Crazy Temporary Solution?...Changing Thermo Coupler | FerrariChat
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Crazy Temporary Solution?...Changing Thermo Coupler

Discussion in '348/355' started by MRONY, Sep 4, 2009.

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  1. MRONY

    MRONY Formula Junior

    Mar 17, 2007
    707
    New York City
    Full Name:
    Mike O.
    #1 MRONY, Sep 4, 2009
    Last edited: Sep 4, 2009
    Since my DS fan ('97 355) stopped cycling properly, causing overheating, I finally tried bridging the connector, and the fan came on and stayed on, as it should. Does that conclusively prove it's a bad thermocoupler (the brass piece at the top of the radiator)? If so, anyone know the best place to buy a reliable replacement and the procedure for replacing it? If not, what else should Ilook at (the tank bleeder hose was not replaced during the major, so I'll need to do that JIC.)

    In the meantime, any reason I couldn't wire in a switch and put it in the cabin so I can switch the fan on and off while driving to cool the radiator when necessary? Seems pretty simple and practical a solution until I get the new piece and can install it. I might run the fan a lot, but that's better than blowing a head gasket or such. And I want to drive my car!!

    Also: Any convienient holes in the heat shield to run the wire without drilling? If not, I can just run it out the bonnet cover and duct tape it to the side of the car and paint it all Swatter's blue to match :) (JK)
     
  2. PAP 348

    PAP 348 Ten Time F1 World Champ
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    #2 PAP 348, Sep 4, 2009
    Thats what I would do! :D:D

    Start the car and turn it on straight away. Cant go wrong that way. ;);)

    Im sure you wont forget to turn it off after you shut the engine down, as I am sure you will be able to hear the fan still going! :p:p
     
  3. No Doubt

    No Doubt Seven Time F1 World Champ

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    Mr. Sideways
    #3 No Doubt, Sep 4, 2009
    Last edited: Sep 4, 2009
    No, it's not a conclusive test, per se. Air bubbles in your coolant, for instance, will prevent a good thermosensor from giving a fan-on signal. You could replace that part 1,000 times and still not turn your fans on if your coolant isn't being bled.

    A bad waterpump that isn't circulating coolant (e.g. broken/loose belt so the pump isn't turning) will also cause a thermosensor to not turn on properly.

    Ditto for bad electrical connections/wiring.

    What your test proves is that your *fan* is good.
     
  4. MRONY

    MRONY Formula Junior

    Mar 17, 2007
    707
    New York City
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    Mike O.
    #4 MRONY, Sep 4, 2009
    The fan is running, but car still overheats. Maybe I boiled off coolant, so will refill with antifreeze and water and see if that helps. Maybe the pump belt was not properly tensioned or the bolts tightened at the major, and it slipped loose? What a pain in the ass.

    BTW, where exactly are the bleeder hoses??? Learning as I go.

    Damn, I did such a nice job wiring in the switch, too
     
  5. mwhitesell

    mwhitesell Formula 3

    Sep 17, 2006
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    #5 mwhitesell, Sep 4, 2009
    It's not that hard to replace that switch. Just unscrew it and watch coolant go everywhere. replace and refill. Or some people will say to drain the coolant first, which will work as well. I have large pans under my lift that can catch stuff, so I usually pick the easy route.

    Also Ricambiamerica.com will have those. Cheap and fast delivery.
     
  6. mwhitesell

    mwhitesell Formula 3

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    #6 mwhitesell, Sep 4, 2009
    Onto the next step. The hoses go from the back of the overflow tank. If you take the cover off from around the coolant tank. 6 or 8 bolts on top. You should see the two thin lines connected to the back. These are the ones. Pull one off, take it to Autozone or wherever and get 3 feet of new hose just like it for a dollar and cut them to fit. Oh, this will be another coolant splashdown if you haven't drained it first. Also note that right by the thermostat is the brass bleeder screw, which you may want to use after you replace and refill. Even though this is a self bleeding system, I always like the feeling like I'm doing something by giving that a few turns until all the air comes out.
     
