Hello All,

This is my very first post, and I need help diagnosing intermittent blue smoke coming from my newly inherited 1996 MB E300. My father has owned the car for 13 years and has taken very good care of it. A little history...He purchased it with 47K miles and it currently has 165K miles. He has always used Mobil 1 Turbo Diesel synthetic every 5K miles. The head was redone approximately 35K miles ago due to a broken glow plug, so valve job and new head gasket. Recently within the last 10K miles the cooling system was gone through due to a cracked radiator. A new radiator, water pump, thermostat, and hoses were replaced. Also, within the last 2K miles the injectors were replaced with new Bosch units, all plastic lines, and delivery seals for the injection pump too. The car was parked up for 6 months due to a diesel fuel leak. My Dad told me that I could have the car if I paid for the shut off valve which was leaking because it had a crack. So, I bought the valve and seal, and with the help of my Dad we fixed the leak and the car is up and running again.

My father referred me to this forum because he has always gotten good advice and help from the members here. So, these are my symptoms with the car. When I start it in the morning, it starts right up with not a hiccup. A little puff of blue smoke only. BTW we use Diesel Kleen or Optilube in the fuel tank at regular fill ups along with Diesel purge every 3 months. When driving on the expressway and the engine reaches 2K rpms, blue smoke starts coming from the exhaust. If I accelerate to 2.5K rpms or higher the smoke goes away? If I punch the accelerator, I get some black smoke from the exhaust. Both me and my Dad are puzzled to what could be causing this. I would appreciate any insight or suggestions from you all.

Thanks in advance,

Brandon

BTW I am a senior in high school and this is my first car.

Congratulations on your first car.

Usually Blue smoke indicates engine oil burning in the combustion chamber. I would keep a check on your engine oil consumption. Don't know how long you have been driving the car since the layup, but you might want to drive it for a while and see if the blue smoke issue clears itself up on its own. Good luck with your new vehicle!!!

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96 E300d

I would suspect a fault in an injector.

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[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.

Blue or gray? Sometimes hard to differentiate. Were the filtrs changed recently?

My second suspicion might be an intermittent head gasket leak at the front passage. I am far from sure and would just continue driving for the time being. My definition of intermittent is that under certain engine loadings some oil may get from the front oil passage into the first cylinder.

You also might find leakage present in the turbo. It may prove wise to examine that system for evidence of oil leakage in the plumbing. How often in miles are you adding a quart of oil to the engine? Actually it is a much better possibility than the intermittent head gasket leak. It of course may be something else but I would tend to target these two things on those engines.

Checking the turbo for a failed or weak bearing seal is not that hard.
Also if in the turbo check for bearing wear. You should not be able to wobble the shaft.

Just my thoughts. Hopefully another member that has much more experience with your engine type. Might have a better and easier source of the issue ideal. Your turbo is the highest probability to me at this point.

606NA, no turbo.

You need more data.

Is it using any coolant? A little white smoke in your normal exhaust can be deceiving.

What is your engine temp? If the thermostat is not allowing the engine to run 85C or so, you can have some unburned fuel (white to bluish). The faster / harder you run it the hotter the cylinders will be and it might clear up at speed.

The head gasket is also a possibility as mentioned above, and a stuck ring is possible. The head gasket should show some loss of oil or coolant, and usually the coolant gets dirty from the soot (and can be detected by testing the coolant). If a stuck ring there will be a lot of blowby, which will show as an oily mess in the breather system. Has this car been run on WVO? This and low engine temps can contribute to stuck rings. Sometimes the fix for sticky rings is as easy as an "Italian tune-up", ... tell your Dad it needs one (hahaha).

Next time you change the oil, it is a good idea to have the oil analyzed (get a test kit). Even if nothing is found, it will provide a great baseline for future concerns.

Congrats on the first car, he picked a good one for you.

Smooth idle? Usually a bad injector will give you a bit of a miss, and it is rare that a bad/leaking injector will idle smoothly.

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Gone to the dark side

- Jeff

Thanks for all the responses! I have been driving the car for about a week now, and I plan on taking it on a road trip this weekend and will report back. Any suggestions on fuel and oil additives? I really do appreciate the feedback and suggestions...thanks again!

Most of the things I can think of would cause it to create blue smoke at other times too.

