Just looked at a newly started MB site and one of the posters stated that valves get tighter not looser over time on 617 engine, me no understand....
William Rogers.........

William,
I have been driving Mercedes diesels since 1967, and have known since then that the diesel valves get tighter. That is one of the reasons they will get hard to start, if you don't keep the valve clearance up to specs. The valves will remain too long,causing a loss in compression.
For some reason the valves in gasolene engines get looser.
Maybe some one can explain why and how.
Bill Lewallen; Lexington,Ky.

Bill....and Bill

I have always made the assumption that the valves would loosen up, so I haven't adjusted mine in over 70kmiles. (ME VERY BAD).

I should probably buy the wrenches and get to it.

Maybe they tighten up because the valve seats deeper with wear? Just a guess.

Joe

I was told the same thing by my mechanic when I had my valves adjusted last. The valves get tighter, whereas on a gasoline engine they get loose and start to sound like there are marbles in your engine.

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1999 MB SL500 (110,000 mi)
2004 Volvo V70 2.5T (220,000 mi)
2014 Tesla Model S 85 (136,000 mi)
MBCA member

I think it's more likeley the overhead cam, everything is upside down compared to push rod engines.

was inspired to adjust the valves on my ageing 240 d today
and they were all way tight of specs (it runs better with less smoke) also gave me a chance to practice before I do my dayly driver 81 sd , I took torch and bent a couple of spare old 14 mm open end wrenchs which made adjusting much eaiser probably took the temper out of them but they worked. Tech on other site said that the valves strecth and that's why they get tighter?
William Rogers.......

I don't know about the 617 engine, but I know BMW air-cooled motorcycle engine valves get tighter as they wear; the valves and seats wear down and the valve recesses into the seat slightly. This has the same effect as raising the valve toward the rocker and adjuster, decreasing the clearance. So, the valves get "tighter" as they wear and must be loosened periodically or they will begin to wear out faster.

I assume this is normal for generic pushrod/rocker arm engine operation.

Hope this helps and,
BCingU, Jim

Can anyone tell me what the clearance specs are for a 85 300TD, and is the first valve the exaust or intake? Thanks, I lost my Haines book and forgot which is which

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85 300TDT 456,000 orig. miles

intake 0.1mm, exhaust 0.35 mm - cold

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'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.

It's also on this black sticker under the hood. Mine is on the driver side radiator support. Don't recall if number one is I or E...

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I'm not a doctor, but I'll have a look.

'85 300SD 245k
'87 300SDL 251k
'90 300SEL 326k

Six others from BMW, GM, and Ford.

Liberty will not descend to a people; a people must raise themselves to liberty.[/IMG]

I've gone about 17k miles so far since an adjustment, and I can tell the difference recently, still starts right away/fine on the first crank rotation, but a little more smoke and not quite as smooth. I'll have it done in a few weeks probably....October at the latest.....definatley before we switch to: Michigan Tundra Mode(TM) I have my new block heater aparatus too, so this winter should be more pleasant...

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

I'm maybe 2000-2500miles and what a difference it made... idle is far smoother and more refined. Next to installing the $6 Blaupunkts I found at PickNPull it's the best thing I've done to the car.

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I'm not a doctor, but I'll have a look.

'85 300SD 245k
'87 300SDL 251k
'90 300SEL 326k

Six others from BMW, GM, and Ford.

Liberty will not descend to a people; a people must raise themselves to liberty.[/IMG]

True, the diesel valves get tighter but gas motors can and will do the same thing.

My 4 stroke motorcycles are a prime example. Every one of them tightens up.

Maybe overhead cam is the reason??

Cheers,

Bill

I've not touched the valves in my 240 since I bought it 25K ago.


and I honestly have no clue how long it'd been since the previous owner had done any work on them.


What's the prognosis!?

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1982 240D.
My name is Michael, and I am an 18 year old binge-drinkin', cigar-smokin', novel-writin', all around unsavory and unnattractive guy. I tell long-winded stories, and I only shave once a week, although I've had to do it every day since I was 16.

I would think the possibility of a burned up motor.

If the exhaust valves are not opening enough the motor will retain the heat.

Cheers,

Bill