  7. No Doubt

    No Doubt Seven Time F1 World Champ

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    #7 No Doubt, Sep 4, 2009
    I might suggest taking her back in to a shop to verify that you have a functioning waterpump, as your car shouldn't overheat with working fans.




    *Hitting or exceeding redline water temperature can warp your aluminum heads, which are pricey to machine back, and which generally causes head gasket failure, which is not cheap.
     
  8. mwhitesell

    mwhitesell Formula 3

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    #8 mwhitesell, Sep 4, 2009
    Also if the heat works in the car, then your water pump is probably working. Turn the heat on to do all these things so when you refill it goes there too.
     
  9. No Doubt

    No Doubt Seven Time F1 World Champ

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    #9 No Doubt, Sep 4, 2009
    His heater has its own separate electric waterpump.
     
  10. mwhitesell

    mwhitesell Formula 3

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    #10 mwhitesell, Sep 4, 2009
    Yes, but I didn't think it would blow hot air without the engine waterpump going.
     
  11. No Doubt

    No Doubt Seven Time F1 World Champ

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    #11 No Doubt, Sep 4, 2009
    It will. It circulates something crazy (maybe 8 gallons per minute).
     
  12. mwhitesell

    mwhitesell Formula 3

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    #12 mwhitesell, Sep 4, 2009
    wow, and I've never thought my heat was that great. Or air con, its kind of weak too.

    I still think this issue will get fixed by the switch, sensor and bleed lines. That should be a service at the dealer to just replace all of those and the two fuses. This would eliminate 95%+ of overheating conditions in under an hour for less than 50 bucks. Well 400 with the FNA markup. :)
     
  13. No Doubt

    No Doubt Seven Time F1 World Champ

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    #13 No Doubt, Sep 4, 2009
    You are probably correct, but the OP reports that his 355 is still overheating even with the fan hardwired on, so he should get the waterpump checked out to err on the safe side.

    Might save him a bundle.
     
  14. PAP 348

    PAP 348 Ten Time F1 World Champ
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    #14 PAP 348, Sep 4, 2009
    Last edited by a moderator: Sep 7, 2017
    Sounds like you have an airlock in the system. ;);)

    Pappy suggests you bleed the air out of the system. :):)

    Are the bleeder nipples in the same spot as they are on the 348? :):)

    If they are, they are on the coolant crossover pipe on the firewall. Circled in white my pic. :):)

    Start the car, let it get to operating temp then crack those bleed nipples to see if you can purge any air out of the system. :):)

    If there is NO air in there, then you may have bigger issues. :D:D
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  15. MRONY

    MRONY Formula Junior

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    #15 MRONY, Sep 4, 2009
    There don't seem to be bleeder nipples anywhere. There is a bleeder nut on the top of the thermostat housing, but no way to get to it within reason, if I even identified it properly!. I have decided to let the shop take the car back and sort it out for me. I'm dirty and done. If it's an air bubble, they didn't bleed it properly. If it's blocked bleeder hose(s) they should have changed them. Of course they'll probably tell me it was the interdimensional Dimagierri ion exchanger, not their fault, and present me with a $2,100 bill.

    I drove the car, and that confused me more than anything. Running at any kind of engine speed, the temp spiked. Off the gas to idle and it came back down while gliding. Fan on or off seemed to make no difference. AC on or off no difference. Radiator full up. After running, idling at a stop lowered it a bit. A friend and afficianado of old F-cars listened to me and said "Yes, that's normal. A Ferrari that tells you it's overheating. Generally I advise you to ignore anythingthe car tells you until something explodes and it will not run. In the long run, this is much cheaper and less frustrating. The bills come all at once and then you go back to ignoring everything until in a few years it happens again. If you stopped and tried to satisfy your wife or your mother or your daughter every time she complained, would you have any time left to enjoy your life? Let the shop worry about the big stuff, and you just go ahead and drive with a smile on your face."

    Probably is an air bubble. I don't have the flexibility to do this. $250-300 for the flatbed. See ya! Can't wait to hearthe explanation.
     

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