1990 Honda Accord runs hot sometimes

Discussion in 'Accord' started by Gene Wagenbreth, Nov 4, 2009.

  1. I have a 1990 Honda Accord. It usually runs with the temperature
    guage in the middle range. Frequently the guage will quicky go up
    to close to, but not at the high end red mark. This happens even
    when its 50 degrees out and I am going 45 mph. If I turn on the
    heater the temperature usually goes back to middle. It goes down
    very quicky, within 10 seconds of turning on the heater. I dont
    believe the heater could cool things off that quickly.

    I have a new radiator and antifreeze. I am not loosing coolant.

    Could it be a hose or chamber that is blocked/pinched, and turning
    on the heater is allowing the coolant to byupass the blockage ?

    Any helpful comments appreciated.

    Gene Wagenbreth, Nov 4, 2009
  2. Gene Wagenbreth

    Clete Guest

    Head Gasket ?
    Clete, Nov 4, 2009
  3. Gene Wagenbreth

    Seth Guest

    I'm thinking thermostat.
    Seth, Nov 4, 2009
  4. Gene Wagenbreth

    Clete Guest

    I hope u are right.
    Clete, Nov 4, 2009
  5. I doubt its the head gasket. It never gets too hot. Most of the time it
    runs fine and doesnt get hot. Why would turning on the heater make the
    temperature go down immediately if it were headgasket.

    Thermostat sounds interesting. Does the heater somehow bypass the the
    thermostat ? How difficult is it to replace the thermostat ? How much
    should it cost to have someone do it (ballpark) ?


    Gene Wagenbreth, Nov 4, 2009
  6. Gene Wagenbreth

    Seth Guest

    The heater doesn't bypass but redirects heat. Those coolant lines go
    through the heater core. With the heat on, a fan blows across it sending the
    heat into the cabin.

    For how to change it...
    Seth, Nov 4, 2009
  7. Gene Wagenbreth

    E. Meyer Guest

    New radiator sounds like a clue. Check for air bubble in the system. I
    believe a '90 has a "burp" screw.
    E. Meyer, Nov 5, 2009
  8. Gene Wagenbreth

    Tegger Guest

    It can indeed! Considering there's only about 20F or so difference between
    "normal" and "overheat", the heater doesn't have to do much to cool the
    engine down sufficiently.

    Why was the old rad replaced? And how old was the coolant that was in there

    Sure does sound like a sticking thermostat. I'll bet it's crappy
    aftermarket, too.

    The heater feed is independent of the thermostat, so it will work even when
    the engine is cold and the thermostat is closed.

    Try a new OEM Honda thermostat. About $40 or so and worth every penny.
    Tegger, Nov 5, 2009
  9. Where is the burp screw ? How do you use it ?

    Gene Wagenbreth, Nov 5, 2009
  10. Gene Wagenbreth

    E. Meyer Guest

    Look in the vicinity of the top radiator hose connection on the engine for
    either a small hex head bolt/screw. Set the heater to max, open it a couple
    of turns until coolant comes out in a steady stream without bubbles. Close
    the screw, top it off & idle the engine until the radiator fan comes on
    twice (heater still at max) then open it again (VERY slowly) and let any
    trapped air out.

    For the next several days, check & top off the radiator & overflow tank
    before the first start in the morning & it should get rid of all the air.
    E. Meyer, Nov 5, 2009
  11. Gene Wagenbreth

    Observer Guest

    Is this the same thing as using the drain screw at the bottom of the
    radiator? Not sure if this Honda has one but some cars had it.
    Observer, Nov 5, 2009
  12. Gene Wagenbreth

    3rd & Long Guest

    I doubt Honda manufactures their own thermostats -- instead buying them from
    one of the high quality specialty manufacturers-- as they do for so many
    parts and subassemblies of the car.

    Why not just buy a high quality well designed/manufactured aftermarket
    part -- not just some Big Box POS-- and save the extra dough?
    3rd & Long, Nov 5, 2009
  13. Gene Wagenbreth

    Tegger Guest

    They don't. The ones I see are made by Nippon Thermostat, are marked
    "NTCL", and are of superlative quality.

    Because OEM is built to Honda's exacting and stringent specs. Aftermarket,
    even from the same manufacturer as the OEM stuff, is built to be cheap.

    Aftermarket is crap, and aftermarket thermostats are crappy. There is no
    acceptably "high quality" aftermarket thermostat available for Hondas.
    Anything other than OEM is a step down.
    Tegger, Nov 6, 2009
  14. Gene Wagenbreth

    3rd & Long Guest

    OK, thanks. You convinced me...
    3rd & Long, Nov 6, 2009
  15. Gene Wagenbreth

    Tegger Guest

    You gave in quick.
    Tegger, Nov 6, 2009
  16. Gene Wagenbreth

    Jim Yanik Guest

    how do you KNOW the aftermarket part is "well-designed/manufactured"?
    At least with a true Honda part,you know it meets all specs.

    Now,if you could find out who is Honda's OEM manufacturer for that part...
    then you could go buy it aftermarket.

    Jim Yanik
    dot com
    Jim Yanik, Nov 6, 2009
  17. Gene Wagenbreth

    Tegger Guest

    And that makes ALL the difference in the world.

    It's why a FRAM oil filter is of excellent quality when purchased with a
    blue can and the "Honda" logo on it, but an aftermarket FRAM has a
    questionable reputation.

    Honda thermostats are made by Nippon Thermostat (NTCL).

    AFAIK, NTCL is like Showa, in that they do OEM-only. No aftermarket.
    Tegger, Nov 6, 2009
  18. Gene Wagenbreth

    dgk Guest

    No, air goes up. You can't drain air from a system at the bottom.
    dgk, Nov 6, 2009
  19. Gene Wagenbreth

    dgk Guest

    I replaced the thermostat in my 91 Accord. It still gave me no heat. I
    replaced it again, no heat. I gave up and took it to Honda. They
    replaced the thermostat. I got heat. I learned my lesson.
    dgk, Nov 6, 2009
  20. Gene Wagenbreth

    Clete Guest

    You probably were putting it in upside down to begin with. OEM SchmoEM
    , a thermostat is a thermostat. Company A bids on a contract to supply
    Honda with them , Honda jacks price by 30% . You are buying the exact
    same aftermarket product 9 out of 10 times in most parts.
    Clete, Nov 6, 2009
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