Blue smoke at startup - cause? - JeepForum.com
 
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post #1 of 7 Old 08-06-2020, 10:41 AM Thread Starter
three_jeeps
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Blue smoke at startup - cause?

2004 4.7L SO with 130K miles. Been noticing some puffs of blue smoke on morning startups. Sometimes see it later in the day.
Engine seems to run fine, no smoke under normal or hard acceleration.
I have a few possible causes but would like to hear other opinions.
Thanks
J

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post #2 of 7 Old 08-06-2020, 10:48 AM
GmanWJ
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Rings or valves, probably both. I recently replaced all my valve stem seals on my 4.7L which helped a ton with overall oil consumption, yet it still sometimes puffs a blue cloud at startup which is surprising to me. I guess it's not going away without a full rebuild.


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ok mostly just repairs, but we are closing in on a lift
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post #3 of 7 Old 08-06-2020, 10:50 AM
222Doc
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first thought would be valve stem seals. I am not all that familiar with the 4.7. But in general that can be one cause. Check plugs for fouling as well.

as well the PVC system.

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post #4 of 7 Old 08-06-2020, 11:14 AM
TrueGrit
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Here some info that should help give you a better idea:

Pro-Tip: Blue smoke during acceleration means your vehicle’s piston rings may be damaged. During deceleration, however, blue smoke means the cylinder heads’ valve guides are damaged. Either way, something is damaged that shouldn’t be. Help your technician diagnose the issue by taking note of when the blue smoke occurs, then head to your nearest Firestone Complete Auto Care!

More info:https://blog.firestonecompleteautoca...or-telling-me/
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post #5 of 7 Old 08-07-2020, 06:25 AM
MuloChico
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Quote:
Originally Posted by TrueGrit View Post
, then head to your nearest Firestone Complete Auto Care!

More info:https://blog.firestonecompleteautoca...or-telling-me/
Don't take this wrong, but that is the last place on earth I would take it other than Pep Boys. I've had multiple problems with almost any "chain" repair shop. Find a friend that can recommend a local shop they trust. "Chain" stores usually don't hire quality (see wage expense) they hire newbies (parts changers as a trusted mechanic friend named them). There have only been 2 variances to this rule of mine that I have found in 41 years of owning vehicles. Granted, good mechanics are very hard to find. But unless you do your own work (which I have for many years now because of the lack of good mechanics) a quality, trusted shop is worth the extra $.
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post #6 of 7 Old 08-07-2020, 09:12 AM
PTV99JGC
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Have run synthetic since I bought it with 18K, now nearly 300K.
Used to be my primary ride, but now only gets used very sporadically.

It was blowing a nice puff of blue smoke upon starting it after sitting for a while, and some when just sitting overnight. Never saw anything in mirrors while driving.

I presume it is the valve stem seals.
After deciding the cost to repair the seals is not worth it to me right now, given how much I drive it, I was looking to try something. It was due for an oil change, so 2 weeks ago, I used Mobil 1 10w30 high mileage.
Now I have not seen it blow anything since then.
It may be new oil does not burn blue, or the seal(s) really liked their additive package, I don't know. For now, for me, no more blue smoke. Just fired it up after about a week of sitting, and nothing.
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post #7 of 7 Old 08-07-2020, 12:17 PM
TrueGrit
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Quote:
Originally Posted by MuloChico View Post
Don't take this wrong, but that is the last place on earth I would take it other than Pep Boys. I've had multiple problems with almost any "chain" repair shop. Find a friend that can recommend a local shop they trust. "Chain" stores usually don't hire quality (see wage expense) they hire newbies (parts changers as a trusted mechanic friend named them). There have only been 2 variances to this rule of mine that I have found in 41 years of owning vehicles. Granted, good mechanics are very hard to find. But unless you do your own work (which I have for many years now because of the lack of good mechanics) a quality, trusted shop is worth the extra $.

It was a copy / paste. I didn't want to cut out what I did not write nor take credit for.

As for firestone, I only purchased tires from them. I do majority of the repairs on all my vehicles I ever owned so I to cannot say if Firestone repair services are good. However I am sure they hire ASE mechanics and carry a warranty.

Either way, best of luck removing the block and getting it overhauled.
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