Why won't my coolant return from my overflow to my radiator?

Discussion in 'Fox 5.0 Mustang Tech' started by jaymac, Nov 7, 2005.

  1. Like the question says... After my cooling system swap experience this weekend (another long story), I had to top off my radiator this moring with a few oz.'s of coolant, but my overflow bottle was still at the HOT full mark. The car had been off for more than 30 hours. Why wouldn't some of that coolant return to the rad. and top it off?
    Then This morning after driving to work, letting it sit of 2 hours, then checking it again, The overflow was above the hot full mark, and the rad. was also topped off.
    It's not the first time that the rad. has been low and the overflow has had excess. Is something wrong, or is this normal?
  2. When cold just draw out the excess coolant from the overflow to the cold mark. If you system is burped and the overflow is over the mark then you have enough in the system that it's not going to draw from the overflow.
  3. yeah, I have to go burp it right now...
  4. If your driving it and it remains full (rad) then likely it is burped..is the temp consistant once it reaches the operating temp (what ever temp yours may be)?..if it is then your done and good to go. Trying to burp a full system will only have you putting in too much coolant and filling the overflow past the mark again.
  5. well, it will fluctuate slightly between low 180's and low 190's throughout a 15 minute drive once it's warmed up.
    How long should I wait for the car to cool to let the level in the rad. settle before determining if it needs to be burped or not?
  6. Make sure the hose isnt pinched or kinked up, also pull it off and inspect to make sure its not clogged. Have you replaced your thermostat and rad cap lately?
  7. Temps sound fine..every car will operate differently depending on condition of many items involved..190 with a 180 stat is not a concearn at all. As stated in previous post..if you have a higher milage older fan clutch and or fan is damaged..replace it the RPM's on the old clutch may be well down. I droped almost 10degrees with a new clutch.
  8. I just gave you an update on my clutch in my other thread, but since I'm here...
    The clutch was replaced less than a few months ago, but I *have* heard of new clutches being faulty...

    And yes, my rad. cap is new, and my T-stat is 4 mos. old, so those should both be good.
  9. And the hose looks good; no visible kinks or clogs, and I just installed it (from a boneyard), and cleaned it thoroughly beforehand.
  10. Have you replaced your radiator cap recently? The cap allows coolant to flow back from the expansion tank into the radiator as the car cools down.
  11. yup, cap is less than a month old...
  12. HUUM? I just started experienceing this same issue. I m taking the res hose out to see if maybe its just as simple as a clogged hose. I'll get new Rad cap just in case.
  13. disconnect the hose from the top of the radiator and blow through it. You may have some crud in the hose or on the bottom of the overflow tank. X2 on the cap. You can test that for free at autozone.
  14. Thanks, will do so when car cools down. Just got home
  15. So I opened the cap, coolant level was a little low missing about the same amount in res tank. I blew thru hose n couldnt really tell if there was an obstruction but air went thru fine. lets see tomorrow on way to work ???
    Question, if i unplug the pigtail on the MAM should the car shut off or what?

  16. hmmm... check the cap to see if it is still holding pressure as stated. if that checks out the same kit you "rent" at autozone will pressure test the entire cooling system too. i ran into a similar problem and it took me testing the system twice 6 months apart to realize i had a coolant leak per a bad gasket. hopefully it is just your cap that is on the fritz. the pressure to test the the cooling system is much higher than that to test the cap so double check that so you don't make the same mistake i did and have to rent the thing again.

    and whats an MAM???
  17. Mass air meter
  18. ahhh... yeah, i believe all my vehicles died whenever i unplugged that while running.
  19. I was thinking about a bad straw - it will carry pressure when blown into, but might collapse when suction is applied. Maybe it is time for a new return hose if the obvious stuff checks out.
  20. Thanks guys, This morning Temp stayed true to 180 as before it kinda went up almost half way which to me was the indicator something was amis. The real test is after work, I have a world of errands and will put it to the test but again so far this morn it ran cool n temp didnt flutuate like it did before