I have an 02 malibu that has been leaking antifreeze out of the reservoir since we purchased it. We have replaced the radiator, the thermostat, water pump, head gaskets, and lower intake manifold gaskets. The fans turn on okay and it cools down but at times it is still leaking dexcool out of the reservoir tank. Does anyone know what else there could be that I might need to replace?

 

Welcome to the forum. You said you replaced the head gaskets but did you have the heads sent out to be checked? Reuse torque-to-yield bolts by any chance? Check the spark plugs for telltale signs of coolant leak into the combustion chamber?

 

My boyfriend is in the Auto Repair program at our local college and he had his teacher check out the heads and he told us they were not cracked. We didn't reuse the bolts because the head gasket kit we bought came with the bolts. I can have him check the spark plugs but is there anything else it could possibly be?

 

I can't think of anything unless something was botched. Cooling system problems shouldn't be that difficult to figure out. Just let him follow diagnostic procedures in the service manuals and double-check everything.

 

If you're losing coolant FROM the reservoir, it might have a fine crack.

 

the maxx i just got had the same problem. would leak from the reservoir. changed the cap. not sure on the 02's but the 07 cap has O rings that let the overflow through the middle/bottom of the tank. i didn't think it would work, thought there was a crack, but that was the first and cheapest step and it worked. good luck

 

We have replaced the head gasket, thermostat, coolant temperature sensor, the reservoir, and hoses. The temperature, once erratic and bouncy, now shows a steady temperature of 210ish after only minutes of running with occasional illumination of the coolant low light.

For a test, I filled the reservoir to the cold fill line, started her up, and observed. The upper part of the reservoir tank slowly drains and the lower portion slowly fills with coolant. The coolant rises above the fill line until the lower portion is full, then overflows, spilling out.

Then the lower portion drains into the system, causing the level to dip below the coolant sensor, causing the illumination of the light, then slowly fills, until the light goes out and the level rests below the fill line. The upper portion remains empty. Then the cycle continues and the quantity of coolant remains constant with no more loss in the system, for days, weeks, and months.

The temp gauge stays constant with an occasional drop when the coolant in the lower tank drains into the system. Both fans run constantly when above the normal 190 mark. Any ideas?