350SDL (gulp) question
 

Yes, the 350SDL.
What a wonderful car.
It purrs at idle, almost inaudibly with zero sound insulation.
It achieves fuel economy equivalent to the 3.0 liter.
It is very quiet and refined at speeds of over 100 miles per hour.

It also loves to bend rods 50% of the time on original motors. Ooops!

This particular one's different. FAR different from mine and its obnoxious nature! Remember that black 350SDL I was driving for a stint? Well, it's developed the classic insatiable thirst for synthetic blend diesel oil.

There is almost no blowby.
The intake manifold, and crossover sections are clean as new.

She starts up instantly. No skipping, but a constant cloud of blue at idle when warm or cold.

Consumption? Average city 50/50 highway mix = 220 miles per qt. My father and I (he's driving it now) took it down on a business trip to Connecticut at about an average speed of 75 mph. IOW, 100% highway.

Consumption? Highway 100% = 130 miles to the qt.

You'd never know it. What could it be given the available data? Could it be the headgasket oil passage being blocked? There is NO BLOWBY in this sucker. None!

The engine is pretty smooth at idle. Almost inaudible. But when it is revved, I swear I hear something that resembles a heavy metallic lifter-like clank at the front of the engine. But it could be me and my paranoia getting the better hold of my conscience.

Well...I think it may be time for a compression check...It may be TIME.:uhoh:

Good Luck, :)

Your turbo is shot.

The oil is getting in the combustion chamber some how. Yes your turbo seals could be on the way out, or valve stem seals, etc.

Sounds like the turbo. Considering the engine I'd do a compression test first to rull out a dead cylinder.

Come on how long are you going to nurse this thing! I'd have a rebuilt turbo on hand Friday and be swapping it Sunday.:D

If the intake is clean as new and dry in a recent check it kind of rules out the turbo seals leaking perhaps unless the oil is getting out the exhaust side. I would kind of suspect almost a dripping oil pipe in that situation at the oil consumption numbers quoted plus the exhaust side has positive pressure to some extent. If the rod has bent the noise he may be hearing is because the piston is now somewhat loose in its bore that is now out of shape. I hope I am wrong and also freely admit have no previous experience. The compression check or leakdown of cylinders is indicated. Harbor freight has their diesel compression set on sale for 16.99 in catalogue perhaps an auspicious time to spend a little money..Guess the clang could also be the turbo blades hitting the housing if the centre bearing has pretty well given up the ghost as well causing the noise as well.These unfortunatly are just the guesses of a guy that has never worked on one of these engines but tracked the trouble profile. Another quick test I think is not definative but certainly indicative is to loosen the injector line fittings one at a time to see if the blue smoke or noise you hear stops on any given cylinder. But again do not know if fittings are easily accesable on those engines. Anyways best of luck.

I still have to figure out why my SDL smokes after being left to idle for about 5 minutes. Big plume of white stuff... no coolant loss, oil level is normal, and the like.

I still am curious if valve seals go bad on these as my vehicle sat for about two years...

if the white stuff
 

dissapates quickly it is steam and you need a head gasket.

if it lingers and eventaully wafts away it is smoke. white or more correctly light blue is unburned fuel and can be caused by leaking or dribbling injectors.

unfortunately i have a hunch it may be a leaky head gasket or cracked head. the latter actually. as it warms the head expands and opens a crack that allows water to seep into the combustion chamber and make steam. then as it gets hotter perhaps it closes up again or you stop noticing it.

hope i am wrong

tom w

I recently purchased an inexpensive "rebuilt" OM603.97 turbo on ebay. Long story short, it turned out to be dumping oil directly into the exhaust downpipe. Prior to this experience, I wasn't aware that oil could bypass the combustion process in this manner--now I know. Valve stem seals are also a source of oil loss. If the seals are original, then they're virtually assured to be brittle. These engines do see brief durations of intake manifold vacuum, which can pull oil past brittle intake stem seals.

At this consumption level, if the turbo is the culprit, you can easily see the oil accumulate in the turbo outlet and the crossover. The pipes will be heavily coated with oil droplets. The oil pools in the manifold and the crossover pipe and the engine takes in a huge amount when it's revved. Idle smoke is fairly minimal.

If you don't see any of this accumulation of oil when you pull the crossover (you can start it and watch the turbo for oil discharge), then, I'm afraid that you have the classic problem with these engines. A compression check would surely confirm this......one cylinder will be exceptionally low.

It puffs out, then slowly wafts away. Hopefully it's a few leaky injectors, I have a bunch sitting here that need to be rebuilt. I plan to balance and clean them myself hopefully.

There is no coolant loss with the car. If it's a head, it is... I have a few around the house I need to rebuild then install one. My SDL also passes that upper hose firmness test too.

Can valve seals be replaced with the cylinder head still in place similar to the M103s?

It doesn't seem to be the turbo as the oil loss is minimal.

Yes, the stem seals can be replaced with the head in situ.

I'm going to do injector rebuild/balance first, then if the smoking still is there I will go to valve stem seals.