360 - Radiator Coolant Pressure Test - Sharing an experience | FerrariChat
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360 Radiator Coolant Pressure Test - Sharing an experience

Discussion in '360/430' started by hessank, Apr 17, 2025.

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  1. hessank

    hessank Formula 3
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    Fred
    #1 hessank, Apr 17, 2025
    Hopefully this will be useful to others.
    Sorry for being long-winded.

    Last FALL, before I put her to bed one of the two issues on my mind was that my son had reported seeing a wee bit of coolant under the right side of car (the other issue was swapping in the Porsche Cayenne TBs and store the OE ones). It was late in the Fall and getting colder every day and I was not able to investigate before storing it. I know the Pressure Relief hose runs down to the left side of the engine and so I was hoping that it was the under-body tray directing the drainage to the other side. I figured that asap in the spring I would perform a pressure test if just to lower my BP.

    Over the winter months I looked at several testers and after lots of internet searches I found this one for $86 (no affiliation with Amazon). It even comes with a special wrench to tighten or loosen the cap.
    https://www.amazon.com/dp/B0D3F6M7RC?ref=ppx_yo2ov_dt_b_fed_asin_title

    For those interested, #16 screwed on real tight but I could not get the system to pressurize. After settling my nerves (thinking it would have to be a really bad leak) I calmed down and decided to look at the equipment. I checked the other styles of caps and #22 was not only a perfect fit but it allowed pressurization. I then suspected that the inside rubber seal on cap #16 did not mate properly with the sealing lip of tank.

    I pressurized the cooling system to 15 PSI (g) and after 5 minutes the reading was 14.5 PSI(g). Fantastic, Oh Joy!

    Here are some pictures
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  2. EastMemphis

    EastMemphis Formula 3
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    #2 EastMemphis, Apr 17, 2025
    I think from a technical standpoint, drawing a vacuum might be more effective in testing the integrity of a pressurized system. If there are any leaks, even tiny ones, the pressure rises quickly. For a leak down type test, a lot of air has to escape to drop the pressure significantly.

    Then again, musings of a madman.
     
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  3. hessank

    hessank Formula 3
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    #3 hessank, Apr 18, 2025
    As in the AC system it will also id that you have a leak but NOT where it is leaking from
    Pressurizing it shows where the coolant is dripping from if a leak exist.
    So I prefer the pressurizing process for this reason
     
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  4. EastMemphis

    EastMemphis Formula 3
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    #4 EastMemphis, Apr 18, 2025
    While I agree that finding a leak is a lot easier with positive pressure, assuring a system is leak free with a vacuum is far more certain. Losing 1/2 pound of pressure from 15 psi over 5 minutes is a significant loss. I would question your conclusion that the system is sealed.
     
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  5. yelcab

    yelcab F1 World Champ
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    #5 yelcab, Apr 19, 2025
    Rambling:

    1. Vacuum test is good in that it tells you there is a leak. It is no good in telling you where it leaks.
    2. I then have to fill the system, connect a pressure tester, and look for a water leak, and fix that.
    3. A 15 to 14.5 psi leak in 5 minute is a bad leak. Although, it could also be the test cap that is not perfect for the tank.
     
  6. Rifledriver

    Rifledriver Three Time F1 World Champ

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    #6 Rifledriver, Apr 19, 2025
    Agree 100%. Finding a leak is secondary to determining if there is one.Vacuum is much better at that.
    And .5 lb in 5 minutes is a failing grade.

    No mention of cap testing either. Those caps are a very well known failure point.
     
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  7. hessank

    hessank Formula 3
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    #7 hessank, Apr 19, 2025
    Based on the above, I redid the test today. Over a 30 min period (lunch) when I came back it was still at 15. So maybe my initial pressurization was at 14.5 and not 15. Thanks for all the above comments.
     
    EastMemphis likes this.

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