Intermittent overheat only at Idle?

Discussion in 'Hino Trucks' started by likemlow, Aug 8, 2017.

  1. likemlow

    likemlow New Recruit Mechanic

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    Hi all! We have a 2012 Hino 258 flatbed tow truck and the driver is reporting Intermittent overheating at idle. It occurs only when he idles for 20 mins or so then it will start creeping up. At the beginning of summer we brought in all the trucks and blew out the radiators/intercoolers etc. We double checked the radiator and it was clean on the front and full of coolant. The fan clutch felt somewhat loose so we replaced it. (with Hino Brand) Two shifts later he said it did it again and coolant boiled over. Even though, in the meantime he idled it often with the A/C on for 20 to 60 mins. between calls. We brought it in, checked everything we could think of, idled it for 2 hours and nothing. He's back on the road now two days later and it hasn't happened again...yet. Any Ideas?? Thanks!
     
  2. FlyingVan
    Barefooter

    FlyingVan Moderator Staff Member Owner/Operator

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    This one is easy. Don't idle. Lol.

    Joking aside, I'm sure one of our hino experts will chime in with something useful.

    Sent from my VS995 using Tapatalk
     
  3. greasytshirt
    Dr Pepper Addict

    greasytshirt Moderator Staff Member Mechanic

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    All of that idling is going to eventually wreck the DPF.

    With that aside, I suppose I'd start looking at the usual suspects, just to rule them out. That includes doing a cooling system combustion gas test. Gas pockets in the cooling system can disrupt coolant flow.

    Sent from my XT1585 using EO Forums mobile app
     
  4. likemlow

    likemlow New Recruit Mechanic

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    Thanks for the replies. I'll tell them not to Idle too long. Seems anything can wreck the DPF on these trucks. Is the Block Tester Fluid Test the best to perform?
     
  5. greasytshirt
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    greasytshirt Moderator Staff Member Mechanic

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    This should work. You want one with the squeeze bulb on top. Amazon.com: UVIEW 560000 Combustion Leak Tester: Automotive

    The burner systems on 11-14 Hinos are a little sensitive. In 2015 they changed the DPF heating system and reliability went way up. The burner trucks can be reliable but they need regular maintenance.
     
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  6. Hino123

    Hino123 Rookie Expediter Mechanic

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    I have seen multiple fan clutch failures as of late. I replaced 3 on 1 truck and 2 on a handful of others. I would check the fan blades for any viscous fluid, also spin it by hand and be sure it has some resistance. Most of the fan clutch failures i see the fan will freehweel when spun, truck will over heat at idle and p0217 overheat code sets.
    I might also mention that if idling for extended amount of time the ac gets weak down here in Florida. High side head pressures will hit near 400psi. I have been telling most of the rollback guys to turn the high idle on (980rpm) This will pull more air across the condensor and lower the head pressure of the compressor.
    As greasytshirt stated, excessive idle time will increase the PM piling, which in-turn will increase the amount of re-gens that need to be pferformed. If you properly maintain your burner this should not be an issue.
     
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