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Gas Smell at startup through ac system


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Anonymous Poster
adamodell@embarqmail.com

Mar 19, 2009, 6:04 PM

Post #1 of 4 (3259 views)
Gas Smell at startup through ac system Sign In

I have a 2004 F 150 4x4 witha 5.4l V8 and 98,000 miles. I was having a problem at startup with knocking until the oil pressure built up. I took it to the dealer and they told me that it was probably the camphasers. it was the gasket had broken on one of them. As the truck has almost 100000 miles I told them to go ahead and do the spark plugs and coolant and thermostat and tension rods along with the belt. They did as well as all new gaskets down to the head as 7 of the 8 plugs welded to the head and they had to take them off and tap them. I have a good relationship with the dealer and mechanica and was able to watch most of the work being done and I trust these guys. They put everything back together and it does not store and codes but my fuel millage has gotten worse not better, and when you start the truck it smells of gas really bad through the ac system for about 1 min. As you start driving it goes away but when you idol it comes back. You can not smell it outside if the enginge is off. We have looked for leaks and can not find any, no gas, exhaust, oil, power steering, trans, coolant or ac. I really think the truck is running rich but as the computer controls all that and it is not storing any codes I don't know. I have thought that maybe the thermostat used was a different temp than the origional. Could that cause the problems. The dealer is not sure. Any advice


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Mar 20, 2009, 12:00 PM

Post #2 of 4 (3250 views)
Re: Gas Smell at startup through ac system Sign In

Aside from the work just done this "oil knocking till pressure builds up" isn't such a good thing! That suggests a worn engine or perhaps because you smell gas the oil is overthinned with gasoline.

Doesn't take much gas to make a lot of odor and can be tricky to find external leaks. You might catch some odor if the injection is leaking down badly upon start up like a flooded engine??

Check oil for fuel smell or if it's overfull! Not good if so and act quick.

With all the work it's possible the odor is greasy something on hot parts that will go away in short order and not fuel smell but still an odor.

Still think you should worry about the knock when starting up and check that out now. Perhaps just changing out type and grade of oil would do wonders with that,

T



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Anonymous Poster
adamodell@embarqmail.com

Mar 20, 2009, 6:39 PM

Post #3 of 4 (3242 views)
Re: Gas Smell at startup through ac system Sign In

The knocking is gone after we changed the cam phasers and tension rods. Explain the injector thing one more time. In order to do heads and plugs we had to take all of the fuel system out. i have wondered if maybe we didn't get the system together correctly.


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Mar 21, 2009, 3:40 AM

Post #4 of 4 (3237 views)
Re: Gas Smell at startup through ac system Sign In

1 + 2:

1 - Knocking: It's gone now but I doubt that was the work you did but probably new oil if changed it with all the work. You shouldn't have to wait for oil pressure AND the pressure shouldn't leak down so much in one overnite as to flatten out oil pressured items like hydraulic lifters. A gauge should be building pressure during cranking speeds in a perfect world which it isn't. It's gone for now so let's forget the knock.

2 - The fuel smell thru the vents is merely because the initial air into cabin should come from up by the wipers no matter what setting you have for climate controls. Alone that mean little but any fuel odor does of course.

* Anything disturbed while moving or removing pressured fuel items - connections, seals (little O rings) or where ever things were touched is suspect now. You said you had this all off to work on plugs you had to remove fuel system parts - the rail by chance and did you separate from the injectors? That whole rail to the injectors must be "fuel tight" and no leaks allowed.

Go back to any area that was touched with fuel under pressure. Powder the area with talcum power if need be to look for evidence of being washed off by fine mist of fuel or something.

Again - anything containing fuel under pressure is suspect so go back and check more closely for the fuel smell.

It's possibly YOUR pic but this shows the fuel rail and the injectors on this engine I think? There are seals that can be replaced for these things. Rail has the brownish/rustish color and injectors have the orange rings....





T







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