Do you get the blue smoke when revving to 2k RPM in park? Once you get blue smoke, does it continue as long as you maintain 2k RPM?

This is really out in left field, like really really out there, but if the answer to both is yes, I'd wonder if you're hitting the resonant frequency of some internal part of the engine that's causing either an oil leak, excessive blowby, or excessive fuel to be injected.

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'83 300DTurbo http://badges.fuelly.com/images/smallsig-us/318559.png

Broadband: more lies faster.

I guess you have to start somewhere. Sorry I thought you had a turbo. I might pull the number one and number two injectors and inspect their faces for any differances.

Leaky head gaskets that are intermittent can and do occur. Again what I suggest is not conclusive but normally both injector faces would look very similar. Any excess buildup or major difference between their appearances would be a pretty sound indicator.

Of course you may not be processing enough oil to show it yet if it is not there.

Check the breather system as it may possibly holding oil and letting it go under higher vacuum.
Is the air filter clean ?. Not collapsing under load ?.
Lastly when you check the engine oil and top up is the car on absolute level ground ?

I am curious to know if when the Radiator Cracked the Engine overheatd.

If it did overheat even though the Head Gasket and Head were previousl fixed it the overheating could have altered or damages something.

If excess Oil is getting into the Cylinders frequently when you pull Injectors and look into the precombustion Chamber you will see shiny wet looking Carbon.

One might also wonder if they used cheapie Valve Stem Seals.

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84 300D, 82 Volvo 244Gl Diesel

... still curious on the WVO question too.

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Gone to the dark side

- Jeff

how well does it accelerate? 0-60 times? the fuel filters can partially clog, resulting in more IP rack travel than it should need to run. this can cause odd blue smoke at certain RPM ranges. check this.

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Sorry, for the late response...

Ok...I changed the oil, air filter (was dirty), fuel filters (filled the large filter with Diesel Purge), added a can of Diesel Purge and Opti-Lube XPD additive in the fuel tank. Took the car on a 200 mile trip last weekend and have driven a total of 500 miles up until today. While driving on the highway, I noticed that when the car decelerated from 3K RPM to 2K RPM it would blow blue smoke as I accelerated back up toward 3K. At around 2.5K RPM the blue smoke would go away as I accelerated back up to 3K RPM. In stop and go traffic and city driving there was no smoke. I checked the coolant and oil levels today and had no loss in both. I should point out that the amount of smoke is decreasing as I continue to drive the car. I suspect that I will need to clean the intake and breather system as suggested by "Murkybenz". I did not think to do so while changing out the shut off valve.

I will answer the questions asked of me...

babymog-

Not using coolant, engine temp is good about 90C, no WVO, smooth idle, and "Italian tune-up" accomplished;-)

patbob-

No blue smoke revving in park. Blue smoke does stay around 2K as described above. The throttle feels like a transmission slipping while it generates the blue smoke. If that makes sense. Then it becomes smooth again as I accelerate past 2K RPM.

barry12345-

I have not checked the injectors yet for comparison.

Murkybenz-

I plan to clean the breather system. The air filter was dirty and I guess could have been collapsing under load. Yes, I checked oil level on level ground.

Diesel911-

The engine did not overheat when the radiator cracked. It happened while pulling out of the parking lot at Home Depot and it was towed home. I will check the pre combustion chamber when I pull the injectors. Not sure about the valve stems. My Dad's mechanic always recommended to use Mercedes Benz original parts from the dealer.

vstech-

The car accelerates very well and smooth through the RPM range. I have not timed 0-60 yet. I changed both fuel filters per your suggestion:-) and added Diesel Purge directly into the large filter.

I really do appreciate all your suggestions and help!

Brandon

I'm wondering if the resonance flap valves in the intake manifold are not working correctly. I think you can test by applying vacuum to each flap to see make sure they are operating smoothly and completely opening or closing. Recommend you research this.

The resonance flap valves open/close in a sequence to change the length of the intake manifold, and provide what I call "poor man's turbo" effect. Similar to a pipe organ, the length of the intake manifold determines an air column wave length, and when that wavelength pressure peak happens at the intake valves, more air is forced into the cylinder by the higher pressure. The two valves allow three different intake manifold lengths, so there are three different RPM that match a wavelength pressure peak, and the engine power curve has three torque peaks instead of one.

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Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC