So, For the last year or so, My 850 turbo has been slowly burning more and more oil at idle. First it started on a hot summer day while idling for a long period of time. Since then, it definitely does it less in the cold temps, but still plenty. ( mostly you just notice it at idle)

I finally decided to bite the bullet, tear down the head, and get it checked out. News back from the shop who specifically and only works on heads is that it checks out fine with no issues. Well, no big, happy to have a "re-fresh" new stem seals ect... But kind of a bummer to find that i spent 400 on parts 300 on the head and nothing to show. ( but I wont really discount this until ive got it all back together ) and see it still smoke.

So, the next question is, where do i look next? Ive taken a peek at the turbo, the shaft "seems" fine, but im obviously no expert. What else can I look at? Specifically before I put the head back on....

Thanks!

- Grae 96 850R

 

Compression test. You'll be pretty sure the valves are sealing properly, so any leakage/low pressure readings will almost certainly be due to ring/cylinder wall issues.

Lynn B.

 

Look towards turbo seals, Cracked valve guide, or even a collapsed ring.
A Wet compression test is defiantly needed.

But keep in mind there will be some residual oil that will need to be burned off...

Turbo rebuild is simple and you can do it yourself...
The would have seen the cracked guide
Collapsed ring is the longest shot ever so I wouldnt worry about that too much..

Are you replacing the PCV system while you have the head off?

 

Man, take one step at a time. Look into the piston area to see if you notice any wall scoring. Other than that, assume that the head rebuild (valve stem seals) fixed it.

 

Bear with me here... Whats a "wet" compression test?
Residual oil as a normal day to day, yes, but not a ton right?
I was thinking i might upgrade turbos anyway..
Im "Cleaning the heck out of the PVC system, that's for sure "


Will do, and yes, i hope. Maybe some detailed pics of the cylinder walls for you to peruse?

lol .........HOPE it did! Wont know till then

 

Wet test is a couple drops of oil in the cyl before you do the test.

Residual oil after the rebuilt head is on it may smoke slightly on first start up..
I would just replace all the pcv components... and clan your PTC while your there

 

wheres the PTC ?

 

btw, What is the sensor thingy called, that's attached to the snorkel in this pic. It seems to be part of the PCV system, but isn't mentioned as an individual component on FCP.

http://www.fcpgroton.com/images/prod...ge/9186200.jpg

 

I could not see the image on the pic but the PTC is on the turbo side if the PCV tube that goes back to the turbo. It mounts on the end of the intake tube.

 

Can you buy just the PTC ? I cant find it for sale without the snorkel too

Interesting info from volvoclub.uk regarding the PTC

""This is the heated crankcase vent nipple (also referred to as the Positive Temperature Coefficient heater nipple) used on 90 and later where the air heater tube is deleted. The PTC nipple is mounted in the cold air intake pipe that runs from the air filter box to the turbo. It is in the elbow of the pipe, nearest the turbo. It has one or two vacuum hoses connected that run back to the oil trap. There is also an electrical connector about the size of a spark plug. Volvo decided that the preheat system which was thought would prevent throttle icing would not work on intercooled models due to cooling effect on air through the intercooler before it goes into the throttle. The heater is to vaporize the moist air that comes out of crankcase after start up and while driving in very cold weather. The LH fuel injection system on that car doesn't use the Intake Air Temperature sensor. Occasionally one can experienced a pressurized manifold with too much pressure in the crank case, causing oil to blow from the filler cap or the seals. This can be caused by the PTC nipple valve which can clog. All of the turbos since 1990 have a PTC and they tend to get clogged during cold weather. ""

 

Also, little mentioned fact. There is a channel cast into the OIL pan that leads up into the PCV breather box. I believe it is designed so that it exits above the resting oil level and allows for the lower crankcase ventilation. I worked on one Volvo 5-CYL that had one completely clogged up, it was bad. Took the oil pan off to clean it. I used compressed air to verify it was unclogged.