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  #16  
Old 07-31-2008, 10:34 AM
juanesoto's Avatar
Diesel freak!
 
Join Date: Mar 2006
Location: San Jose, Costa Rica
Posts: 300
Hello folks! I’ve got some further information for the diesel expert at my place. He had some experience with Bosch inline pumps some years ago. He used to be a heavy machinery diesel technician when he was younger.

The explanation follows (its quite long, so you better get a cup of coffee):

According to him, its very possible that the engine oil finds a way into the fuel gallery. He explained that the bottom of the plungers where the rollers push them are in contact with the engine oil that lubs the pump camshaft and the rollers. After many years of service, it is possible that the plunger body wears in the outter side, leaving enough clearance to allow the engine oil to pass between them and the IP body, getting into the fuel gallery.

Since the engine oil pressure is higher than the fuel pressure in the gallery, at least while the engine is idling, the oil will be pushed into the fuel gallery where it mixes with the diesel, causing the white/blueish puff of smoke at take off or under light acceleration.

He also mentioned that some times, when the oil pump is weak or the oil passage to the IP is clogged, its common to see cases of old IP’s where the fuel gets into the camshaft cavity of the IP and mixes with engine oil. This is usually detected by a higher oil level in the dipstick without the white foam of water contamination.

He said I need to make sure I have properlly working injectors, the right IP timing, proper camshaft timing, acceptable timing chain strectch, good valve seals and proper valve calibration. If after this has been achieved, the smoke is still there and only during accelaration or at idle, I need to decide which way I want to go: IP rebuild or piston rings raplacement (and some associated repairs)

Now, this sounds quite reasonable to me, but I’m really looking forward to hear your opinion. What do you guys think?

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1982 W123 300D NA Euro, 300K Miles, 4-speed manual, 3.46 rear diff, early W126 front brakes, Penta rims with 205/60R15 FH900's, custom fitted (by me) audio system, more to come into the money pit... Soon to be installed: Bilstein HD, R107 front discs and 4-piston calipers, HD Suspension springs, wagon front swaybar.

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  #17  
Old 07-31-2008, 11:00 AM
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Like a Mythbusters episode, sounds "plausible" that oil could get in the IP, expecially the explanation of oil pressure being greater at idle. I have decent compression, new head and new timing chain, so my next steps are new injector nozzles and IP timing check.

I'd love to know of any others experiencing the gentle wisp of idle smoke and take off puff of smoke.
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  #18  
Old 07-31-2008, 01:13 PM
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Diesel freak!
 
Join Date: Mar 2006
Location: San Jose, Costa Rica
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You're right Griesl, seems very unlikely, but who knows... The only way is making sure everything else is in place.

I'm pretty sure thatt if the worn plunger body was the reason, there would be some weird noise from the IP since the plunger would be "loose". Unless its a crack in the IP body, which is also very unlikely and AFAIK almost impossible.

Another reason he mentioned was lubrication rings starting to fail. When the engine is at idle, the piston pressure after ignition is minimal, only enough to keep the engine running. If the lubrication rings are partially worn, they won't have enough pressure against the cylinder wall to sweep the oil as the piston goes down and the compression rings are not tight enough to sweep the oil either, leaving a film of oil in the cylinder walls. As you accelerate, the pressure increases, causing the compresion rings to expand, giving them enough contact pressure to actually sweep the oil film, plus the extra heat inside the combustion chamber that burns the oil residues that might be left.

He mentioned that the fact that an engine has a good compresion has nothing to do with lubrication rings. These might be totally worn or even broken and the engine would have good compression and run smoothly if the compression rings are in good shape.

I feel this is more likely to be the reason why my engine is smoking... I really don't think an oil leak inside the IP would be something likely to happen...
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1982 W123 300D NA Euro, 300K Miles, 4-speed manual, 3.46 rear diff, early W126 front brakes, Penta rims with 205/60R15 FH900's, custom fitted (by me) audio system, more to come into the money pit... Soon to be installed: Bilstein HD, R107 front discs and 4-piston calipers, HD Suspension springs, wagon front swaybar.

