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Overheating SBC in 54 Chevy

Discussion in 'The Hokey Ass Message Board' started by rockable, Jun 10, 2012.

  1. rockable
    Joined: Dec 21, 2009
    Posts: 3,278

    rockable
    ALLIANCE MEMBER

    I have a 350 crate engine that is overheating at idle. I bought this car and did not build it. I have been sorting it out for about 6 weeks and I thought I had this problem fixed but I didn't. I replaced the thermostat with a new 180 degree unit last weekend and replaced the coolant. Today it was in the upper 80s and it's still overheating at idle.

    It has a large radiator, not aluminum, but it should be ample. There was no rust when I drained the system.

    It has one of those chrome Edelbrock water pumps on it and it has that convoluted flexible SS hose with about 1 1/2" i.d. on both the top and bottom. It also has a polished aluminum thermostat housing but I doubt that matters. The hose goes by the name Flexi Kool, etc. It has rubber couplings and a chrome sleeve that slip over the rubber couplings.

    The only two things I can think of that may not be up to snuff are the suction side hose may be too small or the water pump may be bad. I've never seen a non-leaking water pump go bad.

    So, I'm looking for experienced suggestions here. The engine runs at about 190 degrees when cruising (higher than the 180 degree thermostat) but will climb to 240 or higher when idling and start to boil. Not good.

    Thanks for your help.
     
  2. landseaandair
    Joined: Feb 23, 2009
    Posts: 4,411

    landseaandair
    Member
    from phoenix

    Sounds like an airflow problem.
     
  3. Bypass or heater hoses ?
    Old radiator shouldn't be assumed on.
     
  4. 19blockhead72
    Joined: Feb 17, 2012
    Posts: 204

    19blockhead72
    Member

    You didn't mention a thing about a fan or shroud. Thats one of the most important parts while idling.
     

  5. nachodog
    Joined: Dec 24, 2009
    Posts: 111

    nachodog
    Member
    from socal

    You didn't mention a fan shroud, i added one to my truck and no more overheating at idle or low speeds. I've driven in 100+ degree weather in traffic, at stoplights and climbing uphill and have yet to see my temp go past 195.
     
  6. Jay Tyrrell
    Joined: Dec 9, 2007
    Posts: 1,631

    Jay Tyrrell
    Member

    So what about the fan? Electric or Pulley?
     
  7. rockable
    Joined: Dec 21, 2009
    Posts: 3,278

    rockable
    ALLIANCE MEMBER

    Oops. Has a flexi fan and a shroud. Good airflow. A sheet of paper will stick anywhere on the condenser.
     
  8. rockable
    Joined: Dec 21, 2009
    Posts: 3,278

    rockable
    ALLIANCE MEMBER

    Has a vintage air system. Nothing bypassed.
     
  9. nachodog
    Joined: Dec 24, 2009
    Posts: 111

    nachodog
    Member
    from socal

    I would invest in a good electric fan.
     
  10. tudorkeith
    Joined: May 10, 2009
    Posts: 454

    tudorkeith
    Member

    try a back flush on the rad. while I was building mine, a rodent made a nest in the rad while it was off. can't hurt
     
  11. 71nova
    Joined: Nov 6, 2010
    Posts: 25

    71nova
    Member

    You may want to check your timing. Could be off.
     
  12. in order to cool you need just a few things.
    flow of coolant
    heat transfer into and out of coolant
    big enough radiator.
    air flow


    most of that is easy to check.
    the apparent problem is the heat transfer in the radiator. sometimes they get a buildup on the inside and that actually acts as insulation.
    check that out.

    Edit:
    Maybe some genius powder coated the outside of the radiator
     
    Last edited: Jul 26, 2012
  13. Get rid of that flex fan and get a quality steel fan and shroud it, but sounds like a timing issue also.
     
  14. scibjenkins
    Joined: Jul 10, 2005
    Posts: 492

    scibjenkins
    Member

    Take advantage of the situation and cook a couple pizzas! The heat transfer may help a little bit :D
     
  15. BrerHair
    Joined: Jan 30, 2007
    Posts: 4,602

    BrerHair
    ALLIANCE MEMBER

    Man your problems are timely for me Rock. So much to learn. Profited from the take-home message in the MII thread . . . guessing that one of the take-home messages here will be . . .

    Electric puller.

    Going to school on this '54 :D
     
  16. George/Maine
    Joined: Jan 6, 2011
    Posts: 949

    George/Maine
    Member

    I had a 52 chevy car and used a 67 camaro raditor with stock fan worked good.
     
