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Old 10-21-2010, 03:39 AM
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Join Date: Jun 2008
Location: Northwest Oregon
Posts: 79
Blue smoke at idle, but with a twist!?

Ava is our beloved 1982 300TD - 617, with 345,000 miles - my main PA hauler for over 3 years. Yearly, I adjust the valves, diesel purge, change filters regularly - and oil, etc. She's always been a very sluggish driver, nominated the "Worlds most gutless car".

Long story short, last year restored compression to the 360 range in all cylinders, (thank you Andrew) then recently had the injectors rebuilt, then finally found the lack of power to be a bad ALDA.

So, I was hoping solving the ALDA issue may also take care my next biggest concern - terrible blue smoke at idle, and often beyond (no, really, blue smoke means oil, and she uses plenty, so I knew the ALDA wouldn't have any effect, but still I hoped

Anyhow, tonight, while driving the stoplights in town, and watching the huge embarrassing cloud of smoke behind me, I made some interesting notes.

Ava "tends" to idle rough. But not always. But often, a steady lope-lope-lope-lope, and blow clouds of smoke. I noted today, if I increase the idle (with my foot) from 750 to 900 or 1000, the lope goes away, and often the smoke does too.

At the first stoplight (smoke is real obvious with headlights behind me), I let Ava idle and smoke, then watched as she blew a gawd-awful smoke screen behind me through 1st and 2nd gear, then quit smoking almost entirely as I leveled out in 3rd at 35mph...

The next stoplight, I held the idle up to 1000rpm = no smoke, then pulled away when the light turned green, and observed little or no smoke...

Very strange. I'm wondering if anyone else has noted similar issues with smoke.

Myself, I'm thinking it's time for Turbo work. I gave it a feel the other morning, cold, and can wiggle the shaft side to side enough to get a little audible 'clunk' out of it...


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Old 10-21-2010, 04:51 AM
mach0415's Avatar
Diesel Weasel
Join Date: Mar 2010
Location: Lawndale, NC
Posts: 648
Mine is doing the same thing. I was starting to think turbo seals, although loping will probably not be cause by that. I am leaning toward injector issues on mine, as mine does smoke at idle until warmed up and both irregular skip and smoke goes away. If I were you, I would consider a possible injector issue as well. Which injectors did you go with? There is plenty about Bosch quality issues here on the forum. I would have them tested to be sure.
Mark in NC

"Spark plugs?...We don't need no stinking spark plugs!"
1985 300SD "Der Silberne Schlitten" 420,000 mi

Wish these were diesel:
2003 Ford Club Wagon 130,000 mi
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Old 10-21-2010, 05:26 AM
layback40's Avatar
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Location: Victoria Australia - down under!!
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Maybe valve guide seals ?
Grumpy Old Diesel Owners Club group

I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving
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Old 10-21-2010, 07:30 AM
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Join Date: Jul 2008
Location: virginia
Posts: 496
At a higher idle you are keeping the combustion temps up a little higher and burning the oil better. Same thing happens on my tractor, just set the hand throttle up a little and it will clean up the exhaust.

How did you get the compression up? If you honed and put new rings in, I would not expect the oil to be coming from bad rings, so valve guides, or turbo seals. If you did not hone and put new rings in but just soaked them, and they loosened up enough to get good compression, then I would say the oil ring may be rather weak.
1977 240D turbo
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Old 10-21-2010, 07:50 AM
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Join Date: Aug 2010
Location: UK
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if you've done compression etc then rough idle is injectors, injection timing or injection pump
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Old 10-21-2010, 11:08 AM
toomany MBZ's Avatar
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Location: central Va
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Originally Posted by layback40 View Post
Maybe valve guide seals ?
I'll agree, perform a leak down test, this will let you know if that or the rings are the issue.
83 SD

84 CD
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Old 10-21-2010, 12:09 PM
gastropodus's Avatar
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Join Date: May 2010
Location: Portland, OR
Posts: 434
What did you do that restored the compression? Marvel Mystery Oil soak?

- '79 240D - engine swap complete! Engine broken in! 28-31 mpg! Lovin' the ride!
- '86 190D (W201-126) - 2.5 NA engine, 5 speed, cloth interior, manual climate controls, 33-34 mpg (sold to forum member).
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Old 10-21-2010, 01:41 PM
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Location: Nova Scotia, Canada.
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First I would loosen one fuel injector line at a time to establish if the smoking is one cylinder specific. Just let it idle for enough time with each cylinder disabled to see if there is a difference.

Next if the condition seems to not be an individual cylinder remove the boot from the turbo and idle again. This just establishes it is not some odd turbo seal problem. I know it does not sound like the turbo. Except for the large cloud of smoke on acceleration. That may be an indicator of picking up from the pooled accumulation of oil . If it is also wet with oil in the boot is of course another indicator. It should be dry.

