Why is my '79 300D so much faster than my '81?
 

It is much, much faster, has more pickup and will easily gobble up hills. However, it smokes like a freight train to do it. Even with the smoking it gets 23-24 mpg. If I let off the accelerator it will stop smoking but much of the power will go away with it. You can literally hear the sucking sound coming from the air filter housing inlet from inside the cabin.

Any ideas?

I have attached pics of the IP to show what appears to be mounting holes for what should be a VCV. Unless this model didn't come with one, it has been removed. If so, is there a reason I shouldn't do the same to my '81? I am having shifting trouble as it is so I wonder if I could bypass some of that it I removed the VCV if it were doable.

Also, is that the ALDA next to it? The flying saucer looking thing? If so, it has no line going to it or away from it. Does this matter? Has it been disabled?

well the screw and nut on the ALDA looks like its been messed with.

You don't have an alda on non-turbos.

That's what I was beginning to understand. If not, what is that thing with the adjustable screw/nut and does it look like something has been removed where the VCV should be?

The injection pump is probably set up differently on them. Timing and amount of fuel are both adjustable and a skilled mechanic can make them hum if something is not optimal. A little smoke is often the accompanying sign of good power.

Tom W

I think it is still some sort of altitude adjustment thing, just doesn't utilize boost. I have no idea what messing with it does to be honest.
Are 79's and 81's geared the same? I'm guessing the '79 has the 3:69 rear end. Does the '81 have the same, or the 3:45's??

I believe it's simply a barometer of sorts that reduces fuel at higher altitudes and increases at lower.
I wonder if I could pressurize mine here in Colorado and produce black smoke?

that IS an alda in the pictures, did someone bolt a turbo on the car too? you should just have the round ADA on a 79 123

No turbo unless they look a lot different than I would expect.

There is this contraption in the right fender well behind the headlights. It has coolant hoses, vacuum lines and electrical plugs running to it.

I don't think it does anything because the vac lines have deteriorated near the battery and I have been cannibalizing the line and fittings.

I have attached pics of the contraption and the exhaust manifold under the air filter to verify that it has no turbo. I have unplugged the vac lines on the contraption but I haven't done anything yet to the electrical plugs. It looks like it has a Mercedes part number on it too.

I also just completed a valve adjustment on it and found that all the valves had been adjusted to .10mm like only the intakes should have been. I then adjusted the exhaust valves to .30mm as required. The first time I drove it there was a "freeing event" that took place when I hit the accelerator. It was running a little better than it did before and smoked a little less just putting around. I also couldn't believe how much air it was pulling in from the air cleaner housing. It reminded me of my 4.0 Jeep Cherokee I used to have after I "unrestricted" it's airways.

Can you tell me anything from the VIN? It is: 12313012120688.

OK, I have another question. On my '81 I have the round thing where the ALDA is on the '79 but it doesn't have a line attached to it. Can I remove it as well without impairing performance/reliability? I am having some trouble with it's shifting patterns right now so I am trying get it as simple as possible.

Something must really be different with the '79. I know that it has been wrecked once and repaired. The speedometer reads up to 115 mph on it but the '81 only goes up to 85. Is this car a Frankenstein?

That contraption is the ACC Servo. You probably don't have a fully functioning climate control system. Can be replaced with a new solid state system that is reported to be more reliable.

Kevin

1979 240D manual
1978 300D in transit

Thanks for the info.

No, I do not have a fully functioning climate control system. If the compressor wasn't whining I could get cold air only when I depress the defrost button. No other button will even turn the fan on. I have disabled two actuators because when I got it the two center vents wouldn't blow and the defrost vents stayed open. Now I have it to where all four dash vents will blow only cold air. I can't get the heat to work nor can I get any of the other hvac options to turn on the fan.

Do you know anything else about this solid state system? What should I look for, etc?

I'd check out this web site http://www.unwiredtools.com/

This is the path I'll be taking if my soon to arrive 1978 300D has a future (seems to be a certainty) servo malfunction. They don't call it the "dreaded acc servo" for nothing, apparently.

Kevin

1979 240D manual
1984 300D in transit

If the car is running that powerful and well, reguardless of the thing smoking. I'd just leave it alone and drive it. Whatever is causing all of the smoke might be why the car moves so well. Maybe the engine is just that loose, but who cares? Just drive it and enjoy it. If you stop the smoke, you might make it slow and sluggish if you replace or remove anything.

I don't mind the smoke but I am trying to sell it and the new owner might.

I guess I could just sell the other one...