Would changing my pump timing change the timing chain stretch from 3 to 5 degrees?

Should I change the timing chain - it is now showing 5 degrees of stretch?

Plus, back to my black smoke - since this is new SINCE I timed this injection pump, I'm assuming this is unburnt fuel - is it more likely to result from too far advanced or too retarded pump timing?

ryan

__________________
RG Newell

1984 300D
1972 250
1986 560SL
1991 300CE

Well changing the pump timing is not going to change the chain stretch. That is a wear factor. How did you read the stretch? Always turning engine in the same direction? By the crank bolt?

I believe black smoke is a sign of injection being retarded. I would try marking the flanges with a pin punch so there can be no confusion. Try your car with the pump moved to between the two current marks. The mark you started with and where you landed up. If no longer pinging and smoke is gone stay there for now. Another way to look at is you want that pump as much toward the original mark if I read your marks correct. That being towards the block consistant with that pinging not being present. Half way between is a good place to try. . It may be just fine.

Really to do the stretch measuring properly you have to use the dial gauge method to be accurate. Make sure to read the postings on checking chain stretch as well. There will be lots in the archives.

Congratulations, You learnt something by tackiling it yourself. From now on it is easier. I suspect a few members are mulling over your results. I am not perfectly clear in my mind myself. If you did the timing all alone and the hand primer was leaking bad there might be a little discrepancy entered into the end results. The loss of the pinging noise does mean the pump was too advanced since it is now gone.

Barry,

Thanks for your response - I tried all afternoon (literally) to use the dial gauge w/o success. I just couldn't figure it out and a 1 inch lift dial gauge really doesn't help. Frustrating, but I think my problem was I couldn't keep the gauge perfectly still and tight in position - I think it was moving just a bit.

Anyway, I lined up the marks on the cam tower - did this several times and each time it comes out 5, 5.5 degrees of stretch. Before I drove the car to Ohio, it consistently measured 3 degrees... I just thought of something - I rotated the engine using the power steering pump???

I have no idea if there is a woodruff key in or not, I am thinking of just rolling in a new chain - and replacing the tensioner. I have looked over this chain and I think it's the original- I see no riveted link anywhere.

As to the smoke, if it results from timing being retarded, then I need to move the pump CLOSER to the engine as I didn't advance it far enough, right?

ryan

I am planning on driving this car over 3000 miles in the next month - so I am just trying to get things lined out much as possible.

__________________
RG Newell

1984 300D
1972 250
1986 560SL
1991 300CE

On reviewing your posts you have taken the top of the pump closer to the block and the pinging has stopped. Do I have this right? I find this the exact reverse of what I would have expected. Both from the pinging perspective and the black smoke on reflection.

Trying that intermediate setting between the two still applies. If the smoke goes away and the pinging is not present leave it there. . There is some kind of issue hiding here somewhere in my humble opinion. Should not impact reliability in my opinion either and you are driving three thousand miles soon.

Normally I would have thought you would have smoked more in your former setting. For some reason that was not the case. Thats the primary reason I am suggesting the intermediate setting. It is still more advanced than your original setting was. Again if there are no negative effects at that point stay there.
I am not sure what is really giong on. You did not loosen the two nuts on the nipple flange where the injection line for #1 screws on the pump did you?

One last thought for now. Your air filter is in reasonable shape? If really obstructive car will not burn all it's fuel. Again though it is probably just fine as the smoking started with the timing change.

I had a non-Mercedes fuel injection pump with retarded/late timing and it put out a lot of billowing white smoke.
When the pump was timed OK the white smoke went away.
Oddly I am having a similar problem to yours but not nearly as bad. When I first start up and let it idle I am getting some hazy smoke for about 1 minute or so. Maybe my pump is a litte too advanced also.

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84 300D, 82 Volvo 244Gl Diesel

The smoke is not that bad and I do notice some on acceleration - I think it's a little worse than before...I'm not too worried about the smoke at this point - except as to what it tells me about the injection pump timing. I'm sure I had smoke before, just didn't pay much attention...

This car has the MW injection pump with the mechanical governor.

I really went to timing this thing because of new injector nozzles, sluggish starts from stop, and then the engine pinging - which was VERY noticeable on the way home from Ohio. Advancing the timing (moving the pump CLOSER to the engine has helped the pinging especially)...And I didn't touch the nuts on the pump flange and I have a new air filter.

Now, I am more concerned about the timing chain and if I need to change it out before I leave...

I have read thru all posts regarding replacement vs. key, and I don't really see the benefit in putting in a key, especially since I suspect this is the original chain (I have maintenance records going back years and I see where changing the chain was recommended, but I don't think it was ever done). If I decide to replace the chain, I am going to replace the tensioner as well. Has anyone done this? Do you really have to remove the AC and bracket, as well as the fan and water pump pulley?

I will experiment with the timing issue AFTER I sort out the chain issue...

ryan

__________________
RG Newell

1984 300D
1972 250
1986 560SL
1991 300CE

A lot of members have changed their chains. Locating a proper tool locally to deal with the chain link peening is probably the biggest problem. The other problem with keeping an older stretched chain is it slowly damages the sprockets the longer it gets.

