Car smoking at idle?? - PeachParts Mercedes-Benz Forum

siral3x · #1 03-11-2008, 10:24 AM

Here is the deal:
-car has 188k miles now on what I believe are the original injectors;
-valve adj. is due in a few hundred miles;
-the glow plug system works perfect, and was just serviced;

The car always had a small missing at idle(while still cold) in frigid Michigan winter weather. I have no block heather or any way to plug in the car at nite since I live in a apartment complex. The car always started this winter, but gradualy the missing/stumble started to get worst and with it came more blue thick smoke. The smoke and stumble used to go away as the engine warmed up to 80-90C but this morning did not.
I know the injectors need new nozzles badly, but I was going to wait till we get at least in 45+ weather to swap them on my next valve adj.
I also blamed the missing/loopy/stuble idle when cold on somewhat uneven compression when cold. Now the smoke goes away at abt 1k rpm and no more stumble/missing/looping, untill back at a stop or light even when the car is fully warmed up. The car did not lost any power since the day I bought it and pulls hard. It also does not burn any noticeable amount of oil between oil changes.
Now for the questions:
1.What kind of damage would ocur if I drive the car as is for another month untill the weather warms up so I can work on it??
2.Could a stretched timing chain/timing advance cause my poor idle?
3.Any other sugestions on what should I start troubleshooting??

rrgrassi · #2 03-11-2008, 10:32 AM

When you serviced the GP system, how many GP's did you replace? Also, when was the air filter last replaced.

Diesels will smoke a bit, especially when really cold at start up, like you get there in MI.

siral3x · #3 03-11-2008, 10:48 AM

Quote:

Originally Posted by rrgrassi

When you serviced the GP system, how many GP's did you replace? Also, when was the air filter last replaced.

Diesels will smoke a bit, especially when really cold at start up, like you get there in MI.

-I found 1 GP bad and I replaced it. I wish I could have done all but it was too frigid outside. I do have a set of Bosch revised glow plugs that I'm going to swap sooner or later.
-I have not replaced the air filter myself yet. Why would the air filter cause smoke/miss/bad idle?
-Well it always smoked a bit at startup, but now it smokes while warm too, that's why I'm rulling out GPs.

rrgrassi · #4 03-11-2008, 10:55 AM

A plugged up air filter means the intake system has to pull air from somewhere...

I did not know they made revised GP's for the 85. Please explain revised, since the 85 already had the pencil type plugs.

I do understand about it beeing too cold to work on the engine. Numb hands and slipping wrenches are no fun.

Also check for fuel leaks at the returun lines and the primer pump.

siral3x · #5 03-11-2008, 02:31 PM

I belive there are fast glow plugs??They heat up quicker according to the website I bought them from, and the revised relay keeps them glowing more.
Primer pump is wet, now that I think abt, and always had been. I was thinking it was dirt on it, but I guess is kinda wet around it. What to replace, and how easy is it?
Wich return line are u talking abt? The one from the injectors to main filter??or filter to tank?and where to check?

P.E.Haiges · #6 03-11-2008, 02:37 PM

siral3x,

What color is the smoke?

P E H

siral3x · #7 03-11-2008, 02:54 PM

Quote:

Originally Posted by P.E.Haiges

siral3x,

What color is the smoke?

P E H

Amm...light blue.

rrgrassi · #8 03-11-2008, 02:45 PM

The braided lines on the injectors.

Replacing the primer pump is not difficult. 17 or 19 mm wrench, IIRC. A leaky primer pump can introduce air into the fule, and will result in a rough idle or a "miss".

siral3x · #9 03-11-2008, 02:56 PM

Quote:

Originally Posted by rrgrassi

The braided lines on the injectors.

Replacing the primer pump is not difficult. 17 or 19 mm wrench, IIRC. A leaky primer pump can introduce air into the fule, and will result in a rough idle or a "miss".

I belive there is an updated primer pump available if I remember right, correct??

rrgrassi · #10 03-11-2008, 03:37 PM

Yes, there is. I bought mine from Fastlane, the sponser of this site.

Have you monitored the engine oil levels?

Do the valve adjustment also. A few hundered miles either way will not hurt.

siral3x · #11 03-11-2008, 04:57 PM

Quote:

Originally Posted by rrgrassi

Yes, there is. I bought mine from Fastlane, the sponser of this site.

Have you monitored the engine oil levels?

Do the valve adjustment also. A few hundered miles either way will not hurt.

