98 Chevrolet Astro Van overheating
Not a great mechanic but tryn to troubleshoot cheap stuff before I take anywhere. Girlfriends Astro Van ran hot two nights ago..It was 10 degrees due to the polar weather deal and she left work at 1 am and drove about 7-8 miles and it redlined on the temp gauge so she pulled over and I picked her up. Drove it the remaining 5 miles the next day but temp starting getting really hot when pulled in driveway..She has had a very small leak for over a year and tops off the coolant every 5-6 weeks so its a small leak..Anyway, shes just been using water so I thought maybe it just froze up with the dramatic drop in temp for first time this winter and probably has more water than antifreeze in it at this point..I heated it up in my garage for a day, drained all the antifreeze/water out and flushed it with hot water and then refilled with just water to let it circulate and check for leaks or if drain/freeze plugs had came out.. No leaks anywhere but just in the ten minutes I had it idling temp went up to 240 in 10 minutes..Its 50 degrees outside also..So obviously the water isn't circulating, I'm thinking possibly the water pump although it was replaced last summer, is there anything else I could check first? Someone had mentioned I may need to bleed the air out of the radiator or something like that as its lost its prime or something. Anyway, just asking for ideas, or even could the freeze have caused the thermostat to malfunction or stick? Any help is appreciated. Thanks
It could be the thermostat. Is the heater working ok (blowing hot air) when its starting to overheat?
No, it stopped working that night as well. Well, it blows air, but just cold air since that night.
Using to much water in the coolant mixture might have caused the thermostat to built up rust and stick closed. They are easy to replace. if this is the cause of the problem it would be your best case scenario.
When first reading the issues, my first thought was water and no antifreeze so in cold weather the radiator froze and no circulation. Second guess would be a blockage of the radiator preventing air from flowing through the radiator fins. (snow or cardboard obstruction.) These would be the easy fix. Then as steveq stated above, your thermostat is closed sue to rust or just being tired and refusing to work. Since you don't get warm air into the heater, water is not flowing, so it points to the thermostat issue. IF replacing that does not fix the problem, the water pump is the other answer to the problem. Using water also may have clogged the radiator with rust or hard-water calcium deposits and either a new radiator or having it rodded out if that is still done these days will work.
Thanks for the info! Changed the thermostat today and so far no problems, not running hot and heater is blowing hot air again so i got my fingers crossed. THanks!
Glad we could be of assistance. Stay warm my friend.
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