I am also not an expert.In fact very far from one. Still I would think on a serious leaking injector issue the smoke would be black rather than blue. On that basis I would put off an injector checking again at least until the two tests where done.

Posting the oil consumption rate of this engine could also be an aid to figuring what may be the possible cause.

Last edited by barry123400; 10-21-2010 at 02:04 PM.
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Old 10-21-2010, 01:57 PM
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Posts: 18,356
Does your vacuum pump vent into the air cleaner?
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13
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Old 10-25-2010, 05:36 AM
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Join Date: Jan 2008
Posts: 57
Having the same issue here...

Totally having the same issue here, so any light on this would be fantastic.

Smoke is blue/white and reeks of unburnt diesel. Car just crossed 369,768 miles (1982 300SD). Started to stumble and run rough at idle; what used to be a barely glow car to start has turned into something that does not want to start in 50 deg. weather.

Symptoms are the same, huge cloud of smoke at idle, and part throttle. Get on the highway, all smoke stops. Go back to idle, and whammo, fog machine.

Mileage has also suffered; I think I managed to barely get 20mpg at the last fill up. No access to a compression tester, but the car's power is just like it always is on the highway, and she takes off quite smartly.

I'd be very, very curious to see if this boils down to an injector issue, valve stem seals, or what have you.

Please keep us posted!


Last edited by znuh; 10-25-2010 at 05:36 AM. Reason: Forgot to put in the model of the car
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Old 10-25-2010, 06:29 AM
t walgamuth's Avatar
Join Date: Apr 2005
Location: Lafayette Indiana
Posts: 36,880
Unburnt diesel will smoke light blue.

Never look at your smoke in the rear view mirror at night. Even a good running diesel will look smokey under those conditions! Look in the daytime.

Of course smoke looks worse in the lower gears, your engine is turning (pick a number...) four times for a given distance compared to what it does on the highway, it does not have a chance to dissapate as fast.

And a miss from lack of compression whether it is from ring seal or valves will always be most prevelant when idling, as the rpm picks up the seal will be better as the leak does not have as much time to dissapate your compression, plus at higher rpm it is just harder to feel a slight miss.

And yes, I too am interested in what was done to improve compression.

And I would ask what oil you are running?

Just some general thoughts....
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.
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Old 10-25-2010, 11:09 AM
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I had very similar symptoms with my SD. Installed new valve guide seals and the problem went away.

1980 300SD - 495k miles - 'The Ambassador'

Former Family Members
95 C280
73 280SEL
90 300D
87 300SDL (X2)
86 560SEL
84 300D
80 300SD

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Old 10-30-2010, 03:51 PM
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Join Date: Jun 2008
Location: Northwest Oregon
Posts: 79
Sorry for the delay - way busy week with the wife opening a new store, etc + I wanted to observe Ava a bit more.

OK, I run Delo 400, usually 30wt. I've been a bad shade-tree-mechanic, and have not logged oil consumption, but will start in earnest with the next oil change.

A year and a half ago, we thought we'd start at the top, and checked compression - it was all across the board, something like 240-360. A valve adjust, and running the main fuel filter full of AT fluid brought 4 cylinders into the 360 range, but #1 dropped to 150psi!

Biodiesel300 had me soak #1 for a few days with a couple ounces of brake fluid, and that brought all cylinders within the 345-360 range. This may be a key.

I also know she's in need of a set of glow plugs, and have the plugs and reamer on order.

Wondering: could the rack dampener being faulty or out of adjustment create a smoking issue?

***So, for example: last evening, after a gig, we started her up, and drove about 6 blocks to the grocery store. I waited with the car - running, while my wife shopped. Sat in the lot for 10 minutes - temp gauge at 60 (half warmed up) Idling beautifully, and not a puff - absolutely NO smoke, or anything - I couldn't see any exhaust at all - very well lit lot - smooth idle - wonderful.

Then out on the highway 14 miles and stopped at her store - Ava sat chugging and smoking.

Keep in mind there seems no consistency to the issue. Sometimes she smokes cold...

I have a hard time believing that bad rings come and go, but maybe they do. I have new glows coming, and also plan the valve adjust and purge, although the latter 2 have not affected this issue much in the past...

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Old 07-24-2013, 10:15 PM
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Join Date: Dec 2010
Location: North Alabama, USA
Posts: 129
Inquiring minds want to know if you found and corrected the problem with the blue smoke at idle.

I have an 87 300D with the same issue.

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Old 07-24-2013, 11:11 PM
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Location: Out in the Boonies of Hot, Dry, Dusty, Windy Nevada
Posts: 9,585
His last activity was a year ago, so probably gone. too bad he didn`t let us know what the out come was.


there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works
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