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2002 S500, 1993 Nissan 300zx
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Discussion Starter #1
I could really use some quality input here.

I have acquired a 1988 560SL that has been sitting for some time. The engine turns over nicely, and actually runs well too, but black smoke is pouring out of the exhaust.

I have read numerous sources that cite all kinds of differnet things from bad gas to fuel distributor to cold start valve to temp sensor to ecu to bad plugs and that it needs a good fuel injector cleaner run through it to any and all of the above. I don't have that kind of time, and certainly not that kind of money to throw at it.

While all of that is fine, I would appreciate it if anyone here could leave me some infor about what they did to solve this same problem on their vehicle. Please don't point me to some other spot on the web...I have already seen it.

Please describe whatever you have done yourself (or had done by a shop) that fixed the problem.

Your input is appreciated so much...come help me solve this, and I'll buy the beer.

Randy
 

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500SLC #2624. Black on Black.
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5,120 Posts
I know this might not solve your problem, but it also might.

Have you tried giving it an Italian Tune-Up? A good thing to do before you get stuck into it, that won't cost you anything, and won't take up too much of your time.
 

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500SLC #2624. Black on Black.
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5,120 Posts
Also Randy, how are we going to come help you and collect that nice cold beer if you don't put your location on your profile? ;) Although I bet wherever you are it's too far for me to come for just one beer.
 

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2008 E320 Bluetec, 1988 560SL totalled unto death). 1997 Dodge Ram 1500, 1983 300CD
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1,315 Posts
black smoke

Usually indicates a rich-running condition. There are those who would counsel getting right into adjustment of the fuel distributor enrichment screw. I say, don't do it. Those adjustments seldom go out on their own. If the factory installed lead plug is in place on the fuel distributor, leave it alone. If it is not, there is a possibility that a previous owner/mechanic has messed with the adjustment and fouled it up.

You say car starts and runs o.k. I would proceed as follows:

1. Look at air filter. Make sure it is clean. Replace if not. If that does not do it, then:

2. Car has been sitting for some time. How long? If years rather than weeks or months, drain fuel and replace with fresh. Change fuel filter. If that does not do it, then:

3. Remove cold start valve, clean by spraying inside with carburettor cleaner until black gunk is gone. One quick shot of WD40 and reinstall. If that does not do it. then:

4. Check your warm-up regulator (WUR). I don't know off-hand how to do this but ALLDATADIY does. There are probably voltage readings one can take to determine if it is working correctly.


5. If still no joy, come back to us.
 

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1988 SL560, 1989 560 SEL
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516 Posts
Mine is doing a little of same thing, but I think maybe new vaccuum hoses will help, which I plan to do soon. Alson getting it out on open road for a long hard run may do a world of good. I know I drive mine too many short runs
" if you aren't living on the edge, you're taking too much room "
 

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2002 S500, 1993 Nissan 300zx
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115 Posts
Discussion Starter #6 (Edited)
Still No Joy - Lots of Black Smoke

Usually indicates a rich-running condition. There are those who would counsel getting right into adjustment of the fuel distributor enrichment screw. I say, don't do it. Those adjustments seldom go out on their own. If the factory installed lead plug is in place on the fuel distributor, leave it alone. If it is not, there is a possibility that a previous owner/mechanic has messed with the adjustment and fouled it up.

You say car starts and runs o.k. I would proceed as follows:

1. Look at air filter. Make sure it is clean. Replace if not. If that does not do it, then:

2. Car has been sitting for some time. How long? If years rather than weeks or months, drain fuel and replace with fresh. Change fuel filter. If that does not do it, then:

3. Remove cold start valve, clean by spraying inside with carburettor cleaner until black gunk is gone. One quick shot of WD40 and reinstall. If that does not do it. then:

4. Check your warm-up regulator (WUR). I don't know off-hand how to do this but ALLDATADIY does. There are probably voltage readings one can take to determine if it is working correctly.

5. If still no joy, come back to us.

Here are some answers to your suggestions (thank you very much by the way).

The enrichment screw has been adjusted by a previous mechanic, and probably improperly. I have attempted to adjust it both directions without success. Tell me: which way makes it rich, and which way makes it lean? I could not make any determinations on that because the amount of smoke is significant.

1: The amount of black smoke being pumped out is far more severe than a dirty air filter would cause.

2: Near as I can figure the car has been sitting for about a year and a half or so. The amount of gas in the tank was negligible...pumped in a fresh 5 gallons of 91 octane today, added a 20 gallon treatment of Techron too. Fuel filter is not clogged at all...fuel supply is not the problem at all. It pumps like crazy, and the old gas has now been run out of the system. The gas coming out now is fresh.

3: Pulled the cold start valve yesterday and cleaned it up pretty good, but was told that the only way to test it properly is under pressure. I will pull it again this evening and do your procedure and see if that helps.

4: Will check on this tomorrow. Anyone have an alldatadiy.com accopunt for this make of car they would let me use? lol

5: I'm baaaaack!

Thanks so much...please keep any more information coming. This car is going to be the death of me. I need to finish it and sell it before it becomes an obsession.

