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Discussion Starter · #1 ·
Hello,
First time poster here. Not sure if this is the best place to post this, but I need some help diagnosing an issue. Sorry if it's out of place...
I have a 2009 Quest (3.5L) with 194,xxx miles on it. Regularly serviced and runs great. The engine has always used some oil but seemingly normal for the 3.5L. It leaks a few drops but not a significant amount. It has no CEL, no missing, idles fine.

Just got back from a long trip to Florida over the holidays - about 1500 miles round trip, including running around miles. On the way down to FLA, it used a half a quart of oil for 600 miles. That was the most I've seen it use. Typically, its been a quart every 2000 miles in city driving. While there, I changed the oil/filter using 10w/30 synthetic as it was due a change. On the trip back it used about 1 qt for 600 miles - double the amount on the trip down. While in FLA, we noticed it starting to puff blue smoke on startup that clears up in a 10-15 seconds.

The smoke at startup happens even after it has sat for 1 hour. It's definitely oil burning based on color and smell. After it clears, it does not smoke when running or accelerating as best I can tell.

As a side note: Both valve covers and PCV have been changed within the year. PCV about a year ago when I changed the rear valve cover. The front valve cover replaced just before our recent trip down to to FLA.

Any suggestions for a fix or what to look for? My wife loves her van and wants to keep it!
 

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A good way to test for oil burning is to first fully warm up the motor. Stand behind the car. Have someone rev the motor to 4,000 RPM and hold at that RPM for about 15 seconds. If you see a lot of blue smoke come out of the tailpipe, the motor is burning excessive oil.

If you see a lot of blue smoke just at startup and no other time, then the valve stem seals are most likely worn.
 

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Discussion Starter · #3 ·
A good way to test for oil burning is to first fully warm up the motor. Stand behind the car. Have someone rev the motor to 4,000 RPM and hold at that RPM for about 15 seconds. If you see a lot of blue smoke come out of the tailpipe, the motor is burning excessive oil.

If you see a lot of blue smoke just at startup and no other time, then the valve stem seals are most likely worn.
I actually did this today after reading through some other threads on the subject. It did not have any smoke doing that procedure.
I suspect worn valve stem seals too. I did find a kinked PCV hose running from the front valve cover to the rear cover. I installed the correct hose tonight, but don't have much hope that is the issue. I used heater hose and it had a kink in it.
I'm wondering if the trip to FLA wiped out some stem seals that may have already been brittle or nearing end of life. Bummer!
 

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I actually did this today after reading through some other threads on the subject. It did not have any smoke doing that procedure.
I suspect worn valve stem seals too. I did find a kinked PCV hose running from the front valve cover to the rear cover. I installed the correct hose tonight, but don't have much hope that is the issue. I used heater hose and it had a kink in it.
I'm wondering if the trip to FLA wiped out some stem seals that may have already been brittle or nearing end of life. Bummer!
One sure-fire way to tell if you have worn valve stem seals is to perform a cold engine test. When your vehicle has been sitting overnight or for a longer period of time, the top of the head of the valve cover area will have some oil left over from the last time you drove. When you start the engine, the oil ends up getting sucked down through the worn seal(s) into the combustion area, producing a blueish smoke out of the tailpipe. This will generally last for few moments and then clear up as you start to drive.

Another way to test for worn valve stem seals is to be aware of what happens while your vehicle is idling. When your vehicle is stopped for a significant amount of time, high vacuum levels will cause the oil to build up around the valve stems while the valve is closed. In a faulty valve seal situation, when you begin to accelerate again, this oil can end up getting sucked past the seal into the combustion area. This causes more of this blueish smoke, due to the burning of oil, to come out the tailpipe. Again, this will generally last for few moments and then clear up as you start to drive.
 

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Discussion Starter · #5 ·
So the cold engine test is definitely pointing to a worn valve stem seals(s). Even after replacing the PCV hose - which removed the kink - is still smoking on start up for a minute until it clears.

Haven't tried the idle test. Will try to do that as well.

Had really hoped to get about 250k out of this engine. Not sure that the cost to replace the seals would be worth it.
 
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