14, right? We should meet up sometime. I too like W115 diesels.

As for deciding to replace the chain or go with an offset key, I just went through all of this myself on the '74. I decided to go with an offset key.

I started by measuring the cam timing in relation to the crank following the "2mm #1 intake valve down" method. I found the cam to be behind the crank by about 3.5 degrees from the specified range, at the crank (1.75 degrees at the cam).

I read into it and came to the spot you are now - chain or offset key? More information and thought was needed.

One thing I did was to check for an offset key being in there to begin with. I was able to do so by loosening the cam gear bolt part way and pulling the gear forward enough to have a look at the woodruff key. I used the bolt to stop the gear from coming all the way off, to provide just enough of a slot to shine some light on part of the key. I was able to do it without pulling the exposed slide rail. I found that my engine did not have an offset key.

Something I read about was damaged teeth on the timing related sprockets, and the need to replace the cam, crank, and intermediate sprockets, and maybe the injection timing device too. The damage is caused by the chain rollers contacting the teeth in the wrong way, from them wearing on the pins that center them. So I took a close look at teeth on the cam, the intermediate wheel, and on the crank sprockets. After cleaning the oil off in places and using magnification I could see a wear pattern down in the space between the teeth, but I could still machine marks on the fronts and backs of the tooth tips. Nothing indicated to me that an advanced wear patter had set in.

With that information I decided to go with the offset key, one that advances the cam 2 degrees (4 degrees at the crank). In the process of doing that I dropped and lost the offset key! There's a thread devoted to that recently updated chapter . . .

Now, If I had found an offset key in there to begin with I'd have wanted to install a new chain. But in the '74's case I figured I could go for a while on the offset key, since the "stretch" was not so bad with a straight key installed.

And something funny I discovered during the hunt for the lost woodruff key was that the engine had a new chain installed at some point anyway, albeit with unknown hours use as of now.

Sum: Do the 2mm intake test to get a firm number on how far behind the cam is. See if it already has an offset key. Check for wear on other components. Make decision.

I've got the dial indicator for doing the 2mm test. I'd help roll a new chain in if you decide to go that route. I'll send my contact information via PM.

Where's Stretch with all his links?

__________________
- Greg -
1973 220D, The Prodigal Benz
1974 240D

Just want to chime in here to say I'm in the same boat as Phil.

I can't offer any guidance but I would be happy to send an extra injection line if you would like to make a "drip tube tool". PM me with your address.

Also, thanks Gregory for the info.

I have a new chain on order for my OM617. As a race engine, it's cheap insurance as I have NO clue about the state/age of the existing chain. Besides, I want to advance the cam a bit for performance reasons - the guys in the Diesel Performance section say it's a power-adder and I need all I can get. So 2* and a 5* key are also coming.

Really, I just wanted to say that this thread is what makes this forum worthwhile! I love that the OP got helpful support without a lot of crap!

Yea, US!!!!

Dan

Re racing, I would think retarding the valve timing would give more power at high rpm, since that is true in gasoline engines, and it is the same issue of getting max air charge into the cylinder. Gas engine "timing sets" often have 3 or 7 keyways so one can pick an advance or retard from the "straight up" design. Advance gives better low rpm performance (torque) and mileage. Drag racers go w/ the retarded settings. They don't care about low rpm because they rev the engines at the starting line and release the brake, or slam the tranny in (sometimes explodes). I had a friend who drag raced a Pinto and would retard the timing (rubber belt) one tooth before racing.

Re an offset Woodruff key, I see no issue using one as long as the chain isn't so worn that the teeth aren't meshing correctly. If you ever fooled with bicycles, you know you need a new chain when it only contacts the first teeth and is slack behind. Too worn and the chain starts skipping on the front sprocket. Otherwise, there is already plenty of slack in the timing chain, so as long as the tensioner can keep it tight on the return side, there should be no problem.

I am fooling with this currently, and trying to get a good measurement with my dial indicator. Last time I checked my 1984, it had 2 deg crank retard, which is the factory 10,000 mi wear-in spec, but I recall using the marks to measure that (inexact). I replaced my tensioner chain because the original was riding cocked (contact circles ~1/2 off) and the rubber liner appeared hard & cracked when I removed it.

__________________
1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans

Right Bill - I misspoke, thinking about advancing the IP timing. Silly me!

Dan

Ok folks, so gmog220d (Greg) helped me out a ton the other day. We got a few things sussed out: oil change, valve adjustment, checking timing with the 2mm method, pulling out my cam gear to see the offset key and were finally left with the question of what is a #18 camshaft? More specifically, we couldn't find the cam timing specs for the #18 camshaft, which is what my engine has on it. From the tag on the block, it looks like it is a Mercedes-Benz rebuild.

Things I thought I knew before working at Greg's shop:
-The timing chain was stretched about 5 degrees using the camshaft notch/tower notch against the crank.
-The IP definitely needs timing.

After the work:
-I have a camshaft with 18 stamped in the back.
-18 is not listed for cam timing specs.
-Against the 2mm valve test, my crankshaft balancer reads 16~17 degrees.
-Cam gear wear is very minimal. Teeth look good. Chain looks good.
-I have what we think is a 2deg offset key installed right now.
-My IP was missing the overflow banjo bolt/drain tube.
-I really should replace my front main seal...

