Hey guys,

I put on an off road Y pipe a few months ago and ive noticed that since ive done that if i let my truck sit for 2 or 3 days without starting it i get a puff of greyish smoke at start up

i know thats usualy an idication of valve seals leaking, but has anyone else ran into this after removing their cats?

its a 2004 tahoe with a 4.8 with a 150 shot of wet nitrous

 

Its probably just moisture that built up in the pipe. My does that when its cold.

 

agreed. There's always condensation in the pipe even when running. Also the cats burn out excess fuels. so without them you may be blowing out any unburnt fuel that has been evaperating in the pipe.
Nothing to worry about. If your valve seals are leaking you'd probably see Black smoke, not grey

 

i would think more along the lines of blue/grey but stinky if your valve seals were shot, the smell of burning oil is quite pungent and obvious, it stinks. Black indicates unburnt fuel, and obviously has that smell, usually seen on hard accel. in a rich condition, or if it has pooled into the cylinder from last shutdown from a leaky injector. You aren't adding oil to keep up the level are you? If not, i wouldn't worry a bit about it.

 

yeah i just thought it was strange, im not used to letting it sit for more than a few hours lol. im a tech at a gm dealer, so i did an injector leak down test and they all came back within .3% of eachother, and i havent needed to add oil or coolant so i figured i would just ask if any of you other guys with ORYs had the same condition

thanks!