I think my stock turbo is blown...

[float_6969]

So I'm bringing this back from the dead. The oil consumption DIDN'T stop. The oil consumption is sporadic. I can run a tank of gas through it, and it won't burn a drop. Then I can re-fill and it will burn a half a quart on the next tank. Totally unpredictable. What is predictable is that the oil consumption is isolated to the #2 cylinder. A couple of months ago the car stared running poorly and the CEL came on. Checked the plugs and the #2 was so badly fouled it stopped firing. The other 3 looked fine. Replaced the plug and all is well again.

Also, the car will blow oil smoke on startup. Sometimes you can't see it. Sometimes it like a crop duster just flew by and you're surrounded by it. The oil consumption is still random. I know that it uses the most oil on decel (high engine vacuum). I discovered this because we were in the mountains and coming down off of the mountain, I was engine braking a lot. As we got to the valley, I got back on the throttle, and the exhaust blew so much oil out of it, that I couldn't see the cars behind me. It also used over a quart of oil on the trip down (I checked the oil at the top of the mountain and topped it off). When I found a spot to pull over to check the car, I thought I blew the turbo as there was oil visibly coming out of where the turbine housing and center section meet. It was also coming out from where the S pipe bolts to the turbo. But as I inspected it more closely, there was also oil coming out of the flange where the turbo meets the exhaust manifold.

So at this point, I'm thinking either a bad PCV valve (It's been replaced once already, but it was a generic from the auto parts store), bad valve stem seals, or bad piston rings. So I ordered a MSP PCV valve from Mazda an installed it. No difference. So then I removed the valve cover and modified it with baffling to keep the oil from getting sucked up into the PCV valve. No difference. At this point, I just turned over 100K miles and I figure I'm due for a timing belt. So I order a belt kit, water pump, front main seal, cam seals, and valve stem seals. I replace all of it, including the valve stem seals, which would have been a really crappy job if not for some special tools I found. Anyway. It made no difference. So I repeat the compression test. Same as last time, 190psi +/- 2psi, engine warm, throttle open, no fuel pressure.

I'm at a loss here. The oil consumption is getting worse. It's starting to use oil predictably now. I go through about 4 quarts every 3K miles. The #2 plug is looking bad again already and I would be surprised if it lasts more than a couple of months. The other 3 still look fine. If I had bad rings, wouldn't it show up on the compression test? Do I need to go buy a leak down tester? What about a worn valve stem/valve guide? Why only the #2 cylinder? Do I need to get a Millenia PCV valve? If it is through the PCV valve, I could test with a catch can, any reccomendations? This is getting really bad. I'm having to add oil almost every tank of gas (It still somewhat random in that sometimes it won't burn any oil on a tank). I've been around cars for a while, but never run into anything quite like this.

 

[got_psi]

you ruled out the turbo seals? yes? no?

 

[tweety2300]

I'd go with turbo seals as mine does the same thing, the intake piping and they're probly covered in oil.

Smoke on a start up is valve seals

 

[float_6969]

you ruled out the turbo seals? yes? no?

If it's the seals on the turbo, it's only on the exhaust. The intake piping has NO oil, not even a little. Looks just like it did when I installed it. Regardless, this wouldn't explain the fouling of the #2 spark plug, only the smoking on startup. Also, if it's the turbo seals, you'll usually see smoke at idle, and I never do. Just during startup, or LOTS of decel and then get back into it.

 

[float_6969]

I'd go with turbo seals as mine does the same thing, the intake piping and they're probly covered in oil.

Smoke on a start up is valve seals

Same thing, no oil in the intercooler piping. Valve stem seals are brand new, they were just replaced a couple hundred miles ago. It made no difference.

 

[duffbuster243]

If you are fouling a plug only in one cylinder you most likely broke a piston ring, or cracked a ring land on that piston. It happens a lot on these cars due to the engine having a long stoke. It puts a lot of strain on the pistons and rings, add boost and its strained even more.

 

[float_6969]

I have considered that, but wouldn't that issue show up as a lack of compression on that cylinder?

 

[Sport23]

This definately sounds like valve seals on the #2 cylinder. I would replace the valve seals (again) and the valve guides.

