Spider cooling system issues

Discussion in 'Front-Engine Rear Drive Fiats' started by pdxgeo, Aug 13, 2014.

  1. pdxgeo

    pdxgeo True Classic

    In the past several months ive had several issues with the cooling system. I will try to be as clear as possible to give you the big picture. These things are in chronological order

    1) Had a thermostat fail. A fairly new one (maybe 2500 miles MAX). Bought a new one and installed it correctly per IAP video.

    2)Heater core (or valve) started leaking in car. I bypassed it. I had formerly installed a Tee at the heater hose which I then noticed was leaking when car was hot. i removed it and ran straight hose still bypassing the heater core.

    3) I burped the system by raising it in front and letting it run 30 mins with the cap off. I did see air bubbles at the rad. I drove it a while then topped it off. it ran at normal temps that day under a variety of driving conditions. It seemed obvious when the thermostat opened as the temp would dip back to the 1 (in 190). Never climbed to any temp that made me uncomfortable.

    4)the NEXT day the car ran hot. Say 210 on the freeway. climbed to 225 sitting in traffic but I wasnt idle long enough to see it go higher. Back on freeway dipped to 210 again. Got home and parked it.

    5) the next morning I noticed that my overflow bottle looked much FULLER than it had before, like maybe 3 inches more fluid in there.

    OK, my general sense is that the system is over pressurizing causing systematic leaks and failures but I dont want to jump to any conclusions. One question I have is regarding air in the system. What does that actually cause? Is it a blockage? Does it just wreak havoc with the temp sensor in the head? Other question is whether any of the above rings any bells, anything I should focus on?

  2. budgetzagato

    budgetzagato Administrator Moderator

    Olympia, WA USA
    Air in the Spider cooling system causes all the things you mention, and can cause the fan switch in the radiator to not close when it should. An air bubble can stop at one of the switches, or in the thermostat, and then those things won't work when they're supposed to.

    When a DOHC Fiat or Lancia runs hot, air in the system is the first suspect. That your overflow bottle is fuller than before suggests that air has entered the system and displaced the coolant, which is now in the overflow.

    The best way I've found to bleed the cooling system on a Spider is to loosen a hose near the top of the engine, with a rag under to catch coolant, and allow air to escape, and tighten again when the air stops and coolant comes out instead.

    Obert has an exhaustive explainer of how to bleed a Spider:

    It can take several tries to get air out it seems, so don't give up immediately. That said, if after you have repeatedly removed any air in the system, and more seems to appear as if out of nowhere, then you may have a leaking headgasket. This was the case recently with my Scorpion. Every drive I took I'd get some air in the cooling system. It started to get worse and worse.
  3. pdxgeo

    pdxgeo True Classic

    turns out

    the "new" thermostat was stuck about 1/8" open. I am baffled at how easily these things fail and always wonder if it is some other "fault" of the cooling system that makes it happen.

    New T stat en route. Also have a new temp sending unit. with the FIAT rad cap hopefully the system will finally work properly.
  4. budgetzagato

    budgetzagato Administrator Moderator

    Olympia, WA USA
    A stuck thermostat is just not going to cool as it should. I think my Scorpion's thermostat was stuck when I got it. Doesn't explain the coolant level but hopefully the new 'stat makes bleeding the system easier.
  5. mikemo90

    mikemo90 True Classic

    running hot

    fiat had a big problem with air in the cooling system. on the later model fuel injected 124's especially. they put an air bleeder at the "tee' on front of the manifold where the hoses meet. and make sure you have the thermostat installed correctly. three hoses to the thermo, and only one way it works. they stepped the hoses to make it a no brainer,... but even the mechanics I worked with could, and did, install it the wrong way.

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