Blue smoke - Turbo or rings?

2000 C70 convertible with 124,000 miles on a 2.4L engine with low
pressure turbocharger. Suddenly began to smoke a *lot* out exhaust.
I've read how this could be the turbo or it could be the piston
rings. There is a grinding noise on start up and the smoke starts
immediately (it does not need to warm up). Grinding noise stops.
After idling a bit it smokes less ... but rev the gas, and smoke pours
out again.

Is there any way to know for sure if it is turbo or rings?

Thanks in advance for your suggestions!

 

compresion test will tell you if it's the rings. Compare all cylinders, they
should be within a few percent of each other.

 

If it happened suddenly that's 99% likely to be the turbo. 124K is
awfully soon for a turbo failure though, have you been running synthetic
oil and changing it on time? Cheap oil and infrequent changes will kill
turbos.

 

If the smoke begins *immediately* on cold start (exhaust stone cold) i would
suspect a piston has broken up and/or rings. I would pull the plugs after
afew moments running and check them for oilyness. If there was a severe
bottom end problem however, i wouldnt expect the engine to be running
sweetly (you make no mention otherwise) and the grating would not suddenly
stop.

Turbo is only other option, but 120k is extremely early for failure on one
of these motors, infact Ive never known any 5 pots with turbo failure yet!!

tim..

 

Maybe a long shot, but good to check anyway: clean the crankcase ventilation
system and make sure it is clear.

I've had heavy blue exhaust smoke when the ventialtion on our '85 turbo was
plugged. The crankcase pressure built up and caused oil to back up in the
turbo drain tube. Cleaning the whole system and ensuring good flow cured it.

Mike

 

My wifes car did that once dont know why and I was at an airconditioning
place at the time .His remark was why fix it its stuffed ?A new oxygen
sensor fixed it all as well the economy improved .But grinding noises
mean fix it fast and use synthetic oil ,real synthetic oil.

 

Thank you all for your comments and suggestions.
I took it to the Volvo dealer where I bought it ... it was the Turbo.
They did a compression / leak down test.
There was faulty oil sump pick up seals (they had to remove oil pan)
and they had to replace the entire Turbro. $2,213.02 before sales
tax.
Ouch!
Then it continued to blow blue smoke really bad. I was told that oil
was in the catalitic converter and would take a while to burn out.
Yeah, about 250 miles.

Again, many thanks for your comments and suggestions.