I have a 2003 Volvo XC90 2.9L T6 AWD and for the most part, it’s been great.

Over the past year or so I’ve had an issue with it randomly stalling at slow speeds which was progressively getting more frequent. Along with this it did start to hesitate on acceleration at slow speeds and fluctuated at idle, but there have been no other symptoms, no lack of power and no odd noises. When it was running, it ran great!

I whittled the issue down to the PCV system and replaced the PCV oil separator box. As with most of these cases, the small rigid line from the top of the box out to the banjo snapped so I replaced it with a more flexible tube (still quite firm, but has enough flex that it won’t snap).

While getting my hands dirty I also carried out the following:

  • Replaced oil and filter
  • Replaced fuel filter
  • Replaced air filter
  • Replaced spark plugs
  • Replaced intercooler charge pipe
  • Replaced as many vacuum lines as I could find
  • Removed, cleaned and refitted throttle body
  • Cleaned MAF (with appropriate MAF cleaning spray)

After putting the car back together it runs like a dream. It’s responsive, no hesitation, has a steady idle and has plenty of power… but, the only issue now is that it’s smoking (white, from the exhaust, not the engine).

My initial thought was the head gasket, but the smoke didn’t seem thick enough, plus on the test drive the car ran great. I bought a head gasket tester kit just to be on the safe side (one of those ones that you put in the header tank, add a coloured solution, run the car for 10mins or so and see if it changes colour), which came back negative (it didn’t change colour).

So, I’m at a loss as to what’s causing the smoke. These are my thoughts:

  • Aside from the issues mentioned at the start of this post, the car was running great, i.e. no smoke at all
  • I find it to be highly coincidental that there were no symptoms of any underlying issues before changing the PCV box, and now it’s smoking like a trooper
  • As previously mentioned, the car is running great with no lack of power or anything else that would be cause for concern
  • I’m not losing any fluids, or at least fast enough that I can notice
  • My code reader doesn’t find any faults

So as you can see, I’m baffled. The car seemingly has no problems but is just smoking enough that I don’t want to drive it so it’s just sat on the drive like a sad lonely tank.

Any help with this would be GREATLY appreciated. The car is like a sixth child and is sadly missed

Thanks a bunch.

  • Welcome to Motor Vehicle Maintenance & Repair! Apr 15, 2021 at 13:53


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