I have tried to find the answer to this question, but as close as I came was reading that it's risky to have it loose. But is there a way to measure this? How do you know WHEN to adjust the tensioner?? The timing chain on Sammy can be depressed somewhat by pushing on it. Has anyone been taught how taut is taut, and when it taut not taut enough? (Say that fast ten times!)

Thanks,

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Natalie

Nat,
Those tensioners are self-tautening (hehe)...the oil pressure does it for you. Provided, of course that it hasn't elongated to the point that you can tie overhand knots in the bloody thing.

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Never a dull moment at Berry Hill Farm.

Thanks Randy! That explains why I couldn't find any 'how to check it' information. DOH! as Homer would say.

Who are the cute pooches? They look more like Chows than poodles...

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Natalie

Jassc,

The chain should have no slop in it with engine not running if the tensioner in OK. There is a spring in the tensioner that keeps the chain tight when there is no oil pressure. Then when the engine is running, the oil pressure makes the chain even tighter. The chain tensioner also is supposed to ratchet open so that even if the spring breakes, the chain can't get too loose.

I had a tensioner that jammed and the chain was noticeably loose. Whether the oil pressure tightened the chain when the engine started was unknown. So I replaced the chain tensioner which tighened the chain and I have had no problems since.

P E H

The timing chain must ALWAYS be under tension. Timing chain stretch MUST be measured to ascertain if valve and injection pump timing are synchronized and if the chain is worn. That IS covered (POORLY in my opinion) in section 5-215 of the engine manual. Just line up the marks on the cam sprocket and cam tower and read the degrees of stretch off of the crankshaft damper using the same pointer used to set injection pump timing.

I learned that the chain on an OM61x engine should be changed when stretch reached 5-6 degrees. I have recently learned that Mercedes allows the life of the chain to be extend out to about 10 degrees of stretch as long as an offset Woodruff key (available in 2 degree steps up to 10 deg) is used to compensate for the stretch, That makes me nervous and is sufficiently involved so I just recommend that chains with more than 6 degrees of stretch be replaced. For the OM60x engine, the allowed stretch is only 4 degrees - more than that and the chain must be replaced, but the chains in OM60x engines seem to wear MUCH more slowly (all seven of the 60x engines I've owned have exhibited a wear rate of between 1 degree every 100-200kmi - so half a million miles of chain life - using Mobil synthetic oils - is possibe). Chain life is largely a matter of the condition of the oil. Switching from conventional oil changed at 5kmi intervals to Mobil/Delvac 1 changed at 10kmi intervals has cut the chain wear rate in my engines by more than half.

Marshall

Marshall,

I'm glad to see that someone else agrees with my use of Mobil1 engine oil and changing it at 10,000 mile intervals.

P E H

It's nice to see that my thoughts on synthetic oil and 10k mile intervals being validated by some history....thanks.

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1976 240D
1987 560SL
2007 E320 Bluetec
1998 C280 (now son’s car)
1982 240D Manual - Sold

PEH,---- "I had a tensioner that jammed "....
WHY did it JAM ? I am sure you will not blame your 10,000 mile oil change intervals...
So tell us what you DO blame....

If oil analysis shows the oil is FINE then blaming the oil for the tensioner jamming is unwarranted! Current MB (including diesels) are scheduled for oil changes at intervals of between 10 and 20kmi or every 2 years. Many older engines can tolerate similar intervals, butt they must be running well or shorter intervals may be required. Oil analysis can estabish that easily. Of course they require synthetic oil to do that.

Marshall

Leather,

I don't know why the tensioner jammed but I was lucky I found it before the timing chain jumped. I discovered it by noticing the timing chain was loose when I was doing a valve adjustment.

The ratcheting part of the tensioner just would not extend any farther even though it was not out to the last detent. It wasn't rusted or corroded and looked OK to the naked eye. It was over 20 years old and had gone 200,000+ miles so who knows why it failed. So I replaced it.

I'm sure it had nothing to do with 10,000 mile oil changes using Mobil 1 synthetic oil. There are other wear points that would show up first if there was a lubrication failure such as oil burning due to worn piston rings or cam timing late from timing chain elongation.

"oil analysis "
I have read of people doing this...
And I know that big companies regularly do this...
But....
Where do you send it ?
How much does it cost?
How fast do you get the results back ?

Don't you figure that most people are going to just pick a distance and change it rather than use ' oil analysis'... since taking a sample is almost as much trouble as dropping the plug out of the pan ?

My 603 had 10* of stretch at 275,000. Oil changed religiously througout it's life.

Most auto manufacturers provide fixed or occasionally pairs of oil change intervals (perhaps one for "normal" and one for "harsh" service). In order to insure that the oil is changed sufficiently soon to prevent damage in 95-98% of those engines (some engines experiencing the most severe service will often still be overdue for change based on depletion/contaminatiion and thus sometimes sustain SOME damage) the oil in the vast majority of those engines will need to be change well before it's exhausted. If a unitary interval is selected (since each engine AND each environment results in a different rate of oil depletion/contaminatiion) a lot of good oil WILL be wasted. When oil was cheap and there was little concern about consumption, changing the oil VERY frequrntly whether it needed it or not was a satifactory solution.

Now that $5+/qt oil is mandated, changing it every 3kmi (when it's actually good for 10-20kmi or even more) makes little sense and is both expensive and immoral.

As to the cost of oil analysis - most of the services I see presently cost between $9 and $15 and analyzing the oil a couple of times can usually allow a baseline for THAT engine and type of service to be established. In my own case, analysis (includng 10-20% driving in bad weather which shortens the change interval) shows that all of my cars can tolerate 10kmi or longer oil change intervals (still, I usually change the ones that are used exclusively in city commute service at about 7.5kmi to be safe) and for the couple of cars that are used exclusively (90+%) for highway driving - mostly in good weather - could be extended to 15-20kmi or even more (but I still get nervous and change them before 15kmi).

Marshall

That sure suggests really poor oil quality OR awfully harsh conditions. All of the chains in all of the OM60x engines I've ever owned had less than 2 deg of stretch at 200+ kmi. I bought a used 601 with an alleged 175kmi that had about 2 1/2. It's exactly this sort of thing that oil analysis will pick up early and allow you to correct before stretch reaches 10 degrees.

Marshall

Where do you send it?
How fast do you get the results back ?
How often per oil fill up do you send in a sample ?

Mandated for 80-85 Diesels ? By whom ?


"when it's actually good for 10-20kmi or even more) makes little sense and is both expensive and immoral"

I suspect you are speaking strickly of the lubrication properties and not the overall situation with regards to the trash it picks up during the course of being in the engine...

You did not say you sent in YOURS.. you said those you ' saw' cost ........
Do you send in yours ?

Perhaps you would feel less " immoral" if you take your old oil out and mix it with diesel fuel and then filter it and put it into the tank....... can you do that with Mobil 1 ?