knocking and smoking
 

new owner of a 83 300sd. I'm not sure if any of this is normal but it sounds bad to me since i never owned a diesel.

Here is what i'm seeing on the car:
i noticed when i take the oil cap off with the car running it pops out smoke like a steam boat. justs puts puffs of smoke in a consistant timing pattern. the car starts with no porblems but makes a knocking noise at idle. seems to go away when i give it gas. another problem is the car seems real sluggish. the oil guage show the pressure a three on the guage so i assume this is good. doesnt seem to have much power as i would expect on a diesel. the exhuast smoke seems normal black and not too execessive in my eyes.


anyone have an idea what my problem could be? i'm thinking the rings are bad (i don't own a diesel compresion guage) and need to rebuild the engine.

RE: knocking and smoking
 

Sounds like this engine is tired? When compression gets by the rings it's got to go somewhere including out the main seals, or when one opens the oil cap...it's called "blow-by"....

You also mentioned knocking, and that it goes away under acceleration! This scenario can indicate worn rod bearings too, called "rod knock"....

With as much blow-by as you indicate, you might want to confirm this with a compression test. The knock could also be generated from other factors. It may be worth having a diesel mechanic have a look before spending money here. There are lots of good used OM617 engines out there for sale from rusted out 123's for cheap and may have several hundred thousand miles left in them for under $500