[grandotitat]

Hi. I just took my Forester to the annual inspection and it was rejected because its was smoking a lot. The didn't even put the machine to test emissions because they say the smoke will harm it. (I seriously don't believe that). I told the guy to show me the smoke. I started the car and no smoke. He revved the car and no smoke. He asked me the favor to rev it so he can see and finally the smoke appeared. It was blue smoke in a moderate quantity. We left the car in idle and the smoke kept coming out and after a while it went out. I went out from the inspection site (very unhappy) with an order to correct the problem within 15 days. The I noticed that sometimes when I revved hard the car, the same smoke came out, but not always. Sometimes I can rev hard and go into boost and no smoke is seen.

I'm having a hard time figuring out the source of the blue smoke because:

- A year ago, I serviced the cylinder heads. All the seals were changed.
(I don't want to think that within a year and 6000 miles the valve seals will fail)
- The piston rings and ringlands were ok. At least by visual inspection. My engine has 66000 miles.
- A month ago I repaired the turbo. They changed the seals off course.

Where else should I look??? I've read that the PCV valve might cause blue smoke which would make me happy as a cause considering the low cost, but I'm also having nightmares thinking of the need to repair the whole engine as the PCV would be something too easy and lucky to get rid of oil smoke.

My logic is that if a ringland is broken or if the piston rings aren't sealing properly, the blue smoke should be there all the time right? Or I'm absolutely wrong? I don't know why the smoke is intermittent.

Thank you for your insights.

 

[stan_t]

Were the guides replaced when heads were rebuilt? It is oil being burned, it can get into chamber via combustion past rings or through guides, or into exhaust through a busyed turbo.

Stan

 

[grandotitat]

Yes, the guides were replaced. I changed my oil like 60 miles ago so really I cannot see yet if oil its being burned. The level mark is still the same as the day it was changed.

By busyed turbo, you mean like with many miles on it? I just repaired the turbo and I like to think that the job was done right but there is still a chance that the new seals are failing I think.

 

[grandotitat]

Here is another insight on this topic. I ended replacing the PCV valve. The blue smoke diminished but it was still there sometimes, mostly when I accelerated hard but a few times it appeared during cruise or at idle. I was hoping the turbo seals were the cause but I did nothing about it. The compression test is something I should've done but I haven't.

A few days ago I decided to go back to my original fuel injectors (I had 660 cc and returned to the oem 420 cc). My surprise was the blue smoke decreased almost to nothing. Only a light puff was seen when accelerating very hard and sometimes no smoke was seen at all during hard acceleration. I was happy and I considered this acceptable. However, today I was running normally and I was checking my rear view mirror and I started to see some important clouds of blue smoke (not as with the engine cleaner but a cloud was able to block your vision). It became more strong when I accelerated after the car being under vaccum. after a while, the car suddenly turned off by itself while I was doing a corner in the suburbs and I though "I baked my engine"... I thought the worst. When I opened the hood, the first thing I checked was the oil level, and it was full. Then I turned my attention to the water overflow tank which was emanating vapor. The tank was empty. I opened the radiator and it was empty as well. The turbo water tank... empty. The temperature needle always read a normal level so I never worried about this. I filled the radiator, the turbo water tank and the overflow bottle until the MAX mark. I started the engine and everything was running smooth and the engine made no weird noises (so I concluded my cylinder head gaskets were ok).

And guess what, the smoke went away! Later after this, I started to see vapor again coming out from the overflow tank and at the same time the car started to throw blue smoke from the exhaust again. I stopped to check the water level and it was empty again. All of it was being leaked through the overflow tank. I replaced both the radiator cap and the turbo water tank cap and filled with water again. Just like the first time, the blue smoke disappeared again. This time water seems to be keeping where it should but the question is:

what is the relation between water on the cooling system and blue smoke coming out of the exhaust? Maybe it has to be on some kind of stress on the piston rings due to temperature?