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[SOLVED] HA4 Overheating (I'm losing my cool!)

Discussion in 'Honda Acty' started by DAN CANAAN, Jul 12, 2021.

  1. DAN CANAAN

    DAN CANAAN New Member

    (*SOLVED*)

    Well, times have changed and something has gone awry.

    I had been hitting the suspension bumps hard with weak springs, even a few times to knock things loose. Everything was running fine, but I hit a couple of railroad tracks hard and then within two miles once I got on the freeway the Honda HA4 (1994) was overheating and I was on the side of the road. It had been running at midrange forever without ever any problems, but suddenly now I'm on the side of the road. Found the recovery bottle top had come off and was spraying coolant around actively. Bah! Did it pop off an lose all that coolant?

    Topped it off with more when a friend came to my rescue. Within a mile it was redlining again. Pulled over, checked- fluid in the recovery tank at least. I assume air in the system at that point. Burped it with the lower hoses at the engine best I could do without tools. Got home.

    I've gone through the bleeding process with the two bleeders on the cooling lines near the spare tire and the two bleeders on the top of the engine. Got coolant through all that. There was some air in the smaller line from engine to radiator.

    Took off on a test drive, was good, but about 10 minutes in, started creeping up. I could turn the heater and watch the needle drop back down a bit. Rev the engine while not under load and it also cooled off some. There's so little actual coolant in these systems, it is very sensitive to changes.

    I plan to drain everything, radiator and engine, redo it, purge, etc. Trying to find the event that cause such a sudden change in behavior.

    NOTE: I don't hear the radiator fan. I only really noticed it when the truck shut off and the fan was still going. I want to check to see if there is any chance that is not running now or got disconnected.

    2ND NOTE: Even after running, the cooling lines near the spare tire- one is hot and the other is barely above air temperature. I'm not sure if that means I have a blockage in the radiator or not. No valves that I know of that would interfere in that system?
     
    Last edited: Jul 25, 2021
  2. DAN CANAAN

    DAN CANAAN New Member

    RESOLVED

    Joey kept losing his cool. Temps at normal until you started going on the freeway or up a steep hill. Temps climbed quickly, and hit the top if you didn't back off. There is very little coolant volume in the system at less than 1.5 gallons, so it doesn't take much to heat soak.

    Bled the system multiple times. No luck.

    Check cooling fan- it didn't turn on even when engine was overheating, but a test of the fan switch showed it was working.

    Checked hose at the engine thermostat housing. Small line going to radiator was hot- very hot. Return line was air temperature. Hmm, that suggests no coolant flow.

    Pulled the thermostat to check it, boil it to test and then I saw this:

    [​IMG]

    AHAH! I have spent decades working on vehicles, even five years selling parts and machine shop service at NAPA and I have never seen a physical failure like this one. No wonder no flow was happening.

    Swapped it out with another from the shop (#3758) and installed it. Got it put back together, bled the system, topped off coolant and took Joey for a test drive.

    No.problems, even at 72 mph on the freeway. Tried hard acceleration, long traffic lights, all the things that should stress it and Joey did great, temp sitting rock solid at mid range like he normally does.

    $6.00 part. Sometimes the simplest items can cause the most grief.
     

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