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Thread: Conflicting Water temperature Readings AND Overheating quickly

  1. #1

    Conflicting Water temperature Readings AND Overheating quickly

    I installed an autometer electronic water temp gauge in my intake. The temp display would jump up to 250 degrees while my Fitech would say under 185. I reinstalled my mechanical water temp gauge to use as a "check" and found that it conflicts with the electronic one. The mechanical water temp gauge is in line with the fitech handheld, and the laser temp reader that I purchased to check the temps.



    Has anyone seen this before? NOTE: MECHANICAL IS CELSIUS and ELECTRIC IS FAHRENHEIT

    Please see video - There's some sort of weird delay (sound vs picture) but you'll get the idea

    https://www.youtube.com/watch?v=h1kC08QXe0g&t

    Thanks,
    Dave
    Last edited by DadofThree; 08-10-2017 at 08:12 PM.
    Dave
    Mk 3.1 - #6882 - 5.0L 302 - FiTech EFI - 3-Link - 3.08 Ratio - 15" Wheels
    Greenhorn and doing the best I can
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    Blog @ BuildaRoadster.com

  2. #2

  3. #3
    From the searching I've done, it looks like getting the fill neck as the highest point while running is the way to do it. I've also seen that putting a funnel into the fill neck is a good way to make it the highest point. Hope I haven't hurt the motor getting it to those temps.

    I've also read that a leak in the head gasket will push the water out of the expansion tank. I am getting water out of the expansion tank.

    Here's the funnel method
    https://www.youtube.com/watch?v=nThsFGa1vuE
    Dave
    Mk 3.1 - #6882 - 5.0L 302 - FiTech EFI - 3-Link - 3.08 Ratio - 15" Wheels
    Greenhorn and doing the best I can
    My photos are at: My Flickr acct
    Videos are at: YouTube Videos
    Blog @ BuildaRoadster.com

  4. #4
    Dave, two questions:
    1) is there flow in the heater hose line during your testing? - if not, sensor might be giving wrong readings.
    2) Is your thermostat installed in the right direction? If backwards, will not open to allow flow to radiator.

    Best test is with both sensors in the same place as different sides of the flow in the engine will have different temps at times.
    I agree with Gordon about there might be an air pocket still in your block causing a hot spot that causes water to boil faster causing the "overflow".
    A blown head gasket is testable with kit that you can borrow from your local auto parts store.

    100° C = 212° F

    Doc
    Last edited by Big Blocker; 08-11-2017 at 11:10 AM.
    FFR3712K (MKII) in Lost Wages Nevada.
    5.0 w/tubular GT-40 EFI, E303 cam, Custom 4 into 4 headers, T5, 3-Link 3.73 rear. Full F5 tubular suspension. Drop Butt mod, Dash forward mod, custom foot box air vents, custom turn signal system. 13" PBR brakes, Fiero E-Brake mod, Flaming River 18:1 rack w/ F5 bump steer kit on Breeze bushings. 17" Chrome Cobra "R's" w/ 275 fronts and 315 rears. MKIV seats. FORD Royal Blue w/ Arctic White stripes.

  5. #5
    Thanks Doc.
    the thermostat has opened in the past. I put the large side into the intake.
    I'll also get that heater core open during testing.

    Because I have SS hoses, it may be hard to "burp" the system. I may disconnect the high point of the heater hose, pick up the pressure tester and try to push the air out of my heater hose. Each time, filling the system as needed until it's time to hook up the heater hose again. hopefully, that will get the air out.
    Dave
    Mk 3.1 - #6882 - 5.0L 302 - FiTech EFI - 3-Link - 3.08 Ratio - 15" Wheels
    Greenhorn and doing the best I can
    My photos are at: My Flickr acct
    Videos are at: YouTube Videos
    Blog @ BuildaRoadster.com

  6. #6
    A couple of points:

    Agree with Gordon that you most likely have air.
    Agree with Doc that to test the gages they need to read from same source, I suggest pulling the sensors and using a pot of hot water.
    Agree with you that you need to burp, and that it will be difficult with your system.

    Looking at your configuration in the video, I do not see how you will be able to avoid future cooling issues with the combination of your filler not being in the highest point and you not having anything at the highest point to remove air. IMO: You may be able to get away with making what you have work, but you should consider a redesign with air removal in mind.
    MKII "Little Boy". 432CI all aluminum Windsor. .699 solid roller, DA Koni shocks, aluminum IRS, Straight cut dog ring T-5, 13" four piston Brembos, Bogart wheels. BOOM!

  7. #7
    Average Moderator Garry Bopp's Avatar
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    I think everyone is jumping to the assumption that you have air in the system ... and that may be the case. However, if you have multiple readings indicating normal temps and only the electronic gauge reading high, I would suspect the gauge.

    Garry
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  8. #8
    Giving it try. I trimmed some of the hose to get the fill lower, and possibly the highest point. It's close anyway. Will try to burp the system. Not really optimistic.
    Dave
    Mk 3.1 - #6882 - 5.0L 302 - FiTech EFI - 3-Link - 3.08 Ratio - 15" Wheels
    Greenhorn and doing the best I can
    My photos are at: My Flickr acct
    Videos are at: YouTube Videos
    Blog @ BuildaRoadster.com

  9. #9
    Here is the temp that my water gauge showed when I turned on the key. Car had been sitting for a couple of days.

    Dave
    Mk 3.1 - #6882 - 5.0L 302 - FiTech EFI - 3-Link - 3.08 Ratio - 15" Wheels
    Greenhorn and doing the best I can
    My photos are at: My Flickr acct
    Videos are at: YouTube Videos
    Blog @ BuildaRoadster.com

  10. #10
    If you've run the engine and the T-stat has opened, you'll notice a quick delete of water into the engine. At that time you can add additional and let the engine idle. Some will come out and burp a bit, but by the looks of your issue, it's either a bad gauge or incorrect sender with my opinion being the gauge. Especially since you've checked with two other sources which read the same. Another thing to remember is the engine is at normal temp when the "lower radiator hose" gets hot. That's where the water/coolant enters the engine. It lets you know the T-stat has opened and coolant is flowing. You can also check with a thermometer (small tester) in the cap opening with the cap off and engine idling. That should verify your consensus.
    I'm just a victim of a thousand physic wars!
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  11. #11

    It was the Ground

    I have my dash loose, and have only hooked up my water temp gauge using a gauge feed wire to get the 12V and the sending wire. The ground was connected to the gauge lights grounding cluster. because that wasn't plugged in, I wasn't getting a ground for the gauge. I ran a pigtail from the ground on the gauge to a ground stud on the frame and the dial dropped to where it should be.

    Now I can take care of this cooling system without worry.


    https://www.youtube.com/watch?v=cTG4l4rjRGk



    2017-08-12_03-45-30 by D. R., on Flickr
    Last edited by DadofThree; 08-12-2017 at 03:32 PM.
    Dave
    Mk 3.1 - #6882 - 5.0L 302 - FiTech EFI - 3-Link - 3.08 Ratio - 15" Wheels
    Greenhorn and doing the best I can
    My photos are at: My Flickr acct
    Videos are at: YouTube Videos
    Blog @ BuildaRoadster.com

  12. #12
    Nice job running this one ... down.


    John
    MK IV Roadster #8631
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