240D Can't stop the smoke!

[billhard]

I have been chasing a smoking problem my w115 240D and can't seem to stop it. I get a little white mostly grey smoke after idling at a stop light for more than a few seconds. No smoke while idling but it is strong as I pull away through first gear and about half way through second it clears. Interestingly I can rev the car while sitting at the light and get just a little smoke, but as soon as I put the motor under load pulling away I see smoke buffeting off the grill of whoever is behind me. The car otherwise runs great, has outstanding compression(400, 380, 390, 390), pulls strong and starts in relatively cold weather without a problem (I live in San Diego). My MPG's are a little low 23.5 and I can get puffs of black smoke when strongly revving the car in neutral.

What I have checked:

• Vacuum pump is not leaking oil.
• The diaphragm in back of IP was leaking and I replaced it. When doing so I was sure to get all the little pieces and followed the FSM directions.
• The valves are correctly adjusted.
• I have removed the oil bath air cleaner and taken a roughly 15 mile drive, still smokes.
• The injector nozzles have been replaced and calibrated with in the last 1500 miles.
• New fuel filters in place.
• I am not burning / loosing coolant.
• The engine burns roughly a quart of oil every 1000 miles

I commented on the Weekend Wrenching post about this to which mercmad6.3 responded:

Originally Posted by mercmad6.3

Smoke is also a symptom of a lack of air . Make sure the throttle and the pump are both reaching full position together.
On a gasoline injection system you get smoke if the throttle balls are worn and the same thing happens to the 616 engine like yours.

Our understanding of how the IP on 616 in the w115 chassis functions are different, and I am not sure who is correct. To my knowledge the fuel flow for IP's on the 115 is pneumatically controlled (a vacuum line from the rear of the IP to the intake manifold behind a butterfly valve) and the mechanical linkage act only as a damper.

SO.... I feel the car is running rich since the smoke occurs strongly under initial acceleration. Possibly it is burning oil but with such high compression figures it seem unlikely to me. How can I lean it out? What would you check next?

Sorry for the wall of text, any ideas would be welcomed.

[79Mercy]

Make sure the vacuum pump isnt getting oil in the intake, if that checks out okay then move on to the next possible issue, valve stem seals.

Replacing the valve stem seals on a OM616 is very easy, and the parts are rather cheap.

[billhard]

Originally Posted by 79Mercy

Make sure the vacuum pump isnt getting oil in the intake, if that checks out okay then move on to the next possible issue, valve stem seals.

I removed and inspected the vacuum pump "exhaust" line from the pump to the intake manifold and it is dry as a bone, no evidence that oil is escaping.

Originally Posted by 79Mercy

Replacing the valve stem seals on a OM616 is very easy, and the parts are rather cheap.

Interesting idea I might just pursue that.

[79Mercy]

let me know if you need any help with that, i did the valve stem seals on my old non turbo OM617.

[billhard]

Originally Posted by 79Mercy

let me know if you need any help with that, i did the valve stem seals on my old non turbo OM617.

I will certainly take you up on that, after reading the procedure over in my FMS, seems a little daunting.

[unkl300d]

Give it an Italian tune up and add some transmission fluid to the fuel tank.
Trans fluid has cleaners in it.

My 300D gets smokier at start up off the line in winter. BUT I use the trans fluid and 'Italian tune up' and it clears up.

Also try Redline diesel additive to help control smoke.

Keep it simple. Before you go out of your way and dump a wad of dough !

read...
http://www.peachparts.com/shopforum/diesel-discussion/309367-warning-all-diesel-owners.html

[79Mercy]

Its really easy in my opinion.

pull the injectors out, and the valve cover. rotate the motor until none of the cam lobes are pressing the the rocker arms in that set and remove that set of rockers, then rotate some more and pull that set of rockers out.

Start with the 1st cylinder, make sure the piston is at TDC, so when you release the valve it will just rest on top of the cylinder.

Remove the adjustment nut and lock nut and them pull the valve spring out.

Pry off the old valve stem seal and slide the new one back down in place. Be sure that you feel the new valve stem seal pop into place on the valve guide when you press it on.
Then put the valve spring and nuts back on and move to the next valve in that cylinder.

then re-assemble all that and do a valve adjustment.

Just be sure that your piston is at TDC when you start on another cylinder, you dont wanna drop a valve into the cylinder.

[mercmad6.3]

Originally Posted by billhard

• The diaphragm in back of IP was leaking and I replaced it. When doing so I was sure to get all the little pieces and followed the FSM directions.
  
• The engine burns roughly a quart of oil every 1000 miles

I commented on the Weekend Wrenching post about this to which mercmad6.3 responded:



Our understanding of how the IP on 616 in the w115 chassis functions are different, and I am not sure who is correct. To my knowledge the fuel flow for IP's on the 115 is pneumatically controlled (a vacuum line from the rear of the IP to the intake manifold behind a butterfly valve) and the mechanical linkage act only as a damper.

SO.... I feel the car is running rich since the smoke occurs strongly under initial acceleration. Possibly it is burning oil but with such high compression figures it seem unlikely to me. How can I lean it out? What would you check next?

Sorry for the wall of text, any ideas would be welcomed.

Ok, you have strong compressions but on these engines with their throttle plate,you get a lot of oil sucked into the engine by worn valve guides.
Changing them is dead easy.
if you have the FSM, it will out line the process.
1 quart of oil per 1000 miles is excessive.
BTW, the vacuum is the governor for the pump ,it doesn't actuate the rack which is why they will still start but smoke really badly . The rack goes to full fuel but because the throttle plate doesn't open ,there isn't sufficient air..rich running is the result.

[unkl300d]

What was the mileage on the subject engine??

[billhard]

Originally Posted by unkl300d

Give it an Italian tune up and add some transmission fluid to the fuel tank.

It's a 4 speed manual and a 240D, so pretty much every drive is an Italian tune up.

[billhard]

Originally Posted by 79Mercy

Its really easy in my opinion.

pull the injectors out, and the valve cover. rotate the motor until none of the cam lobes are pressing the the rocker arms in that set and remove that set of rockers, then rotate some more and pull that set of rockers out.

Start with the 1st cylinder, make sure the piston is at TDC, so when you release the valve it will just rest on top of the cylinder.

Remove the adjustment nut and lock nut and them pull the valve spring out.

Pry off the old valve stem seal and slide the new one back down in place. Be sure that you feel the new valve stem seal pop into place on the valve guide when you press it on.
Then put the valve spring and nuts back on and move to the next valve in that cylinder.

then re-assemble all that and do a valve adjustment.

Just be sure that your piston is at TDC when you start on another cylinder, you dont wanna drop a valve into the cylinder.

Thanks for the info, I ordered the parts and I will give this a whirl. A few question about your description?

1. Can I remove the glow plugs instead of the injectors, so I do not need new heat shields?
2. I assume you locate TDC on each piston based on cam lobe position?
3. The FSM calls for a drift to seat the seals, you are saying it can be done without?
4. Should I replace any other parts (valve springs, guides and so on)while I have this area apart?

[tram]

What about drip timing the IP? Injection sounds too advanced to me. Smoking and poor MPG would both be symptoms of this.

[79Mercy]

1. you can, however its easier to stick a thin piece of metal thru the pre-chamber so you can tell when the piston is at TDC just to be sure.

2. yes

3. I used my fingers and made sure i felt them all "pop" down over the valve guide

4. nope, all other parts should be okay.

[billhard]

What are the two small plastic tubes that came with the new valve seals?

[mercmad6.3]

The sleeves fit over the top of the valve stem and you slide the guide over them to prevent damage .