Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum banner

2003 trailblazer 4.2 getting hot at highway speeds

3K views 11 replies 2 participants last post by  princej99 
#1 ·
My daughter asked me to look at her above truck. I found there was a leak coming from water pump as it was parked in drive way. I purchased new water pump and fan clutch. Installed parts. Let vehicle set while I also replaced wiper motor control board.passenger side actuator for blend door. top off radiator and recovery tank. Start truck and find vibration was gone. Old pump and clutch had wear. Start and let sit in my drive for a good 30 minutes with ac on and temp gauge stayed a hair below 210. I never drove down road more than a mile or two.No high temp on gauge. She picked up truck today as all little gremlins seemed to be gone. On way home she call saying it got about three marks past 210 and reported hearing tank vibrating when she got home. Overflow tank. This seems backwards to me. My experience with overheating is at idle not going down the road. Any help most appreciated.

radiator flushed and thermostat new.
 
#3 ·
During the idling after repair I only had ac on to try and work the engine. My daughter said the overflow tank was vibrating I would assume from the over heated radiator. According to my daughter when temps outside are below 70 f truck stays just under 210. above 70 f is when the over heating issue occurs. The next day when I rechecked the radiator and overflow tank,after initial repair, everything was full. The getting hotter while driving is what is throwing me. Never seen or heard of that.
 
#5 ·
Yes the overflow tank was vibrating from the over flow entering it. she called to day telling me at idle waiting for husband with ac on it stayed just below 210. tried creeping above it driving down road. talking with her she says she really likes truck so I think I will follow the thread and put a switch in cab to allow her to run fan. I'd prefer she get rid of this thing in the fall and get a mid 90's truck.
 
#7 ·
radiator cap removed as radiator filled. Pulleys and belt fine. Sounds like when GM built this vehicle their r and d was poor. Testing something with new components in a lab is never the same as real world with degraded parts. THe "mechanic' they bought it from in the fall when it was cool probably decided he didn't want to fool with it. Probably why GM went back to a tried and true mechanical fan clutch which was used for years with excellent results.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top