348 - No coolant temp / oil pipe leak | FerrariChat

348 No coolant temp / oil pipe leak

Discussion in '348/355' started by FSM348, Jul 28, 2019.

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  1. FSM348

    FSM348 Formula Junior

    Feb 13, 2017
    469
    Midwest
    Full Name:
    Dan Smith
    Finally got the 348 running after a light restoration. As part of the restoration I replaced all 4 coolant sensors, powder coated water manifold pieces and re-pinned the both left and right engine harnesses. It started right up with no issues (after filing down the ground contacts on the valve covers due to injectors not firing at first) and oil pressure, oil temp, RPMs all showed their respective info. Unfortunately the coolant temp isn’t reading even after warming the car up to the point that the fans kick on.

    There are the two water temp sensors with two pin connectors that send data to the ecu’s. Then there are two sensors (one a thermistor facing rear of vehicle and one is the thermometric in switch facing the firewall/water pump) and I’m curious if the sensor facing the water pump does indeed control the temp gauge on the gauge cluster? If so, what does the other sensor control?

    I originally thought that the thermistor facing the rear of the car had provided temp readings to the gauge but was lead to believe otherwise after a search in the forums


    Also, I can’t seam to get rid of a small oil leak on the short oil pipe connections that runs over the AC compressor between the block and the oil cooler. Any issues with this from others?
     
  2. Koenig1

    Koenig1 Formula Junior

    Aug 25, 2016
    328
    Ottawa ON
    Full Name:
    Sandy
    Have you checked your multi pin(9 pins/from memory) connection (just in front of left rear shock tower) to verify all is making contact? maybe use a wiring diagram to verify which pin is associated with your coolant gauge and test with a ground wire(just touch for a second). With ignition on, your guage should jump to max. Maybe use a good ground and touch the sender's outside socket head(ignition on/engine hot) and see if guage responds. Maybe your powder coat has coated the threads and not allowing the sender threads to ground? You didn't install the senders with Teflon tape??
    Oil leak, did you use new copper washer? I learnt something the other day... if you don't use proper copper washer(that will spread when crushed), but use a standard plumbing washer(copper) it will not crush properly. For those that use a regular copper washer, one must heat washer(red hot), then let it cool, and voila, copper will crush easily!!! Apparently an old wooden boat trick when using copper nails... the nail will act like a rivet(mushroom out), hammer 1 side, anvil on the other....
     
  3. Qavion

    Qavion F1 World Champ
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    Feb 20, 2015
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    Ian Riddell
    I would have thought so too. There are two sensors with the same part number, so you would assume these were for the ECUs. That only leaves the one facing the rear. The other device/s are switches.

    Can you you see the wire colour/s on the sensor facing the rear? The wiring schematics show a grey wire with (it seems) the body of the sensor acting as earth.

    The wires going to the ECU sensors are grey and grey with a black stripe. i.e. two wires per sensor. and only talk to the ECUs. According to the diagram, the ECUs do not send water temperature data to the gauge.

    https://www.ricambiamerica.com/car-diagrams/ferrari/v6-v8/348-group/348-1989-1992/water-pump.html

    Item 47 would be my guess for the gauge.
     
  4. Qavion

    Qavion F1 World Champ
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    Feb 20, 2015
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    Here's the wiring diagram.

    Instrument Wiring Diagram

    Look for the contact on the gauge marked "SIG" and follow the grey wire (colour code "H"). Good luck!
     
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  5. yelcab

    yelcab F1 World Champ
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    Nov 29, 2001
    13,700
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    Mitchell Le
    The third coolant temp sensor is the one that sends temp data to the dash board. Same as a 1995 F355.
     
  6. FSM348

    FSM348 Formula Junior

    Feb 13, 2017
    469
    Midwest
    Full Name:
    Dan Smith
    Thanks everyone! I will check this evening and report back.
     
  7. FSM348

    FSM348 Formula Junior

    Feb 13, 2017
    469
    Midwest
    Full Name:
    Dan Smith
    By third you mean the sensor between the two ecu temp sensors? Or do you mean the sensor opposing them all by itself?
     
  8. FSM348

    FSM348 Formula Junior

    Feb 13, 2017
    469
    Midwest
    Full Name:
    Dan Smith
    Thanks! My colors are different than this diagram though. The sensor( furthest of the two from the water pump) has a brown wire. Hard to see what the color of the sensor signal wire closest to the water pump is but I will investigate more tomorrow after work.
     
  9. FSM348

    FSM348 Formula Junior

    Feb 13, 2017
    469
    Midwest
    Full Name:
    Dan Smith

    The connector near the shock tower is wheel speed/abs correct?

    I did use Teflon tape because I was getting a slight leak. Not a problem on the other sensors though but fair enough question and worth considering.
     
  10. m.stojanovic

    m.stojanovic F1 Rookie
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    ernie likes this.
  11. Qavion

    Qavion F1 World Champ
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    The one with the brown wire may be for the oil radiator cooling fan. i.e. component 92 on the bottom left of this diagram...

