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#1
09-29-2012, 12:43 AM
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1975 240d runs rough and smokes at bottom of downgrades
On two occasions, at the bottom of a 1/4 to 1/2 mile fairly steep grade, the car started billowing blue smoke and was running very rough. The first time the car was shut off and towed home after finding that it had lost a quart of oil in about 15 miles. I pulled the injectors and found obvious oil in the first 2 cylinders. I did a compression test and came up with readings from 520 to 580, with the oily cylinders being higher. Since the car also blows a large cloud of smoke starting cold, I replaced the valve seals (without removing the head).
Test driving the car it ran well for a couple days then did the same thing going down the hill. This time I just stopped and revved the engine. It returned to normal operation. Since replacing the valve seals, I've driven about 15 miles and lost a little less than 1/4 of a quart of oil but the downhill smoke, rough running problem is still there. The engine has about 100K miles and injectors were replaced about 6 months ago. It has a manual transmission. In addition to smoke at start up (which the valve seals did not help), there is some smoke with hard acceleration. I've noticed that the car exhaust has a rather arcid smell. Not the typical diesel smell. There is no indication of oil in the coolant or coolant in the oil. The vacuum line from the vacuum pump to the intake has some black in it, but not what I would expect for the amount of oil being burnt. Any ideas of what is going on or what I should check next? 
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#2
09-29-2012, 09:42 AM
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This happened on my 85 TD. On a long downhill run from the Eisenhower Tunnel on I-70 in relatively cold weather where I did not step on the accelerator for about 15 miles, the engine was running rough and putting out blue smoke. I can't explain the problem. Car ran well before and after. Sometimes it puts out blue smoke on short steep downhills in town if the engine is cold but it doesn't run rough. No explanation for that either. Perhaps it is caused by a cold engine and high vacuum in the cylinders sucking oil past the oil rings.
__________________
1977 300d 70k--sold 08 1985 300TD 185k+ 1984 307d 126k--sold 8/03 1985 409d 65k--sold 06 1984 300SD 315k--daughter's car 1979 300SD 122k--sold 2/11 1999 Fuso FG Expedition Camper 1993 GMC Sierra 6.5 TD 4x4 1982 Bluebird Wanderlodge CAT 3208--Sold 2/13
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#3
09-29-2012, 10:53 AM
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I think you will find oil is going from the vacuum pump to the intake of the engine. You can duplicate the condition by jacking up or elevating the front end sometimes. My feeling is that as the engine is tilted more oil is able to get through a leaking diaphram on the pump somehow.
Disconnection of the return or exhaust line from the vacuum pump may prove this. Also if you think about it most the oil put into the engine from that source would show up in the first couple of cylinders as you experienced. Simply put the diaphram in the vacuum pump is leaking is the prime suspect. The clue to me is a long time ago there was a member with a simular issue.It took awhile to nail it down. At the same time I of course cannot be positive it is the issue. Just that there is a good chance it might be. If this is indicated to be the problem a rebuild kit for your older pump is not that expensive.
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#5
09-29-2012, 12:39 PM
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X2 with barry123400's suggestion - check for oil at the air throttle valve
__________________
1992 W201 190E 1.8 171,000 km - Daily driver 1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone 1965 Land Rover Series 2a Station Wagon CIS recovery therapy! 1961 Volvo PV544 Bare metal rat rod-ish thing I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior  Don't leave that there - I'll take it to bits!
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#6
09-29-2012, 01:29 PM
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Thanks for the responses. I had kind of ruled out the vacuum pump since it feeds the intake with a clear hose and there was very little that looked like oil stuck in the hose, but there is some. I think I will explore that further, it does sound like the most likely explanation. I will let you know what I find.
Regarding the compression, it is a cheap gauge. I don't trust the accuracy of the absolute numbers, but relative to each other the numbers are close, so no single cylinder appears bad.
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#7
09-29-2012, 08:00 PM
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Does this car have a throttle blade in the intake? If so how about this theory.
If the throttle blade is miss adjusted / has loose linkage, it might shut completely when coasting down a hill. This would allow high vacuum in the intake and allow oil to enter the cylinders by pulling oil past the rings and / or pulling oil from the breather system.
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#8
09-30-2012, 08:29 AM
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Quote:
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#9
09-30-2012, 09:04 AM
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If I'm not mistaken, this model can also suck oil into the intake under high vacuum conditions from the IP if the diaphragm in the IP is ruptured. I believe there was a thread with a video on this topic in the last year or so from a member in one of the Carolinas.
__________________
1977 300d 70k--sold 08 1985 300TD 185k+ 1984 307d 126k--sold 8/03 1985 409d 65k--sold 06 1984 300SD 315k--daughter's car 1979 300SD 122k--sold 2/11 1999 Fuso FG Expedition Camper 1993 GMC Sierra 6.5 TD 4x4 1982 Bluebird Wanderlodge CAT 3208--Sold 2/13
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#10
09-30-2012, 12:28 PM
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Quote:
(That was the problem that chap who did the video of the caterpillar had wasn't it? I've forgotten his user name for the moment...) If however oil is being drawn from the IP then there is serious trouble 'cos that's not connected to the engine supply is it? It has its own little sump doesn't it.
__________________
1992 W201 190E 1.8 171,000 km - Daily driver 1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone 1965 Land Rover Series 2a Station Wagon CIS recovery therapy! 1961 Volvo PV544 Bare metal rat rod-ish thing I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior Don't leave that there - I'll take it to bits!
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#11
09-30-2012, 05:53 PM
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Yep, the caterpillar guy. I can't remember his user name either.
__________________
1977 300d 70k--sold 08 1985 300TD 185k+ 1984 307d 126k--sold 8/03 1985 409d 65k--sold 06 1984 300SD 315k--daughter's car 1979 300SD 122k--sold 2/11 1999 Fuso FG Expedition Camper 1993 GMC Sierra 6.5 TD 4x4 1982 Bluebird Wanderlodge CAT 3208--Sold 2/13
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#12
09-30-2012, 08:58 PM
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__________________
- '79 240D - engine swap complete! Engine broken in! 28-31 mpg! Lovin' the ride! - '86 190D (W201-126) - 2.5 NA engine, 5 speed, cloth interior, manual climate controls, 33-34 mpg (sold to forum member).
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#13
09-30-2012, 09:20 PM
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Quote:
__________________
1977 300d 70k--sold 08 1985 300TD 185k+ 1984 307d 126k--sold 8/03 1985 409d 65k--sold 06 1984 300SD 315k--daughter's car 1979 300SD 122k--sold 2/11 1999 Fuso FG Expedition Camper 1993 GMC Sierra 6.5 TD 4x4 1982 Bluebird Wanderlodge CAT 3208--Sold 2/13
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#14
09-30-2012, 09:23 PM
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After work today I unbolted the vacuum hose from the intake manifold and there is oil everywhere. Looks like it is indeed the vacuum pump. I will be ordering a rebuild kit for it tomorrow. Thank you all for your suggestions.
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#15
10-01-2012, 12:29 PM
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Quote:
http://www.peachparts.com/shopforum/diesel-discussion/306080-high-idle-white-smoke-shifting-funny-help-75-240d-3.html
__________________
1992 W201 190E 1.8 171,000 km - Daily driver 1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone 1965 Land Rover Series 2a Station Wagon CIS recovery therapy! 1961 Volvo PV544 Bare metal rat rod-ish thing I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior Don't leave that there - I'll take it to bits!
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