240D Can't stop the smoke!

[billhard]

I finally got a chance to recheck the seating of the valve seals. Could someone verify a couple of things for me from the picture:

1- Is the valve seal used to short? By that I mean should it cover all of the section the red arrow points at?

2- Does the silver band which rides on the valve stem itself (yellow arrow) stay compressed into the seal as shown or should it accordion out further?

3- Whilst I have the seals off, how tight a fit should the valve stem be inrelation to the valve guides? Might I make an educated guess as to the condition of the guides by feeling for slop?

Sorry to over think this simple thing so far.

[Govert]

If you see my new valve stem seal, it appears to sit lower:



Did you use the tool?



But mine is a new engine with higher valve lift.

2. Should be slightly extended I think.

3. The difference between good and worn-out is about 0.2 mm. The valve shafts are 9.92-9.94 mm in diameter, the inner diameter of the valve guides is 10.000-10.015 when new. So if you can feel the valves move in the guides, it is not good.

[billhard]

Originally Posted by Govert

You did replace the membrane, but did you check whether the governor housing is air tight? It can also leak from the axle of the poppet cam (and it frequently does).

Thank you for this info. I do in fact have a leak in my governor housing and MB says this part is no longer available. It would seem if the two o-rings / seals on the outside of the axel were replaced along with the housing gasket all would be well.

How have you gone about this fix? The seals or o-rings seem to either be of a unique size and shape or have deformed over time. The o-rings I have trial fitted which are sized properly for the axel do not have a large enough cross section to fill the exterior opening nor rest firmly against the retaining washers. Perhaps I could install two o-rings on each side.

Sorry the thread drones on and on, everyone;'s advice has been appreciated.

[Govert]

Originally Posted by billhard

Thank you for this info. I do in fact have a leak in my governor housing and MB says this part is no longer available. It would seem if the two o-rings / seals on the outside of the axel were replaced along with the housing gasket all would be well.

How have you gone about this fix? The seals or o-rings seem to either be of a unique size and shape or have deformed over time. The o-rings I have trial fitted which are sized properly for the axel do not have a large enough cross section to fill the exterior opening nor rest firmly against the retaining washers. Perhaps I could install two o-rings on each side.

Sorry the thread drones on and on, everyone;'s advice has been appreciated.

MB only sells the entire back cover of the governor housing, including poppet cam. Bosch sells the parts (bearings and O rings) seperately. It is not only the rubber O rings, but also the bearings of the poppet cam axle which should be replaced.

I did repair it with seperate parts from a (Bosch) diesel centre once, but I also heard from people who bought the entire back cover. I think MB charges a lot for such a cover or it is no longer available as you say. The back cover is also available from Bosch diesel centres.

[billhard]

Originally Posted by Govert

MB only sells the entire back cover of the governor housing, including poppet cam. Bosch sells the parts (bearings and O rings) seperately. It is not only the rubber O rings, but also the bearings of the poppet cam axle which should be replaced.

I did repair it with seperate parts from a (Bosch) diesel centre once, but I also heard from people who bought the entire back cover. I think MB charges a lot for such a cover or it is no longer available as you say. The back cover is also available from Bosch diesel centres.

I have been on the phone with MB dealership and Bosch USA. MB says the entire back cover is no longer available and Bosch has no parts of any kind for that model injection pump.

[Govert]

If you go to this topic:
White Smoke 220D - Page 2 - Benzworld.org - Mercedes-Benz Discussion Forum

you can see a PDF and a parts list from the Bosch website. The following parts do list as available/current on the Bosch online catalogue
Bosch Automotive Aftermarket - Products

1 900 210 105
1 420 100 634
2 916 083 010
1 420 410 005

The best is to call/visit diesel workshops/engine overhaul companies that have these parts still on stock. When an MB diesel engine was overhauled, they usually replaced some of the parts of the pneumatic governor too. I saw the back cover not so long ago myself at an engine overhaul company in the Netherlands.

[Govert]

xx

[Govert]

Bosch has a sight that provides old technical information, parts lists, exploded views, old-to-new numbers lists etc.:

Bosch Automotive Tradition

You have to register there for free, and then you can search their database.

[billhard]

Been a long time since I updated this.

