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Help please, car overheating...odd

Discussion in 'Boxers/TR/M' started by bpu699, Oct 27, 2019.

  1. bpu699

    bpu699 F1 World Champ
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    1987, 17,000 or so miles, did the major myself about a year ago...

    Was driving with my daughter, last drive of the year...car running great... it’s 55 degrees out here, chilly...

    Car is running great, but temp needle is always at the middle, or 1 mm over...odd, as it’s cold out side...

    At stop signs it nudges right, about 1-2 mm, barely over the middle mark.

    Get on the highway, goes down slightly, it still above the middle by a mm or so...

    I turn on the heat, as it’s getting cold in the car. Heat doesn’t work, BLOWS cold?! Press all the knobs, no change. Odd, as it worked after the major when I bled the system...

    Park the car...temp shoots up to the 3/4 mark. Fans do NOT go on... double odd...heater still blows cold...

    Wtf???

    Checked oil level, normal, no intermixed coolant
    Checked coolant, normal, no milkshake...
    Checked connectors in the frunk... normal, no burnt connectors...

    Now I know this can be 2 separate issues, but what would make the heater blow cold, and fans fail?

    The heater blowing cold throws me. Electrical issue with a valve somewhere? Air bubble???

    Plan next weekend is to jump the fan relays, make sure they work. I also think there is a temp sensor in the right radiator. Need to jump the sensor see if that works too.

    But again, the lack oh hot air throws me?

    This can’t be a stuck thermostat, can it? I would think if it were driving wouldn’t bring the temp down...

    The water pump impeller couldn’t have worked loose, could it? I would think that would cause catastrophic overheating, moving or not...

    Any help appreciated.
     
  2. fridolin_pt

    fridolin_pt Karting

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    Yes, it can.
     
  3. Steve Magnusson

    Steve Magnusson F1 World Champ
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    #3 Steve Magnusson, Oct 27, 2019
    Last edited: Oct 27, 2019
    No, the heater should work regardless of what the thermostats are doing -- so either an electrical problem or something like a kinked heater hose.

    This does seem like a thermostat problem. You should be able to do some diagnosis just with some careful touching of some of the tubes. If the thermostats are in the correct position to send the hot coolant exiting the cylinder heads to the radiators, the tubes 33 and 34 here:

    https://www.ricambiamerica.com/car-diagrams/ferrari/v12/testarossa-group/testarossa-1990/cooling-system.html

    should be the same (hot) temperature as pipes 4 and 5 here:

    https://www.ricambiamerica.com/car-diagrams/ferrari/v12/testarossa-group/testarossa-1990/engine-cooling.html

    If either tube 33 or tube 34 seem much cooler = bad sign for that thermostat. The radiator fan thermoswitch is only in the LH radiator, so if it's tube 33 that seems cool, that would explain the radiator fans not coming "on" even though the dash gauge is reporting above normal.

    Of course, no radiator fans condition could be an electrical problem (but you already know what to try there).
     
  4. turbo-joe

    turbo-joe F1 Veteran

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    this sounds for me as if there is air in the cooling system. bleed the sytem first on all 3 bleeders and see what is going
     
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  5. bpu699

    bpu699 F1 World Champ
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    Thanks guys, will do all as suggested, and will report back next weekend...

    Is changing thermostats fairly simple? Those thermostat bolts look aweful to get to...
     
  6. turbo-joe

    turbo-joe F1 Veteran

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    only the 2 to the front of the car :)
     
  7. bpu699

    bpu699 F1 World Champ
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    Is there a cross reference on the thermostats? I see the Ferrari part is $150, each...

    Seems a tad high for what is certainly a generic part...
     
  8. turbo-joe

    turbo-joe F1 Veteran

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    BMW has the same, but don´t know what type - sorry

    but it is unusual that both thermostats going wrong.
    use an infrared thermometer and meassure the temperature on both radiators top and buttom. the switch for the radiator fans is only on the left radiator. I put in a second switch also in the right radiator at my competition.

    you bleeded the system already?
     
  9. bpu699

    bpu699 F1 World Champ
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    Cant work on it til this weekend. Will find the laser thermometer...its somewhere in the garage...somewhere
     
  10. ross

    ross Three Time F1 World Champ
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    its the thermostat.

    but, i once had a funny one on the 512tr where i could not figure out the overheating-like issues, and it turned out to be the rubber gasket on the radiator cap that had worn out and was not sealing correctly.
     
