I am having an issue with my s-10. It runs hot but is not overheating. It started when I replaced the temperature sending unit and thermostat. I put in an additional thermostat to make sure the first was not defective. I replaced the radiator a year and a half ago with a brand new one. Flushing the coolant has not fixed the problem either.

The truck has had performance issues. In the mid range power, the truck stutters and seems to miss. I think that this issue is related to my cooling issue because the power stutter is more pronounced when the engine is warmed. I ran a compression check to see if my power loss is due to a lack of compression in one cylinder but all 4 cylinders have the same compression.

The fan clutch seems to be fine too. Any thoughts?

  • Checked the timing?
    – Nick
    Aug 8, 2012 at 4:56
  • It's also worth checking if there's residue in the radiator. The flow through the radiator can reduce over time due to deposits from the coolant.
    – Diamond
    Aug 8, 2012 at 9:54
  • 1
    You could also remove the thermostat temporarily to make sure that is not the issue, but I'm not guessing that it is OK since you have already replaced it.
    – JeremyP
    Aug 14, 2012 at 4:06
  • I think this can also happen if ..it's the wrong thermostat?
    – elrobis
    Apr 9, 2019 at 21:50

1 Answer 1


Check the coolant level and antifreeze concentration. Anything above 50/50 can make the engine run hot because the more antifreeze the less heat absorbtion. Make sure the fan shroud is in place. Taking out the thermostat can make the engine run hot because the coolant flows thru the radiator so fast it can't disapate the heat. Warm the engine up with the radiator cap off. Look into the radiator you should see coolant flowing thru the radiator. If the flow seems slow suspect a bad waterpump impeller or a clogged radiator. In 1995 most of the emission controls relied on some kind of vacum hose. Small vacum leaks can cause a lean condition and make the engine run warm. Some of the hoses are only active or have vacum when the engine is warm. Check the hoses, where most leaks occur is at the connection point and at sharp bends.

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