Register now to get rid of these ads!

Technical '51 Runs hot @ idle

Discussion in 'Traditional Hot Rods' started by Arch177, Oct 7, 2020.

  1. Arch177
    Joined: Jan 8, 2020
    Posts: 6


    Hey, gang. I have a '51 Chevy Styleline Deluxe, w/ a 285hp 350. The radiator is 3-core aluminum with an electric fan. I recently installed a 180 stat in the cooling system. The water pump is new.

    Driving, the temp is perfect. If it idles more than a few minutes, no matter the outside temp, the motor spikes to 245-250. It has never boiled over.

    The problem I see is the hood covers the top 2/3rds of the radiator.

    Any ideas on how to get rid of some heat at idle?

    Thank you! - Arch
  2. gimpyshotrods
    Joined: May 20, 2009
    Posts: 17,671


    What is your ignition timing set to at idle?

    Where is your vacuum advance connected?
    deathrowdave likes this.
  3. 51504bat
    Joined: May 22, 2010
    Posts: 2,161


  4. 49ratfink
    Joined: Feb 8, 2004
    Posts: 17,855

    from California

    if that was the issue they would all overheat.
    VANDENPLAS and olscrounger like this.

  5. jaracer
    Joined: Oct 4, 2008
    Posts: 514


    Does the electric fan come on? If it does, I think you need a bigger fan since it only happens at idle.
    firstinsteele likes this.
  6. Are you sure you don't have any air trapped in the radiator? HRP
  7. Moriarity
    Joined: Apr 11, 2001
    Posts: 19,241

    Staff Member

    yup, overheating at idle is not enough fan or fan shroud. Why can't you run a mechanical fan???
    olscrounger likes this.
  8. It sounds like an air flow problem. Is your fan running, if so what temp does it cut in? Have you room to install a larger fan or a second fan?

    You don't say if your fan is a pusher or a puller. If its a puller, a more effective fan shroud might help get more air through the radiator.
  9. olscrounger
    Joined: Feb 23, 2008
    Posts: 3,983


    Lots of good replys--I have done many 40's with 327 etc and ac. All have had Cooling Components elec fan setups. Never a heating issue no matter how hot or in traffic. They come on with AC, from engine sensor at 180 or manual if needed-- no issues.
  10. Doublepumper
    Joined: Jun 26, 2016
    Posts: 654


    Correct water pump? CW or CCW...?
  11. Mr48chev
    Joined: Dec 28, 2007
    Posts: 27,544


    From personal experience I would say that it is an air flow problem. Simply because as soon as you get enough speed for enough air to go though the radiator it quickly cools down.
    Is the fan large enough to cover as much of the radiator as possible ? do you have a shroud around the fan to direct air though the fan so it pulls air from the whole radiator? Does the fan have proper blade design and enough CFM to pull enough air? Note if you check the Spal listing on their fans (standard of the aftermarket fans) they have different cfm ratings for the same size fans. A cheap Ebay or parts house fan may not pull enough air.
    It doesn't sound like the air flow is blocked as it does cool at speed.

    My personal observation was that the wrong rotation pump would somewhat cool at an idle but the engine would over heat at speed. That was back in about 1992 when someone stuck a mid 60's 327 in an early 80's Camaro and then a shop installed a pump for the model of the Camaro rather than the model of the engine with V belt drive.

    To the OP, you still have to have the correct pump for the BELT setup you have. V belt taking a clockwise rotation, Serpentine taking a counter clockwise rotation. Check the part number to make sure that your pump matches your belts. I don't think it is an issue but one thing to check mark off the list.
    olscrounger likes this.
  12. The Shift Wizard
    Joined: Jan 10, 2017
    Posts: 2,107

    The Shift Wizard

    Air moves from a high-pressure area to a low-pressure area. At road speed, on the highway, this is simply a natural event due to the air stacking up in front of the radiator and the engine compartment being at a lower pressure. This is why your vehicle doesn't exhibit any overheating while driving but does when idling or in traffic jams. This is a major clue telling you where to look.
    A fan is a mechanical aide to create a low-pressure effect behind the radiator for those times when you are not pushing down the road. But you need a properly designed shroud so the fan will only scoop and expel air that has passed through the radiator. The shroud is sort of like a dam that keeps engine compartment air from displacing the air that you do want to move.
  13. Try a big steel bladed mechanical fan, summit has them, I use a 17" on my Deuce & Brenda's wagon,never any overheating problems. HRP

  14. proartguy
    Joined: Apr 13, 2009
    Posts: 452

    from Sparks, NV

    See post #2.
    Retarded initial timing will cause low speed heating.
    If that is ok then look at improper proper air flow.
    gimpyshotrods likes this.
  15. Arch177
    Joined: Jan 8, 2020
    Posts: 6


    Thank you all for the suggestions! I knew I could count on you. I have no shroud. Looks like I need a bigger and better electric fan or may go back to a 17" mechanical and build a shroud. I'll check the timing. I know there's no air in the system.

    Thank you again!

    Attached Files:

  16. olscrounger
    Joined: Feb 23, 2008
    Posts: 3,983


    I have used the fan HRP shows on a few cars with a shroud and worked well but too tight in a 40. A guy had a 40 with a 327, no ac and a walker radiator. Had a good mechanical fan as well. There were no issues until he went up his hill about 10 mph-it was maybe a 1/2 mile or more. By the time he got to the top it was pegged. Put a Cooling components elec fan on it--problem gone
    Last edited: Oct 8, 2020
  17. harpo1313
    Joined: Jan 4, 2008
    Posts: 1,975

    from wareham,ma

    I think if you build a shroud you will be all set , not only to cool the radiator but also direct airflow over the engine.
  18. Arch177
    Joined: Jan 8, 2020
    Posts: 6


    Annnnd the pump I put on was an extra my friend had. His is a newer 350 w/ a serpentine. Mine is 25 or so years old. Doh! Guess I need a a proper pump.
  19. oldsman41
    Joined: Jun 25, 2010
    Posts: 1,282


    Check timing first then do a shroud. I would build the shroud anyway

Share This Page

Register now to get rid of these ads!


Copyright © 1995-2020 The Jalopy Journal: Steal our stuff, we'll kick your teeth in. Terms of Service. Privacy Policy.

Atomic Industry
Forum software by XenForo™ ©2010-2014 XenForo Ltd.