Last week I was noticed blowing blue smoke from my exhaust. I also noticed a smell of oil around that time. I checked my oil and found it a quart low. Has only been about 3,000 miles since last oil change, so I threw in a quart of castrol gtx 5w-30. Should I worry about this? S40 has 170,000 miles on it. Time for new gaskets?

 

A compression test will show if the rings are the problem. Another could be the turbo is wearing out the bearings in the center section. Those two areas would be my first guess.

 

Thanks for the ideas Hudini :-)

 

Say, do you or any one else know what this compression test would involve, how much it would cost, and what if any repair it may lead to? Sounds like it could turn into some overhaul or something. Or maybe just status quo in terms of preventive maintenance on a 12 year old car. Oh yea, the turbo too, probably needs cleaning huh?

 

I forgot to mention you can check the color of the spark plugs to see if they are burning oil. They will be covered in black oily gunk. Also check if all 4 are the same color. If the spark plugs check good then unscrew the top O2 sensor and check of it's covered in oily black residue.

If the turbo is smoking due to oil getting past the seals and into the exhaust housing then it needs a rebuild or replacing. You can actually rebuild a turbo yourself for fairly cheap. There are tons of sellers of turbo rebuild kits on ebay and elsewhere. It is surprisingly easy with only a few tools. The sellers will have videos too. Also look on Youtube.

Harbor Freight sells a compression tester on sale now for $20. It's real easy. Remove all spark plugs. Screw in compression tester into #1 cylinder. Open throttle fully. Pull fuse for fuel pump. Crank engine several times until compression gauge won't go higher. Reinstall tester into #2, then #3, then #4 repeating the process. Compare your numbers. The actual pressures will be approx in the 150-180 range. The important thing is that all 4 are close together in pressure. If one is very low then you would investigate further.

Compression Test Kit

 

Thanks again for the good troubleshooting techniques, Hudini. I'm looking to investigate just how this turbo thing works!