2000 Grand AM water vs coolant

5

Asked by Jul 04, 2016 at 07:41 PM about the 2000 Pontiac Grand Am GT

Question type: Maintenance & Repair

Ok guys I'm sorry but this could be a long post as I feel you need to know everything I've done to maybe give an informed answer.

I have the above car. When I bought it, It would over heat on me all the time. I replaced the water pump thermostat and hoses, still overheating. So I did research on it and it turns out that I needed to burp the cooling system. Now I didn't have the money to put coolant in so I ran water and everything was great it ran (depending on how I drove it) from 180 deg to 195 deg. Next payday I bought 2 gallons of 50/50 antifreeze (green) and it ran at 210 deg to 230 deg (again depending on how I drove it). Thinking I ran the wrong coolant I bought 2 gallons of 50/50 extended life (orange) and it ran the same as the green.
I took the car to GM to have the ignition recall fixed (only made a key for me) and asked the tech why the car ran cooler on water than coolant. He explained the difference between running water and coolant but that didn't answer my question.

He said if you run water it will rust the engine unless you run distilled water. Then he told me running straight coolant the car would never reach operating temperature. Thinking like that I drained 1 gallon from the system and replaced it with straight concentrate antifreeze.

So here is my question, if it has mostly antifreeze (which is suppose to make run way below 195 never reaching operating temperature) why does it run at a constant 230 no matter how I drive it, and can someone explain why it runs cooler on water.

I appreciate your feedback

Thanks

2 Answers

25,805

I believe the optimal mix is 50/50 water/coolant. The water dilutes the antifreeze so it flows better through the radiator and water is a better 'coolant,' but antifreeze has properties needed that water alone can't provide - it is a rust inhibitor, and it doesn't freeze and has a much higher boiling point. Too much water, and it has the potential to boil away, lowering coolant levels, and causing the engine to overheat. Too little water, and the coolant mix is thicker and doesn't achieve as low an operating temperature. However that is not really an issue, so long as the engine stays withing operating ranges. With water alone, you also have the potential to never achieve optimal operating temperature, especially if you live in a cold/cool environment. I won't mention what a bad idea it is to just have water in the radiator if you live in a cold area as I think everyone knows about that. Your owner's manual will list the optimal temp for your engine.

69,325

It has to do with heat exchange. Some liquids absorb and release heat at different rates. Much like aluminum cools down much faster than cast iron. In the old days, 1950s and earlier, you ran straight water during the warmer months and straight antifreeze, usually alcohol based, in the colder months. Back in those days the typical cooling system ran at about 6 or 8 PSI (Pounds per Square Inch) of pressure and the thermostat, if used, was 160°F. These were low compression, low performance engines. During the '60s when horsepower and engine sises increased "permanent" antifreeze came into use. This was a huge improvement because instead of having to flush out the cooling system twice per year it was now done every two years or 24,000 miles. Whichever came first. In addition the new antifreeze, at the time, was designed to work in the higher, 180°F or 190°F engines. My '66 Cadillac, for example, called for a 180°F thermostat. It was made before emissions standards came into effect in 1968. When that happened car manufacturers switched to 190°F for faster warm up times and lower tailpipe emissions. Operating pressures on cooling systems also increased to 16 PSI to raise the boiling point of the coolant to 260°F with freeze protection to -20°F. This equates to about a 60/40 mixture of water and antifreeze. Later on the concentrate was changed to 50/50 to increase boil over protection and freeze protection to -50°F (I believe). My guess is that you need to bleed the air out of the cooling system using a vacuum/purge tool. If that doesn't seem to work, check for a blown head gasket. With a 195°F thermostat you should be running between 195°F and maybe 210°F maximum if you're stuck in traffic on a hot day with the air conditioning on. HTH. -Jim

Your Answer

Pontiac Grand Am Experts

  • #1
    tenspeed
    Reputation
    7,760
  • #2
    John Saffrahn
    Reputation
    1,610
  • #3
    Tom Demyan
    Reputation
    1,520
View All

Related Models For Sale

Used Pontiac Grand Prix
39 Great Deals out of 2,725 listings starting at $1,200
Used Pontiac Firebird
10 Great Deals out of 815 listings starting at $1,900
Used Ford Mustang
752 Great Deals out of 42,817 listings starting at $1,300
Used Chevrolet Impala
611 Great Deals out of 34,797 listings starting at $1,250
Used Pontiac Bonneville
519 listings starting at $1,799
Used Chevrolet Malibu
1,247 Great Deals out of 78,132 listings starting at $1,500
Used Chevrolet Camaro
424 Great Deals out of 31,920 listings starting at $2,395
Used Honda Civic
850 Great Deals out of 78,667 listings starting at $900
Used Chevrolet Monte Carlo
12 Great Deals out of 1,350 listings starting at $995
Used Honda Accord
1,027 Great Deals out of 63,281 listings starting at $999
Used Chevrolet Cavalier
965 listings starting at $1,000

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use.