1981 300SD with a 617 engine. approx 300k, bought about a month ago and wasn't sure when they were last adjusted so i just thought i'd do it as a general maintenance sort of thing. the engine seemed to be running decent before but i figured i'd try and get more performance out of it. anyways, adjusted intakes to .1 mm and exhaust to .3mm, the feeler gauges slid through with just enough resistance to feel them touching the lobe and to wipe the oil off the gauges as i pulled them out. when i start it up its idling around 600 (instead of the usual smooth idle at 1000) and i have to give it gas to keep it from stalling. running pretty rough. also some blueish smoke from the rear, it may have been white its dark outside and hard to tell. anyways i only ran the engine for a minute, and drove it into the garage to try and figure out what i did wrong.

maybe they were too loose? i thought i read somewhere that its better to have them on the loose side. should i tighten them a hair? i also am considering doing a purge. would it be best to leave the valves loose and purge the fuel system or what?

before i started all the valves were tight.

If the above happend to me I would re-check the Valve Clearances again paying particular attention to which part of the Cam Lobe I did the adjustment on and re-identifying which was the Exhaust and Intake Valves.
And, yes I have made mistakes on all of the above in the past; but so far not on the Mercedes.
Some of the reasons: I did not realize had grabbed the wrong Feeler gauge; I did not turn the Engine enough and I made the adjustment on the wrong part of the Cashaft (later I tried to convince myself that the Engine must have rolled back a little); I lost track of which Valve was the Exhaust and Which was the Intake so I used the wrong Feeler Gauge.
The above made more possible when in a hurry, tired or your mind focused on something else.

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84 300D, 82 Volvo 244Gl Diesel

X2.
Very easy to make a small mistake...

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1980 240d ,

chain elongation, cam marks reference:
http://www.peachparts.com/shopforum/diesel-discussion/10414-help-i-need-check-stretch.html

http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html

evap fin cleaning:

http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator

A/C thread

http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html

i just pulled the valve cover and double and triple checked everything against the sticker on the frame for clearances. its actually 0.35 for the exhaust and 0.1 mm for the intake. i was able to put the feeler gauge through the gap between the cam lobe and the curved surface it rests on, and tried the next size up and couldn't get that one through. there were a couple of them where i could barely get the next size up through, so i tightened those up a pinch and now i can barely get the feeler gauges through the ones i adjusted. everything really looks like it was done perfectly. its really odd. i triple checked that i didnt have the intake and exhaust mixed up, im going to put it all back together now and see if maybe there was just some connection i overlooked?

when i was taking things apart the first time i broke a little bit off the plastic vacuum connector coupling that connects to the vacuum on top of the valve cover. the part i broke is the collar that one of the vacuum lines goes into. there's 3 vacuum lines going to this piece, which is plugged into an interface on the valve cover. i doubt this would have affected anything, as it didnt really break enough to be losing air or suction. i just shoved the vacuum line into the collar a bit more and it seems to be sealed.. i just thought id mention it just in case.

Vacuum would not affect roughness.

Check the fuel supply: Make sure you didn't knock anything aside, check the filters, rule out leaky primer pump.

Sure thats mm and not "? The car is supposed to idle closer to 600 not 1000.

Vacuum could certainly affect roughness, are you sure you plugged those line in correctly? Try unhooking the EGR.

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http://superturbodiesel.com/images/sig.04.10.jpg
1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42

i'm sure its mm. i didnt measure anything in inches. when its idling i have to give it gas to keep it from stalling, so i know that the idle is too low. maybe the previous owner adjusted some kind of idle compensation screw instead of doing the job right and fixing the valves.. and now that the valves are adjusted right, the idle screw is making everything all out of whack??

when you say "try unhooking the egr", are you referring to the vacuum lines going to it? my car is the california model if that makes any difference.

i also tried starting the engine with the oil fill cap unscrewed, this had no affect on the performance of the engine.

Make sure all the return hoses are on securely, and not leaking. It could be a source of air entering the filter assembly.

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For Sale: 1982 MB 300TD
1995 Chevrolet Suburban 6.5TD

Sold: 1980 IH Scout Traveler- Nissan SD33T Diesel

Leaking or loosing vacuum will affect things like stopping the engine with the key, power brakes and door locks, but vacuum or the loss of vacuum does not effect the running of a diesel. It has no carburetor and creates no intake vacuum, none!

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Junqueyardjim
Christianity, if false, is of no importance, and if true, of infinite importance. The only thing it cannot be is moderately important. C.S. Lewis



1983 Mercedes W123 240D 4 Speed 285,000 on the road with a 617 turbo, beautiful butter yellow, license plate # 83 240D INDIANA

2003 Jaguar Type X, AWD. beautiful, good mileage,
Mom's car, but I won't let her drive it!

Might you explain that in a bit more detail? Especially the part about a leaking return hose allowing air into the air filter assy.

Are you sure you put the throttle linkage back together correctly? This should not have any affect on the idle but it would on some other things. Have you messed with the rack pin?

Also, assuming that you adjusted the valves with the pointy ends of the cam lobes in the 1 o'clock position? Did you twist the springs up or hold them still? Did you make a sheet when you did it, to be sure to get the right sequence? IE: Exhaust, Intake, Intake, Exhaust, Exhaust, Intake, Intake, Exhaust, Exhaust, Intake.

Don't overlook the obvious either. Like a rag or tool or something else getting sucked into the air cleaner assembly. This is easy to do on the 300D. Not sure about the SD.

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AJ

1985 300D (SOLD)

This is just a thought........did you do the valve adjustment with the engine cold or warm/hot? The adjustment should be done cold.......the valve adjustment does change a bit (materials expand) when the engine hits operating temp.
Believe me I have made that mistake on some pretty finicky cars that would not run right until I went back and readjusted when they were stone cold.

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FRED

Daily Driver: 98 E300TD 199K
Hobby Car: 69 Austin Mini
Past Diesels: 84 300SD, 312K
87 300SDL, 251K
94 Chev. K-1500 6.5Ltr.TD, 373K

air in the lines. hooked it up stock and it worked fine. i have a wvo kit and the filter before the mech pump was messing everything up. the gasket for the bolt that the fuel filter screws onto was leaking air, i replaced that gasket with an oil drain hole fiber gasket and its working fine. any ideas if this will react with biodiesel and should i eventually replace that gasket with something from the dealership?

That would have been nice to know.

You should fill out a signature and put that in it.

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AJ

1985 300D (SOLD)