Engine Cooling System Question

Discussion in '1994 - 1995 Specific Tech' started by joetrainer31, Jun 3, 2013.

  1. joetrainer31

    joetrainer31 Member

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    I'm a bit perplexed. Maybe some of you brainiacs can help. I recently completed a successful lifter R&R + top half restoration (i.e., replace whatever looks old) on my 95 SVO GT40 GT. The ran like a champ for 1 week.

    Then the problem started. This past Saturday it was 105 degrees outside. As I was driving around the neighborhood my car started to get a lot hotter than it should be. The temp gauge was on the "A" in "NORMAL." At this point I shut the car off because it demonstrated no signs of cooling down. I cannot understand what the problem is. In order to be helpful, below is a list of what I have done to diagnose this issue so far.

    - New 180 balanced thermostat
    - New bypass hose
    - New Rad cap.
    - Made sure system was purged of air (sitting nose up & heater full blast).
    - Performed compression test for rings prior to this concern (all cylinders were spec).
    - Checked timing (factory)
    - Checked for KOEO codes because this tests the fan's 2 speeds. Fan worked great, no codes.
    - Pressure tested Cooling system to 16psi (tester from Autozone). After about 2-3 minutes the pressure was at 14.5psi.

    Question(s): how long should the system hold pressure?
    I can observe no leaks on the ground, nor any wet spots on the engine, or coming from hoses. I've checked several times while the system is pressurized yet observed no leaks.

    What is my next step? Your help will be much appreciated.
     
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  2. 95Vert383AOD

    95Vert383AOD Active Member

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    What is your timing set at?
     
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  3. joetrainer31

    joetrainer31 Member

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    Hello 95Vert. My timing is set at 10 BTDC (factory). I investigated a little more and made the following observations:

    1) My brand new Autozone radiator cap pressure tested at 13.5 psi, and no higher. I ordered a motorcraft cap from Amazon.
    2) There are ZERO bubbles in my radiator (via head gasket leak).
    3) There is no milky substance in my oil. In fact, it looks fresh out of the bottle (oil change 40-50 miles ago).
    4) My original pressure test on the rad could have been off because I did not have the mechanism fully tightened (i.e., the locking cylinder). I will test again and record the results.

    One other bit of info. When my car got so hot the other day, after it cooled, I looked into the radiator and there was no observable missing coolant. I let the system cycle w/the heater on high & nose inclined. When the stat opened, the coolant level went down only about 1-2 inches at best. Trying to be as descriptive as I can.

    What say you?
     
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  4. 95PGTTech

    95PGTTech Member

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    If, when it is exhibiting these symptoms, does it help if you blast the heat on full power? I realize this may not be the most comfortable solution to the problem, but a good diagnostic step.
     
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  5. joetrainer31

    joetrainer31 Member

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    Thank you for your question 95GTTech. I honestly did not keep the car on long enough to try that test. I was less than 2 miles from our house when this happened. I simply went home, after eating my fatburger of course.

    I plan on pressure testing the system again shortly, but I do not plan on driving it until I put the new cap on, and I'm thinking that I will remove the 180 balanced stat and install a 195 balanced stat. When those two things are completed I'll drive and see what happens. Do you have any other questions, observations, or advice?
     
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  6. 95PGTTech

    95PGTTech Member

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    Instead of switching thermostats, remove it completely. This will help eliminate a lot of variables.
    Right now, I'm leaning towards excessively hot day caused it to slowly creep up because your system simply wasn't cooling fast enough.
     
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  7. WhiteCobra95

    WhiteCobra95 Member

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    Was the fan actually running when the temp got up to the "A?"

    On hot days when I get stuck in stand still traffic, my temp gauge will go up to about "A" or "L" before the fan kicks on. Once the fan comes on, it drops to the "N" or "O" pretty fast.

    I'm running a Mr. Gasket 180 stat, but my fan setpoints (cal) are still stock. The fan doesn't kick on at the right time which creates an odd temp operating range for the engine were it will sort of bounce around on the gauge.
     
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  8. joetrainer31

    joetrainer31 Member

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    It was certainly hot -100 degrees. I'm wondering how much of a role the rad cap was playing seeing that it was tapping out at 13.5psi when I tested it. Obviously my coolant system lacked the proper pressure.
     
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  9. joetrainer31

    joetrainer31 Member

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    Yes, the fan was running on high. I tested the fan's operation this morning by running a KOEO scan. It operated both fan speeds. Furthermore, my coolant sensor is brand new, and my coolant temp sender is too.

    After I let the car cool for several hours I cycled the system with the cap off. The fan came on and the thermostat opened simultaneously at "R" in the "NORMAL" range.
     
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  10. joetrainer31

    joetrainer31 Member

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    Thank you for helping me think through this guys!
     
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  11. joetrainer31

    joetrainer31 Member

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    UPDATE: I found the leak!

    I decided to run one more pressure test to see if I could find a leak. I pumped up the system to 16psi, but instead of it holding for a couple of minutes it proceeded to immediately loose a small amount of pressure. After looking all over the radiator area I discovered, by way of a small developing puddle on the ground, that my radiator has a leak.

