Hey all. These may be dumb questions but here goes.

When I run my truck without the radiator cap on coolant starts to pour out of it. Is this normal?

Also when I let it cool down and take the cap off my resorvoir bubbles like crazy for a second and fills up more.

I've been having issues with temp gauge fluctuating and will be changing the t-stat soon. Only really occurs when the heat is on. Only a minor fluctuation with the heat off. Will that have anything to do with it? My fluid level stays constant except when i take the cap off and I have to tranfer some fluid from the resorvoir back into the radiator.

Truck does not overheat but fluctuates between a little below a quarter of the gauge up to right before half. Temp sensor was repalced 6 months ago, t-stat, aftermarket cap and a flush about a year ago. Radiator doesn't seem to suck the coolant back in from the reservoir like it should. Bad Cap or bad seal between radiator and reservoir?

Thanks

 

there might be air in the system and yes, it's normal when the cap is off, it'll bubble over.

 

Thanks alot! How could air be getting into the system? My guess is the aftermarket cap, or it wasn't burped correctly when it was flushed out since everything else seems to check out fine.

 

could be the cap, could be the installation. could be a hole in the hose....

get looking. replace the cap, still there? check hoses. still there? process of elimination and go from there.