  11. turbo-joe

    turbo-joe F1 Veteran

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    sure?
    I doubt that just at the same time both thermostats going wrong?
     
  12. ross

    ross Three Time F1 World Champ
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    what makes you think both of them have to be bad?
     
  13. turbo-joe

    turbo-joe F1 Veteran

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    I don´t think so ross. also I have written before that I doubt that just at the same time both thermostats going wrong?

    you have written the thermostat and so I understand you mean both.
    may be missunderstanding?
     
  14. bpu699

    bpu699 F1 World Champ
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    I think he is suggesting if the left thermostat goes bad, the left radiator doesn't heat up, and the fans don't go on...
     
  15. bpu699

    bpu699 F1 World Champ
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    Alright guys need more help... I’m scratching my head. Would appreciate some input before digging into the thermostat and other things...

    Did trouble shooting
    1) jumping relays, all the fans work
    2) radiator overflow full, not low

    Now here’s where it gets odd and I’m scratching my head...

    Went to bleed the car while running...NONE of the air bleed screws produce radiator fluid. Doesnt matter how long you leave them open. Panic ensued, figured maybe water pump spun off or something like that...

    But, took the overflow hose back to the radiator, and flow is fabulous. Cool and is clearly circulating.

    Radiators get hot, return and supply lines get hot... didn’t have the courage to run it to 195 degrees until I posted... up to 180 or so, all seems fine. Fans didn’t turn on, but they don’t turn on until 195 I believe. Left radiator was slightly cooler than right...

    I looked at the testarossa cooling system a dozen times. If there’s flow and pressure to the radiator over flow, then there’s flow and pressure to the radiator bleed nipples... except there isn’t.

    Oddly, my heat worked for a bit while sitting at idle, blows warm/hot air...


    Questions, maybe I’m an idiot...

    1) should the bleed screws work before the thermostats open? I recall they always did...
    2) if the radiators are getting hot, clearly at least trace coolant is getting to them. Why the heck isn’t it shooting out of the bleed valve?
    3) wtf?
    4) I suppose if both thermostats are closed, and they have no air bleed holes, then there’s no circulation to the radiators until 195 degrees when/if they open...


    Am I just paranoid?

    Left radiator feeling slightly cooler suggests that thermostat may be going awol... will get laser temp to check...

    Could the left thermostat going bad explain it all? Certainly flow to thermostat would decrease, which means fans come on late...

    I just can’t explain none of the airbleed screws working...
     
  16. Veedub00

    Veedub00 F1 Rookie
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    My bleed screw on the passenger side always bled coolant when I filled it at the reservoir.
     
  17. Steve Magnusson

    Steve Magnusson F1 World Champ
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    The opening that the bleed screws near the radiators close off can get blocked with rust/gunk. Also, the passages in the bleed screws can get blocked/gunked up. With the engine not running and at zero coolant prerssure (i.e., with radiator cap removed), completely remove the bleed screws to inspect/clean them, and poke a straight wire down the fittings to ensure the orifice is open into the large tube..
     
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  18. bpu699

    bpu699 F1 World Champ
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    #18 bpu699, Jun 27, 2020
    Last edited: Jun 27, 2020
    Steve was hoping you would chime in... my car is possessed....

    Took the bleed screws out, they are clear no gunk. Put the bleed screw back in, applied a vacuum suction, antifreeze easily came out...

    Ran the car up to about 160 degrees (1st tick mark before 195)... put a clear silicone tube over the nipple, open to air. As it approached 160 degrees fluid started coming out and filled about 1 foot of the hose, and stopped. Car was still running. Shut the car off, it got sucked back into the line...

    So, went to the garage got my laser thermometer...

    Started with cold car...

    Passenger side radiator pipe went up to 120 degrees pretty quick, left was at 100... within 2-3 minutes they matched though, about 130...

    So, I got creative and jumped both radiator fans at the relays, so both ran. Car started at 130 degrees, very slowly climbed to just past what I presume is the 160 tick mark, and stayed there indefinitely...at least at idle, as I didn’t drive it that way.

