2008 bobcat 463 overheating

Discussion in 'Mechanic and Repair' started by woodlanda, Jan 22, 2013.

  1. woodlanda

    woodlanda LawnSite Member
    from Canada
    Posts: 7

    Bought a used 2008 bobcat 463 with 940 hours,
    it has a Diesel kubota engine
    -previous owner had replaced the radiator

    its my first bobcat so not to sure whats going on

    -used it three separate times for about 2 hours each time in temps ranging from -10 to -15 C weather , no issues

    i went to use it again, had it running for about 30 minutes clearing snow and noticed the temp gauge was in the orange, (outside temp -12 c) immediately went to park it off the street and i throttled it down gauge instantly jumped to low green again... when i rev ed it up to move it to the garage the gauge jumped instantly again to orange.

    -checked the coolant levels and they are full, checked the air filters, they seem pretty clean,the radiator is clean and no debris, oil level is good, fans are working, can feel the air flow going through the rad

    the next day my dad and i started it up, just idling and within about 5 minutes the gauge went up and was reading orange and remained orange, we had an infrared thermometer to check the temp of the coolant hoses and cylinder heads, the temperatures seemed to be running at around 180 f, we disconnected the fans to see make sure they were, the engine temp would rise a bit and when we reconnected them the temp would go down based on the infrared thermometer, the gauge in the cab is however reading orange/ overheating, Not sure what is causing the problem, or if it is actually overheating

    we checked for air in the coolant and no bubbles coming up in the funnel

    had the machine idling and ran at full throttle for close to 20 minutes and the infrared thermometer temps remained around 180 f
    when we went from full throttle to idle the temp cab gauge didn't go down

    the outside air temp was -10 c

    Ive been reading online and not sure if it has a cracked cylinder head, bad thermostat, bad sender or gauge, water pump?

    anyone know of or have had experience with similar problems and know how to fix or troubleshoot the problem or to determine if in it is actually overheating or just a gauge issue or
    WORSE CASE scenario: what are the symptoms for a cracked cylinder head without pulling the engine apart? I hope it isn't!!

    any help suggestions would be appreciated
  2. Landrus2

    Landrus2 LawnSite Platinum Member
    Posts: 4,812

    Replace radiator cap :waving:
  3. teckjohn

    teckjohn LawnSite Senior Member
    Posts: 258

    If its hot and the jumps to green sounds like it was stuck and then opened.
  4. woodlanda

    woodlanda LawnSite Member
    from Canada
    Posts: 7

    Fixed temp gauge problem

    Changed the radiator cap to a 13 psi originally had a 15 psi cap, changed the thermostat as well as the sensor for the temp gauge, seems to have fixed the problem

    - I replaced coolant and noticing a steady stream of bubbles coming into the overflow container from radiator, not sure if it is air in system

    I'm going to run the the machine and keep an eye on coolant levels
  5. teckjohn

    teckjohn LawnSite Senior Member
    Posts: 258

    Cool Glad ya got it. why did you change to a lower pressure cap?
  6. piston slapper

    piston slapper LawnSite Platinum Member
    Posts: 4,245

    By changing the thermostat...sender..and a lower pressure cap...at the same time...it is impossible to nail down the exact cause or causes of your temp issues...however...it looks like you made the right call...
    The lower pressure cap will allow the coolant to be diverted to the reservior at a lower temperarure...lowering engine temps..
  7. ecurbthims

    ecurbthims LawnSite Senior Member
    Posts: 468

    I think the only thing wrong was the temp sender ,as there is nothing overheating at 180 degrees ,if anything thats running on the cold side .
  8. Landrus2

    Landrus2 LawnSite Platinum Member
    Posts: 4,812

    Originally Posted by TheKirbyMan
    What would happen if you ran a cap with too low of a rating?
    A 50/50 mixture of antifreeze and water boils at 227 deg F at atmospheric pressure. As you increase the pressure, you increase the boiling point. The pressure vs boiling point looks like this:

    0 psi 227 F
    4 psi 236 F
    8 pis 248 F
    12 psi 259 F
    16 psi 267 F

    So, if you run a lower pressure cap, you coolant will boil at a lower temperature. About the only time you would notice this is when your engine overheated for some reason, or when you shut the engine off and the coolant in the engine block heated up.

    I have always run 7 psi caps on most of my cars, including cars with 205 degree thermostats. But, I am willing to live with the possible consequences. For example, if for some reason my engine overheats, it is going to blow off coolant. I keep several gallons of water/antifreeze in my car at all times. I also make sure my overflow line to the overflow tank is in good condition and is not leaking. When I shut the engine off on a really hot day, sometimes some coolant will belch into the overflow tank. When the engine cools, it draws it back into the radiator again. It will only do this if the entire cooling system, including the overflow hose, is well sealed.

    The strain on hoses and water pump seals is a lot lower at 7 psi. Since switching to 7 psi caps (20 years ago) I have never had a hose blow out on me or a water pump shaft seal leak.

    If you run a lower pressure cap, be prepared for the occasional emergency.:waving:
  9. piston slapper

    piston slapper LawnSite Platinum Member
    Posts: 4,245

    Thank you...TheKirbyMan........ for some really good info on radiator caps..
    You can never get too much good information..
  10. Landrus2

    Landrus2 LawnSite Platinum Member
    Posts: 4,812

    Yes we all can learn from him:waving:

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