So I just wrapped up a head replacement and new intake on my stock 2001 XJ, fire it up, added coolant, and noticed a good amount of white smoke from the back driver's side after running it for a few minutes. It went away after a bit but wondered if this is a normal thing, maybe solvents or whatever burning off the new parts? Also snapped my serpentine belt in the process, but that's another story.

 

Smoke in the engine compartment is never normal. It might have been some oil you spilled on the exhaust manifold, but it's certainly not normal.

 

if you have done a bunch of work under the hood there is a good chance that you had some fluids that you spilled during the job burning off.

 

I know I've sprayed solvent or some kind of cleaner on the block getting it ready for the swap, that's the only thing I can think of..this week's been a blur with putting this thing back together lol...I'll check again once I get my new belt on sometime tomorrow. And I'll remember not to torque it down so tight this time.

 

It's pretty normal for new exhaust part to smoke for a bit as the oils burn off.

 

If you sprayed some kind of cleaner on the block, chances are there will be some burnoff on the first start and warm up. Did the smoke progressively get worse, or did it ever start to dissipate after running for a little bit

 

It started to dissipate, and I took it for a test drive down my street and noticed more once I came to a stop. Turned around and pulled in my driveway and that's when I noticed my belt snapped, so I'm thinking that could've been it. I did clean the block off, but can't remember what I used. And I also sprayed a ton of carb cleaner in the throttle body before I put that back on the manifold. Maybe I'm reading into this too much...

 

If the belt snapped after it was smoking, it very well could have been. Now to figure out why the belt snapped.

 

Oh that was totally my fault...tightened the idler pulley to the point that it wouldn't move. My bad!

 

whenever I do major engine work, which always involves cleaning & degreasing, I expect a lot of burn off for a few minutes.

I monitor this from outside, as there is a chance some fluid leak is causing it..I do not drive it on the open road till I am sure no fluid is leaking, and smoky burn off has ceased

having smoke pouring from you bonnet on the roadside is dangerous, and embarrassing