A leak down test may be in order.

 

[float_6969]

I'll try and get a leak down done in the next week. Why would another set of valve stem seals fix it? Replacing the valve stem seals is a BIG pain in the ass, and I don't see why another set would do anything. Is it possible that the stem on the valve is worn and not sealing because of that? Or if the guide is worn, wouldn't that make it leak as well? It just acts like every other bad valve stem I've ever seen, but the seals didn't make any difference, and the old seals looked find when I pulled them out.

 

[duffbuster243]

I have considered that, but wouldn't that issue show up as a lack of compression on that cylinder?

If there's enough oil leaked into that cylinder you will get a false reading.

 

[mazdaspeedp]

my msp does the same thing lol. Cheapest option is to just keep topping up the oil. Mine leaks a bit less now that i replaced the oil line on the turbo.

 

[float_6969]

Just finished the leakdown test. Specs are as follows:
Tested @75psi (I know 100psi is the normal, but my compressor maxes out @ 90psi and the tester said that the inlet pressure needs to be at least 10psi higher than the regulated pressure, and the tester had a convenient chart for 75psi, so I used that).
Leak down was 3% on all cylinders (inlet = 75psi, cylinder = 72.5psi). They were all exactly the same, and none of the cylinders were leaking past the valves.

Is it possible for the oil from the PCV system to end up on the #2 cylinder? My brother-in-law thinks that's what the issue is (he was an airplane mechanic in the Army for years in the 90's and has co-owned an automotive repair shop with his dad (my father-in-law) for the last 15 years).

 

[Sport23]

I was thinking that it was a a valve guide issue. I would replace the valve seals at the same time since it is such a pain.... Dunno if I'm right or not.

Keep us posted. I've never heard of the PCV leaking into only the #2 cylinder but that doesn't mean it's not possible. I would start there since it is the easiest option you have atm.

 

[float_6969]

I'm in the middle of testing the PCV system right now. So far things seem to have improved, but I don't want to say it's fixed for sure, and what I did, until I know the issue is resolved.

 

[mikewashere]

sounds almost identical to the issues I've been encountering. Looking forward to an update!

 

[float_6969]

I've only run a half a tank through it so far, so I don't want to say it's fixed, but things are looking good right now. It hasn't smoked on startup over the last 8-10 starts, which is a huge difference already. Once I'm convinced it's fixed. I'll post pics of what I did to the PCV system.

 

[mikewashere]

fingers crossed!

 

[float_6969]

Well, it started smoking on startup again. I have totally, without a doubt, in every way, shape and form, eliminated the PCV system. Both sides are going to an air/water separator (the side that goes from the valve cover to the turbo inlet doesn't have a drop in it) and the side going from the cover to the PCV valve, has SOME oily water in it, but it's mostly just water. Regardless, I used clear line so I could see inside the pipes and they're both clean and clear after the air/water separators.

I'm at a loss here honestly. I'm wondering if maybe it's a worn valve guide or valve stem. If that was the case, it wouldn't show up on a compression test, it wouldn't show up on a leak down test, but it might allow enough play in the valve itself to let oil past the BRAND NEW seal.

Another thought I just had was maybe I have 2 issues. Maybe the turbo is blown, and that is the oil on start-up, and then maybe I had a PCV system issue before, but now I've fixed it with the catch can/separator setup? The blown turbo would explain the oil smoke on start up and the PCV system would explain the fouled plug. My plan right now is to let it go as it sits and see if it fouls the #2 spark plug again. I should know in the next few months if it's going to happen. If it doesn't foul the plug, then the PCV system was the culprit for that, and the turbo is blown. If it does foul the plug, I have a damaged valve guide/valve stem and oil is getting past the seal, even though it's new.

Any other idea's?

 

[Sport23]

I think you're on the right path here. I like how you are narrowing it down instead of throwing parts at it. Let us know what you find!

 

[BRIAN_MP5T]

If its the turbo seal it can go into the intake or Ex side. It is difficult to diagnose the hot side but if the inlet and outlet are noticeably different, then I would say the seal is shot.