Now, do any of you folks with the super secret Mercedes knowledge have the timing specs on that #18 camshaft?

Thanks all!

Phil Forrest

__________________
1972 220D "Trudy," named by a friend.

"The 220D sounds good... I suspect it is the only car that you need a calendar for, rather than a stopwatch, when doing acceleration tests."
Tom Abrahamsson

The W123 FSM has a bit of information about the OM615 in the non turbo section

http://www.startekinfo.com/StarTek/outside/12265/disc_2/program/Engine/615/05-215.pdf

There is a 08 cam specified for the OM617 (non turbo) but I wouldn't feel safe using those specifications just yet.

My (non turbo) OM617 had a non listed code (code 11 if I remember correctly) which also made me wonder about woodruff keys...

...someone (I think it might have been JT20 - what ever happened to him?) looked up the data for me in EPC and there was more information about my cam code. In my case it turned out to be the same as code 08 and was specified in EPC as such.

(so after all that information)

Check in EPC - there might be some information in there.


I personally would just replace the chain.

I did a little bit of measuring based research on these woodruff keys and determined that their supposed correction values are a bit off. (I can link to this if you're interested)

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

Glad to see this posted Phil.

Cam #18 was a surprise to me. I've done the 2mm test on a few cars and always found the cam code on the chart. I'm interested to see how this one shakes out.

G

__________________
- Greg -
1973 220D, The Prodigal Benz
1974 240D

Bump.

Phil Forrest

__________________
1972 220D "Trudy," named by a friend.

"The 220D sounds good... I suspect it is the only car that you need a calendar for, rather than a stopwatch, when doing acceleration tests."
Tom Abrahamsson

Hey Phil, Looks like it's time to give Benz a call about that cam code.

__________________
- Greg -
1973 220D, The Prodigal Benz
1974 240D

My W115 71 220D where the engine is actually a 1973 220D has a camshaft # that was not listed in the manual too. It might have been a #18 as well. I was trying to make sure it has the correct camshaft for the valve rocker arms and nuts (soft vs hardened), but never was able to figure it out.

On the chain situation, when I had the engine apart, I closely inspected my chain and saw 2 tiny metal shavings embedded in the chain links and preventing the chain from swiveling the way it should in two spots, so I had to replace it. If it hadn't been damaged, I would have reused it with an offset key (about 6 deg. stretch).
Against everyone's recommendation, I decided to use the beck/arnley chain. The reasons (not necessary in order of importance):
1. It is a continuous chain and doesn't have to be crimped (obviously it can only be installed with the crankshaft and all guides out of the block).
2. It is made in Japan.
3. It costs $45 shipped.

The IWIS chain may be better, but it costs $120, the crimp tool is very expensive and there is the chance that you might not crimp it correctly.

That is why I would vote for using an offset key unless you are doing a full rebuild, but that's just me

Now a question for you - You said "I've adjusted the IP and linkage to compensate for the lower air density here."
can you elaborate on that?
I am in Salt Lake City (4400 feet altitude) and I get gray smoke when first taking off in 1st and halfway trough second, and through 3rd and 4th I see some black smoke when accelerating. My diaphragm spring had 2 thick and 1 thin shim, I removed the 2 thick shims and the smoke seems much less - I assume that the same amount of vacuum will now be able to pull the rod a little more toward less fuel. What else is there to be adjusted? And what about the ip linkage? Maybe the tickler shaft engagement - it is half ball length right now (per FSM), maybe increase it to full ball's length so that at idle and low throttle, the tickler is slightly more pulled back and applies less fuel?

X2 this is an EPC / WIS look up problem now

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

Called the Albuquerque, NM Mercedes dealership and talked with parts for a minute who knew exactly what i needed and transferred me to the service department. The parts guy is great but he just didn't have the service system access to find the timing for that camshaft. So, this was formerly the most helpful Mercedes dealership for odd questions I had on my old diesels. I've inquired a bunch of times about my old 1979 300D as well as my current 220D. This last call to the service department was unacceptable. After explaining my issue in detail, the service rep said, "You're free to bring it in for us to check it out and we'll correct your timing.You probably need to upgrade to a double row chain and need all the other parts in there replaced" I replied, "I have a double row chain and I'm going to do the work myself, I just want to know how the camshaft is timed since this code is not in the FSM." He said, "Well, there are forms online for that." And I promptly hung up on him.

I'll see if one of my contacts in north Jersey can help me with that code.

Now to the adjustment of the IP in tedd's question.

tedd, I removed one of the thick spacers under the diaphragm spring then have been tweaking the linkage to get the air/fuel proportion correct. I think, as the fuel impulse is a set amount per-injection, the throttle body linkage has to be adjusted separately. This is the one that crossed over the valve cover. I lengthened it this morning by one full turn on each end and she's smoking a lot less. There was some gray smoke but now it's only black after the car is warmed up. As the engine and IP are set nominally for sea-level, the lower air pressure at higher altitude will result in slight air starvation, even if the linkage is adjusted proportionally because of the log change in oxygen with altitude. Really, I need the engine and IP to be timed properly before I could get this mixture correct.

Thanks all for the help.

Phil Forrest

__________________
1972 220D "Trudy," named by a friend.

"The 220D sounds good... I suspect it is the only car that you need a calendar for, rather than a stopwatch, when doing acceleration tests."
Tom Abrahamsson