In 2002 we purchased a 2001 Olds Alero and everything was fine with it up until about 100,000 miles. You expect some problems with a 12 year-old car with a 100,000 miles on it. Time to start changing out worn parts before they go - boom, at the wrong time. I didn't get to the Water Pump in time, so it overheated and was towed to the mechanic we were using at the time. Turns out we shouldn't have been using that shop - flaky work.

Among the many thing they 'repaired' was the Water Pump and Coolant Reservoir tank that had cracked. After this the car ran a bit hotter than it ever had, especially on hot days, at traffic lights, with the A/C on. Two months after the Water Pump was replaced the Radiator sprung a leak and needed replacing. The car continued to run hot. We changed Mechanics (for a plethora of reasons) only to end up with a mechanic that wasn't concerned about our complaint. It wasn't overheating, so what's the problem? And never mind the fact the new reservoir cap is impossible to get off / on.

So now, 3 years after the overheating problem, it's losing coolant at an alarming rate. There is a fine mist of coolant being sprayed all over the place constantly. It appears to be the coolant / radiator hose with a hair-line crack that is not quite all the way through. I was going to replace the tank anyway - so no big deal. Initially I thought of the Water Pump - which led me down a rabbit-hole or research. I found out why it is running hotter.

Sometime around 2007 GM decided ALL their cars would use 'Stamped Steel' impeller type Water Pumps. Up until this time it had been a mix of Stamped Steel and Cast Iron. ALL 3.4L and 3.1L were designed to run with Cast Iron impellers. For many 'technical' reasons - they run cooler with this impeller. So - if you had your Water Pump changed and you or the mechanic just installed a new, off-the-shelf Water Pump it is highly likely you got a 'Stamped Steel' impeller type Water Pump. The two biggest symptoms are: 1.) higher pressure, lots of little leaks spring up 2.) constantly runs at a higher temperature - and significantly higher on hot, humid, days while in traffic - especially with the A/C on.

If this sounds familiar to you - get a new Water Pump. Get one with a Cast Iron impeller like your cooling system was designed to have. They normally have 9, curved, veins on them as opposed to the 6, rather straight, "Paddles" of the Stamped Steel variety. The 'new' AC-Delco Water Pump is stamped steel impeller and sells for the outrageous price of $90 on Rock Auto. Their 'Professional' model is cast iron and is about $20, which is consistent with every other Water Pump out there. Oddly enough the NAPA and Autozone re-manufactured Water Pumps are cast iron - and sell for twice as much as the 'new', stamped-steel pumps. That said, you can get a 'new' "GMB" brand, cast-iron type impeller for your 3.4L Alero for about $18.

 

I had a problem with a pin hole in the Metal Line that runs from thermostat housing along the Frame and then up around back of engine to the heater core
it was leaking

I got a new Pipe instead of fabricating one because I got it for 50 bucks. it has a T in it and has some custom bends But I could have made one out of copper
but for 50 bucks I just got the OEM one

then i had problems with thermostat sticking
this engine a 3.5 Litre 6cyl version of the norstar v8
has a very odd themostat

expensive and I had to seem to fail on me
But real problem was a head gasket leak pressurizing the water jacket
this would build pressure up to 18ps the Radiator Cap rating very quickly before thermostat would open and the pressure was keeping thermostat from opening
I simply bought a 7 Lb radiator cap and that fixed the problem with the thermostat sticking