98'sierracooling System Problem

[gilv]

my truck had been leaking coolant from the water pump area.

the leak is not constant sometimes it leaks sometimes it doesn't (hot or cold)

someone told me there is a pressure vent on the water pump.

I was having a hard time getting the air out of the rad the thermostat did not seem to open so I changed it, now I've got the air out (I think) lots of heat

when the engine cools my upper rad hose collapses and I noticed when the truck is idling the hose is fine if I step on the accelerator the hose collapses

since I've changed the thermostat I haven't seen any coolant leaking

anyone one know what my problem or problems could be

[gilv]

I managed to get all the air out

and the top rad hose stopped collapsing when I stepped on the accelerator

it had pressure in it

I took it out for a run and all seemed well

but when it cooled down the top hose sucked in and the problem is back

is this a head gasket or is it possible the water pump could be worn and is letting air in to the system

[98 Z71 SLT]

You still have a large air bubble in the cooling system

 

Let the truck run for awhile, while refilling coolant, with the pressure cap off

 

Keep topping up coolant as it warms up. You want that temp gage to hit near 210 degrees.

 

If you see a constant flow of little air bubbles in the coolant, that never stop, then you may have a blown head gasket.