Within the last month my 2000 F-250 7.2L (153,000 mi) turbo diesel began spewing blue smoke out the tail pipe. It originally came out when I decelerated, and was at its worst if I down-shifted. A local repair shop couldn’t find anything obvious 1st visit. The problem got worse. On the 2nd visit, they tested the injectors and replaced the O-rings. The problem got worse again, and is not consistent. I seem to be burning about a quart every 1000 miles. Any ideas as to what the problem might be?
I have no idea exactly how most newer diesels work, but I know on some older ones, you could get problems where the crankcase ventilation system would malfunction and your engine would start running on a mixture of diesel and your engine oil!
Other than that, probably something worn out or damaged internally. Sorry I’m not more help.
Reality…Sometimes those claims about engines lasting 350,000 miles need to be taken with a grain of salt…
A slight fault in an air-cleaner allowing a small amount of unfiltered air can result in disappointing engine life…
I’d say a compression test is the next step.
Compression test should be the first step.
You might also check the intake tract and see if there are oily deposits from cooked turbocharger seals.
I would suggest that you may need a new shop.
Since your truck is turbocharged, you could be getting the oil from a leaking compressor shaft seal. One way to check this is to disconnect the compressor outlet hose and see if oil has collected inside. As previously noted a compression check will verify the state of the piston rings. Remember that a diesel engine does not develop much vacuum on the intake stroke as there is no throttle restricting the air flow so oil is unlikely to drawn by the vacuum past the intake valve quide and rings.
Hope that helps. Let us know how this problem is solved.