    While I still cannot see the actual leak location (even crawling underneath the car), I can see that there are drops coming down from the passenger side of the rad. I can also see a light stream of coolant coming down the side of the rad. It seems that the leak must have been very small and is also in an area that is not observable while the rad is in the car. This is probably why I could not observe it before.

    So, I had a faulty rad cap and a leaking rad. Its no wonder the car was running way to warm. Thank The Lord that I saw the leak, and thank you guys for your willingness to help me diagnose the issue.
     
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  12. 95PGTTech

    95PGTTech Member

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    Good find. Since it's on the passenger side, make sure you can isolate it one way or another between the radiator and the coolant overflow (plastic) tank - a very popular leaking point.
     
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  13. joetrainer31

    joetrainer31 Member

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    Good morning 95GTTech,

    Ok, so the plastic overflow tank has a predisposition to leaking? Am I understanding you right?

    Assuming I'm understanding you correctly I have a question. Sinse the leak is from up toward the top of the radiator and the overflow tank's fluid level was lower than the leak point wouldn't that then disqualify the overflow from being the source of the leak? Also, the light flow of coolant was clearly down the side of the rad. What do you think? Is my reasoning sound? IS there something I'm missing?
     
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  14. 95PGTTech

    95PGTTech Member

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    Yes, it is very prone to leaking/cracking.

    Can you describe the side of the rad better? We're working on the passenger side. Is it coming from the endtank or the finned center section? Is it coming from the rear, front, or side of the endtank?
     
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  15. joetrainer31

    joetrainer31 Member

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    Gladly,

    The light, thin flow of coolant appears to be coming from the endtank. I saw it coming from the top area of the rad & down the side.

    My theory is this: before my last pressure test I filled the coolant upto the top of the rad neck. Next, I immediately put the tester on and performed the test. The pressure immediately started a slow decline. I kept pumping up over and over while looking for a leak. I finally found the one I am speaking about. Considering that my rad cap only held 13.5psi (brand new), the system's pressure never achieved the proper level (or coolant expansion height), therefore the coolant was not leaking out of the rad. I could smell faint traces, but could never observe any leaks. I theorize that the lack of pressure/fluid expansion with the defective cap on never allowed a fluid level high enough and/or pressurized enough to force its way out of the tiny hole. I theorize that a high fluid level & temporary correct pressure level allowed the leak to manifest itself in an observable manner.

    I hope this was helpful in its description.
     
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  16. 95PGTTech

    95PGTTech Member

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    If you saw the actual crack in the endtank itself, replace the radiator. I thought you had said you couldn't directly see it, sorry. I agree with most of your theory, but arrive at the same conclusion at the end - not able to hold enough pressure = slow overheat.
     
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  17. joetrainer31

    joetrainer31 Member

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    Hello 95GTTech,

    Sorry, I probably was not clear enough. I [did not] see the actual crack in the rad. What I did see was a faint trail of coolant coming from the top area of the rad, and running down the side (end tank). The beginnig point of the faint stream looked to be higher than the water level in the overflow tank. It was by adding those to evidences together, and the faulty rad cap, that I constructed my theory.

    Sinse you most likely have more experience and knowledge than I do in these matters can you please tell me where you disagree with [parts] of my theory? I realize that theories are not facts. I'd like to learn something if you have something to teach. Also, I totally agree with the low pressure/overheat comment. Thank you!
     
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  18. 95PGTTech

    95PGTTech Member

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    Considering that my rad cap only held 13.5psi (brand new), the system's pressure never achieved the proper level (or coolant expansion height), therefore the coolant was not leaking out of the rad. I could smell faint traces, but could never observe any leaks. I theorize that the lack of pressure/fluid expansion with the defective cap on never allowed a fluid level high enough and/or pressurized enough to force its way out of the tiny hole. I theorize that a high fluid level & temporary correct pressure level allowed the leak to manifest itself in an observable manner.

    I think it's more likely the crack was not bad enough at that point or the coolant was just not seen by yourself or not hitting the floor - the lower radiator support being hollow tends to hold a lot of fluid drips. When you are doing the pressure test, it causes the coolant to pressurize to the point where it will find any leaking point regardless of its height. Regardless, we arrived at the same diagnosis and repair.
     
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  19. joetrainer31

    joetrainer31 Member

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    Ah, I think I understand what you are saying. When you say, "When you are doing the pressure test, it causes the coolant to pressurize to the point where it will find any leaking point regarless of its height." do you mean that when I pressurized the system w/the pump to 16psi that it forced the coolant level to rise up to the point that it "found" the hole and leaked out?

    I'd like to not stumble upon the right answer, but be able to critically think through what happened. Thank you for all your input 95GTTech.

    By the way, I ordered a new cap from motorcraft. Its a bit more $$, but I trust the quality a bit more than, say, Stant...
     
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  20. revhead347

    revhead347 I have face herpes.

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    Don't get all caught up in it. The cooling system shouldn't leak at 16psi or even 25psi for that matter. Just make sure it's not a hose that's connected to the radiator that's leaking.

    Kurt
     
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