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  #1  
Old 12-29-2004, 08:26 PM
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350SD, oil consumption worsens

I own a '91 350SD with 286K miles on the clock. For those that don't know, I have been monitoring oil consumption tendencies from over 1 year ago in August. From there, consumption was 1500 miles per qt. on average. Consumption has steadily increased, and the last fill noted the 250 mile per qt marker. I have no idea what's going on. Could valve seals be out of the question for cylinder #1?

Here is a comparison.

One soundclip is in normal speed. Comparing a 3.0 liter OM603(not mine) that needs a new set of injectors to my 3.5 liter(2nd half of sound bite).

http://www.ejzcars.com/350soundnorm.wav

The next soundclip is 50% the speed of normalcy. I suppose it would help to isolate the sounds of the engine.

http://www.ejzcars.com/350sound.wav

The car is starting to blow oil smoke embarrassingly heavy right now. Just happened as of today. Any speeds below 2K rpm cause it to smoke excessively. At an extended idle, upon taking off, the vehicle behind me is engulfed in the blueish, foul smelling haze. At the very least, on the optimistic side, I don't have any tailgaters anymore. However, there are no noises from the engine. Except excessive injector knock from cylinder #1. It looks like <100 miles per qt. if this keeps up.

Should I be concerned?

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1987 300SDL (324000)

1986 Porsche 951 (944 Turbo) (166000)

1978 Porsche 924 (99000)

1996 Nissan Pathfinder R50 (201000)
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  #2  
Old 12-29-2004, 08:49 PM
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Join Date: Sep 2004
Posts: 142
I don't know if my experiance applies to your troubles, but I'll shar with you some thing I've been through with my cars. My '78 300CD leaks oil, but it has never burned it, so I don't have any experinance with a mercedes diesel burning oil. I have had experiance with my '88 560SEL burning oil, about at the rate you're talking. Mine happened fairly suddenly, my oil light came on, I added a quart, and drove on. 300 miles later the oil light comes on again, add oil and make it another 250 miles, then 200, then 100 (with mostly city driving) It's exhauset looked like my diesel on a cold morning.

I finally broke down and did a top end rebuild, which I'm just finishing this holiday break. When the heads were at the machine shop, it was found my guides were shot and several were able to be wiggled by hand. This is most likely the cause of the oil consumption. I'll know for sure when the car is running to the point I can put some mileage on it.

Does the smoke seem more promenant after you start the car and for the next 5 minutes, or is it fairly constant on continuus driving? My gut tells me if its more promenant upon startup its either the valve guides, or something else from above. If it's all the time, it could be piston rings. Either way, I hope I'm wrong.

Best of luck!


Scott
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  #3  
Old 12-29-2004, 09:07 PM
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Join Date: May 2003
Posts: 2,220
It is usually a little more smokey at startup, but even when the engine is warm,... it misfires and throbs quite a bit when coming to a stop and pukes oil out at all times. Especially bad after takeoff.

All engine speeds above 2K rpm's, now, produce a sizeable amount of oil smoke. In other words, all speeds < 50 mph.

Thanks for your help. I appreciate it.
I am hoping it is valve seals. However the culprit is definitely cylinder #1 only.
__________________
1987 300SDL (324000)

1986 Porsche 951 (944 Turbo) (166000)

1978 Porsche 924 (99000)

1996 Nissan Pathfinder R50 (201000)

Last edited by DslBnz; 12-29-2004 at 09:15 PM.
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  #4  
Old 12-29-2004, 09:18 PM
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Join Date: Jul 2003
Location: Ocean Isle Beach, NC
Posts: 2,479
Do a search, maybe in the Diesel Forum. The 350SD's have serious known oil consumption/engine problems. You're lucky yours lastest as long as it did. Do you know if it's the original engine? The typical solution is a new crate engine.$$$$ Hope you find somehting else cheaper is the cause.

Len
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  #5  
Old 12-29-2004, 09:30 PM
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Join Date: Dec 2003
Posts: 228
DslBnz,
Do a compression test. If #1 is low on compression a bent rod is possible. If all cylinders are equal run the engine with the crossover tube remove to check oil leakage from the turbo.
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Paul
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  #6  
Old 12-29-2004, 09:32 PM
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Join Date: May 2003
Posts: 2,220
The turbo is bone dry last time I checked(1 week ago).

It has been reluctant to start in temps less than 15 degrees fahrenheit. Last year, it would start 10 degrees below zero. I suppose that might substitute as a compression test?[]

However, with so much oil built up inside, could that have affected the starting? Sometimes the started locked while cranking....ughh but when it cranked, the engine refused to fire(I glowed it thrice). Temp was 13 degrees, it had been as low as -2 the night before. Took my trusty SDL with 280K miles to class that day.

__________________
1987 300SDL (324000)

1986 Porsche 951 (944 Turbo) (166000)

1978 Porsche 924 (99000)

1996 Nissan Pathfinder R50 (201000)

Last edited by DslBnz; 12-29-2004 at 09:52 PM.
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