The other concern is your reading 5-5.5 degrees stretch now. Yet reading only 3 degrees stretch only a month ago. If the additional stretch has really occured it could be signalling something is changing fast. Far too fast.

Most believe the chain fails because of a problem with another component. This may not be totally true in all situations. I find myself wondering if the pinging that became noticeable during the trip but not present during the initial part of the trip. Could that have been because of a sudden elongation of the chain? Moving the pump ahead seems to have gotten rid of it. That almost proves it in my mind.

When stretch is present the chain may side whip a little when running. This produces a lateral force component. If that over time does fatigue the side links the chain is going to let go at some point.

Still something funny here though. Or I should say at least beyond my grasp at the moment. Needless to say if the chain had suddenly elongated it would have retarded the injection pump and cam. That should not have induced the pinging. In effect it was just retarding the pump. I think the cam change was not signifigant enough as well but may be wrong here. Also strange the pinging should lessen when advancing the timing.

Since you are pretty sure your elongation tests where done by the same method. I would change that chain much sooner than later as you are questioning the sudden apparent change. At first I suspected it was just your method for the strange change in the readings. Not sure at all now when thinking this whole thing through.

I am a very slow thinker at times but re reading your posts seems to indicate you probably know what you are doing. Or at least enough to be in control of the situation. Some of the questions you have now seem to possibly add up. Not all mind you but certainly some.

You may also have noticed something almost by accident. Some chains might issue a warning. Most of us will never catch it though if true. A sudden increased of stretch rather than over time. We expect a new chain to stretch a little fairly fast when entering service. Not a well used chain to gain 2-2 1/2 degrees apparent increased stretch in a months use. Almost double of what it initially aquired over a lot of years.

Sorry about some of my earlier questions. There was no intent to question in any form of negative fashion. It was basically because things were not adding up correctly. Still are not totally but the chain has to go. In my opinion it is too risky not to change it. The 5.5 degees of stretch do not disturb me. Its the apparent rapid rate of change that does.

When you get the old chain off clean it in solvent. Examine all the links with a magnifiying glass on both sides. If no cracks are found side load the chain over various areas. See if the chain forms the same side radius over its length. Or are there almost kinks in areas. Post good or bad. It may help others down the road.

There have been recomendations by obscure parties to change chains out at every 150k. You might have discovered the reason it is mentioned here and there from time to time. Hindsight is great but those parties might have experienced or seen evidence of fatigue in some chains. Just a thought at this point.

Barry,

Thank you for your very thoughtful response - I appreciate your help. I am pretty sure that I am dealing with the original chain (I have talked with the last 2 owners), so I am going to change it (275,000 - 300,000 miles on the car).

I am not sure as to the pinging and the advancing/retarding of the timing - and I don't know why it occurred all of a sudden. I thought that it could be related to bad diesel at some point on the trip home to Ohio, but the problem has persisted. The timing chain stretch has DEFINITELY showed some change over that past 2500 miles - again I don't know why, but I do know that I used the same procedure to check (and re-check and re-check) both times.

I am going to change the tensioner - do I need to change the tensioner rail? I have tried to look at mine as best I can (I know it's difficult with the old chain still there) but it looks fine.

ryan

__________________
RG Newell

1984 300D
1972 250
1986 560SL
1991 300CE

If that is the original chain the engine might be in exceptional shape for the milage. The chain is the best indicator of oil changes. It wears fast with dirty contaminated oil. The primary barometer in fact as nothing else in an engine wears as fast with neglect.

If the chain guide looks pretty good and no evidence of loose plastic. It should be good to go. I think at this point I will lay back in the shallows like an old alligator and see how things go for you. Keep posting as you go along. I feel there may be something to learn here.

What we do not know cannot hurt us is an old untrue expression. Had you taken the car in for a pump timing. Chances are the mechanic would have discounted your suspicion of the rapid recent chain elongation. Drip set the timing and further adjusted it a little to get rid of the smoke somewhat at best and that might have been it. The chances of running across a really good mechanic still interested in these older cars is not too good.

Sure enough somewhere far from home the chain might have parted. Had you not been checking the car yourself the sudden elongation would not have even been noticed. There are many other areas on these older cars that require some thought from time to time.

I really enjoy getting my hands dirty. Just not enough time usually. The local service places here are out of the question. I even have to service and source parts for our newer cars starting when the warranty ends. A lot of members talk about being leaned over their fenders. I just refuse to assume that position myself.

I have the same concerns here - I can not find anyone that can, or wants to work on this car - especially when it comes to something like timing the injection pump. I have never had it done and I know this is hard to believe, but I don't know if it's ever been done on this car until I just did it a few days ago.

I do think the engine is in pretty good shape and I know (from PO records) the oil was meticulously changed - I also have real good compression across all 5 cylinders.

Interestingly, I checked the timing chain stretch again last night and noticed only 3-4 degrees this time - again using the lining up cam marks method - which is really tricky getting the marks to line up just perfect. This has led to my trying to measure cam timing using the 2mm method (see my recent thread - really frustrating as I can't figure it out!).

ryan

__________________
RG Newell

1984 300D
1972 250
1986 560SL
1991 300CE