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Need Help, overheating 390 Ford

Discussion in 'The Hokey Ass Message Board' started by eddie1, Aug 4, 2009.

  1. eddie1
    Joined: Jul 27, 2006
    Posts: 558

    eddie1
    Member

    I need some help solving an overheating problem. It has a fresh rebuild 390, bran new Edelbrock waterpump, 3 year old rad, factory cooling fan with a dealer installed fan shroud for A/C cars. The car overheats in about 5-10 minutes. seems like the thermostat was not opening, bleed the system at the upper heater hose so I do not think we had any air in the system. Removed the thermostat & it still overheats, just takes longer. We were thinking is we had an air lock at the thermostat & without the t-stat the coolant was flowing to quickly to cool down in the radiator. I drove the car about 8 miles without the t-stat & while driving the temp. was stable but went up everytime I stopped for a traffic light & the temperature would not come back down when driving. Installed another t-stat, this time with a 3/8 hole drilled through it at the top to release any air trapped behind the t-stat. Overheated more slowly just like it did without the t-stat. Was now thinking had one ore both of the headgaskets install backwards blocking the rear coolant passages. removed heads to find the gaskets had been installed correctly. Timing has been checked & rechecked, & if anything it is running a little rich not lean. We are pulling our hair out & any help from you FE guys would really help.
     
  2. SHRUM
    Joined: Feb 25, 2005
    Posts: 616

    SHRUM
    Member

    What size is the Radiator.
     
  3. hemi35
    Joined: Dec 9, 2006
    Posts: 282

    hemi35
    Member
    from Australia

    How much overbore did you go? 390's can be thin in the cylinder walls. Did you cleanout the radiator?? And is the temp guage accurate? All things to consider.
     
  4. RAY With
    Joined: Mar 15, 2009
    Posts: 3,133

    RAY With
    Member

    New motors some times are set up tight and they tend to run hot. Its also possible your motor was bored out and may have one or more thin spots in the cylinder walls generating more heat. A 3/8 hole is not good but when we drill out the stats we use a 1/4 inch just to relieve pressure and trapped air. It would seem to me if your not way over on compression your lacking in radiator size since the over haul. Some times more cuin needs a little more water to cool it. You can test this out by running down the road and when the temp starts going up turn on your heater and see what effects if any that has since all a heater is nothing but a little radiator with a fan.
     
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  5. I'd check to make sure the oil isn't gettin contamiated 1st. Rad is fairly new, was it OK when you used it before the rebuild? I think the previous poster (Ray With) has a good point. Engine may be to tight after rebuild. I am not a great fan of additives but in this case I might try that shit you can put in the coolant system that helps with overheating.,,Guys use it at the track quite a bit...lotsa people swear by it...Great to say that but I can't remember the name of the stuff. Any parts store should be able to steer you to it.. Good luck I hope it come around for ya
     
  6. Shifty Shifterton
    Joined: Oct 1, 2006
    Posts: 4,965

    Shifty Shifterton
    Member

    I'd be tempted to verify TDC with a piston stop or some other means to be 100% certain the marks are right. Massive heat build up at idle is a classic retarded timing symptom. Are you confident the distributor advance mechanisms are working properly and not sticking?

    What are your crankshaft and water pump pulley diameters? Any chance you've stumbled into a severe underdrive?

    good luck
     
  7. RancheroMan
    Joined: Mar 31, 2006
    Posts: 260

    RancheroMan
    Member

    whats the status on the fan clutch?
     
  8. eddie1
    Joined: Jul 27, 2006
    Posts: 558

    eddie1
    Member

    Radiator is a stock replacment size, is .040 overbore, radiator was flushed, temp. guage is working & I do not need a guage to see a giezer of coolant coming out of
    the rad cap, running hot is one thing, overheating is another. Timing has been checked & double checked & I am using a new MSD distributor.
    Another thing I forgot to mention is that we did confirm that there are no combustion gases in the coolant.
     
  9. hemi35
    Joined: Dec 9, 2006
    Posts: 282

    hemi35
    Member
    from Australia

    Did you sonic check the block before boring it?? Some 390's will go behond .040 and run fine some will NOT. Do you have a decent fan on it? Think what you have changed during the rebuild and the answer must be there somewhere.
     

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