I have a weird problem now. I went to check my coolant and saw a leak, a trail of white residue coming from the recovery tank and some liquid on the frame crossmember. The level in the tank looked full though. So I waited for it to cool down, and opened the cap. The liquid is all the way up to the filler neck! it had overflowed thru the cap relief valve! But it was cooled down. So I drove a little, warmed it up, and checked everything again. Here's the situation:

Temp gauge - normal. Normal time to reach operating temp.
Air Vents - hot air.
Hoses - all are hot including heater & radiator hoses.

But the overflow tank is filled completely, and starting to ooze from the relief valve! When cool down, the level does not settle back down. And it used to - I had a full service flush with thermostat last winter and the level was at the "full cold" line, never higher. What could be causing it to be so high, and even though I've lost a little it is not shrinking back down!

Could it be the pressure cap not holding pressure? Water pump not working? I have never seen this before.

 

Several things can cause this. A non functioning or not functioning correctly thermostat. A water pump about to go. There could also be a air bubble in the system.

Try putting the heat on and let it run for 10 min after it warms up. See if the water goes down. You might have to Burp the system. I am not sure how do diagnose a blown or starting to be blown head gasket? Is there any bubbles in the bottle?

 

well I did have the heat on as it was chilly this morning, that didn't help. There are no visible air bubbles.

How would I know if the water pump is going? It is not visibly leaking, and there is no bearing noise. Would this mean that its not pumping the coolant? But if that happens, wouldn't it register as running hot?

I was also thinking possibly the reservoir cap not making enough pressure?