I have just replaced the injection pump on my 603 because the old one was leaking. I used the opportunity to check the timing marks and found them a bit out. I reset all the marks and when I ran the motor it runs MUCH better than before. It also solved the excessive smoking problem I had. The issue I am having is this, the engine seems to misfire intermittently when cold and also seems to have knocking noises that were not there before at idle when the engine is cold. Any suggestions how to alleviate the rough running at idle when cold?



E Eggertsson
87 300SDL 316K

Certain you set the IP timing correctly?

When I had the timing out on my SDL mine sounded a 12V 5.9L Cummins at idle.

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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]

Have your injectors tested for pop pressure and spray pattern.

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1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine

Sounds like the timing is off. Pull the valve cover and see if the crank and cam line up, then hook up the RIV light and check the IP.

603's are picky, they need to be damn near spot on. +/- 1 degree.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

How long do you let the glow plugs warm before starting the engine?

Do you use the light as your guide?

How did you "reset all the marks" during the IP timing procedure?

I use the light on the instrument cluster as my reference when to start always. Otherwise it does not start correctly. I tested the glow plugs when I had the intake manifold off the engine and they work great.

I aligned the marks visually on the camshaft and crankshaft with the valve cover off to verify the position of the cam lobes. I then rotated the pump to align the mark in the port on the side of the pump itself. I did notice that when the cam marks are dead on, the crank is about 1 degree off. 11 degree ATDC instead of 12.

I ran the car like this and the engine performed much better than before but, the coolant temp climbed a bit higher than before. Occaisionally getting above the 100 degree mark and then coming back down. Previously it never reached any higher than about 95 degrees.

I retarded the IP then and it ran terrible and smoked like mad. I the adjusted the IP again, advancing it, but not as far as before. It is running well when warm and the temp is a little cooler. Still reaching 100 degree when running uphill.

When the engine is cold it has an intermittant misfire as well as a metallic "kink" kind of noise. The kink is what really concerns me. Sounds like metal against metal.

Is there any place to rent the A-B timing light for this engine?

Thank you all for your thoughts,

Eddie E.
87 300 SDL 316K and cruising!
This site gives me peace of mind

You can rent it in the tool rental forum. Sounds like the timing is off, you need the light. Close won't work on 603's they need to be spot on.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200