I recently purchased a 2008 MCS (3 weeks ago). During the test drive I let the car idle for 10 minutes and then revved it up...no smoke. Maybe I didn't let it idle long enough.

Yesterday I get behind a junky cement trunk that was going 30 miles an hour on a two lane road and I had nowhere to pass. Finally I get an opening and get on it a little...blue smoke. WTF? It's been in the back of my mind all day. I finally get home and do the same idle test...blue smoke.

Is it possible that it could be something else, or should I go ahead and count on buying a turbo? Boost gets to around 12psi and it seems to run fine.

Thanks

 

Check the intake after the turbo and before the intercooler, see if you have excessive oil in there. My car also smokes a little bit after idling or coasting...

 

List of mods? Try a compression and / or leak-down test --- cylinders should all be within 5 --- 10 PSI of each other. Don't invest in a turbo until you're sure it's shot. Lotsa causes for "blue smoke".

 

You're burning oil, I think everyone is right on, get a compression/leakdown test performed. A leakdown test is preferred. It could be something as simple as a valve cover or turbos pressure seal leaking oil, the only other indication is valves or rings.

 

No mods with 93k.

I can do the compression test. I have an old one to get me started. If they check out OK, should I still have a leakdown test?

Jeez, what did I get myself into? I did some research on MC before I got this. I knew they were not the most reliable, but I figured I could take care of most things myself. Not sure I am ready for a overhaul. Uggg

Thanks for the replies!

 

Most of the time it you see especially an 07 MCS for sale 8 times out of 10 the owner is fed up with pouring money into a money pit. Did you ask the previous owner why he was selling it? Sometimes that question can show the owners hand if you know how to read his body language, like playing Poker. Does he avoid eye contact when looking at you, stuff like that.

 

Bought from a dealer. Service history was good based on the Carfax. Had the timing chain done too. Hopefully it's PCV or Turbo (crazy for me to say that).

 

Yeah I get it, replacing a turbo is a lot cheaper than rebuilding or buying a new engine, even the timing chain assembly costs far less than a new engine.

 

I pulled the spark plugs and did a compression test on it. The plugs had no signs of oil burning. The compression was all pretty close.

#1 - 152psi
#2 - 150psi
#3 - 144psi
#4 - 150psi

I guess the next thing will be to pull the intake/intercooler hoses and see what I find.

 

I did a search, but I have not found a conclusive answer on the following questions:

Can you hear your turbo? I can hear what appears to be my turbo whistle right after idle. The best way I can describe, it sounds like a big rig turbo (or a bro-dozer) but not as loud. It is not real noticeable, except in the parking garage. I never heard my VW 1.8t when I had that car.

I have seen a lot of issues on here with PCV. But nothing seems to be resolved or no closure on the threads. How do you check your PCV system? I have not seen anyone replace their valve cover that actually resolved their issue.

 

Can't comment on turbo noise --- mines a Garrett.

When the PCV goes south, crankcase pressure builds up and prevents turbo oil from returning to the crankcase --- it's a gravity-feed return system. So, if the oil has trouble returning to the crankcase, it's forced thru an oil seal into the air inlet chamber, which then is mixed with air and flows thru the FMIC and all the post-turbo plumbing into the intake manifold, etc. This is only one symptom of a bad PCV system, there are probably more. This is a problem I've been fighting for a long time --- trying to establish a PCV system that can handle 30PSI manifold pressure.

One way to check for turbo seal leakage is to remove the air inlet plumbing and look for oil in the chamber. I get a puddle after 100 miles or so. If your chamber is dry, the PCV system MIGHT be OK. If you find any oil there, check to see if the nearby PCV tube is dry or oily. If it's dry, the oil is from the turbo seal. If it's oily, the PCV system MIGHT be OK, and more testing is needed.

While you're in there, check for turbo shaft "wobble", to ensure the bearings aren't worn --- they could take out the seal if the shaft wobbles. Shaft should only spin, either direction. Maybe a little movement along the shaft axis --- barely noticeable. All this with "educated fingers" --- don't want to introduce damage!

There are still other causes for burning oil, but the PCV system is probably the cheapest to fix. A valve cover is pretty easy to replace.

Best of luck finding the problem.

 

Took my my air intake from the air box to the turbo off. This is what I found.



Looks the PCV tube is dumping oil into the intake. The bearings on the turbo seem fine. Is there a way to make sure before I drop $300 to $400 on a new valve cover? Could I just disconnect the PCV valve tubes and let idle for 10 minutes? If it still blows blue smoke, then I would think it could be something else. Thanks for help on tracking this down!

 

Disconnect the PCV hose from the turbo air inlet hose. If your PCV tube is dry, the oil is coming thru the turbo seal because of high crankcase pressure. Disconnecting tubes and letting it idle will just cause more smoke --- crankcase pressure is relieved thru these tubes when activated by manifold pressure. PCV is short for Pressure Control Valve. High pressure (boosting) vents thru the turbo hose, while low manifold pressure (vacuum) vents directly to the intake manifold. All this is controlled by the valves internal to the rocker arm cover.

