I have a w115 300D NA 5 cylinder diesel that has zero blow by and plenty of pep with a low mileage MB remanufactured engine. It smokes heavily I believe which could be due to IP settings but somewhere I saw a reference to oil consumption and a ruptured IP diaphragm -is this possible. This car seems to be at high rpm at 70 which could also contribute as it seems to be geared low with the 3 speed automatic . . . any thoughts on this? Thanks!

Are you speaking of the Vacuum Shutoff (diaphragm) that is on the Fuel Injection Pump? As a cause of smoke that is un-likely.

I have read where the Diaphragm Type Vacuum Pumps can cause Oil to go into the intake Manifolds when the Diaphragm has a hole in it.

I have also read claims where that when the little O-ring in the Fuel Supply/lift Pump go bad the Oil in the IP mixes with the Fuel and gets injected into the Engine; causing Oil consumption.

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84 300D, 82 Volvo 244Gl Diesel

Time to check both Vac pump and lift pump but vac pump would have oil in line, yes? Thanks!

no. the vacuum pump does not have an oil line, but on your car, there are two air lines. one to the vacuum supply of the car, and one to the air cleaner. if the line to the air cleaner is full of oil, then the pump diaphragm has ruptured. on your motor, I think the oil is separate from the engine oil. I think your vacuum pump has a dipstick and a sump for it's own oil supply. if your motor has a vacuum shutoff, check that line for oil. you could be sucking it in there, and pumping it into the motor via the air cleaner line.

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Vac pump dip stick? Huh? This is a '75 car, can't imagine that it does but who knows, perhaps never noticed before . . . . if ruptured diaphragm wouldnt I have door lock/shut down issues? Wild! Thanks!

Ooops, just rereading, I think you meant dipstick for IP vs dipstick for Vac pump

The W115 300D doesn't have an IP with a diaphragm, it has a mechanical governor. So it cannot cause smoke.

The car doesn't have a three-speed automatic, but a four speed. It starts in second gear (if you are not in L/2 or use the kickdown).

What colour is the smoke? When does the smoke occur?

The vacuum pump does have a diaphragm, as mentioned, a torn diaphragm can cause smoke and oil consumption.

It can leak oil through it and still have presentable vacuum.

Thanks! Time to pull Vac pump and check diaphragm!

Thanks, good to know, time to pull Vac pump!

You can just disconnect the air tube that goes from the vacuum to the intake manifold, you don't have to pull the vacuum pump at this point. If that line has oil in it, the diaphragm is leaking.

Thanks for the reminder!

The line coming of my vac pump to intake (there are two) is opaque white - I was thinking that if I was burning oil this way via ruptured diaphragm wouldnt I see oil quite clearly in this line?