puff of smoke on occasion when first starting engine.

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Jerry G.

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I have a 2007 ST with 93,000 miles .I am currently using a full synthetic oil . Sometimes when I first start the engine a puff of smoke comes from the tail pipe . It may happen twice in a week or once in a month . That Is the only time I see smoke .Its not a lot of smoke just a puff then it goes away and no more . It is not using oil . Usually thats a sign of valve seals leaking a little but it does not do it often . Anyone have this same experience ?
 
If you dont suspect valve stem seals. What about the ECU, might be too rich on fuel @ startup. Or a seeping injector.
 
Hook up a fuel pressure gauge to the fuel rail
And start the engine, let it run for a few seconds, just until the pressure is stabilized
Then turn the engine off, you should only lose maybe 1 or 3 lbs of pressure, if you lose anything over 5LBS in under 1 hour, then you could have a leaking injector and the only way to figure out which one, is to pull the whole fuel rail out with the injectors and pressurize them and watch and see which one leaks


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Hook up a fuel pressure gauge to the fuel rail
And start the engine, let it run for a few seconds, just until the pressure is stabilized
Then turn the engine off, you should only lose maybe 1 or 3 lbs of pressure, if you lose anything over 5LBS in under 1 hour, then you could have a leaking injector and the only way to figure out which one, is to pull the whole fuel rail out with the injectors and pressurize them and watch and see which one leaks


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ok thanks for your reply . I will hold on to this .
 
I wouldn't rule out valve seals. You may not always see the smoke, particularly if you're looking for it through your mirrors. It doesn't take much oil to create a puff of smoke and the seals could be in an early stage of failure.
 
I never have any smoke from my 2002 ST and it has 150,00 miles with the v6 4.0
I did when I first got her and the former owner used synthetic oil and I switch to regular oil 5w40 and no longer have smoke
I would try changing to regular oil for one time and see if the smoke goes away
Synthetic oil is a great cleaner and really doesn’t do anything to help seals to stay soft
I know this for a fact, as I’m a retired/ disabled master tech of 40 plus years
Working on everything from fords to million dollar show cars and rebuilding and maintaining massive power plant motors for Large machinery. With synthetic oil it will find any and all leaks and hard seals and show the signs of old and warn seals
Just give it a try, it will not hurt your engine
The tails of ( you can never change from regular oil to synthetic or synthetic to regular oil are uneducated rumors )


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I never have any smoke from my 2002 ST and it has 150,00 miles with the v6 4.0
I did when I first got her and the former owner used synthetic oil and I switch to regular oil 5w40 and no longer have smoke
I would try changing to regular oil for one time and see if the smoke goes away
Synthetic oil is a great cleaner and really doesn’t do anything to help seals to stay soft
I know this for a fact, as I’m a retired/ disabled master tech of 40 plus years
Working on everything from fords to million dollar show cars and rebuilding and maintaining massive power plant motors for Large machinery. With synthetic oil it will find any and all leaks and hard seals and show the signs of old and warn seals
Just give it a try, it will not hurt your engine
The tails of ( you can never change from regular oil to synthetic or synthetic to regular oil are uneducated rumors )


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My only experience with bad valve seals was a Chrysler 400 lean burn using Mobil 1 synthetic oil.
 
I never have any smoke from my 2002 ST and it has 150,00 miles with the v6 4.0
I did when I first got her and the former owner used synthetic oil and I switch to regular oil 5w40 and no longer have smoke
I would try changing to regular oil for one time and see if the smoke goes away
Synthetic oil is a great cleaner and really doesn’t do anything to help seals to stay soft
I know this for a fact, as I’m a retired/ disabled master tech of 40 plus years
Working on everything from fords to million dollar show cars and rebuilding and maintaining massive power plant motors for Large machinery. With synthetic oil it will find any and all leaks and hard seals and show the signs of old and warn seals
Just give it a try, it will not hurt your engine
The tails of ( you can never change from regular oil to synthetic or synthetic to regular oil are uneducated rumors )


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Thanks for the info . Its funny because I was just thinking about dumping this synthetic oil and replacing with 5x20 and no synthetic . Maybe my ST with 93,000 is too much for full synthetic . We will change this out and see what transpires . PS I'm retired also and I can do my oil changes yet but I'm limited at 75. Have a good summer.
 
My last oil change was a switch to Mobil 1. I now have a valve cover leak onto exh-manifold. The Penzoil plat syn, did not leak.
OMG! There is a slight chance the gasket was ready to go . I would hesitate to blame the oil . YET! Either way I know your frustrated . Hang in there my friend .
 
Like i said, Full synthetic oil will make a small seepage turn into a leak, full synthetic is excellent for keeping the inside of the engine clean regular oil will allow dirt to clog up any gaskets that may be leaking and just look a little wet but when you switch to synthetic it will clean it and cause it to leak


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What color is the smoke ?? it could simply be condensation burning off...
 
Like i said, Full synthetic oil will make a small seepage turn into a leak, full synthetic is excellent for keeping the inside of the engine clean regular oil will allow dirt to clog up any gaskets that may be leaking and just look a little wet but when you switch to synthetic it will clean it and cause it to leak


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Thats what I have heard . That is the down side of full synthetic . It will leak where most other conventional wont . I will be changing this out very soon . Common over I've had some beer in the fridge for over a year LOL we can talk about it some more .
 
I have heard full synthetic will leak where conventional oil will not (Eric the car guy) so maybe thats what mine is doing . I will find out as soon as I change it .
 
One other major problem that has played forwards with the plastic Plenum and intake systems. If you do not maintain the PCV valve‘s properly and excessive amount of oil wall cumulate inside of the Plenum which is the top part of the intake, you can remove the throttlebody and take a long screwdriver with the rag attached to it and stuff it inside there and push it towards the bottom. And when you pull it out, The rag will have oil on it ,so that is also another possibility that the Plenum has an excessive amount of oil buildup inside of it


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One other major problem that has played forwards with the plastic Plenum and intake systems. If you do not maintain the PCV valve‘s properly and excessive amount of oil wall cumulate inside of the Plenum which is the top part of the intake, you can remove the throttlebody and take a long screwdriver with the rag attached to it and stuff it inside there and push it towards the bottom. And when you pull it out, The rag will have oil on it ,so that is also another possibility that the Plenum has an excessive amount of oil buildup inside of it


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Thanks buddy . I am changing my oil from full synthetic to conventional oil first . Then see what happens . I have 93,000 miles on my 07 that might be too many miles for my full synthetic ,Ill see soon . We dont drive the ST too much at all so a little time shouldn't hurt . If it still happened after the other oil is in there your suggestion is next . I will also research changing the PCV valves . I'm getting where its getting hard to do these things as I myself could use an over haul LOL.
 

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