I keep hearing water movement behind the dashboard? Any ideas? Also, ONLY when I run my heater I smell gasoline. This all seemed to happen around the same time. Any help?

 

You have air in your cooling system. You need to bleed the coolant system correctly to get rid of the air. Remove your bleed screw on the T right above the radiator, remove the coolant reservoir, remove the cap, and raise the resrvoir as high as you can. Once coolant starts coming out of the bleed hole, put the screw back in. Keep the reservoir lifted up and add coolant until it is at the right level.

 

Air in cooling system. Could be from age, low coolant (external leak around a clamp), or exhaust gas in coolant from blown head gasket. Will cause overheating (won't move the computer controled gauge - at first. Best read with a scaner or Ultra Gauge). Purge air from cooling system, refill. If continues or comes back do more tests. There is a chemcial test for exhaust in coolant that is about $50 at parts store, it changes color as an indicator. It is NOT the ph strips for checking coolant acidity.

As for gasoline smell, suspect fuel leak under hood and sucking in fumes thru fresh air intake. No fuel lines inside cab. Could be external HG leak, but usually noisy like an exhaust leak.