2005 Pontiac Grand Am overheating

2005 PONTIAC GRAND AM
178,000 MILES • V6 • FWD • AUTOMATIC
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WRODRIG007
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My car is overheating. I replaced the thermostat first and bleed system filling tank it stop overheating for one day then it started again. Found a leak in the water pipe that goes across the front of eng all the way to a line by fire wall. Still overheating. Replaced water pump ran for a day or so and started the same problem..Check the small tubes from water re savor they were packed full of gunk no water going thru. I replaced them and put a new radiator. I thought problem was solved but it ran for a day and the problem changed a little. Now the heater keeps cutting off just cold air then the temp would go up and heater would work and temp would go down. So I replaced the thermostat again. This time I drove for 95 miles and no trouble. Thought it was solved but I drove it tonight and no heat so I stopped and check the coolant and bleed the system again. No luck I had to baby it home because nit keep overheating. It took me 1 and a half hrs to get it home. Put another gal of antifreeze in half way home when I checked it at home it was a gal low. By the way the old radiator was clogged bad with crud. I broke open the tank it had chunk's of crud in it.. My question is where do I go from here. I don't think its a head gasket because the system holds pressure.
Thanks
William Rodriguez
Jan 21, 2015 at 12:24 AM
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WRENCHTECH
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You are likely losing your heat because of air in the system and heater core. The air is likely being pumped into the system due to a blown head gasket. This engine is ver notorious for that. There are a number of different tests that can be done for this but to tell you the truth, most of them are inconclusive. The one reliable way to test is to use an exhaust analyzer to sniff the fumes coming off the coolant for hydrocarbons to indicate combustion gases in the coolant.
Jan 21, 2015 at 2:13 AM
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WRODRIG007
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Thank you for your quick response to my problem. By what you are saying I assume that the system can hold pressure and still have a blown head gasket. Is this true. Also where is all of the coolant going it is dry under the car when I park it for the night there is never any coolant on the drive way. The only time it leaks is if I loosen the cap on the fill tank. That cap is so hard to screw on to the tank by the way.
Thank you so much for your help,

William Rodriguez
Jan 22, 2015 at 8:26 PM
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WRENCHTECH
  • CAR REPAIR CONTRIBUTOR
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If it truly have a bad head gasket, then a couple things will be happening. The pressure in the system is created by combustion gasses leaking into the cooling system. You would also have a coolant loss due to coolant being drawn into the cylinder and burned through the exhaust.
Jan 23, 2015 at 2:01 AM