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  #19  
Old 07-31-2008, 05:18 PM
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Any further thoughts on this?
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1982 W123 300D NA Euro, 300K Miles, 4-speed manual, 3.46 rear diff, early W126 front brakes, Penta rims with 205/60R15 FH900's, custom fitted (by me) audio system, more to come into the money pit... Soon to be installed: Bilstein HD, R107 front discs and 4-piston calipers, HD Suspension springs, wagon front swaybar.

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  #20  
Old 07-31-2008, 05:42 PM
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Location: South Wales U.K.
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IF there is lube-oil getting into the fuel, it wont be coming from the plungers as described earlier...

The cam-box and tappet area in the pump are Not under oil-system pumped pressure. They are at the same pressure as the crank-case, ie-oil breather pressure, as the oil from the pump must drain back to the crank-case.....

Also, If the plungers were That worn, then they wouldn't generate the 120 Bar pressure needed to inject fuel!

The Lift-Pump Could leak in oil into the fuel supply, as its a plunger-displacement pump...Easy way to tell.....

Change your fuel-filter, and cut open the old one....

Is the paper inside black....?--If so, Thats where the oil is getting in as the fuel is first pumped by the lift-pump to the fuel-filter, then to the I.P.

(Usually faults of the type you describe are due to mis-timing, Cam and or pump, poor injectors, lack of compression or bad valves and stem-seals.....)
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Alastair AKA H.C.II South Wales, U.K. based member

W123, 1985 300TD Wagon, 256K,
-Most recent M.B. purchase, Cost-a-plenty, Gulps BioDiesel extravagantly, and I love it like an old dog.

W114, 1975 280E Custard Yellow,
-Great above decks needs chassis welding--Really will do it this year....
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  #21  
Old 08-01-2008, 10:19 AM
juanesoto's Avatar
Diesel freak!
 
Join Date: Mar 2006
Location: San Jose, Costa Rica
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Alastair, the fuel pump leak sounds like a more likely reason. How does the fuel pump work? Is it a diaphragm and a lever moved by a cam in the IP? How would the oil get from the IP into the fuel pump? Any other syptom like low fuel delivery pressure?

I’ll do some further work this weekend. I’m planning to check the IP timing and the fuel pump. Also, I’ll try to make a compression test if I can get a tester from a friend. Which is the desired cylinder pressure?

I’ll be getting back with an update ASAP.

Anything else that I should check while I’m working in the car?

Thanks again to all of you for your advice!
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1982 W123 300D NA Euro, 300K Miles, 4-speed manual, 3.46 rear diff, early W126 front brakes, Penta rims with 205/60R15 FH900's, custom fitted (by me) audio system, more to come into the money pit... Soon to be installed: Bilstein HD, R107 front discs and 4-piston calipers, HD Suspension springs, wagon front swaybar.

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  #22  
Old 08-02-2008, 08:48 AM
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The lift-pump, the part the pre-filter is plumbed to on the side of the main IP is a plunger-type pump. Its run from an eccentric on the Pump cam-shaft, it has a roller on the end of the plunger....

The Pump cam runs in an oil bath down there, so there is loads of oil round. Any wear of the lift-pump Could allow fuel to leak into the lube-oil and also the lube-oil to leak into the fuel its pumping, Especially if for some reason there is a restriction in the fuel-lines from the tank or the pre-filter is getting a little choked, causing a higher than normal 'suck' at the lift-pump....

The plungers at the top half of the pump are a very fine tolerance part, and lube-oil leakage there would be very unlikely due to the very high fuel-pressures--The fuel would leak out faster down the length of the plunger (under pressure) than the lube would leak upwards...

Also, these parts are above the tappet-chest part with the return-springs below. Although there is lube-oil at this higher position in the pump, there isnt a vast amount around, as there are only the springs and rack in there which dont need a huge amount of lube...
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Alastair AKA H.C.II South Wales, U.K. based member

W123, 1985 300TD Wagon, 256K,
-Most recent M.B. purchase, Cost-a-plenty, Gulps BioDiesel extravagantly, and I love it like an old dog.

