Oh you diesel guys, just helpless with the common cars ;~)

Sounds like you might have a valve seal issue. Not terminal, but it will require removal of the cam cover and rocker assemblies, valve springs and retainers, pressurize the cylinder through the spark-plug holes to keep the valves closed, or TDC on the cylinder you're working on, not sure how it's done on the 103 but I'm betting someone here will.

Funny thing about gas engines, they have this thing called "vacuum". It is greatest when the engine is running closed-throttle, watch your mirror when exiting the freeway or just downshift when coming to a stop. Tell-tale sign is to run the car up in RPM in 2nd gear, let off and let the car slow back down a bit, then give it gas again. If you get a quick puff of blue each time you push the gas pedal trying this, it's valve seals. With a stickshift it is easy to see, automatics hide it a bit.

1st gear is too jerky, and 3rd is probably too fast to get a good puff in the wind.

Good luck.

<> Also, leaking valve stem seals often cause a blue puff when starting the engine.

__________________

Gone to the dark side

- Jeff

It doesn't put out any blue as far as I've been able to tell....if you drive gentle for a while then "punch" it, it actually lets out a slight stream of black smoke, then it clears up. Oil consumption seems to be too low to be valve seals....less than a qt per 1000 miles.

Hey now, I am gaining ever more love for diesels because of this car! If this thing keeps being a pain to maintain (funny how that rhymes ) I'll be looking for another diesel!

__________________
-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

Leaky valve seals don't really consume much oil. The probem is that when they leak the most is at high-vacuum, which is when the throttle is closed and there's not much other than oil going in the cylinders. The other time is when the engine is off and the oil runs down the valve, starting with a good shot of oil on the valve to hit the combustion chamber at once. Little oil but at bad times for the plugs. The other way to tell is to look in the intake at the intake valves which of course means removing the intake if you don't have a scope.

It's either than or someone's been giving it a steady diet of Slick-50 and the rings are now gummed up/stuck, ... your call. Have a compression tester?

__________________

Gone to the dark side

- Jeff

I suppose I could pick up a compression tester.....what should the values be for a healthy M103?

I am probably in denial....perhaps it does need a valve job. Is it hard to do? It doesn't sound like something I'd be comfortable tackling....

Can I hire you to do the seals?

__________________
-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)