78 300D smoking need help w/diagnosis - Page 2 - PeachParts Mercedes-Benz Forum

deferr · #16 10-16-2005, 08:53 PM

hamster training would be very impressive!

I will try your bumping the pump trick but do I need to loosen anything to do this? Or do i just tap with a dead blow hammer?? I have noticed the top half leaves pretty quick also.

I will also drive her a little harder because most of my trips are 10-15 min.

barry123400 · #17 10-16-2005, 09:19 PM

Now i remember, your the gentleman that got the problen down to no smoke with # 3&5 injector lines loose. and changed injectors out. You have already eliminated a common cylinder problem. A comparison leakdown test between # 5 cylinder and the other cylinders will tell you by the amount of escaping air into the crankcase if #5 rings are bad. Originally thought of bent crank in injection pump but since #4 runs clean that was eliminated. Also since #4 runs clean cam is not twisted. There is another gentleman that has simular problems but has almost exhausted himself and is hopefully awaiting the solution to your problem. I would post problem in technical section as well and list as many things as you have done and know. Secondly would try to find an older active or retired mercedes mechanic and have a talk with him. since two forum members seem to share common symptoms there is a good possibility mercedes has seen this problem many times before. Will be watching your thread. Could be totally bad valve seal on # 5 I suppose. Valve stem seal problems were murder on old mercedes gas engines but since there is very little mention of seal problems on 123 diesels I assumed they were not a problem. Assumptions can be dangerous. Loose valve guides are not unknown on these engines as well I think. Will be watching your thread.

JimmyL · #18 10-16-2005, 11:55 PM

Quote:

Originally Posted by barry123400

There is another gentleman that has simular problems but has almost exhausted himself and is hopefully awaiting the solution to your problem.

I resemble that remark!

barry123400 · #19 10-17-2005, 08:28 AM

Yes Jim I kind of knew you would be out there. I know he has changed his injectors out and after thinking about it overnight he should loosen 3&5 again to make sure the smoke is gone again just to eliminate the chance of a bad lot of replacement injectors. Not really likely but should be checked. Really at this point I will wait and see what inputs come in and try to keep this thread at least towards the top of list. I really think it will be found it just takes time unfortunatly. There is someone lurking out there that probably has experienced the same problem as you two and hopefully he will post. Wish the guy who keeps mentioning the valve seals would quote his experiences or perhaps one of you could private message him for information. As for the seals if one wanted to change them they can be purchased for about 10.00 as you do not need a complete kit to do them just probably makes it easier. Do not think it is overall pump timing as it would burn dirty on all cylinders in my opinion but if present position is marked it should not hurt to move the pump. Somethings almost seem to defy logic and even after found almost leave you shaking your head. His is a low milage engine to boot. But besides the smoke it is also running a little rough in some respects apparently.

mike2005 · #20 10-17-2005, 10:27 AM

I don't know if this will help. My VW TDI began to smoke noticeably w/ 30k miles, with no oil consumption. Also idle a little rough at times. Oil changes every 4-5k miles. Took to dealer (under warranty) where service manager first suggested engine could be carboned up. But I informed her that I use BG44K. She then indicated that it my be caused by the fuel filter. They ran diagnostics and found no problems but did replace the fuel filter. Problem solved, no more smoke. This defied my original logic (thought smoke was from excessive fuel), but from thread message above, I am now thinking that the filter was restricting fuel flow which in turn effected injector nozzle spray pattern.
Have you cleaned your fuel system recently? How about filter change interval? Has anyone had similar experience with a Benz Diesel, I have only owned mine a couple months?

Stevo · #21 10-17-2005, 11:10 AM

"I will try your bumping the pump trick but do I need to loosen anything to do this? Or do i just tap with a dead blow hammer?? I have noticed the top half leaves pretty quick also."

Maybe we better hold off on the IP "adjustment" for now. How are you fixed for a place to work, tools, shop manuals, etc...? Have you been able to drive the car hard as in "Italian tun up", since you got it? You probably have done all that but it just seems that your problem is fuel related so you wanta make sure you've done all the "cheap & easy" checks before moving on to more drastic things. I could send instructions about timing &/or "bumping the IP" but it would be good, like berry mentioned, if you could find someone to do some "hands on" diagnostic work for you. Compression test, things like that. I had a neighbor that was experienced with MB diesels when I started with these "oil burners" who came over an bailed me out more than once.

deferr · #22 10-17-2005, 11:39 AM

I don't have a lot in the way of shop manuals. I'm not sure what/where to get them. I rely a lot of the forum to guide me through. I'm trying the "driver her like you stole her" technique for now.

