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  #1  
Old 11-11-2007, 10:11 PM
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Question Oil consumption and possible vacuum pump problems

I have been very pleased with the preformance, economy, and drivability of my '79 240D. I starts easily, has better acceleration than I was expecting and has given my 30+ mpg around town economy. This is saving me big $s comapared to my previous transporatation choises and I am enjoying driving for the first time in years. However, the oil consumption has seemed a little more than the power, startability and economy of the engine would indicate(about 1qt./ 800 mi.).

Today I was playing with a vacuum check valve that came out of the '80 240D that donated the engine. I found a lot of engine oil coming out of the vacuum pump side of the valve. I am now concerned that the vacuum pump may be in need of a rebuild. I might add that I cleaned the engine very well and installed new gaskets on the filter houseing, cam cover and lower oil pan before I installed it in the car and there are no oil leaks at all to be seen around the engine.

I previously thought that the valve seals might be the cause of the oil consumption, but now I am concerned about the vacuum pump. Especially, after reviewing the thread about the timming chain failures and how a bad vacuum pump can lead to timming chain failures and wreck the engine.

Any comments on the subject would be appreciated.

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82 300SD 290k(needs engine swap)
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  #2  
Old 11-11-2007, 10:19 PM
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Could be a failed diaphragm. Rebuild kit is not that expensive and it's about an hour and half job. Could be getting oil into the intake through the vent line that goes to the air filter if the diaphragm is torn. You should be able to see oil in that vent line with the engine running if the diaphragm is breached.
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Old 11-11-2007, 11:26 PM
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Its probably leaking more oil than burning, they usually are.
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Old 11-12-2007, 03:14 PM
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No leaks

I cleaned the entire engine squeaky clean before installing it. Also, replaced lower pan, oil filter houseing and rocker cover gasket before installing it. I watch it pretty closely and doubt that it has leaked 1/4 teaspoon of oil past any external accesory in the last 5k mi. Thats why I am concerned about the vacuum pump, especially after finding some oil in the check valve. I guess I could be passing some oil around the valve seals as well, but they won't destroy the timing chain.

Will a vacuum test let me know if the diaphram on the vacuum pump is leaking?
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82 300SD 290k(needs engine swap)
79 240D 354k with new heart transplant w/220k
82 240D w/auto tranny soon to be manual 4 speed
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  #5  
Old 11-12-2007, 04:32 PM
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Here's a thread

That may help you. It's pretty long but there is some good info in there.

Suddenly leaking a lot of oil from air filter housing - Help!!!
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Last edited by slarson80; 11-14-2007 at 02:58 AM.
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  #6  
Old 11-12-2007, 04:44 PM
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A vacuum test may indicate nothing. Inspect the vent line from the vacuum pump. If there is oil in it you either have a leak past the diaphram now or this engine had one in a prior life.
There are only three possible sources of oil supply to your vacuum lines on your vehicle I believe.
Most likely is the vacuum pump followed by the shut off on the injection pump. Last but least possibly is transmission fluid drawn up from the modulator valve assembly if you had an automatic.
I am not positive it can happen on a 240 automatic yet iit is a source. I cannot think of any other sources of oil vaccum line contamination. Eight hundred a quart is not out of line if the majority of driving is primarily high speed highway driving. You are using 15-40 grade oil?
Also outright failure of the vacuum pump resulting in engine destruction is not that common on a 240d.
If you rebuild the pump just check the mechanical components of the pump for excess wear. A leaky diaphram from age and use is not unusual. It's amazing they last as long as they usually do.

Last edited by barry123400; 11-12-2007 at 04:52 PM.
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Old 11-12-2007, 05:01 PM
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If you pull the v/p check for excessive end play in the timing device, that can kill a v/p and also go on to kill your engine with the broken bets of pump. The early type of pump is cheaper and easer too rebuild anyway.
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Old 11-13-2007, 01:02 PM
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Thanks for all the replies!

I looked at the line from the v. pump to the air cleaner and there is no oil there. Maybee the shut off valve on the injector pump was bad and replaced at one time. I think I am going to rebuild the pump anyway though. Just to be safe.
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82 300SD 290k(needs engine swap)
79 240D 354k with new heart transplant w/220k
82 240D w/auto tranny soon to be manual 4 speed
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  #9  
Old 11-13-2007, 04:28 PM
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Quote:
Originally Posted by sedecrem View Post
Thanks for all the replies!

I looked at the line from the v. pump to the air cleaner and there is no oil there. Maybee the shut off valve on the injector pump was bad and replaced at one time. I think I am going to rebuild the pump anyway though. Just to be safe.
Not a bad idea with 300+K on the clock. The 82 240D that destroyed the v/p because of end play of the timing device had 300+K on the clock, and who knows if the v/p had ever been replaced.

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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"
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