I’m not a mechanic, but I did have this issue for almost 2 years with smoke coming out of the exhaust like that in the morning. In my case, changing my O2 sensors made the smoke problem stop. The o2 sensor by the exhaust manifold looked particularly burnt, but I changed both, so couldn’t say for sure which one it was. I know it may seem silly, but it’s not an expensive fix to try, in case you haven’t already. It worked for me and thought I’d share.

 

Thanks for that tip. I will pass it on to the mechanic. They have the vehicle now.

 

​​​​​​​​​​​​Being an "old" mechanic in two ways, meaning I'm old and only work on pre-computer cars, I had to do some research on O2 sensors. As stated it seems silly that an O2 sensor could cause this problem. I will still pass this on to the shop because they certainly know more about these complicated digital machines than I do.

I still suspect valve seals. However, on the way to the shop there's a nice long downhill run. At around 40 MPH I dropped the Hummer down a gear and with my foot off the accelerator. That should have provided maximum vacuum thereby pulling oil past the seals/guides. When I stepped on the accelerator I got no smoke.

So I'm still very confused. This problem didn't exist before the head was removed. And I'm beginning to think the shop doesn't believe me.

Thanks again.

 

I wanted you to look inside the intake for oil blowing back through, to cause as much smoke as you have, there would be a lot, not a tiny residue.

You need a compression test and leak down as Happy Hummer suggested. Your shop should have done that BEFORE doing any work.

H3s do not have issues with valve seals, but that would depend on what the shop installed. The I5 head issue is about valve seats, not seals.

 

Forgot to mention, run some searches here, others have delt with smoke on start up problems.

Good luck.

 

Doc, thanks for staying on this. When I looked at the TB with it closed I saw no signs of oil. I wish I had opened it. I will pass this on to the shop and request the leak down and compression test.

And I did do a search on here before I made my first post but didn't find much. I will do it again.

Thanks again

Bill

 

White or Blue?

 

In the pictures I posted it certainly looks more white than blue. In real life it it appears as white with a slight blue tint. I hope that helps.

 

Appears white? Use your sense of smell.

• Hot oil: Not so appealing as making funnel cakes in the kitchen.
• Syrup: The sweetish smell while the car is running could be the ethylene glycol in the coolant.

 

Well, the antifreeze level has not changed in two weeks. So that's not it.