    Checked temps at both radiator aluminum pipe inflows to radiator... about 165 degrees. Outflow about 145 degrees. Radiators themselves 114 degrees.

    Totally symmetrical.

    Checked temps all over the motor, symmetrical. About 175 near the heads, 165 over piston base/block.

    Without the fans jumped it goes over 195...

    So scratching my head...

    Seems to suggest the issue is the radiator fans aren’t getting triggered by the temp sender in the left radiator, potentially easy fix.

    Maybe the left radiator thermostat is opening later than the right/intermittent, causing an occasional overshoot?

    I just can’t explain fluid not coming out of the bleeders...

    Clearly fluid is circulating... otherwise it would over heat like crazy...

    Plan for tomorrow:

    1) will poke the radiator bleed screws with a wire, though doubt that makes any difference
    2) pressurize overflow verify bleed screws work

    My heat works great again by the way, super hot... weird as hell...

    Possible explanation:

    1) one of the thermostats isn’t opening completely... no issues at idle, but issues on highway
    2) thermoswitch is wonky, not activating fans regularly

    What I’m most concerned about is that the impeller somehow came off/got loose. But I don’t see how that possible while getting heat/flow to the overflow tank, and no antifreeze oil leaks. I would assume if the impeller somehow got loose, you would leak like crazy at the weep hole....
     
  19. bpu699

    bpu699 F1 World Champ
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    With the car running, shouldn’t the bleed screw be pressurized? Meaning, should it literally be shooting out? Maybe I’m tired and overthinking it...

    Maybe I’m sleep deprived but I always remember cracking the bleed screw open at idle to let the air out...
     
  20. turbo-joe

    turbo-joe F1 Veteran

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    as long as there is no pressure on the water system only a very little water will go out at the bleeding screws. so when the radiator cap is not closed you will not get pressure on the system

    because of the fans not running I think the sensor in the left water cooler is not working right

    what about the temperature during driving on highway. normaly thefans then not will come on because of the driving wind.
     
  21. bpu699

    bpu699 F1 World Champ
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    I drained some coolant today. Tomorrow will remove and test the thermostats.

    Will recheck all the bleed screws...

    If that doesn’t fix it the thermosistor in the radiator is next...

    I really wonder if I have a screwed up driver thermostat... that would explain a lot...

    I replaced one thermostat 12 years ago... found my old threads... :)
     
  22. turbo-joe

    turbo-joe F1 Veteran

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    when the radiators get warm top and buttom then the thermostats are working fine

    thermosistor? you mean with this the temperatuire switch in the left radiator? before you change this just connect the 2 wires and see if the fans are running. if not then you know you have a problem between this switch and the fusebox. if they run then replace this switch. no need to take a F part, nearly all cars have the same, only with a little different temperatures.
     
  23. bpu699

    bpu699 F1 World Champ
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    If the thermostat opens partially, would that cause these symptoms? Either way, committed to checking at this point...

    I think my thermostats may open at 2 different temps. Left side stayed cooler longer than right. And it’s odd that at idle with both fans jumped it stayed at 160 degrees or so, rather than 195...

    Haven’t poked around yet for the temperature switch... can I get to it just by reaching under the car? Or do I need it on the lift with the tire off?
     
  24. turbo-joe

    turbo-joe F1 Veteran

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    this depends how much weight you have ;) to go under the car. but I think you may lift the car in the back ( not at the left side, the rear window may break then )

    problem is: the temperature at the gauge shows the water temperature at the engine where both cylinder banks comes together. in my competiton I put in sensors also in each radiator top and buttom to see when something is not ok
     
  25. c4b4the04

    c4b4the04 Karting

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    The fan switch is the same part as a 77 Scirocco if I recall. Check the cross reference thread to be sure, but I’d check for corrosion on those connectors. I’d guess you’ve got an issue there as to why fans aren’t coming on. The switch is more towards the left outer edge of the driver side radiator. The inner fender liner coming out would simplify your testing, I’m not 100% sure the wheel has to come off but it’s easier for sure.

    So you pulled the bleeder screws, and verified they are clear all the way through and at the tapered seat opening? What about the 10mm bleeder between thermostats, I’m sure you’re getting fluid there.


    Sent from my iPhone using FerrariChat.com mobile app
     

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