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Thread: Engine temperature

  1. #51
    Join Date
    Apr 2019
    Location
    Arlington
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    752

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    Sorry it took so long for an update. After I had the fan clutch replaced by Prevost, we took a trip to Kerrville and it was still running hot with the dash AC on. After limping into Kerrville, I found that the belt tensioning system was only at 20 psi. I had asked Prevost to double check that but I guess they forgot. I adjusted the regulator up to 50 psi hoping that would solve the problem. I was assuming that with only the fan, 20 psi was adequate but with the added load of the dash AC compressor it was allowing the belts to slip.

    Leaving Kerrville, it was running hot even without the AC on. We stopped in Fredericksburg and checked the air pressure ... still 50 psi and noted that the fan was just idling. So locked the fan in place with the new style tabs. With the fan locked in, she never ran over 195 even with the AC on. You could watch the water jacket thermostat work between 180 something and 195.

    Back home a little trouble shooting pointed to a failure of the main fan relay #99.

    So, now with a new fan clutch, proper air pressure and some new relays, things appear to be running fine. I am in now in the camp of it runs cooler with the dash AC on. With the AC on and the fan in high, the temperature appears to be primarily controlled by the thermostat and never goes over 195. Without the AC, the temperature appears to be primarily controlled by the fan and you can see it go over 195, the high speed fan kick in and then back down to 195 when the fan goes back to low speed.

    I will send a second post with pictures of the disassembly of the locked up fan clutch and my thoughts on failure.


    Mark and Debbie Fratto
    1998 Parliament

  2. #52
    Join Date
    Apr 2019
    Location
    Arlington
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    752

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    Here are pictures of the locked up fan clutch. As you can see it had multiple problems. The bolts securing the heat sink to the flange were driven into the outer rotating assembly locking them together, the locating pins were all sheared off and the bearing for the inner rotating assembly was fried. Definitely glad that I replaced the clutch. I am thinking that it was all caused by the heat sink to flange bolt issue. This put the rotating assemblies in compression and then it was one failure after another.

    1) Fan clutch assembly prior to disassembly
    2) Fan clutch assembly prior to disassembly
    3 and 3A) Heat sink flange which is pinned to the inner silver rotating assembly. Note that all of the pins are broken!
    5) Note that the bolts that held the heat sink to the flange were driven into the outer rotating assembly effectively locking these two pieces together!
    6) Outer rotating assembly removed exposing the inner rotating assembly. Note the broken pins that should tie this to the heat sink flange.
    7) This is the spacer that goes over the shaft but inside of the inner rotating assembly. Note the extreme heat damage on the bottom which was in contact with the failed bearing in the bottom of the inner rotating assembly.
    8) Inner rotating assembly removed.
    9) Inner rotating assembly with its base removed.
    10) View of the failed bearing in the bottom of the inner rotating assembly.
    12) Spacer removed. Note the bevel which should face down towards the rotating base.
    14) Rotating base removed. This is keyed to the shaft.
    15) Note the degradation of the material holding the windings and note the exposed windings.
    Attached Images Attached Images


    Mark and Debbie Fratto
    1998 Parliament

  3. #53
    Join Date
    May 2012
    Location
    Beverly Hills
    Posts
    4,652

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    Thanks for the follow up. Make sure you replace the speed control relays as well as R99.


    Gil and Durlene
    2003 H-3 Hoffman Conversion

  4. #54
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    Apr 2019
    Location
    Arlington
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    I turned on the AC to prove that the high speed worked. I did not want to wait around for it to warm up for the low speed so I did replace that relay at the same time just to be safe. I bought extra relays just in case the high speed relay fails. After your note, I may just replace it anyway and keep the one in there as spare.

    Thanks for all of the back ground knowledge you guys provided. It sure helped in the trouble shooting process.


    Mark and Debbie Fratto
    1998 Parliament

  5. #55
    Join Date
    May 2012
    Location
    Beverly Hills
    Posts
    4,652

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    Take the good relay you removed and break the tabs off that energize the coil. That relay will engage the clutch to the speed you inserted the relay in, High or Low. This works if R99 and the clutch are good. This relay that can't energize is good for troubleshooting. FWIW, the DDEC energizes the relay to turn off the associated fan speed.


    Gil and Durlene
    2003 H-3 Hoffman Conversion

  6. #56
    Join Date
    Apr 2019
    Location
    Arlington
    Posts
    752

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    Great idea thanks Gil


    Mark and Debbie Fratto
    1998 Parliament

  7. #57
    Join Date
    Apr 2019
    Location
    Arlington
    Posts
    752

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    Trip before last, the high speed relay failed but it was older so thought nothing of it. This last trip, the low speed relay failed and it was new :-(
    Has anyone had multiple relay failures?

    Good news is that I am getting Indy 500 fast at locking in the fan ha!


    Mark and Debbie Fratto
    1998 Parliament

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