# Blue Smoke and emissions leak



## Richman (Jan 3, 2015)

Even though I have read that blue smoke can be caused by bad valve seals or rings, I would like to explore all possible causes and contributing factors before I engage on a drastic course. 

*The symptoms:*
The blue smoke coming from the tailpipe of my 2003 Nissan Altima S started all of a sudden one morning which is why I have a hard time believing that the seals or rings went drastically bad all of a sudden over night. It was not preceded by or began with a slow, progressive little bit of blue smoke that has gotten progressively worse over time. This car, even though it has 170k+ miles on it, literally did not ever smoke until one morning, and ever since that morning, it will start blowing blue smoke, not immediately, but about 10-20 seconds after starting in the morning. This is a considerable cloud that seams to have the ability to choke anyone within the vicinity of my house lot and driveway and tends to float down the neighborhood. It lasts for about a minute or two before it clears. It usually will not smoke again the entire day but does sometimes after it siting for awhile .... seemingly precipitated by the engine cooling off and getting cold.

*Proceeding this event:*
The day before this happened, even though it should have had no effect, I replaced the valve cover with an aftermarket one since the Spark Plug Tube seals were shot. I also attempted an oil change but since I couldn't get the filter loose and didn't have the right wrench, I just drained and refilled the motor oil. Someone I met that said he was a mechanic told that if it was up to him, he would have started running High Mileage Oil in this vehicle long time ago. So I put Valvoline High Mileage oil in it. Q1- Could the HM oil have an additive that will make more smoke or could this in any way contributed to the smoking or is it just a coincidence that I put this oil in the day before this issue started?

*Things Checked:*
PCV valve was removed and even though it did rattle, albeit not crisply, I replaced it with, in my opinion, an astronomically high priced new one 
for $14 thinking this may contribute to the smoke issue. The new PCV valve did nothing to eliminate the blue smoke. I did notice however that engine oil was being sucked into the intake from the PCV valve and hose since there was noticeable engine oil both in the tube and intake port and tells me that this is where the blue smoke is coming from. I was thinking of excessive crankcase pressure but then why would CC pressure be so much higher literally overnight so that it pushes oil through the PCV the next day and unnoticeable the day before. However it doesn't seam to keep pulling oil through the PCV after a couple minutes of running. 

The CE light also come on periodically and when on throws out a code (don't remember the actually code) that says the vacuum canister has a leak and there is an emission issue. At the time the EC started coming on I notice that Air no longer rushes into the tank when the gas cap is removed. Even so, through some testing, I have determined that the cap seals just fine and the problem must be some valve or something on the emission system that is preventing it from sucking the fumes out of the tank. Q2 - Could this emissions leak be causing or contributing to the blue smoke in some way?

*Interesting note:*
I have heard and read a bot pre-cat going bad and being recalled thus causing a sand like substance being sucked into the engine on the negative stroke but I have never noticed any grittiness in the engine oil. This vehicle may have also undergone the recall since I am the 2nd owner and purchased it in 2007 after the recall should have been or was issued.

Any help would be appreciated as I was gong to give this vehicle to my mother in 2015 but don't want to give her a vehicle that is going to prove problematic or have major issues. She only drives about 8k miles a year and figure that before this issue reared its ugly head that, if continued to be taken care of, it would last her 3-4 more years or until she wrecks it.


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## Richman (Jan 3, 2015)

*Update*
Seams odd to me and forgot to mention, but I didn't notice any blue smoke when starting this vehicle the last two days, Friday and Sat. Jan 2-3. It was warmer, in the 50 degree range. Could it be possible that on warm days the rings seal better and don't get as much blow-by or maybe some other thing that is effected by warmer weather? Today on Sunday however it returned to its blue smoke on start-up as has been the case for the last two months.


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## smj999smj (Jan 1, 2006)

Ok...let's start with the evaporative emission issue. First, when you remove the gas cap, you are release pressure out of the tank, not letting air into the tank. A lot of people get this wrong. The gas cap has a pressure vent and anything more than 0.5 psi is released. Gasonline vaporizes and causes the buildup of pressure; the evaporative emissions canister is supposed to store the fuel vapors until they can be later introduced back into the engine and be burned through the normal combustion process. It would help if we knew what the code was, because it would be key to the diagnosis. The system will need to be diagnosed to properly determine what the exact cause is. This can involve scantool testing with a Mity-vac tool, or a smoke machine. That said, a lot of problems are often due to a bad canister vent control valve, which bolts to the evap canister. They are normally "open" to vent the system and commanded "closed" by the ECM to test the system for leaks. They often stick and the valve has been updated several times over the years. Again, without testing the system properly per the Nissan service manual procedure and using the proper equipment, it's impossible to say if this is your problem or not, but it won't cause your engine to smoke or burn oil.

The issue with the catalytic converter is that the ECM would run the engine in such a way that it would cause the upstream converter catalyst to break down. The engine used the variable valve timing for EGR as opposed to a conventional EGR valve type system. It doesn this by slightly opening the exhaust valves during the intake stroke to introduce inert exhaust gas into the combustion chamber. If the catalyst substrate breaks down, bit of it can get sucked into the combustion chamber and score the cylinder walls, creating a poor sealing surface for the rings. The recall covered a number of fixes that would vary to the individual vehicle based on testing results. In general, they reprogrammed the ECM with updated programming, added heat shields to the converter and exhaust and performed a compression test. If the compression test failed, then a new short block was installed, and later, a long block assy. was installed. Also, in these cases, the exhaust manifold/catalytic converter assy. was replaced. 
For you, I would recommend a compression test and cylinder leakdown test. Not only do you have to be concerned about the ability of the rings to seal, which could be caused by the converter issue, but also of a blown head gasket between a combustion champer and oil channel. Head gaskets are not an unheard of problem with the QR25DE and a failure to an oil channel would explain smoke and why the problem occured suddenly. I'd also be suspect of the aftermarket valve cover, as the PCV baffle is part of the cover and if defective, could cause excessive oil to be sucked through the PCV valve into the engine, where it will be burned and cause smoke. I would also smell the oil on the dipstick for fuel odor, as gas contaminated oil will be thinner and cause smoking, as well.


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## ragulin (Oct 17, 2018)

Hi, did you manage to solve this? I have exactly same issue now.


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## Timbhmaxx22 (Nov 16, 2019)

I know this is a older post but I wanted to ask if anyone has ever had any luck finding out what the problem is and were able to fix it? I have the same and problem of heave blue smoke on startup only startup driving around no smoke, thanks


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