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'73 450SL, '83 300CD, '01 E320 4matic
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Discussion Starter · #1 ·
My 300D has been smoking at idle since I've had it for a month now. Injectors were suggested. I purchased some injectors, (135 bar) for a turbodiesel. Mine is N/A. I asked ahead of time whether or not it mattered, and the general consensus is that it would run well with 135 turbo injectors.

So I took them to a diesel shop today, and had them tested. The fella there said they were low mileage, and that they should run very well. They were all very closely matched, and had a good spray pattern, according to him.

So I came home and changed them. I also changed all of the overflow hoses, and the crush washers/gaskets that fit at the bottom.

Started the engine up, and took it for a drive. It runs 100% better. It's a lot smoother, and a lot quieter.

My gripe is that it smokes (blueish) at idle, and it stinks. WTF is causing this? It's very annoying. My 78 300CD never smoked at idle once it warmed up a few minutes.

Is this going to be a timing issue?
 

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'73 450SL, '83 300CD, '01 E320 4matic
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Discussion Starter · #2 ·

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1984 300CD, 2015 Sprinter 3500, Coach House Platinum II
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2,722 Posts
You don't think that the 318,000 miles might have something to do with it?
 

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'73 450SL, '83 300CD, '01 E320 4matic
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Discussion Starter · #4 · (Edited)
The 78 300CD I had was horribly neglected and had 340K+ on it and ran well.

This one has a few less miles and has been fairly well maintained. If the engine is in good condition, it should not smoke like crazy with a million miles on it.

It does not burn a drop of oil, good compression, almost NO blowby, valves adjusted well... I'm trying to figure out if it's a fuel delivery issue.
 

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1991 300 SE
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18,534 Posts
I had an 81 300 D with over 410,000 miles with exhaust like a gasser.

Is this going to be a timing issue?

I'm trying to figure out if it's a fuel delivery issue.
I believe that’s it – the smoke is unburned fuel, it could be something as simple as a dirty air filter or an obstruction in the air intake. Since you’re replaced the injectors I’d check the timing and IP.
 

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'73 450SL, '83 300CD, '01 E320 4matic
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Discussion Starter · #6 ·
Yeah, I'm pretty sure it has nothing to do with the mileage... as I said, when the 78 was warmed up it hardly smoked at all, and it certainly did not smell.

This car stinks bigtime.

I'm thinking the injection timing is a little off. That's about the only thing left.
 

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1985 380SE
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When was the last time the valves were adjusted? That might have something to do with it. My bet is on the fuel/air delivery though.
 

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'73 450SL, '83 300CD, '01 E320 4matic
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Discussion Starter · #8 ·
Valves were adjusted a couple thousand miles ago according to the PO service records, and I checked it myself and they were still very much perfect.
 

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'73 450SL, '83 300CD, '01 E320 4matic
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Discussion Starter · #9 ·
:bump:
 

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1984 Mercedes-Benz 300SD Turbo; 1985 300CD Turbo
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My bet is on the fuel/air delivery though.
I'm with 240 Benz and everyone else on this one. I had a similar issue with my '85 300CDT when I first got. Smoked like a chimney! But after I did a diesel purge, swapped out the primary and secondary fuel filters, and installed a new air filter everything was fine. Very little investment for those three things (talking...what...$40; air filter is on sale at autohausaz for $13), and considering the mileage on the car it wouldn't hurt just to do as general routine maintenance.

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'73 450SL, '83 300CD, '01 E320 4matic
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Discussion Starter · #11 ·
I'm with 240 Benz and everyone else on this one. I had a similar issue with my '85 300CDT when I first got. Smoked like a chimney! But after I did a diesel purge, swapped out the primary and secondary fuel filters, and installed a new air filter everything was fine. Very little investment for those three things (talking...what...$40; air filter is on sale at autohausaz for $13), and considering the mileage on the car it wouldn't hurt just to do as general routine maintenance.

[email protected]

Done, Done, Done.

Out of the little Mercedesshop book that came with the car:

"Excessive Smoke: ...... If you get a blueish smoke at idle with a strong smell, your injection timing may be off."


I'm very sure it's an issue of pump timing. Everything I've read points to it. I've been doing some reading on how to time the pump. The pump timing is 'late' according to everything I've read. All the research I have done has said that the timing goes 'late' as the engine ages.

Which way should I move the pump to advance it a couple degrees... toward, or away from the engine?
 
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