Z28Envy
12-16-2010, 08:54 AM
A friend I work with told me her cherokee wasn't blowing any heat. I asked her if the temp gauge was real low when driving and she said it was just a bit over the 100 mark when driving in this cold weather. I told her it needed a thermostat more than likely so I told her I would do it for her being she doesn't have much money and was moving into a new apartment. I put the new thermostat in and started it up topped off the coolant and let the thermostat open. The engine got up to operating temp and the heat was good. I took it for a drive and didn't even make it a few blocks down the street when the heat started to go down. It got pretty cold just going around the block but the temp stayed just below the 200 degree line. I figured there was air in the system but I don't see any bleeders any where so I decided to put it up on ramps hoping that would help get the air out. The radiator cap was cold when I got back from driving it too.
I let it cool down then took the cap off being there was still pressure in the system. I started it up without the cap on and the fluid started to slowly rise until it started to overflow slowly. Never got any air bubbles just a steady overflow like the water pump is pushing it out. Maybe this is normal though I haven't seen this before on other cars that I have bleed air out of. Once the thermostat opened the coolant went down but would come back up everytime. Must be the thermostat opening and closing? I put my scan gauge on and the temp will move up and down from about 190 to 210 even while driving but doesn't go below. I tried another t-stat but the same thing happens. I have read about blend doors being a common problem on these but don't think this is what my problem is. I have also read the heater cores get plugged on these a lot too and the hose going in is hot and coming out is cold after I drive it and the heat goes away but if you let it idle like in the warm building I change the t-stat in the hoses are both hot so I don't think it's the heater core?
Could it be a bad head gasket or exhaust gasket and that is what's pushing the fluid out at idle with the cap off?
I let it cool down then took the cap off being there was still pressure in the system. I started it up without the cap on and the fluid started to slowly rise until it started to overflow slowly. Never got any air bubbles just a steady overflow like the water pump is pushing it out. Maybe this is normal though I haven't seen this before on other cars that I have bleed air out of. Once the thermostat opened the coolant went down but would come back up everytime. Must be the thermostat opening and closing? I put my scan gauge on and the temp will move up and down from about 190 to 210 even while driving but doesn't go below. I tried another t-stat but the same thing happens. I have read about blend doors being a common problem on these but don't think this is what my problem is. I have also read the heater cores get plugged on these a lot too and the hose going in is hot and coming out is cold after I drive it and the heat goes away but if you let it idle like in the warm building I change the t-stat in the hoses are both hot so I don't think it's the heater core?
Could it be a bad head gasket or exhaust gasket and that is what's pushing the fluid out at idle with the cap off?