Got it. Thanks, makes sense. Can you reseal old seams? I’d need to take some of the headliner down to do that, right? Or can it be applied to the outside? Sorry for all the questions, while I’ve worked on cars a fair deal throughout the years this is my first leak issue I’ve stumbled across.

 

I would apply on the outside to keep the water on the outside.

 

Correct!
Sealer a coat (as of size) applied to prevent subsequent coats of paint or varnish from sinking in.
Waterproof exterior seal is the key to success!

 

lol makes sense!

I didn’t want to start a new thread over this but I also changed the spark plugs. I noticed one plug had corrosion and so did the corresponding coil pack. This was in the cylinder closest to the radiator. Any idea what my plugs are showing? I’d take it I need to at least replace that one coil pack now but I wonder how it got like that. Engine seemed to run fine.

 

Your front coil pack got like that because it is OLD and in the front where moisture can get to the easiest.

I would not have replaced it. Learned a long time ago: Don't fix it if it ain't broke.

 

Doc appreciate all your advice.

I have also been trying to troubleshoot the evap code. In the picture below there’s a hose that runs from the head gasket to the intake (circled in yellow). It’s secure on the valve cover but there is some play in it where it enters the intake. Any idea if that should be a little loose or did it become disconnected within plastic intake housing (I unfortunately can’t see in it).

I’ve cleaned the purge valve, vent valve and checked the PCV hose on the other side of the valve cover (though the hose is starting to show its age with some spider webbing in the rubber).


I left the coils alone but did change the spark plugs (figured 17 years old with 80k+ miles is close enough to GMs 100k mile interval).

 

Ignore where I said head gasket I meant valve cover and I’m not sure how to edit the post

 

Post your "evap code"

 

Its P0446 EVAP Vent Solenoid Valve Control System.

There was a receipt in the car from a local shop that replaced the vent valve last year but maybe I have a bad wire somewhere.

 

"There was a receipt in the car...."?

HUMMER DTC P0446

Cause:

• The fuel tank vacuum is greater than -12 inches H2O vacuum for 5 seconds.
• OR
• The fuel tank pressure (FTP) is less than -2.5 inches H2O or more than +5 inches for 60 seconds after a cold start.