Help! We've tried quite a few repairs and car still runs hot on 1998 Toyota RAV4

RAV4 started running hot - radiator was changed - several months later - ran hot again - head gasket replacement recommended but another mechanic found no leaks and said all cylinders were in spec. He changed thermostat and sensor - 2 weeks later - temp light came on again - we're not sure where to turn

by in Eustis, FL on December 30, 2010
1 answer 5 comments
ANSWER by on December 30, 2010
Is the cooling fan engaging? Did the mechanic checked if there is CO2 in the coolant? Zee
COMMENT by on January 01, 2011
I just started car and let it run for 10 mins. - this ws the first it ran today - slight white smoke coming out of exhaust with some water droplets - no sweet smell. double fans did ot engage as the car started to run in hotter range as temp climbed - could it be the fans - when are they supposed to come on?? Does the slight white smoke indicate bad head?? As far as I know no check for CO2 was made
COMMENT by on January 01, 2011
I'd test the fan motors if they are working. Could be bad motor, fan relay, coolant temperature sensor or wiring to the above components. I'd also rev up the engine while squeezing the radiator hose and see if pressure builds up to see if the water pump works. There is a test available to check the coolant for CO2, if it fails the test there is a cyl. head gasket problem. Zee
COMMENT by on January 08, 2011
Fan relays were replaced - car ran ok for first day - 2nd day car started to run hot again. I barely made it home - I had to turn heat up to max. I'm stumped - I did notice that the overflow coolant recovery cap kept coming off - it looks like it's worn - could that make the car run hot???
COMMENT by on January 09, 2011
Go to a repair shop and ask for a leak down test and also test the coolant for CO2. If combustion gases leaks into the cooling system due to cyl.head gasket leak, this test will show it. You can also remove the spark plugs and if one looks extremely clean (steam cleaned) comparing to the others, this also an indication of the head gasket leak. Zee
COMMENT by on January 13, 2011
yeah this used to happen to my car..end result was cracked head gasket