One more possibility --- the turbo oil drain hose might be plugged / damaged and not letting oil out of the turbo. Not likely, and a pain to get at, but possible.

 

I did the 10 min idle test cold, no smoke (which I may have done before I bought it). Did it when it was up to operating temp and got smoke.

I pulled the turbo inlet hose. I can see oil/water vapors in the pcv hose. I can't say it looks abnormal. No oil in the turbo inlet like yesterday. I think I'll just replace the valve cover. I hate throwing parts at a issue. Hopefully it will stick.

Stupid question. If the oil seal/bearing of the turbo was bad, how would oil get to the air intake? Wouldn't the oil be working against the air coming into the turbo?

 

The turbo oil seal is not necessarily bad. If oil can't flow back into the crankcase, it goes past the seal into the air inlet chamber. The turbo compressor wheel is sucking air from the filter AND the "high pressure" PCV hose. There is no pressure gradient in the chamber to overcome any leakage past the oil seal --- it's like a vacuum cleaner, sucking up everything it can get and pushing it thru to the FMIC --- serious turbulence, spraying oil everywhere in the chamber.

It's almost impossible to see into the PCV hose at the turbo without separating the two hoses. If the PCV hose is wet, that's probably the source of your puddle in the photo. This is what an OCC is used for. A dry PCV hose and the puddle, indicates high crankcase pressure and a probable faulty valve cover.

PCV issues are complex. You might want to consider getting a dealer's SA diagnosis.

 

Here is my 2 cents on this, I seen this problems on my previous vehicles. It sounds like it could be a PCV problem. From what I have read the 'blue' smoke happens only after standing idle or near idle then stomping on the throttle. The PCV (Positive Crankcase Ventilation) valve is designed to control the flow of crankcase fumes back into the intake. At idle the intake is at a high vacuum (16-17Hg) and the minimum "blowby" gases being created. The PCV is designed to provide maximum restriction flow during idle, there by preventing gases, oil, etc into the intake. During acceleration or higher RPM the PCV opens up and allows the vapours to be cycled into the intake. (Turbo or Supercharged engine have a different PCV design because they create high intake pressure during operation).


So this is what I think is occurring. During idle the PVC valve is not restricting the flow of blow-by gases and oil vapour into the intake and is pooling in the intake manifold area. Once you stomp on it the "pooled" oil is being sucked into the combustion camber and being burnt and being seen and "blue" smoke during a dead stop acceleration. At normal speed on the freeway there should be no evident of smoke from the exhaust.


So, the best course is to swap out the PCV vale with a know good one to verify if this is the cause..
Good Luck.

 

I think this link below is what is happening. I hope not, but it is what it is. I'll throw a Valve Cover on and update.

https://www.northamericanmotoring.co...ml#post3937798

 

I was thinking about ways to eliminate possible failures and thought of this.

Could I disconnect my downpipe and run it for 10 minutes and the see if it sprays oil when I rev it? It may not be good test because the cat could be causing the issue with back pressure. I know its a pita to get it off, but I would really like to make sure before I drop the money on a new turbo.

 

I replaced the valve cover/pcv valve. Did not fix it. Anything else I should do to be 100% sure its the turbo?

 

Couple more thoughts --- check the turbo oil return hose to the crankcase --- no kinks, plugs, etc. Oil needs to flow freely in this tube. Mine was kinked and MIGHT have been my original problem --- it was NOT contoured, and had a kink from bending to fit the Garrett. Probably the wrong material too.

Also, find a gauge and monitor the crankcase pressure --- should be zero or negative. Takes some extra fittings and a gauge, but it's do-able.

Both these are painful, but might save you a few bucks.

 

I have ordered new oil lines and also a new DP. I also ordered a back pressure gauge to see if the cat is clogged with oil. Wonder if I can use that for the crankcase. Anyway, thanks for all the suggestions and advice!

 

If you want to peak into seeing your cat remove the first O2 sensor, with a flashlight you can clearly see the top of the honeycomb as I like to call it.

 

I couldn't really see much into the cat. I guess I could not get the flashlight lined up with my eye through the O2 sensor hole. Here is pic of the sensor. It look like it's running a bit rich, but it does not look oil coated. Thoughts?

 

I can't help with the sensor --- not enough experience.

For crankcase pressure, a quick check is to get it idling, then remove, or loosen the oil filler cap. If you have pressure, it will be difficult to remove and / or pressure will escape thru the filler hole. When idling, the PCV system should be pulling crankcase gasses into the intake manifold, creating either a slight vacuum or equilibrium to atmospheric pressure. This test might also cause idling problems while the cap is off --- don't leave it off too long. Best to find a gauge and connection method.

 

It is pretty difficult to remove. It seems like the PCV system is working properly. I did replace the valve cover with no change. Well, it actually seems to have gotten worse in last few days. I went ahead and pulled the trigger on a turbo. It will be a good test of my mechanical abilities.