Good news is my IP now holds vacuum per spec. I ended up contacting the classics center over the cam housing. They directed me to Pacific Fuel Injection (650) 588-8880 where a man with a heavy German accent said 'ya i have them'. $100 all in to my door. Sad side note when I asked if he wanted my core, the response was no call form them.

Bad news is my car still smokes when pulling away from a stop light! I guess I am left with valve guides unless someone here can point me in any other direction.

[79Mercy]

How much side to side play could you feel in the valve stem in the guides? You shouldnt have been able to feel any with like new guides.

[billhard]

Originally Posted by 79Mercy

How much side to side play could you feel in the valve stem in the guides? You shouldnt have been able to feel any with like new guides.

Little if any movement was felt.

[Govert]

Some acceleration smoke is normal.

The MB test for excessive smoke is driving up a slight hill in third gear at full load. If smoke is still visible one meter from the car, that is too much.

Do you press the accelerator pedal fully when pulling away? The full load screw can be turned back a bit.

Timing was OK?

[billhard]

Originally Posted by Govert

The MB test for excessive smoke is driving up a slight hill in third gear at full load. If smoke is still visible one meter from the car, that is too much.

Yes under these circumstances my car produces black smoke far in excess of 1 meter. The higher I am in the RPM range the more smoke. For example I climb a very steep hill about a mile in length regularly. The car cannot maintain speed in 3rd gear so I climb in second careful not to over rev. If I maintain 75% throttle I see no smoke, if I press more throttle lots of black smoke pours out. I know you said a slight hill, I am just offering more information.

Originally Posted by Govert

Do you press the accelerator pedal fully when pulling away? The full load screw can be turned back a bit.

No I do not press full throttle, quite the oposite I often try to use minimal throttle to lessen the smoke. The smoke clears as i get up to speed. When first starting to move the car makes a lot of smoke , shift to second more smoke then it fades.

Originally Posted by Govert

Timing was OK?

Checked IP timing again, 24 before TDC, was at 25 - 26 and after adjusting if anything more smoke.

Camshaft timing = what the FSM calls as new chain.

[Govert]

Black smoke would indicate unburnt diesel.

The throttles (there are two) are operating as they should? The second one is opening together with the first throttle?

Did you only replace the back cover? or did you take the governor apart any further? If there is too much preload on the governor spring, you can get smoke too.

Try screwing in the full-load screw by1/4 turn each.

Did you ever do a compression test or a compression leak test?

When you check the timing, did you replace the copper washer in the delivery valve holder and torqued to specs?

The poppet cam control is adjusted to specs?

The car smokes with cold and warm engine?

[billhard]

Originally Posted by Govert

Black smoke would indicate unburnt diesel.

The throttles (there are two) are operating as they should? The second one is opening together with the first throttle?

By 2 throttles I assume you are talking about the 2 butterfly valves in the intake. From what I can tell, the rear valve floats on it's own, only being forced to move when at higher throttle settings by the front valve. Is this correct? Could you elaborate more on how they should work together? My FSM makes no reference to this that I can find. Also I notice it looks like I should have a spring on the front valve, none is present.

Originally Posted by Govert

Did you only replace the back cover? or did you take the governor apart any further? If there is too much preload on the governor spring, you can get smoke too.

I replaced the diaphragm anf then later the back cover. I followed the Service manual when doing this including adjusting the compensating path, no adjustment was required.

Originally Posted by Govert

Try screwing in the full-load screw by1/4 turn each.

I see no mention of any such adjustment in the manual, can you elaborate?

Originally Posted by Govert

Did you ever do a compression test or a compression leak test?

Compression test not leak down. The compression in all four cylinders was above 380 PSI (26.2 bar).

Originally Posted by Govert

When you check the timing, did you replace the copper washer in the delivery valve holder and torqued to specs?

I did put the washer back in place, I did not install a new one. Yes I did torque with correct method and to spec.

Originally Posted by Govert

The poppet cam control is adjusted to specs?

I have no idea how to adjust the poppet cam, could you elaborate?

Originally Posted by Govert

The car smokes with cold and warm engine?

Yes warm or cold, but the car often runs on the cold side. About 150F (65C), I assumed this is just old wiring / sender.

Thank you so much for the helping me stumble through learning this.