I just thought of something. Last winter I had trouble starting the car because I beleive the fuel gelled up. It was a day at like 10 below in the morning and my car was in the culdasac all night. I haven't changed either filter since then and I was wondering if maybe this would cause the filter to become clogged up even after it warmed up?

The car also used to sit A LOT. I met the former owner who said he hardly ever drove her and NEVER did in the winter. I have been kicking around the idea of possibly algae in the fuel tank???

WANT '71 280SEL · #23 10-17-2005, 01:18 PM

Heavy smoke, wouldn't that indicate an abundance of fuel, not a lack of? We did crack all sorts of injector lines and cracking them would make the engine bog down but make no noticeable difference in the smoke. The key here is, it's also running rough, not just heavily smoking. And this isn't the kind of smoking that could be cleared up with an Italian tune-up, this fogs the neighborhood up pretty bad. I think his next step should be a compression test, once he knows he has compression, he then should move to the fuel system. He said the smoke has come one gradually, and I think we did see maybe two bubbles on the dipstick but the engine was off. Could those two bubbles be an indication of needing a headgasket? I think that reaffirms the need for a compression test. Dan, changing the fuel filters certainly won't hurt so I'd go ahead and give it a go. You can replace both for well under $10. Also, make sure you buy a clear in-line filter, not a milky looking one like you have on there now.

Thanks
David

Thanks
David

RAYMOND485 · #24 10-17-2005, 01:53 PM

1984 300d Turbo 134k
Valve Seals Leak Oil When You Shift & Slow Down And When You
Speed Up The Oil Is Their To Burn Smoke, This Is A Diy Work 3-7hrs
The Guide Book At **************.com Is Very Good Guide The No
1 Valve Set Tdc At Crank 0, 140 Deg Added Crank No 2 Its All In The
Guide Book Buy The Kit $76.00

boneheaddoctor · #25 10-17-2005, 01:59 PM

Quote:

Originally Posted by deferr

hamster training would be very impressive!

I will try your bumping the pump trick but do I need to loosen anything to do this? Or do i just tap with a dead blow hammer?? I have noticed the top half leaves pretty quick also.

I will also drive her a little harder because most of my trips are 10-15 min.

you never want to hit the IP with any object....and certainly not while its running.....they ave very tight tolerances...doing it when running could potientially kill it.

WANT '71 280SEL · #26 10-17-2005, 04:18 PM

Dan, there are several bolts that have to be loosened before it can be adjusted. To move it, use a large pry bar that is applied to some stable point giving you leverage. I remember that from reading about it here on the forum, do a search first, obviously.

Also, a little off topic, but here's a link to a place that sells body parts for old MB's. They don't list 108s on their website but you can call and they'll give you a quote.

Thanks
David

deferr · #27 10-18-2005, 12:24 AM

David,
The link didn't show up.

I plan on changing the fuel filters to see how this helps. If no help then I'll probably move to a compression and leak down test.

Any more votes for valve seals??? would valve seals cause a loss of compression?

WANT '71 280SEL · #28 10-18-2005, 12:27 AM

www.kkmfg.com

I think that's it.

Did you ever find out how to do the leak-down test? How about contacting someone about a compression gauge? If you pull the head to do the headgasket, then you can check the condition of the guides and go ahead and replace the seals. If you do the seals with the head off it's easy and could be done by you. The guides need to be machined however. Plus, if you have the valves lapped, that may be better done at a machine shop as well. However, only do the valve seals if you pull the head as I don't think that's where your smoking problem lies.

Thanks
David

Thanks
David

deferr · #29 10-18-2005, 12:46 AM

there is a guy with a compression guage and leak down tester that I can get in a week or so. So I'll probably do that.

The smoking has since gotten very inconsistent. Every once in awhile it will just stop smoking. Then after another couple minutes it will start up again. I'm trying fuel filters.

WANT '71 280SEL · #30 10-18-2005, 12:50 AM

hmmmm. I hope it's not an IP problem. This is just one weird problem. You're not using large amounts of any fluids and cracking injectors doesn't isolate the problem. I'm baffled. Go ahead and do the tests then let me know how those come out. Does it ever start very easily?

Thanks
David

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