Randy
Orange County, CA
2002 CL500 AMG (just sold)
2002 S500 AMG (just purchased)
1988 560SL (current project)
2001 BMW 740iL (totalled in wreck)
1988 BMW 635CSI (Shark - sold 6 months ago)
 

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2002 S500, 1993 Nissan 300zx
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115 Posts
Discussion Starter #7
Re: Italian Tune Up

I know this might not solve your problem, but it also might.

Have you tried giving it an Italian Tune-Up? A good thing to do before you get stuck into it, that won't cost you anything, and won't take up too much of your time.

If I can get the thing running good enough that I won;t get arrested for being a gross polluter, we have a long series of hills around here where an Italian Tune Up would be ideal (not to mention a lot of fun).

PS: I'm in Orange County, CA which is about an hour south of Los Angeles. Don;t come for one beer...come for a keg.

Randy
 

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2002 S500, 1993 Nissan 300zx
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115 Posts
Discussion Starter #8
Re: Vacuum Hoses

Mine is doing a little of same thing, but I think maybe new vaccuum hoses will help, which I plan to do soon. Alson getting it out on open road for a long hard run may do a world of good. I know I drive mine too many short runs
" if you aren't living on the edge, you're taking too much room "
I appreciate that input. I intend to give it all new vacuum hoses soon, but right now my priority is to solve this smoke issue.

The black smoke is very significant. Air filters and vacuum lines are not going to solve it. It is something much more in depth.

Randy
 

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2002 S500, 1993 Nissan 300zx
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Discussion Starter #9
I will PAY ANYONE ON THIS BOARD IN CASH to help me solve these issues! Come over, turn a wrench, drink a beer...hell I'll even get crazy dancing women to come along...just help me fix the GD car!

Please keep the suggestions coming. I am headed to a junkyard tomorrow in search of a fuel distributor, ecu, injectors, cold start valve, heat sensor, and anything else I can think of that may or may not be the solution.
 

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1978 280slc
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3,198 Posts
Here is one easy solution, go behind your car when it is smoking and stick your face in the tail pipe. If it is running pig rich you will smell gas in the exhaust, but black smoke sounds like oil getting into the combustion chamber. I had my car running really really rich before and never ever saw black smoke, so I think you might have oil getting in. My bike has an issue with either the PCV or valve guide seals and it burns oil, you can tell the smell of unburned gasoline and burned up oil.

Good luck!
 

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Premium Member
1975 450SL
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2,440 Posts
Here are some answers to your suggestions (thank you very much by the way).

4: Will check on this tomorrow. Anyone have an alldatadiy.com accopunt for this make of car they would let me use? lol


Just an FYI: a lot of public libraries have subscriptions to either Alldata or Mitchell online. You can get the procedure to your job printed out for 5 cents a page or so.

Scott
 

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2002 S500, 1993 Nissan 300zx
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Discussion Starter #14
Re: Burns Oil?

Here is one easy solution, go behind your car when it is smoking and stick your face in the tail pipe. If it is running pig rich you will smell gas in the exhaust, but black smoke sounds like oil getting into the combustion chamber. I had my car running really really rich before and never ever saw black smoke, so I think you might have oil getting in. My bike has an issue with either the PCV or valve guide seals and it burns oil, you can tell the smell of unburned gasoline and burned up oil.

Good luck!
Burning Oil would be indicated by gray smoke...we have NONE. But you brought up an interesting point...I made the mistake of standing behind it yesterday when a buddy revved the motor and it spit so much black stuff at me that it got on my shoe...and stayed there. It washed off, but if I had been thinking, I would have taken it to the nearest CSI lab and had them do an analysis of the material. lol
 

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2002 S500, 1993 Nissan 300zx
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Discussion Starter #16

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2010 Mercury Milan Hybrid, 1993 BMW 325i convertible
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You know...I thought about that too. That may be next on my list.
That could be part of the problem - if the sensor is bad, the system goes into closed loop and runs rich, but I don't think it's the whole problem. The enrichment adjustment on the engine is very touchy - small adjustments make big differences. I don't suppose you have an exhaust analyzer? That's the only way I've been able to get mine running properly.
 

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Outstanding Contributor , Bob's Your Uncle!
-----'83 280 SL----- 5 speed....The PIG
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I had the same problem three years ago.....turned out to be the WUR.
But I don't think a 560 has one.
Helpful, eh?
 

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1990 560 SEC(gone but not forgoten) 1988 560SL 1998 E320 4matic wagon
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258 Posts
Had this problem with mine at 120k It was oil, ended up doing the heads. Of course while doing that did the chain and guides water pump ect. Bill was $5400 and change.
 

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2002 S500, 1993 Nissan 300zx
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Discussion Starter #20
NOT OIL

Had this problem with mine at 120k It was oil, ended up doing the heads. Of course while doing that did the chain and guides water pump ect. Bill was $5400 and change.
Guys, it's not oil related. It is definitely gas related.

Thanks for all the input...I found another post on a different board buyt a MB Guru mrchanic. His thought is that the old gas varnished the interior of the fuel distributor so bad that it drips excess gas. The other thought was clogged injectors. Both of those were hunches of mine to begin with...it's just frustrating because those are the high dollar items.
 
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