LOTs of BLUE smoke! Could it be Valve Adjustment? - PeachParts Mercedes-Benz Forum

777funk · #1 07-07-2007, 09:12 PM

We all know what blue smoke means. I'm getting a good amount of it on my 300sd with 617 turbo. I know that's oil burning.

What are the sources of oil burning (not WVO, motor oil

)?

The car starts great with about 20 seconds of cranking with the glow plugs unplugged so I'm assuming the compression is ok (rings too???)

But could it be my bad valve adjustment? I was in a hurry. Can a bad valve adjustment cause oil burning? My guess is that since oil is in the valve cover, valves that open too far could let some into the combustion chamber. Am I wrong here?

Knightrider966 · #2 07-07-2007, 09:21 PM

I don't think you can blame this one on a incorrect valve adjustment, but I do think that you could look into worn valve guides! It starts without glow plugs which usually would indicate good compression. If your valve guides are worn out, and I've seen this before, then when your valves open to let in air and let exhaust out, you would have engine oil dripping into the cylinders from worn guides and since the valves are hot when the engine is running, them smoke would appear every time your exhaust valve opened. I would pull your head and have a machine shop go over it and do an overhaul. I know your burning oil, but When a Benz Diesel starts burning oil, it won't start without glow plugs if the oil burning is due to piston rings that are shot! Keep us informed!

777funk · #3 07-07-2007, 09:26 PM

Take the head off. Youch that sounds like a lot of work! I like working on cars but that sounds scary!

Knightrider966 · #4 07-07-2007, 09:30 PM

It can be, but there is no other way to do it right and if you keep driving it like this you will not only make enemies of other drivers, but the local constable will get to know you too. Not to mention that your going to damage something else if you keep driving it like this!

Sorry man, but when the head needs work, it needs work. I did mine and it runs great now and no more smoking!

(Unless it's rubber peeling out on the pavement!)

777funk · #5 07-07-2007, 09:34 PM

Ok so where do I start? Also, what's the key to get that thing back on in timing?

Knightrider966 · #6 07-07-2007, 09:43 PM

OH, BOY! What a loaded question! You need to start with the right service manuals and a new set of head bolts, a good machine shop you can trust, stopping the motor at TDC, getting all your gaskets and parts ready to go and with that kind of mileage, you should consider replacing the timing chain while your in there! OH, Yeah, and one more thing, lots of patience! I would not even start unless you have at least a Haynes service book to follow the removal procedures. And you will need a good torque wrench! This is major surgery, be prepared to spend some bucks! I did mine for about $1000.00 with parts and machine shop included. DO NOT let ANYONE tell you that you can use the same head bolts! These are stretch bolts that must be replaced as new!

Biodiesel300TD · #7 07-07-2007, 09:53 PM

If you didn't have blue smoke before the valve adjustment and you think you did a sloppy job one the adjusment. I would pull the valve cover back off and check all the clearances again. Do this before you tear into anything else. Make sure they are right before you assume something else needs fixing.

777funk · #8 07-07-2007, 10:10 PM

Will do it.

Hope I don't have to take the head off. At $1000, I may as well not mess with it. I bought the car for $350 and it'll need another $500 in suspension axles, etc. It runs great, but I'm sure I can get another good running car for less than what I'd pay to fix this one and without the headache. But first a valve adjust to see if it clears anything up.

Heck I may take the head off for the fun of it. Not sure it'll be fun, sounds like a LOT of work but good learning experience.

#9 07-07-2007, 10:51 PM

just put another 50k on it as it is and junk it after that. cheaper, less time consuming and more fun!

DslBnz · #10 07-08-2007, 12:20 AM

My brother-in-law's '87 300D has needed valve seals/guides for the last 70K miles.

It goes through a quart every 6 - 800 miles and smokes like a fiend. It is also one of the peppiest OM603's I've ever known.

Jeremy5848 · #11 07-08-2007, 12:31 AM

Quote:

Originally Posted by DslBnz

My brother-in-law's '87 300D has needed valve seals/guides for the last 70K miles.

It goes through a quart every 6 - 800 miles and smokes like a fiend. It is also one of the peppiest OM603's I've ever known.

My wife's '87 300D also smokes (not a lot -- mostly upon acceleration) and uses oil, about a quart in a thousand miles or so. The compression is apparently very good. I did an experiment -- cranked over a cold engine without allowing any preglow time -- and the engine fired after about 5 seconds.

The wife says it's "embarrassing" to drive a Mercedes that smokes so next week I'll have the valve guides and seals checked. If it's just the seals, fine, they have to be removed to wiggle the valve stems so they'll be replaced anyway. If it's the guides, I think we'll just have to put up with it. I don't want to pay to have the head pulled and I don't want to tackle it myself.

Jeremy

vstech · #12 07-08-2007, 10:48 AM

how's the blowby? a lot of oil in the exhaust can be lots of things. turbo seals, bad vacuum pump diaphragm, dirty air filter, etc. my point is check the general things first. look at the air filter. is it covered in oil? pull the ccv tube, clean it out. pull the valve cover. clean out the baffles. pull the U tube, is it covered in oil? clean all these things, figure out where the oil is coming from. then and only then worry about pulling the head.

captainmonk · #13 07-08-2007, 01:15 PM

pulling a head is way too extreme. How much smoke is therte really can u see cars in back of you? How much oil consumption? A quart of Lucas oil treatment will keep her running longer then you want to keep it I know that is a statement by an infidel nonbeliever but i just wanna drive em not fix em

Knightrider966 · #14 07-08-2007, 01:23 PM

How you fix or not fix it depends on how much you like the car! I like my 1983 300D enough to spend the money to have the head done right and later on, the engine case too. If you just want to drive it go ahead, but worn valve guides can drop a valve into the cylinder and do a lot of engine damage!

Chances are it won't be worth fixing then.

Blowing a lot of smoke out the back will not only get you greivances from other drivers, but this could also be a road hazard and you will meet the constable if he is behind you and he can issue you a fix it or ditch it ticket and cancel your registration until it is repaired or junked.

If this is one of those picky heads and this is your only problem and you know it needs work, why not? What's the worst that could possibly happen? You might get a lot more mileage out of it?

777funk · #15 07-08-2007, 03:10 PM

Yeah, I'll check the obvious things first. We'll see what happens. It seemed to me it didn't smoke this much before my valve adjustment. I really didn't note much smoke at all if I recall. I put about 15% gas in the fuel to help clean a sticking injector. Maybe that caused the smoke??? I doubt it. But I'll re-adjust the valves and see what happens. It seems to have good vacuum. So I don't think it could be the vacuum pump. I don't know. I do know the car has 300k on it. It runs like a top but just LOTs of smoke when I give it some throttle. And it's not white smoke or black smoke it's blue so that bothers me. I'll give her a good cleaning later today hopefully. I consider working on a 617 somewhat relaxing. Well, when things are going good and I know what I'm doing. So I give it some time this afternoon and see what happens.