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Blue smoke after 5 min. of idling


New member
May 18, 2003
Santiago de Chile
This is the third time my 740 starts smoking blue after 5 minutes of idling. It starts smoking for a minute and then smoke dissapears completely. It does it when it sits for a overnight. If you drive it and then turn it off and restart after let's say half an hour it does not smoke, so I don't think it's the valve seals (they where replaced when I installed the squirter block.) I am using an upgraded T3 turbo. Do you guys think is time to replace the turbo? PCV system is clean and there is no noticeable blow-by. No smoke in accelertion or decel. Engine uses almost no oil after a 200 mile trip, is just a minute of smoke and then nothing.
I've seen this before with Mitsu's as they develop play. While it may be something else, id say it's time to start saving up for another turbo.
I've seen what you describe be valve stem seals or second rings on the pistons....

+1. Will do this when hi milage has been racked up. nothing much to worry about. Maybe go to a tad thicker oil . A can of STP at oil changes will help it too.
Volvo does not recommend anything thicker than 15-40 in that motor. Even if there is no harm in running 20W50... it will hurt fuel economy. Run a good synthetic if you are not already... Find out what is causing the smoke or live with it.
Have you tried draining the intercooler? Old turbos blow a little oil past the seals and it winds up in the bottom of the intercooler. Look on the bottom of the intercooler for the plastic plug.