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Water pump, Thermostate, or temp Sensor?

Discussion in 'Chevy Trucks' started by jrm123180, Nov 3, 2005.

  1. jrm123180

    jrm123180 Senior Member
    Messages: 156

    I'm having trouble with my cooling system. My temp gage doesn't seem to climb at all...only slightly, almost not even noticeable. I had the truck running the other day for about 20-30 minutes, drove it down the street and back (maybe about a 1/4 of a mile) and the same on the gage. The upper and lower radiator hoses aren't getting that hot...Cool enough to grab on to. There's also no pressure in the radiator; none when I squeeze the hoses, or release the valve on the cap.

    Any suggestions would be of grate help.

    Thanks again,
    Steve

    PS 1979 Chevy K10 with a 350sb
     
  2. kingriver

    kingriver Senior Member
    from alaska
    Messages: 217

    Sounds like thermostat to me, but I aint no mechanic. :cool:
     
  3. shooter

    shooter Junior Member
    Messages: 13

    your t-stat is stuck open....
     
  4. Foxfire

    Foxfire Senior Member
    Messages: 153

    Stat

    Or you dont have one !!!:eek:
     
  5. MickiRig1

    MickiRig1 PlowSite Veteran
    Messages: 3,617

    Thermostat is stuck open. Your hoses should be so hot you can not hold your hand on them for more then a few seconds. After you shut down the engine it will have big time pressure in a few minutes.
     
  6. jrm123180

    jrm123180 Senior Member
    Messages: 156

    Thanks Guys....the thermostate was my suspission.

    I'm going to change it out.

    Thanks again.
     
  7. Robhollar

    Robhollar Senior Member
    Messages: 766

    It sounds like a bad Tstat, but you may have an air lock going on. Have you added antifreeze lately? How is the level of antifreeze now. Don't overlook the easy things. Keep us informed on your progress....Rob
     
  8. douglasl330

    douglasl330 Senior Member
    Messages: 356

    Don't think you have one in from the way your describing it unless you also have a large capacity radiator! 5 minutes and you should have it fixed
     
  9. jrm123180

    jrm123180 Senior Member
    Messages: 156

    Well I haven't gotten around to checking my thermostat yet. Had to rebuild my carb first.

    I do have a large capacity Radiator installed in my truck. Would that have anything to do with this?

    Thanks.
     
  10. murphyslaw

    murphyslaw Senior Member
    Messages: 443

    umm if yo had an air lock the motor would over heat. id bet its the thermostat. its happened to me before. and even if you did have a large radiator it would warm up just a little slower. i have the big 5 core from the diesel in my truck with a 350 and i bairly notice a time diff. in warm up. but in the winter i do have to put stuff infront of it cause the heater dosnt work that well from over cooling.
     
  11. sonjaab

    sonjaab PlowSite.com Addict
    Messages: 1,425

    Does your heater put out any heat?
     
  12. jrm123180

    jrm123180 Senior Member
    Messages: 156

    it does, but very little.
     
  13. Robhollar

    Robhollar Senior Member
    Messages: 766



    It is true if you have an air lock it will overheat. But if the lock is near where the coolant temp sensor then it will not give you a good temp reading. I just had that the other day on a 4.3 liter. I had to vac the coolant system and then refill it to get it to cool rite. But like I said before the thermostat is prob bad. Oh ya don't over look the radiator cap. Even this probably doesn't have anything to do with this problem its a good thing to change every once in a while.......Rob
     
  14. jrm123180

    jrm123180 Senior Member
    Messages: 156

    Well i changed my thermostat tonight, and my temp sensor seems to now be working. I'm still not getting pressure in my radiator though. I'm going to change the radiator cap first and if that doesn't work, then I’m moving onto the water pump.
     
  15. shoman44

    shoman44 Junior Member
    Messages: 7

    Water Problem

    Checked the Fuse right?
     
  16. MickiRig1

    MickiRig1 PlowSite Veteran
    Messages: 3,617

    It should not have pressure unless it's over the temp. The idea is to shunt the over pressure to the recovery tank when you shut down and it boils/pressures. Then as it cools it sucks antifreeze into the system and purges the air.
     
  17. jrm123180

    jrm123180 Senior Member
    Messages: 156

    right now, when I warm it up, it temp comes up on the gage to about the first like (sorry, not sure how high that really is). I'm going to try and block the radiator with some cardboard or something to see if that helps bring the temp up higher.

    Thanks,
    Steve
     
  18. douglasl330

    douglasl330 Senior Member
    Messages: 356

    Just a thought when the truck is running do you see flow in the radiator after a couple of minutes. When you rev the engine the flow should increase. This will tell you if the waterpump is functioning. Is the fan belt slipping by any chance? (v-belt for that age). Getting back to the large radiator--I went from a 2 core to a 4 core and never had toasty warm heat again. The engine ran extreemly cool-- 150 to 195 when the thermastat opened and cooled it back down to 150. I would just put cardboard in front of the radiator on really cold days!:redbounce :bluebounc
     
  19. MickiRig1

    MickiRig1 PlowSite Veteran
    Messages: 3,617

    Are you getting good heat / air flow out of the heater? The Gage should run about 1/3 of the range of "normal". If no good air flow try taking the blower motor out and cleaning the stuff out that has collected in the housing.
    My Mom's Cutlass had a mouse nest in it and both my trucks were full of leaves and stuff. The heater hoses should be so hot you can't wrap your hand around them for long.
     
  20. jrm123180

    jrm123180 Senior Member
    Messages: 156

    Well, I get heat out of the heater (not as hot as I think it should be, but hot) and my temp gage comes up to about the first line which is about the quarter line (heated up, usually comes up to the middle line)

    Should I be concerned that it doesn't heat up all the way, I ran it tonight for about a half hour with the radiator blocked and stay at the same level.

    I'm thinking that I should jump from a 180* themos to a 195* and if that doesn't work, pull the fan shroud off.

    I'm not too concerned about it running at that temp, as I am not getting as hot heat as I should (keeping warm and keeping the windows defrosted.)

    Thanks.

    Steve