Need Help: Light Smoke, Heat

Greetings, folks. This has been a very informative and supportive community, so I hope your insights can help me figure out what is going on.

First off, I have a 2001 Prerunner, with the 2.7 engine, automatic, standard cab.

I've spent the past several months doing a frame swap, as the truck had a perforated frame, previous owner did not have it inspected in time, yadda yadda yadda. It's been a long journey, but my build is nearing its completion. I started it up for the first time the other day with most of the truck reassembled on the new frame.

Here's the issue I am experiencing: After a few minutes of running, there is very light smoke (really, more of a haze) that begins to appear out of the engine bay, near the fire wall, near the center. It's basically above the exhaust manifold area, or for those of you familiar with the 2.7, in the area of the rearmost spark plug.

My first thought was that it was the exhaust burning off dust and grease, etc., as it warmed up. I turned the truck off, let it cool, did it again, same results. Today, I turned it on and let it run for a few minutes, the haze happened, did not get any worse, but did not go away. After several minutes, I noticed the RPMs dropped a little, and a minute later, they dropped again. It sounded as if the truck might shut off, so I shut if off myself and decided I had better do some research to figure out the issue.

I noticed that each time the truck ran, the hose containing coolant in this area (center rear of engine bay, attaching to the firewall) is extremely hot, and the whole area seemed particularly warm. No CEL, no rise in engine temp on the dash.

What could be causing this? I looked and looked and there was not clear origin of the haze. There are just too many things I've done during the course of the frame replacement / build to list, but I did change all fluids, put in new spark plugs, and flushed the coolant. I used OEM coolant and it is full. AC is currently not charged, as I will have it vacuumed and recharged when the truck is running. New exhaust gaskets all around, everything tightened down, exhaust sealer added tot he connections for good measure.

I'm hopeful you can help me diagnose the problem. Let me know if there is additional pertinent information I can provide to help. I appreciate your time and assistance on this!

**picture added below**

 

Sounds to me like your heater core,or air in the cooling system. Try bleeding the system and see if your heat comes back and your most goes away. If not I'd look in the direction of your heater core. Real pia to replace if that's it,I've been told. Good luck and keep us posted.

 

Thanks for the tips. I did notice yesterday that the reservoir level had dropped, so I think there was some air that made its way out. I'll bet there is still some more though. I've heard one way to do it is to elevate the front to keep the rad cap as the high point and run it with the heat on.
Anybody have other opinions on what could have caused the haze, in case it's more serious than air in the cooling system?

 

When I did a motor swap it smoked bad from the engine bay for like 30 mins scared me but it went away

 

depends if it smells like oil or coolant.

 

Did you use wd40 on exhaust bolts

 

I had some antiseize in exhaust bolts.
Doesn't smell like oil.

 

I dont know about toyota but some vehicles have a water jacket on the back of the intake that leaks either oil or coolant. Or it could be one of those coolant lines has a small pin hole or crack way down low, that drips on the exhaust and thats how you get the steam.

 

That's the problem. That's why mine smoked bad

 

More then likely the exhaust burning off rust penetrants

 

Sorry for the very late update: it ended up just being the exhaust paint and the antiseize. Everything is all good.