New blue smoke at start-up - PeachParts Mercedes-Benz Forum

R Leo · #1 04-09-2003, 12:09 PM

Greetings Forumites!
A disturbing new development with Marlene, my 83' 300TD, has me here looking for answers.

Literally overnight (this started manifesting itsself Monday morning), she has become hard to keep running at the first start in the morning and is now producing large amounts (heavy but not opaque clouds) of blue smoke until the temp needle starts to move. She fires right up but there is a pronounced 'miss' in the idle until 90 sec to 2 minutes of running. And, if you let your foot off the throttle she may or may not keep running.

After a little warm-up, everything's OK. There's no noticeable decrease in performance from before the start of the smoking / missing-out problem.

After warm-up, all her smoking is routine and customary, ie: some diesel haze on hard acceleration. And there is no evidence of blue or white smoke at any time. The warm idle is normal as are the warm starts.

Facts:
1) I bought her two months ago with approximately 220,000 miles
2) She now has about 224,000 miles
3) There has never been any visable blue smoke it start-up till now
4) She's had two oil changes (DELO 400 + filters) since her purchase in early February.
5) It's spring in Texas; nite temps are in the 50s. It was much colder (20-30s) when I bought her and the starts were significantly easier then.
6) I had an oil change done last Friday

Thoughts:
Is there a possible connection between the oil change and the cold missing-out/smoking??

Could this be a bad glow plug? Maybe more than one?

Any and all advice will be appreciated.

Regards to all,
Randy Leo

leathermang · #2 04-09-2003, 12:35 PM

First, since the car is fairly new to YOU... I would set the valves and change all the fuel filters... just on principle...
And do the "Diesel Purge" treatment with two bottles... at $20 , done at the time of the fuel filter changes this is good base line establishment....
The combination of things you have mentioned sound more like fuel related than piston rings/ valves... which is good news...
Check to see what idle adjustments are availble on your car ...

R Leo · #3 04-09-2003, 12:51 PM

Marlene is relatively new to me but since we met, we've covered quite a few miles together...over 4000 in the last 6wks. In fact, 10 days ago, I put 1200 miles on her in less than 24 hours (http://www.peachparts.com/shopforum/showthread.php?threadid=61082&highlight=road+trip) making a rush trip from to and back from OKC. Both before and after that ride, there was never a a hint of hard starting or blue smoke. The thing that concerns me is the rapidity with which this issue has manifested itsself.

Filters and valve adj are definitely on the agenda for this weekend anyway...the necessary wreches and a set of filters are waiting in the garage.

RL

gsxr · #4 04-09-2003, 03:39 PM

A bad glow plug will make starting hard but won't make BLUE smoke. Blue smoke is oil. What oil was put in at the most recent change - was that also Delo 400?

My guesses are turbo seals, valve seals, or the crankcase breather circuit for the blue smoke. Hard starting is probably glow plugs or valve adjust. But that "miss" is not good...! Hopefully the valve adjust will fix it. Otherwise it's time for Diesel Purge, or testing the injectors, or doing a compression test. My cars fire on all cylinders & smooth out within 5-10 seconds of starting, not 60-120 seconds. Yours should too!

Aaron · #5 04-09-2003, 03:54 PM

Rather than Diesel Purge, pour an entire bottle of Red Line 85+ in the main fuel filter before you reinstall it. This will run it full strength through the system and will also eliminate the need to bleed the fuel system when you restart the car. I never liked Lubro Moly products much myself, I always have preferred Red Line over them. Their products make a noticeable improvement.

R Leo · #6 04-10-2003, 10:39 AM

Weird.

The last couple of times I've started her cold, the "dead" miss is still going on when cold but there isn't nearly as much blue smoke production.

In fact, it seems fairly normal except for that miss...maybe it's valve adjustment afterall.

I hope so.

RL

kerry · #7 04-10-2003, 01:47 PM

I'd start by checking the oil level.

gsxr · #8 04-10-2003, 02:24 PM

rotfl! ya know, Kerry, sometimes the obvious stuff slips by us. You are correct of course, that *would* be a good thing to start with.

Best to check after the car has been sitting overnight, particularly if you use synthetic oil. I believe the fill spec for this car is 7.9 quarts with filter change, but I just dump in 2 gallons of Delvac-1 and call it close enough...

R Leo · #9 04-10-2003, 10:31 PM

Oil was OK on Saturday and Monday. I will check again tomorrow AM before start up.

Thanks all,
R

R Leo · #10 04-11-2003, 10:03 AM

Go figure.

Marlene still has a studder when first started but is no longer producing that blue smoke.

I'll do a valve adjustment because I know she needs it and ohm the glow plugs because it seems like that a failed GP or two would produce the difficult start/rough run at start but OK all other times scenario.

I'll report my results when I've completed this maintenance.

Regards to all,
Randy Leo

Fisherman · #11 04-11-2003, 10:45 AM

I replaced all my plugs with beru glow plugs when I first got my 300 and now have to wait an additional 20 seconds or so after the light goes out in the monring before starting or else I get a rough idle.
I don't know if this could be affecting you but the next time I change them out I think I will go back to Bosch...

gsxr · #12 04-11-2003, 03:23 PM

Fisherman,

Bosch or Beru are of equal quality and should not have caused any differences in starting. Monark plugs seem to have a shorter life span though. Perhaps you have carbon in the prechambers, which should have been cleaned by reaming before installing new plugs? If the old plugs didn't fall out in your hand - meaning you needed to tug on them to get them out, then you need to clean the prechambers. Excess carbon will touch the plugs and soak heat away from the plug, reducing their effectiveness. It's also possible you got the wrong Beru plugs by mistake. (??)

Another nice tip is to install an afterglow-type relay AND plugs. This keeps the plugs hot for 5-30 seconds after startup, reduces smoking & shaking drastically, and emissions too. It's not cheap ($100+) but sure is neat.

The "poor-mans" method for OM617.95x engines is to remove the purple/violet wire from the connector on the glow plug relay. This is the "start" signal that normally turns the plugs off when you release the key. Then they stay on for the full 30 second maximum every time. This works great, except they also light the plugs for 30 seconds on each hot start, so it will drastically shorten the life of your plugs - UNLESS you get the afterglow-specific plugs, which are designed for 30-180 seconds of afterglow. I did this for the winter only, now that it's warm out I'll re-connect the wire. Note that the true afterglow kits have a temperature sensor that reduces afterglow time for hot starts, saving the plugs. Some people do the purple wire trick & connect it to a wire on the dash, which is fine, but usually doesn't fly if it's your SO's car!

Regards,

Fisherman · #13 04-11-2003, 06:35 PM

I did not ream them but inspected the holes and there did not appear to be any carbon buildup. The plugs removed cleanly and did not have any markings on them to indicate a problem.. The only reason that I "think" it is the beru plugs was based on the fact that when I changed them, and nothing else, the rough cold start became evident. Of course we could speculate on all the other things it could be too...

I bought them from Phil so they couldn't be the wrong ones cpould they???

I'm going to change them back this weekend and I'll try to remember to post the results...

BTW- I tested all of them and found the resistance values consistant and according to spec. I sure wish i had read deeper before changing as i also tested the Bosch plugs after I pulled thema dn they were within specs too... oh well. thayt was 50 bucks I could use for the IP diapragm on the 240...