Thread: 4.2L Cooling system issue

I just bought a 2005 with 4.2L 167,000 miles. It was running great for a week and then it overheated. I had to put about 2 gal in the system. It is using coolant and I do not see an external leak. The passenger side floorboard is damp but not 2 gal damp. It doesn't appear to be coming out through the exhaust (no smell or white smoke) or dumping into the oil pan (oil level has not changed). Tonight I noticed that the upper radiator hose gets hot and the bottom one stays cold even at operating temp. The heater core hose from the intake manifold gets hot but the return hose that goes to the water pump stays cold. There is no signs of hydrolock and the engine starts and runs smooth. At first, I was leaning toward intake gaskets leaking into the head, now I wonder if it is a water pump problem. Maybe the impeller has come apart or come loose from the shaft and is not spinning fast enough. May the radiator plugged? Has anyone run into this problem? Thanks.

I pulled back the floor mat further to find standing water in the channel of the rocker panel on passenger side. Got out a heater and dried it out. So I pinched off the heater core hoses and took a ride. First ride was only about a mile. I checked the floorboard and it was still dry. Both radiator hoses we're hot and equal temp. Set idle for a few min and took another ride for about 10 miles. I let it cool down and it didn't use any coolant and the floor is still dry. I am going to bypass the heater core until I have time to replace it. I have some time before the freezing Florida winter gets here. Thanks for all the help!

Oh, noone aswered you.... Did you solve this problem? I have the same issue, and tell about it in repair service. I don't what did they do, but all is good������