Coolant Light and Temp gauge hot!

My coolant light and service engine light keeps coming on. I check the coolant levels and it seems to be fine. However when i open the expansion tank a lot of pressure comes out. Then my service engine light and coolant light comes off. After a week or so the coolant level light comes on as does the service engine light. Again i open the expansion/coolant tank, a lot of pressure releases, coolant levels seems to be fine and then the lights come off. Recently the temperature gauge will read really hot and as soon is i release the pressure in the expansion tank the temprature goes down. What can be the cause of this?

Originally Posted by Henry613

My coolant light and service engine light keeps coming on. I check the coolant levels and it seems to be fine. However when i open the expansion tank a lot of pressure comes out. Then my service engine light and coolant light comes off. After a week or so the coolant level light comes on as does the service engine light. Again i open the expansion/coolant tank, a lot of pressure releases, coolant levels seems to be fine and then the lights come off. Recently the temperature gauge will read really hot and as soon is i release the pressure in the expansion tank the temprature goes down. What can be the cause of this?

Good god.... you open the expansion tank when the cars hot!? you crazy bastard. If that was actually full of coolant/water you would of burned your god damn face off.

Definitely sounds like you have a major coolant leak. DO NOT DRIVE THE CAR WHEN THE TEMPERATURE READS HOT!!!!!!!! DO NOT DRIVE THE CAR WHEN THE TEMPERATURE READS HOT!. Hopefully you haven't already destroyed your engine.

Originally Posted by Henry613

My coolant light and service engine light keeps coming on. I check the coolant levels and it seems to be fine. However when i open the expansion tank a lot of pressure comes out. Then my service engine light and coolant light comes off. After a week or so the coolant level light comes on as does the service engine light. Again i open the expansion/coolant tank, a lot of pressure releases, coolant levels seems to be fine and then the lights come off. Recently the temperature gauge will read really hot and as soon is i release the pressure in the expansion tank the temprature goes down. What can be the cause of this?

Has anyone worked on the cooling system lately?
It really sounds like you need to bleed it, but it doesn't make sense that the coolant is at proper levels when you open the cap. Is it cold when you check coolant level?

If not, check your coolant level when car is cold, top off as required.
I would then remove bleed valve on the top radiator hose, turn ignition key on, engine off and turn the heater on high to open the valve that feeds your heater core to make sure air is not trapped in that hose.
Then continue to pour in coolant into expansion tank until it runs out of bleed valve. If you overfill expansion tank doing this, just suck a little out until it is at correct capacity (old turkey baster works ok for this).
I would then run the car with heater on....let it cool down several hours and top off again. Should be all good unless you have a leak. Some leaks are minor mists, sometimes from the water pump itself. Look for dried white droplets that are created from dried coolant.

You may also have a faulty thermostat, test it if this fails.