W114, 1975 280E Custard Yellow,
-Great above decks needs chassis welding--Really will do it this year....
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  #23  
Old 08-12-2008, 01:06 PM
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Join Date: Mar 2006
Location: San Jose, Costa Rica
Posts: 300
alastair, thanks for the explanation. this weekend I'll do several things to the car and I'll be getting back with details. the planned works are:

check IP timing and adjust if required
change fuel filters and cut open the main fuel filter to check for oil residues
change valve steam seals again, since I think I messed them up during the installation (didn't used the slide jackets to install them, which might have caused damage of the lips against the stems threads)
adjust valves
check timing chain stretch
flush engine to remove carbon deposits and hopefully release partially stuck oil rings
change oil again

My work sequence will be:

Flush engine
Remove oil and oil filter
Remove diesel filters
Let the engine drain while checking fuel filter
Remove head cover and clean cam, lobes and the sorroundings
Change valve stem seals
Adjust valves
Check chain stretch
Put fuel filters and prime
Check IP timing and adjust if required to compensate chain stretch
Put oil filter and pan bolt
Put valve cover back in place
Put fresh oil in engine
Fire it up and pray everything works the way it should....

Anything else I should do? Or something you would do different?

BTW, would it be worth getting the oil of the oil cooler out as well? My concern is the amount of contaminated oil left there during oil changes...
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1982 W123 300D NA Euro, 300K Miles, 4-speed manual, 3.46 rear diff, early W126 front brakes, Penta rims with 205/60R15 FH900's, custom fitted (by me) audio system, more to come into the money pit... Soon to be installed: Bilstein HD, R107 front discs and 4-piston calipers, HD Suspension springs, wagon front swaybar.

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  #24  
Old 08-12-2008, 03:18 PM
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Many have found that setting the Injection Timing to 26 degrees rather than the 24 degrees specified has been advantageous..

(Personally, I believe your fault is Timing related, unless as you say, the valve-guide-seals were damaged when you didnt use a shield over the threads when installing them. The lips on those things are very thin and easily de-formed/damaged--There is a Huge amount of oil flying round up the top end round the cam, Hard work for those tiny seals!)
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http://i190.photobucket.com/albums/z...0TDnoplate.jpg

Alastair AKA H.C.II South Wales, U.K. based member

W123, 1985 300TD Wagon, 256K,
-Most recent M.B. purchase, Cost-a-plenty, Gulps BioDiesel extravagantly, and I love it like an old dog.

W114, 1975 280E Custard Yellow,
-Great above decks needs chassis welding--Really will do it this year....
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  #25  
Old 08-12-2008, 03:34 PM
juanesoto's Avatar
Diesel freak!
 
Join Date: Mar 2006
Location: San Jose, Costa Rica
Posts: 300
Quote:
Originally Posted by Alastair View Post
Many have found that setting the Injection Timing to 26 degrees rather than the 24 degrees specified has been advantageous..

(Personally, I believe your fault is Timing related, unless as you say, the valve-guide-seals were damaged when you didnt use a shield over the threads when installing them. The lips on those things are very thin and easily de-formed/damaged--There is a Huge amount of oil flying round up the top end round the cam, Hard work for those tiny seals!)
Thanks for the advice! I'll have it mind. I really hope that this issue I'm having is due to the seals and the IP timing. I don't have that much of free time to start dealing with major repairs like timing chain replacement or the much more worse and difficult rings replacement...

I'll do the work on friday, since it's a holiday and I'm free. (I hope my mother doesn't get mad at me for using the mother's day to tinker my car... )

I'll be reporting back. Stay tuned and happy "dieseling"!
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1982 W123 300D NA Euro, 300K Miles, 4-speed manual, 3.46 rear diff, early W126 front brakes, Penta rims with 205/60R15 FH900's, custom fitted (by me) audio system, more to come into the money pit... Soon to be installed: Bilstein HD, R107 front discs and 4-piston calipers, HD Suspension springs, wagon front swaybar.

