I have 2006 4.6L with 143000 miles and it sometimes smokes at start up.
For the last year when I would start the truck after several hours or over night, the truck emits at times a cloud of blue smoke, looks like oil and sort of smells like it, sometimes none or a light puff and other times it would emit enough smoke to hide a fleet of Navy ships. There has been no real pattern to the occurance, except it has become more common, almost every morning.

I spoke with my regular mechanic and he felt it was one or more seals in the heads that was allowing the oil to weep into the cylinder(s) and upon start up the oil burned off. He suggested to dispose of the truck as he felt to do any work would not be economically advisable.

he felt that this motor wore faster than the others and that since we use thin oil as required by Ford, any minor wear or variance in tolerance allows the oil to creep into the cylinder(s) and thus smoke on start up

We have a number of 2005 and 2006 F150 trucks with the 4.6 engine and some with over 200.000 miles and none of the others smoke at all.

I have searched the various forums and no one seems to have a similar issue.

Today I was at a local dealer ship looking at their stock on a Sunday when the sales folks are not there and had a conversation with an individual looking at the new 2015 Superduty's and in the conversation he felt that the oil was the result of an ERG malfunction ( think he is totally off on this, the ERG has no access to oil as far as I know), his commet got me to looking though.

Any one have any thoughts on how or why the engine would smoke at start up?

the truck has never run hot, never been abused, ho heavy towing, oil and filter changed every 5000 miles, used the recommended 5W20 oil.

Thank you for your thoughts

 

Has the PCV ever been changed? That can be a direct source of oil into the motor.

Just a thought.

 

Yes, we changed it, plugs, fuel fiilters, etc. at 100,000 miles.

the only time we see the smoke is when it has been sitting for at least an hour. After the hour when we start sometimes there is smoke and sometimes not, the pattern is not consistent, We will change the PCV valve tomorrow.

any other thoughts?

 

It's valve stem seals. Not that difficult to replace. You can try heavier oil to try to minimize it.

 

Regarding the theory that thinner oil caused accelerated wear, these engines are designed to run on it. Clearances are much tighter than grandpa's old Chevy and the thinner oil is required for proper lubrication. Additionally, modern oil is exponentially superior now than before.

As GLC stated, valve guide seals are the source of your symptoms. They can be changed without removing the heads. It's not that difficult, but it's not a job for 'Harry the homeowner'.

 

I agree I would change the valve stem seals myself.