not sure which section to post this so im gonna post in both. over the weekend i installed a magnaflow muffler on my 05 f150 5.4. today when starting it i noticed i puff of blue smoke, i didnt notice this before installing the muffler but thats not to say it didnt ever. my question is could it be the new muffler breaking in or does it sound like something more serious? the muffler was the 5x8x14 si/do with the pipes ran in front of the wheels, looks and sounds awesome any ideas where the smoke is comin from? again its an 05 with only 10,500 miles.

 

Smoke on startup used to indicate oil seeping past the valve stem seals.

How much oil is your truck using? I would be more concerned with high oil consumption over a little smoke. Think of it as added top end lubrication.

Good luck.

 

Yeah, check how much it is burning and listen for any strange noises. As long as everything checks out, it's business as usual.

 

not using any oil, just 10,500 miles so far but today i watched to see if it would do it on start this morning and it didnt so hopefully it had something to do with the new exhaust.