I have to add usualy 1qt every 4k miles.

rrgrassi · #12 03-11-2008, 05:20 PM

That kind of usage is not bad at all. My car still likes to "mark her spot" though not as bad since I finally got the air/oil separator drain tube reattached.

The car is also due for a valve adj, and I will be doing that at the next oil change. A co-worker made the bent wrenches for me.

Properly adjusted valves can reduce the smoking.

Have you done the exhaust sniff test? If it smells like normal diesel, try the valve adjustment and replace the air filter.

When you get the fuel seepage stopped, and the car still nails or misses, time to look at the injectors. Poor spray pattern will also increase smoking.

siral3x · #13 03-11-2008, 07:32 PM

Quote:

Originally Posted by rrgrassi

That kind of usage is not bad at all. My car still likes to "mark her spot" though not as bad since I finally got the air/oil separator drain tube reattached.

The car is also due for a valve adj, and I will be doing that at the next oil change. A co-worker made the bent wrenches for me.

Properly adjusted valves can reduce the smoking.

Have you done the exhaust sniff test? If it smells like normal diesel, try the valve adjustment and replace the air filter.

When you get the fuel seepage stopped, and the car still nails or misses, time to look at the injectors. Poor spray pattern will also increase smoking.

I have been messing with the Benz for the last hour or so, but it was to cold to mess around a whole lot.
Here is what I did:
1. took the lid of aircan off while car was stumbling/missing and NO improvement thus I'm rullign out the filter;
2.Decided to change the injector return lines, and here is the strange part:I removed the last piece of the return line, the one that goes from the no 1 injector to the top bolt on the main fuel filter housing while engine was at idle. Fuel started to spray out of the bolt(conected on the other side to the return lien) every 1 sec or so. Why would the fuel be under pressure/spray on the return line out of that bolt?
3.I did changed all injector return lines and the stumbling/missing got somewhat better.
4.After I changed the inj. return lines I disconected again the last piece of return line going to the fuel filter housing top bolt, and same thing fuel would spray out under pressure.
5.After I put my finger over the bolt to block the fuel from squirting out , 3 sec LATER NO MORE MISS/STUMBLE!!! What in the world??? I connected the injector return line back and still no more miss/stumble, but by that time engine was fully warmed up.
6. I inspected the primer pump assy, AND it is not wet nor leaking, it had just so dried up crud on it that made it look wet.

I'm waiting for 11 to hit and I have to go pick up my lady from work...the engine should be bone cold by then, and I'm looking forward to see what happens with my idle.

Any comments/imputs/advice?????

pawoSD · #14 03-11-2008, 08:20 PM

The fuel will spray from where the return line attaches because the injection pump itself also returns some fuel to that assembly and its easier for it to push out the open hole right there than it is to push it back to the tank...when you cover it with your finger it will go to the tank as usual. If your primer pump area is leaky/wet than it is leaking and potentially introducing air to the system. I'd replace it, its pretty easy to change out and its cheap. Also, the rubber lines between the hard line from the tank to the pre-filter and from pre-filter to primer pump need to be in good shape, sometimes the ends can deteriorate, this can also introduce air or allow a leak.

Siral3x, where are you located in MI? I am in MI too. Nice to see another MI dieseler! My car (actually all three of ours) smoke a bit at cold start too, its normal. Two even have the afterglow system and still smoke. After a few mins it clears up though.

siral3x · #15 03-11-2008, 08:31 PM

Quote:

Originally Posted by pawoSD

The fuel will spray from where the return line attaches because the injection pump itself also returns some fuel to that assembly and its easier for it to push out the open hole right there than it is to push it back to the tank...when you cover it with your finger it will go to the tank as usual. If your primer pump area is leaky/wet than it is leaking and potentially introducing air to the system. I'd replace it, its pretty easy to change out and its cheap. Also, the rubber lines between the hard line from the tank to the pre-filter and from pre-filter to primer pump need to be in good shape, sometimes the ends can deteriorate, this can also introduce air or allow a leak.

Siral3x, where are you located in MI? I am in MI too. Nice to see another MI dieseler! My car (actually all three of ours) smoke a bit at cold start too, its normal. Two even have the afterglow system and still smoke. After a few mins it clears up though.

Ludington...1h north of Muskegon.
Yep the rubber line between 1 hard line and pre-filter to primer pump is wet. I was wondering abt it. I double checked the primer pump and it's fine, no leaks.
pawoSD my car came from an old lady in GR. The car was vandalized and stored by this lady for 8 years. My uncle bought it from her and he had it sit in his yard for 2 more. He ended up with a brand new Jetta TDI, never drove the Benz so I took the Benz and started restoring it somewhat.