Bad heads? White smoke:(

[venom207]

Hey guys, new to the forum, and I'm asking for help already! I just bought an '04 z71 Tahoe with 129,000 on her. Looks great and runs great but...when I start it after it's been sitting awhile it'll blow white smoke out of the exhaust pipe.Not every time ,but 7 out of 10 times.
We checked the overflow tank for gases in the antifreeze, nothing. Also put dye in the antifreeze and checked for it with a UV light in the oil. Nothing. Oil is clean. Checked a couple plugs for an overly clean cylinder and found nothing, though the plugs are new.
These are the 706 heads that I have discovered have problems with cracking under the rockers where the center bolts are.
Short of pulling the heads and having them magnafluxed I don't know what else to do.
Any advice or knowledge would be hugely appreciated!! Thanks ahead of time.

 

[LuSe4]

Are you certain it is burning coolant? Are you sure it isn't bad valve stem seals?

 

[venom207]

I really don't know at all. That's just what "everyone" is telling me. Assuming it's an accumulation of coolant burning off after sitting. The plume of white smoke lasts about 30 seconds then you don't see it again until the next time.

 

[Gzes]

If the head was bad i would assume it would blow out all the time. Ive seen cars with bad heads or gaskets and they continually blow smoke. Its possible that it is bad but im giving you hope

 

[venom207]

Hope is good! I'll take it, and valve stem seals haven't even come up as an option yet.

---------- Post added at 08:13 PM ---------- Previous post was at 08:10 PM ----------

This is what a mechanic friend of mine sent me.
http://www.agcoauto.com/content/news/p2_articleid/148

 

[erikrichard]

It's normal to see a bit of white smoke at startup, that's condensation burning off. Is the coolant level dropping? if not don't worry about it.

 

[doylee4693]

Are you certain it is burning coolant? Are you sure it isn't bad valve stem seals?

I have to agree.Valve stem seals would be my first thought.My last toyota had it,was a common characteristic of the motor because everyones smoked at startup.Never did any damage just was annoying.Also it never really burned any oil and only did it as you said 7 out of 10 times or something close to that.My grandfathers 06 jag xjr does it and has been for awhile,grandfather isnt too worried about it as it hasnt done damage.

 

[Rivieraracing]

How cold is it outside when you start it up and it smokes? Does the exhaust smell sweet, like burned off coolant? Take a video of what you are talking about the next time you start it up so we can see just how much smoke/steam you are talking about!!

 

[venom207]

I will do that! Thanks for the input. It's def not a normal amount. Does smell kinda sweet, but I don't seem to be losing coolant. And it does it regardless of the temp. Seen it everywhere from 30 degrees to 70. Temps are all over the place in New England this time of year.

 

[Rivieraracing]

Might have tons of condensation in the muffler!! Try getting under your truck and wiggling the muffler around to see if there's alot of water in there!