    HVAC Wiring Diagram

    That should have two wires like the ECU temperature sensors.
     
  12. FSM348

    FSM348 Formula Junior

    Feb 13, 2017
    469
    Midwest
    Full Name:
    Dan Smith
    Alrighty, the thermistor between the two ecu coolant sensors is in fact the coolant gauge sender. I cleaned the 9 pin connector with deoxit and then got the car up to temp and then shut it down, turned on the ignition and used a long section of all thread to touch the metal hex part of the sensor and then the other end to ground while watching the coolant gauge. It would move up to near the halfway point thus as some suspected it is a ground issue indeed.

    I will drain some of the coolant this evening and remove the sender and confirm.


    Still not sure if I need to consider replacing the oil pipe section above the AC or not. It’s pretty snug and leaks at a consistent drip.
     
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  13. yelcab

    yelcab F1 World Champ
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    Nov 29, 2001
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  14. Koenig1

    Koenig1 Formula Junior

    Aug 25, 2016
    328
    Ottawa ON
    Full Name:
    Sandy
    Just to add a thought on your oil leak.... I believe there is a clamp to steady the pipe up around the compressor. If that's missing, or not attached... well, they'
    initial post.."Also, I can’t seam to get rid of a small oil leak on the short oil pipe connections that runs over the AC compressor between the block and the oil cooler. " The Bronze 1.5">2"pipe from the Passenger side block to oil cooler.... runs over top of the AC compressor and has a clamp(to AC bracket) to steady any vibrations
    FSM348, glad you found your coolant sender problem. As for the oil pipe, change out the large copper washer with a new OEM one.
     
  15. yelcab

    yelcab F1 World Champ
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    It depends on where it leaks. Does it leak at the connection to the oil pan, at the transition from pipe to hose, or at the connection to the radiator?
     
  16. Koenig1

    Koenig1 Formula Junior

    Aug 25, 2016
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    Sandy
    True... would probably need to remove, and take it to a hose specialist to re-crimp(if lucky). I believe those hoses are not cheap!
     
  17. yelcab

    yelcab F1 World Champ
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    I have seen leaks due to a cracked banjo bolts (twice) so that is the reason to dig deeper for the leak. My recommendation is to remove the hose and have it rebuilt (you don't want to know how much it costs new, trust me). Then replace the gaskets as well as the banjo bolts IF there is a crack.

    Of course, if the oil is coming from above the hose via the valve cover gasket, then … all bets are off.
     
  18. FSM348

    FSM348 Formula Junior

    Feb 13, 2017
    469
    Midwest
    Full Name:
    Dan Smith
  19. Koenig1

    Koenig1 Formula Junior

    Aug 25, 2016
    328
    Ottawa ON
    Full Name:
    Sandy
    ah ok... good luck. i agree with 'yelcab', you don't want to know the price of a new one! I see now there are 2 crush washers associated with the banjo bolt.... memory is fading fast!
     
  20. yelcab

    yelcab F1 World Champ
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    Nov 29, 2001
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    Rebuid it. You live in Indiana, there must be 100 places that do this stuff. It has a huge car culture there.
     
  21. FSM348

    FSM348 Formula Junior

    Feb 13, 2017
    469
    Midwest
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    Dan Smith
    Earls Indy does Indy Car stuff so hopefully they can hook me up.
     
  22. Qavion

    Qavion F1 World Champ
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    Miro, are the pins on the engine side of the plug or the car side? I've added a small pinout graphic of your diagram to my diagram, but I'm not sure on which side of the plug I should put the graphic. Thanks.
     
  23. FSM348

    FSM348 Formula Junior

    Feb 13, 2017
    469
    Midwest
    Full Name:
    Dan Smith
    The pin numbers are on the connector if you look closely. They are very small!
     
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  24. m.stojanovic

    m.stojanovic F1 Rookie
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    I do not remember which view I used (and I think I did not care) since, as Dan also informed, the pins are numbered, on the insides of both halves of the connector, so you just go by that.
     
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  25. FSM348

    FSM348 Formula Junior

    Feb 13, 2017
    469
    Midwest
    Full Name:
    Dan Smith
    Both problems appear to be fixed.

    I took the coolant temp sensor out and cleaned up the threads and put only one round of Teflon tape on it. I also put a bit more torque with the wrench upon install and I didn’t notice any leaks while idling the car up to temp and more importantly the gauge was reading correctly.

    As far as the oil pipe, I took it apart and cleaned it thoroughly. I realized you can actually unscrew the flared section of each end from the crimped hose and quickly found that they were not seated all the way through the threads. This is why the pipe leaks, not because the flared end wasn’t tight enough. I’m curious how many people have replaced this ungodly expensive pipe when all it needed was to have the end pieces screwed back into the crimped ends. It’s nice because if you crack one of the nuts or gouge the flared piece you can rebuild the ends. Good to know!
     
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