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  #26  
Old 08-17-2008, 09:23 PM
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Diesel freak!
 
Join Date: Mar 2006
Location: San Jose, Costa Rica
Posts: 300
Ok, so I did some tinkering on my car.

This pic is of my garage getting ready to start working. "Sorry mom for the hell of a mess I did in the floor!" Next time I wash my engine bay somewhere else...
Attached Thumbnails
Some white/blueish smoke while idling-meche-1.jpg  
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1982 W123 300D NA Euro, 300K Miles, 4-speed manual, 3.46 rear diff, early W126 front brakes, Penta rims with 205/60R15 FH900's, custom fitted (by me) audio system, more to come into the money pit... Soon to be installed: Bilstein HD, R107 front discs and 4-piston calipers, HD Suspension springs, wagon front swaybar.

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  #27  
Old 08-17-2008, 09:28 PM
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Diesel freak!
 
Join Date: Mar 2006
Location: San Jose, Costa Rica
Posts: 300
This pic is my car in the garage and my sister's car outside...

"Mom, again, sorry for the mess!"
Attached Thumbnails
Some white/blueish smoke while idling-meche-2.jpg  
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1982 W123 300D NA Euro, 300K Miles, 4-speed manual, 3.46 rear diff, early W126 front brakes, Penta rims with 205/60R15 FH900's, custom fitted (by me) audio system, more to come into the money pit... Soon to be installed: Bilstein HD, R107 front discs and 4-piston calipers, HD Suspension springs, wagon front swaybar.

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  #28  
Old 08-17-2008, 09:32 PM
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Diesel freak!
 
Join Date: Mar 2006
Location: San Jose, Costa Rica
Posts: 300
And this is my mechanic partner, "Sorbeto" or waffer in english... He really likes sitting around when I'm tinkering
Attached Thumbnails
Some white/blueish smoke while idling-sorbeto.jpg  
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1982 W123 300D NA Euro, 300K Miles, 4-speed manual, 3.46 rear diff, early W126 front brakes, Penta rims with 205/60R15 FH900's, custom fitted (by me) audio system, more to come into the money pit... Soon to be installed: Bilstein HD, R107 front discs and 4-piston calipers, HD Suspension springs, wagon front swaybar.

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  #29  
Old 08-17-2008, 09:34 PM
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Diesel freak!
 
Join Date: Mar 2006
Location: San Jose, Costa Rica
Posts: 300
This is my engine with the valve cover removed, ready for a timing chain check, a valve stem seals replacement (again) and a valve adjustment...
Attached Thumbnails
Some white/blueish smoke while idling-meche-3.jpg  
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1982 W123 300D NA Euro, 300K Miles, 4-speed manual, 3.46 rear diff, early W126 front brakes, Penta rims with 205/60R15 FH900's, custom fitted (by me) audio system, more to come into the money pit... Soon to be installed: Bilstein HD, R107 front discs and 4-piston calipers, HD Suspension springs, wagon front swaybar.

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  #30  
Old 08-17-2008, 09:41 PM
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Diesel freak!
 
Join Date: Mar 2006
Location: San Jose, Costa Rica
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These are my "tool bench", tool chest and a drinking treat... Cheers!
Attached Thumbnails
Some white/blueish smoke while idling-small-bench.jpg   Some white/blueish smoke while idling-tool-chest.jpg   Some white/blueish smoke while idling-carlsberg.jpg  

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1982 W123 300D NA Euro, 300K Miles, 4-speed manual, 3.46 rear diff, early W126 front brakes, Penta rims with 205/60R15 FH900's, custom fitted (by me) audio system, more to come into the money pit... Soon to be installed: Bilstein HD, R107 front discs and 4-piston calipers, HD Suspension springs, wagon front swaybar.

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