I have '85 SR5, automatic, 22re EFI 4 cyl. I'm experiencing some overheating that I can't explain the reason. I've owned it for about 4 months I've replaced the T-stat and the radiator cap and the radiator has been flushed. After letting it cool, I top off the radiator (it usually only takes about a quart to half gallon water, at the most) I get it up to temperature with cap off and the water is flowing across the top of the radiator just fine (so its not the water pump). I took it out for a drive and 10 miles later the temp guage shot up, not gradual, but a fairly quick jump. I let it cool again, checked the flow again (normal) and drove the 10 miles back home and it overheated again just as I got back home . The oil is a normal color and is at normal levels. My friends and I are stumped. Is it possible for the water pump to stop working properly from time to time? I'm sure it works right or not, there is no "intermittent' performance for water pumps. Thanks for any help you may offer.