So my daughter reports that our beloved 850T is beyond repair... The car is blowing oil out "all over the place" (per her local mechanic) and the turbo is not boosting past 12 noon on the boost gauge. I will be swapping cars this weekend to get a better look to see where exactly the oil is leaking. It was suggested that the PCV is clogged (system was replaced a year ago) or can't handle the amount of blow by (I need to do a wet compression test). I need to see if the turbo hoses are intact before declaring the turbo dead. If all is as bad as this sounds, I'll be posting a for sale sign as a parts car (it drives but leaks a quart every 100-200 miles right now). Any thoughts on the zero boost (low power / won't rev past 4000) other than the air hoses? Can lots of blow by exceed what a clean PCV system can handle? (I didnt' do the install so I suspect the tech didn't clean out the ports inside the block...)

I will be getting under the car this weekend and post up what I find for discussion and sympathy :-)

 

Had a similar oil loss issue about a year ago. Turns out it was the Turbo oil supply connection at the back on the block on the passenger side. One of the bolts had shaken out. Worth a look.

 

got the car back to the house yesterday - I think I'll start by removing the heat shield to get a better look at the turbo and the oil return/supply lines as I was thinking the same thing. My sense is my daughter's mechanic saw oil dripping everywhere and didn't really want to work on it... She's getting a great deal on a 2008 Mazda 3i (free from her aunt!) so the 850 is my toy & project car again.

 

The vent hose from the oil separator goes around the block, and connects to a nipple on the plastic intake tube, just before the turbo. That little passageway gets clogged up. I've seen PCV systems replaced, but if that blockage isn't cleaned out then all those new parts aren't going to do any good.
If it's an obvious leak, as described above, then it should be easy to find. If it's just a general sort of leaking all over, then I'd be checking for something that's not allowing internal pressure to vent, regardless of how new the PCV parts are.

 

agreed, that's my thought as well. I think the shop that did the install did the parts but didn't clean the block ports or the other hoses - but there's definately no venting going on right now. Curious if a Seafoam treatment would open anything up... (at the risk of filling the oil trap). I gave them a full PCV R+R kit from FCP too, not just the separator.

 

So I finally got the chance to get under the car today. Took off the heat shield over the turbo and the timing belt cover. Started to degrease stuff as I went. My big disappointment was that it looks like the oil return seal and the line insert into the block appears to be good. What I did notice was oil around and on the air side of the turbo. From up top it doesn't look like the rear cam seals are leaking but I need to pull out the airbox to get a better look. Is it possible that the turbo itself blew a seal enough to spray oil all over the engine bay (to the tune of a quart in 100 miles?)? The front cam seals looked ok as well. So next step is to pull out the air box and look around from that side to see if the turbo is leaking or one of the PCV components. PS - the wife is saying time to donate the car...

 

some small progress this weekend. Found a vacuum line cap was broken which would mess up the turbo's boost. Found the rear cam seal on the exhaust was weeping but when I pulled the cam sensor off, the seal was not out of place (just old I guess). cleaned a bit more but its apparent the PCV is not venting. So next decision point is to pull off the intake manifold and pop off the PCV hoses at the block or sell for parts. Since the PCV hoses and oil separator was replaced a year ago, I'm also tempted to put the car back together as is and see if a few Seafoam treatments can clear up the ports. Worst case is the gunk would clog the oil separator but either way I'd need to do the same work to access the ports in the block.. Any thoughts on that?

 

I would rod the block out. They get so crudded up I don't think sea foam in a few minutes would undo a decade of crud formation.

 

yep I'm betting that's where I will wind up - but I was thinking to just try the Seafoam before I start pulling the intake manifold off and get into it elbows deep!