The vent valve solenoid, mounted on the charcoal canister, by the fuel tank.

 

$28 from Amazon Prime shipped. Haven't changed it yet but ordered a new oem gas cap for $18. Changed the cap and still light on, will do canister this week.

ACDelco 214-2147 OE Service Vapor Canister Purge Valve

oh and so far so good on my radiator, 105000 thousand miles and going. The paper towel spacers has worked well for me thus far.

UPDATE 9/28/14: Its one week after valve install and light is off. Love my Hummer Forum!!

 

The rad on my "new" '09 just took a dump at only a few miles past the 50k mile mark. The one in my '06 lasted till well over 100k.

Unfortunately, the new truck is still under extended warranty so I won't have the pleasure of swapping it out myself.

 

After almost 50k on my Silla replacement, I thought it was leaking too. Turned out to be the vent hose by the fill cap wasn't clamped on tight enough. Its still holding up for me at 1/4 the price of new.

 

Hey guys, I have the same problem with radiator leaking on my 2007 H3 with 65k miles, the local dealer saying the radiator leaking from a "stress" crack atop of the radiator...I have never had this vehicle off road other than dirt roads, so how can a stress crack be caused? thanks in advance -

 

Because the radiator moves too much on the original upper mount in the center, allowing to much flex side to side! That's why I modified the upper mount on my rig.

I used a brass nipple from a garden hose repair kit (for 5/8" hose and has a flat bottom) that I had in my toolbox. It fit perfect and over 2 years later, the rad. is still tight and still haven't lost a drop of coolant.

 

What a great fix! The stress crack makes sense seeing how there is flex. This appears to be a manufacture design defect and not necessary normal wear and tear on the radiator then? ... thoughts?

 

That is correct. Most radiators have 2 upper mounts (1 on each end) to prevent flex/stress. I was going to add more upper mounts, however my mod has worked to keep the rad from moving which has prevented flex/stress.
The radiator should not move! The radiator hoses take all the movement (flex/stress) from the engine.

 

Excellent educational tip! Thank you for your help and insight.

 

I had the same thing happen. cracked all the way across the top. Had the radiator replaced. I bought a piece of black Styrofoam pipe protector that you use to keep pipes from freezing. cut it to length, then cut it lengthwise opened it up and put it between the RAD and cross member. Looks really nice and does the trick.