'79 123 emission control?

One thing I've been curious about and I keep forgetting to ask...
My car, a '79 300TD, smokes like crazy from the exhaust pipe. I pull up to a light, and a cloud envelopes the car to pull up beside me. The
inside of the car gets the smell of burnt fuel too, I'm not sure if I'd say "exhaust" or not, though. It's less noxious on veggie oil, but the same phenomenon occurs regardless of choice of fuel (although when I did Marvel in a tank the problem disappeared for about 50 miles!).
My partner's car, an '85 300D, doesn't noticeably smoke at all and doesn't stink inside the passenger compartment or anything. She doesn't like riding in my car because of the difference.
So, I know nothing of emissions controls except that I know the vacuum diagrams seemed to change every year and it was emissions "stuff" that was notably different. Ultimately, my question is about whether or not I have EGR equipment on my car, could it be fouled or otherwise in need of replacement, how do I find it, and how do I test it? I'm hoping that something like this would be an "easy" fix for me.
FWIW, I've had the car at an exhaust shop and they replaced "cat-back" but said there were no leaks in the system once the rust in the "back" was taken care of, and in my looking I don't see any "smoke" in the engine compartment but it definitely smells like something that it shouldn't smell like (and this smell should not be going into the passenger compartment!).
thanks, -tom!
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What colour is the smoke? http://www.freeautoadvice.com/diesel/smoke.html
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Smoke is unburned fuel. So there are several possibilities (in order of cost): Insufficient air due to a dirty air filter element or other obstruction in the air intake, worn fuel injection nozzles that don't sufficiently atomize the fuel ($50/ nozzle for Bosch re manufactured on an exchange basis) or insufficient compression due to worn piston rings. If it smokes at idle the problem is most likely the latter choices. A compression test will establish which is the cause.
Diesel emissions controls were pretty basic in 1979 and included EGR on California models to reduce NOx. My 1980 (California) has this EGR; I couldn't detect any performance difference with it or without it in a brief test. IMHO the only way EGR would affect your motor, if so equipped, is if the EGR were permanently stuck fully open for I don't believe EGR normally operates at engine idle.
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-->> T.G. Lambach <<-- wrote:

That's one reason why I thought an EGR failure might "fix" it.
The smoke is white; by the link that 'me' provided that suggests that maybe the head is cooling too fast or something, but it doesn't appear to be something I can deal with myself.
Thanks for the info; at what frequency do injector nozzles need to be replaced under typical usage? At the very least I can get a compression test, I think that'll set me back about $100 but it'll be good to know.
Thanks for the info.

The CD manual hasn't aided me in locating these parts and I assumed that there'd be something fairly obvious hung onto the manifold. What should I look for to find this device/system, and is there any diagnosis of it I can do via inspection? I'm not sure that my car was originally intended for California, but I don't think I'd be going too far out on a limb to assume that it is a "native"; I bought it in LA with only 150k miles on it so it didn't see a lot of action.
Thanks again, -tom!
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The car's emissions labels will tell you a lot.
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I changed my car's injection nozzles to eliminate knocking and an idle misfire. The car had done about 90K miles. Smoother afterward. The nozzles can be changed like spark plugs except there's a bit of plumbing involved - the high pressure lines and bleed off hoses (which you may as well replace at the same time).
The EGR valve is attached to the exhaust manifold at the front of the motor and has a metal pipe to the nearby intake manifold.
I suggest a compression test before spending much $$ on this motor.
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Does the engine use more than normal oil? In my experience, white smoke it Oil bypass thru worn oil rings on your piston(s), and dark smoke is excess fuel. I recommend you do a compression check. Maybe you culd rent/borrow a guage at an auto parts store. Hope this helps.
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dntaskwy wrote:

Burns no oil (like, it's not even down a quart at an oil change) and there's neither coolant in the oil nor oil in the coolant.
I realized that by "smoke like crazy" I may have hyperbolized; you can certainly see the exhaust but by no means is it a smokescreen or opaque. It's mostly that at no point does this stop happening. I would call it white but it's not "dense". More of a haze than anything.
By TG's suggestion I'll get the compression test and then figure out where to go from there.
Thanks gang, -tom!
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