Overheating Problem Today - No Fans. Help | FerrariChat
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Overheating Problem Today - No Fans. Help

Discussion in '348/355' started by foxnick348, Jun 20, 2010.

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  1. foxnick348

    foxnick348 Karting

    Nov 22, 2007
    56
    Racine, Wisconsin
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    Nick Fox
    #1 foxnick348, Jun 20, 2010
    Guys,

    My 92 348TB started overheating today in traffic rising to 210-250. I had to pull over and let her cool down. I noticed that the fans weren't operating and the coolant was leaking out of the expansion drain tube. Too much pressure I assume.

    After, I slowly made my way home, I first check the coolant level as well as the fuses and relays. Everything Seems Fine.

    Could this be a bad thermostat, temp switch or bad waterpump?

    I'm hoping for a simpler fix as the car seems to run fine when cool.

    What should I check first?

    Thanks,

    Nick
     
  2. 2NA

    2NA F1 World Champ
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    #2 2NA, Jun 20, 2010
    Sounds like an electrical issue.

    Temperature switch perhaps. Try "jumpering" the switch (right-hand radiator) and see if the fans run.
     
  3. foxnick348

    foxnick348 Karting

    Nov 22, 2007
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    #3 foxnick348, Jun 20, 2010
    where do I jump the switch at? the switch itself or the fuse panel?
     
  4. 2NA

    2NA F1 World Champ
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    #4 2NA, Jun 20, 2010
    Last edited by a moderator: Sep 7, 2017
    Right at the switch. Part number 11.
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  5. eyboro

    eyboro Formula Junior
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    #5 eyboro, Jun 20, 2010
    Check fans fuses first
     
  6. foxnick348

    foxnick348 Karting

    Nov 22, 2007
    56
    Racine, Wisconsin
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    Nick Fox
    #6 foxnick348, Jun 20, 2010
    Fuses are Fine.

    I took the plug off the switch and jumped the switch wires, but nothing happens.

    Should the car be running or just ignition on?

    Nick
     
  7. repsolboy

    repsolboy Rookie

    Jun 5, 2008
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    #7 repsolboy, Jun 20, 2010
    Hi Nick,
    When you start it , you will hear the fans working. As far as i know one of the fan ( left or right) runs steadily and the other one kicks in when the thermostat hits a certain temp ... i had the same problem, they checked if the fans were working , but the problem for me was the fuse ...
     
  8. 2NA

    2NA F1 World Champ
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    #8 2NA, Jun 20, 2010
    Last edited by a moderator: Sep 7, 2017
    Key in the "run" position but the engine doesn't need to be running.

    Get yourself a test light and ground the alligator clip. Touch the tip to each of the wires (one should be "hot" and the other a path to ground). If the light glows on one of them the switch is bad. If it doesn't, it's fuse or wiring.
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  9. foxnick348

    foxnick348 Karting

    Nov 22, 2007
    56
    Racine, Wisconsin
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    Nick Fox
    #9 foxnick348, Jun 20, 2010
    I jumped the wires and nothing happens.

    Tested the wires with a volt meter and it appears to have some voltage though.

    Nick
     
  10. foxnick348

    foxnick348 Karting

    Nov 22, 2007
    56
    Racine, Wisconsin
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    Nick Fox
    #10 foxnick348, Jun 20, 2010
    Last edited: Jun 20, 2010
    Does this mean I should test the fans next for power?

    Jumping the wires to the thermoswitch with the ignition on has no effect.

    Neither fan turns on at 200+ degrees with it jumped.

    Fuses are ok. Relays have been swapped out.

    Also, are the fans suppose to turn on at the same time if they are working correctly?

    If it's the fans, how do I check them?

    Nick
     
  11. Miltonian

    Miltonian F1 Veteran

    Dec 11, 2002
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    #11 Miltonian, Jun 21, 2010
    If you study the wiring diagram a bit, you see that the left and right radiator fans are both triggered by grounding the thermoswitch on the right radiator when the coolant temperature reaches 86 degrees Celsius. The fan on the left radiator should come on once relay "i" is energized and sends power through fuse #13. The fan on the right radiator should come on once relay "m" is energized and sends power through fuse #17.

