Please help solve overheating issues on 98 550 | FerrariChat

Please help solve overheating issues on 98 550

Discussion in '456/550/575' started by robert_fulton, Feb 25, 2019.

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  1. robert_fulton

    robert_fulton Rookie

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    #1 robert_fulton, Feb 25, 2019
    I've had some engine cooling problems since buying the car about 4 years ago... the radiator fans turn on only when the coolant temp reaches well over 200F, then the temp falls to about 190. I figured that the cause was the left water manifold temp sensor (NTC) is out-of-comission, and the right sensor to the Motronic is acting as back-up.
    Recently, the fan has intermittently failed to kick-in and I have had to shut-down the engine to let it cool, so I believe the right-bank NTC is now malfunctioning. (I have checked the fuses and relays are working.)
    Is there a way to test the NTCs without removing the plenum(s)?
    Thanks in advance for your advice.
    robert
     
  2. asgor

    asgor Formula Junior

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    #2 asgor, Feb 25, 2019
    When one of the coolant sensors under the manifold in my 97 456GT went south it left a code that I picked up via OBDII as well as a triggered the Check Engine light.
     
  3. wbklink

    wbklink F1 Rookie
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    #3 wbklink, Feb 27, 2019
  4. robert_fulton

    robert_fulton Rookie

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    #4 robert_fulton, Mar 19, 2019
    Thanks for your recommendation...
    To validate the coolant/radiator/fan/water-pump, I pulled the relays, crimped spade connectors on some wire and shorted the relays to keep the fans running all the time.
    I did this on a rainy day and ran the car in the garage with the fans running and observed no overheating. A couple days ago I took the car out with the fans running all the time, In all conditions, high-speed, lowspeed, lowspeed uphill, stopped in traffic, the temp never reached 190deg F. Apparently, the temp was under control of the thermostat (175deg).
    So I believe the source of my problems is two failed NTC sensors. Still wish I could test them w/o removing the intake plenum. Any suggestions?
     
  5. F456M

    F456M F1 Rookie

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    #5 F456M, Mar 20, 2019
    Just replace the sensors! How high outside temps are you running in?
     
  6. scowman

    scowman F1 Rookie

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    #6 scowman, Mar 20, 2019
    On my 456 the sensor that controls the radiator fan is in the bottom of the radiator. Not on the 550?
     
  7. F456M

    F456M F1 Rookie

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    #7 F456M, Mar 22, 2019
    Thats right. You need to take the intake plenum off to replace the sensors.... Are you sure the sensor is not just for the level?

    Erik :)

     
  8. scowman

    scowman F1 Rookie

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    #8 scowman, Mar 22, 2019
  9. Cribbj

    Cribbj Formula 3

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    #9 Cribbj, Mar 22, 2019
    Ken, on the 550 we have 3 coolant temperature sensors. One each on the Left & Right coolant manifolds or collectors, and one at the casting that joins the L&R collectors.

    The two on the collectors control the fans via the Motronic ECU's, while the third is directly connected to the coolant temperature gauge.

    Edit: The two on the collectors are simple NTC thermistors, and they're relatively cheap. The third one is also an NTC thermistor, but it also incorporates a switch for a lamp built into the gauge, and it costs quite a bit more than the other two.
     
    F456M likes this.
  10. robert_fulton

    robert_fulton Rookie

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    #10 robert_fulton, Mar 22, 2019
    Just to be persnickety... only one of the collector sensors goes to a Motronic, the other goes to the Air Temp Control ECU which is responsible for tuning on the fans under normal conditions. The Motronic will turn on the fans if it senses a temperature somewhat above the temp at which the ATC should turn them on.
    I was made aware of this when my OBDII reader reported a temperature of -40deg on one of the Motronics, and I had to go back and read the manual carefully.
    So, I think my situation is: one sensor (the one going to the ATC ECU) is either bad or disconnected and the other (going to the Motronic) is bad, because it reads a temp lower than the temp-guage on the dash and allows the car to overheat. If only our fiends at the factory had made these easier to access. I am considering wiring a switch to the relays to keep the fans on constantly wile the engine is running, and having the NTCs replaced at the next major, which wight be this year if I can get some driving in soon.
     
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  11. AVIMAX

    AVIMAX Formula Junior

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    #11 AVIMAX, Mar 22, 2019
    While it's not one of my favourite things to do, it's really not that big a deal to remove the intake manifold and change out the sensors. I've done it a couple of times. You need new intake manifold gaskets, new nylock nuts for the manifold, 2 new sensors and an afternoon.
     