  17. Ken Crumley
    Joined: Jan 11, 2009
    Posts: 8

    Ken Crumley
    Member

    FNG here, just something cheap to check make sure that the suction hose out of the bottom of the radiator isn't collapsing, especially while the system is hot. This will restrict the water flow in the system. Also there should be a coil spring in the suction hose it to keep it from collapsing. Check timing, make sure the T-stat works, fan shroud is a plus, good quality fan, back flush the radiator. If non of the above corrects the issue replace the radiator with a fancy expensive new aluminum one.
     
  18. Belchfire8
    Joined: Sep 18, 2005
    Posts: 1,542

    Belchfire8
    Member

    Where is your vacuum advance line plugged in? You want manifold vacuum, not ported. This causes many SBC to idle hot, mine included, switched to manifold vac and problem dissapeared.
     
  19. mustang6147
    Joined: Feb 26, 2010
    Posts: 1,847

    mustang6147
    Member
    from Kent, Ohio

    I have the same problem. Its the radiator. I am not sure what you have, but mine is a recored stock in my 40 chevy. It works fine by itself, block a little air with the condensor, and she is right on the line. Anything above 80, she will over heat when at a light, and never quite cools down once rolling again, the radiators capacity is maxed...

    You can take a house hold square fan, and put it in front of the grill on high, and it should be enough to keep it controlled, if it does, and like you said paper sticks to the front, then its the same problem....

    If it does not, then your pulleys might be turning the pump to slow.... Or some blockage somewhare
     
  20. rockable
    Joined: Dec 21, 2009
    Posts: 3,278

    rockable
    ALLIANCE MEMBER

    Now this is the kind of stuff I'm looking for. I do smell raw gas at idle.

    My stainless steel hose isn't collapsing. I've got good airflow. It's a fairly new radiator. New thermostat. Etc. etc.

    I'm going to check the timing.
     
  21. deto
    Joined: Jun 26, 2010
    Posts: 2,620

    deto
    Member

    Whatever you do change one thing at a time
     
  22. sdluck
    Joined: Sep 19, 2006
    Posts: 2,681

    sdluck
    Member

    Pictures please,base timing and vacuum advance,what are they,what size pulleys are onit,fan needs to be half way out of shroud
     
  23. rockable
    Joined: Dec 21, 2009
    Posts: 3,278

    rockable
    ALLIANCE MEMBER

    Just checked and the vacuum advance is hooked to the ported connection. Jesus. I don't think much on this car is right.

    There is another vacuum line connected to the manifold vacuum port. It is connected to to vacuum switches under the dash. Is that for the torque converter lockup? What else could it be?

    I'm going to know this car before I'm done, even if I didn't build it.
     
  24. junkyardjeff
    Joined: Jul 23, 2005
    Posts: 7,834

    junkyardjeff
    Member

    2nd on getting rid of the flex fan if its aftermarket,I had one years ago that would heat up at idle and as soon as I put a stock fan back on troubles were gone. I try to use factory flex fans from a/c equipped cars on my projects.
     
  25. Jalopy Joker
    Joined: Sep 3, 2006
    Posts: 26,146

    Jalopy Joker
    Member

    just because radiator is "big enough" and no rust when flushed does not mean it is not clogged. take it to radiator shop and have it checked for pressure test and overall condition. raw gas smell could be carb float problem or too big jets.
     
  26. rockable
    Joined: Dec 21, 2009
    Posts: 3,278

    rockable
    ALLIANCE MEMBER

    Am I probably correct on the "other" vacuum switches! If they are for the lock up, does it matter if they are on ported vacuum or manifold vacuum?

    Since timing is easy. I will start with that on my attempt to cure my problem.
     
  27. Belchfire8
    Joined: Sep 18, 2005
    Posts: 1,542

    Belchfire8
    Member

    There may be an unused manifold vac bib on the carb. If the bib is below the throttle blades it should be manifold vac. I have had to put a tee in a tapped and plugged hole in the manifold to get manifold vacuum. I had this problem on a car and was at a car show when a guy pointed out the the vac lines was on ported vacuum. I made the switch and it instantly cured the overheating at idle problem i had with that car for a long time.
     
  28. rockable
    Joined: Dec 21, 2009
    Posts: 3,278

    rockable
    ALLIANCE MEMBER

    Thanks! I will definitely try that tomorrow.
     
  29. mashed
    Joined: Oct 15, 2011
    Posts: 1,474

    mashed
    Member
    from 4077th

    The purpose of the ported vacuum is to raise the temperature at idle to lower NOx emissions.
     
  30. I'm a '51 Merc but SBC and this is my car. My temps don't climb super fast but once it's up there, nothing short of driving 60 mph will help the temps drop.

    One of my culprits is my big cam + tight converter. But I'm going to swap in a new aluminum radiator for $300 too since my radiator might be from the 80's. And a shroud.
     

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