    The fact that the fuses and relays are "good" is insignificant if no power is flowing through them, or if the thermoswitch and the fans are not properly grounded.

    If I were working on this myself, I would check the following:

    1) Is there battery power at terminal 30 for relay i & m ?

    2) Is there switched power at terminal 85 for relay i & m ?

    3) Does the left fan come on when you run a jumper wire between terminal 30 and terminal 87 at relay i ? Does the right fan come on when you run a jumper wire between terminal 30 and terminal 87 at relay m ?


    If I were to make a guess at the source of your problem, my guess would be that you have a slow leak in the coolant system, and there is an air pocket preventing coolant circulation around the thermoswitch at the top of the right radiator, hence the switch isn't closing and the fans aren't engaging because the relays aren't being energized. It's a step by step procedure, we'll figure out your problem if you follow the steps and report back. I doubt if it's anything serious, but don't run the engine long until you figure out the reason why it's overheating.
     
  12. foxnick348

    foxnick348 Karting

    Nov 22, 2007
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    #12 foxnick348, Jun 21, 2010
    1. No batter power at terminal 30 for relay i & m

    2. No Switched power at terminal 85 for relay I & m

    3. Left and right fans don't come on when jumping terminal 30 and 87 on relay I & M

    As a test, I tried jumping the oil cooler fan relay terminal 30 and 87 and that turned right on, so I know I'm testing this correctly.

    Nick
     
  13. Miltonian

    Miltonian F1 Veteran

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    #13 Miltonian, Jun 21, 2010
    Last edited: Jun 21, 2010
    Really! Let me have another look at the diagram. Terminal 30 and terminal 85 draw their power from different sources, so I might expect one or the other to be dead, but not BOTH of them. That's strange. I'll be back.

    Edit: The power source for terminal 30 on relay "o" (the oil cooler fan relay) is exactly the same as the power source for terminal 30 on relays "i" and "m". I don't see how you could have power at relay "o" but not at relay "i" and "m". Can you run a jumper wire from terminal 30 on relay "0" to terminal 87 on relay "i" and see if that turns on the left radiator fan?

    I hope you don't have a problem with the printed circuit boards inside the fuse panel, but I don't know what else would cause this...
     
  14. foxnick348

    foxnick348 Karting

    Nov 22, 2007
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    #14 foxnick348, Jun 21, 2010
    Last edited: Jun 21, 2010
    Ok. both terminal 87 on i and m relays have power. I used a test light to re-check this time.

    Jumping terminal 30 on relay o to terminal 87 on relay i turns on the oil cooler fan.

    Nick
     
  15. foxnick348

    foxnick348 Karting

    Nov 22, 2007
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    #15 foxnick348, Jun 21, 2010
    Ok. so I went through the entire testing process again and started with jumping the wire on the Thermoswitch to make sure I didn't screw something up. I tried a better jump wire with a thick guage wire and that did the trick. The fan turned right on.

    Sooo, does this now mean that the Thermoswitch is bad? or should I try Bleeding the system and see if I had an air pocket in the Radiator.

    Other issue is I still can't get the secondary fan to turn on. Do I need to jump the temp sensor on the engine block to get this one to turn on?

    Thanks for all the help.

    Nick
     
  16. Miltonian

    Miltonian F1 Veteran

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    #16 Miltonian, Jun 21, 2010
    Last edited by a moderator: Sep 7, 2017
    I'm sorry, Nick, I didn't see that Ferrari had changed the circuitry between terminal 30 and terminal 87 between the diagrams and the board itself. Terminal 87 (the bottom one) is battery power to the relays, terminal 30 (the top one) is the feed to the fan. Therefore, if you jump between 30 and 87 on relay "m" (as shown in the attached picture), that should cause the right radiator fan to come on, whether the ignition is on or not, and whether the thermoswitch is hot or not. The jumper runs battery power straight to the fan. The same should be true with relay "i" and the left fan. If the fan does NOT come on when the terminals are jumped, then either the fan is dead, or there is an opening in the circuit, or the fan isn't grounded.

    If the fan DOES come on when you jump 30 to 87, then you need to check and see if you have ignition switch power at terminal 85.

