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Old 06-25-2006, 10:01 AM
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74fj40 74fj40 is offline
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Join Date: Oct 2005
Location: Castle Rock, CO
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Couple of questions -
-about heater hose routing - does it matter which way the coolant flows through the heater core?
-how does the fan clutch work? I know that the clutch is filled with silicone and that when a certain temp is reached the little thermostat at the front forces the silicone, and tightens the fan onto the metal rod it's mounted on - but, the fan always seems to turn, regardless of the temperature - does it just go faster when it engages?
-what to do about a broken heat riser and missing flap?

Originally Posted by treerootCO
  • missing o-ring on top of the thermostat 2Fs have them, not sure about F
    o-ring is there
  • too much antifreeze
  • too lean
    possible, but don't think so
  • too rich
    possible, but don't think so
  • too far advanced
    possible, but don't think so
  • too far retarded
    possible, but don't think so
  • thermostat not opening or opening too soon
    I tested it yesterday in a pan of boiling water with a thermometer - it's fine
  • cavitation
    not sure how to test for this
  • blown headgasket
    brand new oem installed correctly yesterday
  • wrong headgasket
    possible, but don't think so
  • timing is 180 off
    possible, but don't think so
  • oiling problem
    possible, but don't think so
  • bad sender or wrong sender
    brand new with new temp guage same issue with mechanical temp guage sender, which was also new
  • no fan shroud
    fan shroud installed
  • kinked hose
  • scale/blockage
    brand new radiator, head cleaned by machine shop, block inspected and cleaned
  • defective water pump
    brand new, older pump had same issues
  • loose fan belt
  • wrong or defective cam
    correct cam, possible that it's defective, but don't think so
  • miss adjusted valves
    valves adjusted by mechanic when preparing for emissions test
  • vacuum leaks
    possible, but don't think so
  • bad brake booster
    possible, but don't think so - new updated booster from a 4 runner, no leaks
  • choke not opening
    possible, but don't think so - carb inspected by mechanic
  • blocked radiator internal or external
    possible, but don't think so - new radiator
  • any kind of friction internally
  • heater hoses routed incorrectly
    see question at top
  • too much compression
    possible - will check
  • low oil level
  • cracked block/head
  • fan not close enough to radiator some years had spacers
    fan is about 3/4" from radiator
  • lead foot
    yep - but, heats up before we actually drive it
  • assembly lube in oil
    we've changed oil 5 times since rebuild
  • miss adjusted float level
    adjusted by mechanic
  • defective fan clutch
  • defective radiator cap
    new and overheating happenned with older cap too
  • restricted exhaust including that little flapper that usually is broken
    possible - heat riser is broken - flap missing
  • cracked intake manifold
    not yet
  • warped intake/exhaust manifolds or bad gasket
    new gasket, don't believe there are any leaks

2005 Silverado 2500hd Duramax
1972 Toyota FJ40
1967 Porsche 912(100% stock)

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