  12. F456M

    F456M F1 Rookie

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    #12 F456M, Mar 22, 2019
    Last edited: Mar 22, 2019
    I an going to make two manual switches for the fans anyway. It is a very cheap and good thing to do when the sensors go wrong. Then you can also make the fans come on earlier so the engine gets cooler coolant. I want to be able to run one fan continious to make the AC work better and to get a more stable power draw from the battery. And if one relay or fan stops, you can always switch on the other one... I am thinking of making a secret switch panel inside the ashtray. No need to smoke in a Ferrari... and move the Cig lighter so I don’t Need to have the ashtray open while charging the phone. It does not look good...
     
  13. 308 GTB

    308 GTB F1 World Champ
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    #13 308 GTB, Mar 22, 2019

    That's how my F355 is set up...


    Image Unavailable, Please Login



    The switches aren't hidden. But it is, after all, a Challenge car...


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    :)
     
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  14. scowman

    scowman F1 Rookie

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    #14 scowman, Mar 23, 2019
    Ok. Let’s see more pics of the challenge car.
     
  15. F456M

    F456M F1 Rookie

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    #15 F456M, Mar 23, 2019
    Cool. I assume they also work automatic with the original system?
     
  16. 308 GTB

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    #16 308 GTB, Mar 23, 2019
    Last edited: Mar 23, 2019
    Yes, Erik. The switches override the automatic original system. Challenge rules mandated that both fans be running while the car was on the track.

    If you have a North American version 550, you can use the spare switch on the console for this purpose.
     
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  17. 308 GTB

    308 GTB F1 World Champ
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    #17 308 GTB, Mar 23, 2019
    Okay, Erik, I see you have a Euro 550. You'll have to hide your switch(es) as you described.
     
  18. robert_fulton

    robert_fulton Rookie

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    #18 robert_fulton, Apr 17, 2019
    AVIMAX,
    Thanks for the encouragement...
    Based on AVIMAX's "recommendation/challenge" last weekend I removed the Plenum(s) and swapped the NTC's. (AVIMAX did not mention that a good friend is almost required to lift the plenum(s) out of the car)
    One issue I ran into was the brake booster vacuum hoses (15/32 in) that run from each side to the booster. they were impossible to remove from the plenum, having hardened over the "keeper bump" on the pipes, so I cut them and must replace with new hose. Here's the question... can I use standard hose (Continental offers the same grade (SAE J1403) and size) or will I run into problems routing it, It seems the hoses I cut (at least the long one) were rigid and formed to fit the path.
    Also, I have never seen such small/cute hose clams as used under the throttle bodies (I'll post some pics later).
    Looking forward to your advice...
    Robert
     
  19. Cribbj

    Cribbj Formula 3

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    #19 Cribbj, Apr 18, 2019
    It's generally a bad idea to use "normal" hose for any vacuum applications as normal hose is designed to withstand positive pressure, not negative, so it will want to collapse under vacuum.

    I would get the technical spec sheet for any hose you're considering and make sure it states in the spec that it's suitable for vacuum service.
     
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  20. robert_fulton

    robert_fulton Rookie

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    #20 robert_fulton, Apr 18, 2019
    Crbbj,
    That's exactly why I chose the same grade as marked on the existing hose... SAE J1403. The title of the specification is "Vacuum Brake Hose" and the summary states:"intended for use in the power braking systems of vehicles or as connections on vacuum lines of vehicles or systems thereof."
    My question is related to whether the factory part is "preformed" and whether bending unformed hose will cause interference with any moving parts behind the plenum.
    According to the spec, this hose is
     
  21. ferraridriver

    ferraridriver F1 Rookie

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    #21 ferraridriver, Apr 18, 2019
    I'm going to be taking my plenum off in the near future, would you be so kind as to give me the source of the Continental hose.

    Thanks,
     
  22. AVIMAX

    AVIMAX Formula Junior

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    #22 AVIMAX, Apr 18, 2019
    Robert, sorry that I forgot to suggest a helper! The hose you cut may not be preformed, but taken a shape after so many years.
     
  23. robert_fulton

    robert_fulton Rookie

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    #23 robert_fulton, Apr 19, 2019
  24. robert_fulton

    robert_fulton Rookie

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    #24 robert_fulton, Jun 30, 2019
    I found the same hose at O'Reilly, bought 6 feet and got everything together about a month ago and the temps are under control in all conditions now...
    Thanks to AVIMAX for the encouragement.
    Thanks to Ricambi for the manifold gaskets and nuts (as well as injector clips that I lost)
    Thanks to Mr Injector for cleaning/balancing the injectors.
    And thanks to Tom Poje, my good friend who donated a couple of weekends and risked back injury helping with the project.
    Does anyone know a source for GOOD connector boots? It seems that every boot under my hood is petrified.:)
     
  25. Eilig

    Eilig F1 Rookie
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    #25 Eilig, Jul 1, 2019

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