    Sorry for the confusion, I shouldn't have trusted the diagram. The function doesn't change, just the numbering.

    Edit: You posted while I was typing.
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  17. foxnick348

    foxnick348 Karting

    Nov 22, 2007
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    #17 foxnick348, Jun 21, 2010
    I put everthing back together and removed the jumper from the thermoswitch. I jumped terminal 30 and 87 at Relay "M" and the right side Fan turned right on. I then jumped the 30 and 87 terminal at Relay "I", but the fan wouldn't turn on.

    How do I check to see if I have ignition switch power at terminal 85?

    Nick
     
  18. ricardo teixeira

    ricardo teixeira Formula Junior

    Sep 2, 2009
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    #18 ricardo teixeira, Jun 22, 2010
    Sometimes the thermo switch is fine, but there is air build-up on the cooling circuit. It only takes a few minutes to bleed....
     
  19. foxnick348

    foxnick348 Karting

    Nov 22, 2007
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    #19 foxnick348, Jun 22, 2010
    Ok. so after testing everything on the system and everything checking out ok. I decided to bleed the system using the two bleeder valves.

    The lower valve bled coolant right away. The top bleeder valve took a few minutes to allow coolant to flow out. I had to turn on the heater full blast and run the car for a few minutes. Finally some air blew out and then bubbles and then a nice steady stream of coolant.

    Within in seconds of it hitting 195 degrees the right side cooling fan turned on.

    So, problem solved. The car had an air pocket probably in the right side radiator which prevented the thermoswitch from working correctly.

    Back on the road again.

    Thanks All!!!!

    Nick
     
  20. 2NA

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    #20 2NA, Jun 22, 2010
    Rock & Roll!
     
  21. Miltonian

    Miltonian F1 Veteran

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    #21 Miltonian, Jun 22, 2010
    There is only one thermoswitch for coolant temperature, and it should turn on the fans in both radiators at the same time. I verified this on my own 348 earlier today, and it's definitely the way the wiring diagrams show it to work. If you're only getting one fan to run, something still isn't right.
     
  22. ricardo teixeira

    ricardo teixeira Formula Junior

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    #22 ricardo teixeira, Jun 23, 2010
    After so many and helpfull advices from the brotherhood, it feels nice to be able to help once in a while.... ;) Glad to be of help....
     
  23. foxnick348

    foxnick348 Karting

    Nov 22, 2007
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    #23 foxnick348, Jun 23, 2010
    You are correct. The owners book says the following:

    "The right hand radiator includes in the top a thermal contact. This automatically switches on the electric fans when the coolant temperature reaches 185 degress and switches them off when this falls to 169 degrees".

    Clearly says "Fans" as in both right and left fans at the same time.

    So, I guess I need to take off the left hand wheel and cover and test the Left Side Radiator fan to make sure it's not blown out.

    When I jumped the thermoswitch only the right hand fan came on, so something still isn't right here.

    Nick
     
  24. foxnick348

    foxnick348 Karting

    Nov 22, 2007
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    Nick Fox
    #24 foxnick348, Jun 23, 2010
    Ok. so I took off the left side wheel and wheel well cover to expose the left hand radiator and fan. The first thing i noticed was that the connection on the fan to the power supply was all rotten and corroded. I used eletrical cleaner and sand paper to clean the connections and get all the black corrosion off. Then sealed up the connection with rubber shrink product, then wrapped it with electrical tape to seal the connection tight.

    I jumped the thermoswitch and now both fans turn on immediately.

    So, this overheating problem was a combination of an air pocket in the right side radiator causing the thermoswitch and right side radiator not to work and a bad connection on the left side fan causing the left side fan not to work.

    Now, I'm officially back on the road this morning.

    Thanks for everyones help and encouragement to tackle this on my own. I'm sure the dealer would have raped me on the troubleshooting.

    Nick
     
  25. Miltonian

    Miltonian F1 Veteran

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    #25 Miltonian, Jun 23, 2010
    "Fan"-tastic to hear that you fixed it!

    Now keep an eye on that coolant level, in case you have a drip somewhere and you get another air pocket.
     

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