2000 Malibu keeps running hot.

you have a blown head gasket.. doesn't have to have coolant in the oil for a blown head gasket... if hoses are rock hard when running then you have exhaust leaking into the coolant via a blown head gasket...

make sure the radiator cooling fans are coming on. GM has also had major problems with the lower intake gaskets leaking on the V-6 engines. sometimes when refilling the cooling systems air lock can occur. run the engine until it warms up and then turn off and let it cool down, if coolant level goes down repeat this process two or three times. other causes could be clogged radiator, or worse case scenario blown head gaskets. also i have on occasion got bad thermostats from the parts store. the upper radiator hose will get very hot when the thermostat opens. run the engine and hold the upper hose and when the t-stat opens the hose will get hot. then when the cooling fan comes on hot air will rush from from the fans. if the fans come on and the air is cool then there is a circulation problem. t-stat, clogged radiator, low coolant, head gaskets. good luck.

Probably a blown head gasket. Not an easy fix and not for the faint of heart.

If you have coolant leaking out of the muffler the head gasket is most likely blown. The head gasket has passageways through it for coolant water, exhaust, intake and engine oil. Depending on which location the gasket has ruptured you can mix fluids or gasses in several combinations. The only way coolant can get to the exhaust is through a cracked head or blown head gasket. If the head is cracked and another head is installed a new head gasket is installed because reusing a used gasket is very risky. The only to be sure what is broken is to take the heads off. If only the head gasket is blown the head is usually warped and should at least be milled if not replaced. I hope this helps.

Most likely internal head gasket leak, all 3.1L and 3.4L engines are notorious for intake gasket (external leak can be seen on either side of engine intake manifold) or head gasket leaking (usually internally). If it goes thru coolant and there is no obvious leak on the ground than its internally burning the coolant. If leaking on the ground check below water pump while running, it may be leaking also. Ultimately its probably head gaskets.

(step 1 ) the torque specs for the heads are---1998 through 2001 are 37 foot lbs. ( step 2) rotate an additional 90-degrees (1/4 turn). intake manifold bolts ( lower ) step 1-- 62 in-lbs, step 2--115 in-lbs. intake manifold bolts/studs ( upper ) 18 ft-lbs. this is for the 3.1 v-6, have a good day!

the main reasons that an engine runs hot are:
1. the thermostat is faulty( not opening)
2. the radiator is blocked
3. the water pump is faulty
you will have to find which one of these is the problem before you can do anything, other problem could be a blown head gasket ....hope this helps.....cheers

Blown head gasket. You will need to get your head gasket replaced

As long as the heads are not damaged from overheating repairing would be an option rather than replacing the engine. Get advise from a mechanic you trust. The intake manifold gaskets are the most common problem with this vehicle if you have the V6 engine.

Pull the oil dipstick and see if you have a lot of bubbles in the oil. If your head gasket is blown you will have coolant mixing with oil causing the bubbles. If you don't see the bubbles, you may still have a bad head gasket but should consider that it may a be a bad intake manifold gasket. Look on the ends of the engine block - where the transmission attaches on the driver's side and the drive belt is on the passenger side. Look for signs of coolant leaking onto the outside of the block castings at the base of the lower intake manifold chamber (it looks sort of like the flattened bottom of a V) . If it's there you may just have the manifold gasket leak. My '03 T&C with the 3.3l had this problem. It ran rough, and only with no pedal being applied. Driving was tough to get it to the shop since it died at each stop light and required the gas pedal to be feathered to keep it running.

If you have more than amateur skills you can replace it yourself.