Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

350 OverHeating

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Sonny, Jul 21, 2001.

  1. Sonny

    Sonny Newbie

    Joined:
    Jul 21, 2001
    Posts:
    4
    Likes Received:
    0
    Location:
    New Mexico
    My Blazer, which I let sit for a couple of months, started overheating the first time I tried to start it. Only overheats when standing still/ idling. I have replaced the thermostat and flushed the radiator. When I flushed the radiatior I noticed water pouring from the return line of the heater core. I will probably replace the water pump anyways. But just curious about what else it could be?? I think it could be the Fan Clutch because it only over heats when Standing still. The Fan does turn but I don't think at the speed it should. Could that be it?? HELP???
     
  2. Highlander

    Highlander 1/2 ton status

    Joined:
    Nov 25, 2000
    Posts:
    1,204
    Likes Received:
    0
    Location:
    Lakewood Colo
    I would say that if your eng. is at the right temp say 180 or so
    your fan clutch should be very hard to spin by hand if not then it would be the fan. I had a teacher tell me that when you think it's the fan clutch is bad is to tie a peace of string on one of the blades and the other to something in the eng.bay maybe a fender bolt. If it brakes the string it's not the fan. I've never tried this. But after all that you've done sofar it's most likely the fan. good luck to you Sonny let us know the out come Eric

    Lost? i'm not lost i'm just disorienated
    AMSOIL Dealer # 529948
    Cethern@interfold.com
     
  3. Can Can

    Can Can Pusher Man Staff Member Super Moderator

    Joined:
    Feb 17, 2000
    Posts:
    15,552
    Likes Received:
    136
    Location:
    Cochrane, Alberta, Canada
    Here's a couple more things to check:

    1. Although you flushed your rad, you may have a buildup of hard water deposits in the core. It may be worth it to pull the rad and take it to a rad shop and have the rad professionally cleaned.

    2. Spend a couple of bucks and replace your rad cap. If the spring is worn in your present cap, you may not be pressurizing the system enough to keep it cool.

    3. If your water pump isn't leaking from any of the vent holes, I wouldn't bother replacing it. Generally, a water pump either works or doesn't work......

    4. It could be the fan clutch. Another way to test it is to cover the rad from the front with a piece of cardboard and go for a short drive at city speeds. Once the motor/rad gets hot enough, you'll be able to hear if the clutch is engaging. If you do this keep a close eye on the temp gauge....

    Good Luck and keep us posted.........



    <font color=red>PHOTO ALBUM-</font color=red> <a target="_blank" href=http://albums.photopoint.com/j/AlbumList?u=1289798>http://albums.photopoint.com/j/AlbumList?u=1289798</a>.......<font color=blue>TRUCK & HIKING PICS</font color=blue>
     
  4. Waxer

    Waxer 1/2 ton status Author

    Joined:
    Feb 17, 2000
    Posts:
    1,857
    Likes Received:
    0
    Location:
    Long Beach, CA.
    Do you have the fan shroud hooked up? If not then at idle it will overheat.

    Crawlin the rocks with my K5
    <a target="_blank" href=http://www.rockreadyk5.com>http://www.rockreadyk5.com</a>
     
  5. Sonny

    Sonny Newbie

    Joined:
    Jul 21, 2001
    Posts:
    4
    Likes Received:
    0
    Location:
    New Mexico
    Yes the Fan shroud is there and sound. I have replace the Rad safety cap with a brand new one. I'm thinking it is the fan clutch because I can easily turn it by hand when the engine has been warmed up. I do notice a slight deflection downward a couple of degrees in the temp gauge when I rev the engine. At speed down the highway runs slightly warm. 210F but not bad. That was pulling a jetski too. Thanks for all of your pointers. I think I'm going to check the timing also.
     
  6. Waxer

    Waxer 1/2 ton status Author

    Joined:
    Feb 17, 2000
    Posts:
    1,857
    Likes Received:
    0
    Location:
    Long Beach, CA.
    If it cools down when you rev it up from an idle, then thats water pump. I've dealt with overheating problems on many vehicles and especially on my K5. I'd be willing to bet that the fins on the waterpump have corroded and ate away so they arent really pumping the water like it needs to be. I'd check that.

    Crawlin the rocks with my K5
    <a target="_blank" href=http://www.rockreadyk5.com>http://www.rockreadyk5.com</a>
     
  7. Sonny

    Sonny Newbie

    Joined:
    Jul 21, 2001
    Posts:
    4
    Likes Received:
    0
    Location:
    New Mexico
    Another thing when I dumped the Rad after flushing the water/flush was like dirty water. I dumped it into an old cooler so it looked pretty dirty compared to the white cooler. How dirty should it be and what would it look like if I blew a head gasket? I would like to know before I tear off the heads..
     
  8. 84_Chevy_K10

    84_Chevy_K10 Banned

    Joined:
    May 30, 2001
    Posts:
    17,669
    Likes Received:
    0
    Location:
    IL, USA
    Just change your waterpump first and see what happens.

    Tim
    '84 Chevy K10, lifted, loud, fast, and 3/4 ton axles
     
  9. Sonny

    Sonny Newbie

    Joined:
    Jul 21, 2001
    Posts:
    4
    Likes Received:
    0
    Location:
    New Mexico
    Hey Guys, Thanks for all your help. I replaced the Radiator and it works fine. The truck sat for about 4 months with out starting and must of gummed up the Rad. Thanks for all your help and pointers!! Happy Wheel'n
     

Share This Page