Folks,

Thanks to Mercedesshop for looking things up for me and confirming on the heat shields. All went back together fine and it fired right up.

I'm searching for the cause of some very heavy oil consumption on this 3.5L OM603. All guesses would point to the rodbending scenario, but 2 very respected mechanics are telling me it just runs too good.... so we're taking the diagnosis step by step.

The engine runs great, doesn't overheat, no knocking at now just under 160K miles. I'm burning a quart of oil in what I thought was 300 miles, but this last trip back and forth to Raleigh says it may be a quart per 500 miles. A lot anyway. Let the car idle and there is some visible smoke. After idling for 60 seconds, goose it and a big plume of blue oil smoke comes out of the tailpipe.

The compression check had good results. All cylinders were in the 420-450 psi range if I remember correctly from yesterday. We did see some goo in the intake crossover. I had someone else look at it a year ago and they may have cleaned the intake, because there was not a huge accumulation, but the coating was damp not dry. So at the suggestion of Mercedesshop and my buddy I'm working with in Raleigh we decided to test the turbo - intake side at least.

We cleaned the output path of the turbo that attaches to the intake real well, then ran it an spun the engine up to around 3000 rpm for 30 seconds. We saw "tracks" of new oil on the output side of the turbo. So we wiped it down and repeated, and same results - more tracks. Holding a piece of cardboard over the output got a few minor specs of wet oil in the 30 seconds of testing. I guess this would add up over time.

Blue smoke was still coming out of the tailpipe even with the turbo input not engaged, but there may be residual oil in there or leakage on the exhaust side as well. We haven't seen the exhaust side yet, but plan on pulling the entire turbo out today.

On futher inspection of the turbo housing, it appears it may have been rebuilt in the past. There are some markings with numbers stamped into the unit. Our collective opinion here is the turbo is suspect enough to pull and determine if a rebuild is needed. Turbocity in California says about $300 to rebuld....

As always, I'd love to hear your opinions and suggestions.