I have a 1974 240D that is putting out lots of black smoke, it smells like unburned diesel. Is there a way to adjust the fuel delivery at the IP? This is the IP with the red OEL cap and no direct oil from the engine.

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1983 Mercedes 300CD Turbo- 199,370 miles - Lapis Blau
1974 Mercedes 240D - 186,445 miles - Aqua Blau
1982 Volvo 244GL Diesel wagon - 168,956 miles - to be sold
1994 Chevy G30 6.5 Diesel "short bus" converted for camping, painted red white & blue & white stars 78,956 miles
JD F935 diesel front mower

How's your oil bath air cleaner? Have you serviced it recenlty? You should wash out the element thoroughly with solvent (I use gasoline) and replace the oil in the bottom with fresh. If your air cleaner is very dirty it can cause black smoke too. I don't think there is any adjustment for the IP on these.

FWIW my experience is that these engines do put out more black smoke on WOT at high revs than the later ones, it's just the way they are.

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz

BathCity, rather than fixing the result you should fix the cause.

Black smoke means lack of air or poor injection timing. Check your air filter inlet for clogging, clean the oil bath filter and adjust the valves. Your injectors are likely 34 years old too, have them cleaned, checked and adjusted by a Diesel injection shop.

When Fuel Injection Pumps wear they do not put out more fuel.

Let us know what happens after you clean out your air cleaner.

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84 300D, 82 Volvo 244Gl Diesel

Yep, my thoughts exactly - ye wanna reset injection pump timing. Black smoke generally indicates injection pump timing too far advanced.

Not injection pump timing, but timing from low injection pressure and poor spray pattern.

Then yer tacklin it from fouled combustion chamber / incomplete combust approach. Hard to tell without knowin mileage and maintenance history of the vehicle. Specially at 186k miles with TC stretch of probly 4-6* degrees I'd put my money on injector pump timing over injector spray, fer sure.

Spray (injectors) are far more important than pump timing at that age.

D'ye reckon diesel injectors wear out that early though?

FI...this is what I have done this weekend so far, prior to this post
Here's what I've did yesterday.
- I found a vacuum line disconnected & reconnected it. I replaced the seal on the oil fill cap, it's way tighter now.
- I went to remove the valve cover and found that the gasket was split on the "wavy" side. I removed the valve cover, checked the breather tube, it had a small bit of gunk but not much. I cleaned out the breather tube, cleaned the valve cover & used gasket, put a previously used gasket on with some high temp RTV flange sealant in the groove and on the face.
- I removed and cleaned the little oil tube that goes across the intake manifold where it bolts to the head. The breather tube dumps into this.
- I buttoned it all up and took her to the quarter car wash and washed the engine, engine bay, trans, & underside of the car to remove the oil from the fiasco yesterday.
- I ran her at 60 for a couple miles, went home and found no oil leaks this time. New oil fill seal seems to be doing the job
- I bought a diesel compression tester & ran the compression test.
cyl 1=320psi, cyl 2=325psi, cyl 3=325psi, cyl 4=350psi.

This I did today.
- Rechecked chain stretch, 2 to 3 degrees past zero.
- Timing is spot on, recheched with bubble method.
- Oil bath air cleaner has been cleaned & refilled.
- Ran a half gallon from a gallon container that I mixed up with 100%BD (60%), MMO 16oz, Power Service diesel clean the rest. This was run from the gallon caintainer.
- I just pulled the injectors, disassembled them, cleaned with brass brush, rinsed in carb cleaner, oiled with fuel during reassembly.
I noticed that the ends of the pintles do not protrude as far past the end of the injector nozzle as the ne ones I installed in my 240D Volvo last weekend. Gonna buy new nozzles. The ones installed now are 240's, I'll have to check to see what Bosch says to put in it.
Do you think the valve seals have deteriorated to the point that they leak like a stck pig?

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1983 Mercedes 300CD Turbo- 199,370 miles - Lapis Blau
1974 Mercedes 240D - 186,445 miles - Aqua Blau
1982 Volvo 244GL Diesel wagon - 168,956 miles - to be sold
1994 Chevy G30 6.5 Diesel "short bus" converted for camping, painted red white & blue & white stars 78,956 miles
JD F935 diesel front mower

FYI...the previos owner said he had recently replaced the injectors. I checked the other day and there were NOT any heat shields, could the missing heat shields have damaged the pintles. I have put in heat shields, albeit used ones from the Volvo. Ordered 8 new ones this weekend.

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1983 Mercedes 300CD Turbo- 199,370 miles - Lapis Blau
1974 Mercedes 240D - 186,445 miles - Aqua Blau
1982 Volvo 244GL Diesel wagon - 168,956 miles - to be sold
1994 Chevy G30 6.5 Diesel "short bus" converted for camping, painted red white & blue & white stars 78,956 miles
JD F935 diesel front mower

The only way to know if the injectors are damaged or not is to pop test them...most shops will do it cheaply or even for free. It will show you the spray pattern. Having had them installed without heat shields could have damaged them I would think.

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz

A lot of post say could be shot at 100,000 miles. I say the little drilled holes can get plugged before that time especially if the IP timing is not correct or other factors are causing carbon problems in the combustion chamber.

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84 300D, 82 Volvo 244Gl Diesel

I don't see how the combustion chambers could hold compression without the heat shields installed.
I do not think you can take most POs word for things unless there is paper work to back things up. Recently replaced injectors; another used set, a rebuilt set or ?????
As far as pintel damage goes the old but non-turboed Mercedes diesels used a copper or aluminum crush washer that went around the Injector Spray Nozzle and the sealing was done at the bottom of the injector nut not on the tip of the Spray Nozzle. Also the pintels were thinner and they did not overheat.
You mentioned Volvo heat shields; do you also own a Volvo diesel?

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84 300D, 82 Volvo 244Gl Diesel

BathCity, looks like you're on the way to a smooth running machine.

To answer your original question (can I adjust the fuel mixture at the injection pump): yes you can. You use shims to adjust the balance between vacuum force and spring force at the governor. The shims are located beyond the end of the rack at the governor end of the pump. The last thing I'd do in your case, and be forewarned: if you don't get the governor hooked up properly then you may have a runaway engine when you start the engine.

I'd check the vacuum pump while waiting on injector parts. Look at the outlet line - if there's oil in it then fix the vacuum pump pronto.

Then check the foot-throttle rod that's connected to the firewall for sloppy or sticky bushings. That's the real first step for adjusting anything near the throttle body.

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daBenz - 1970 220D