Coolant over flowed with cap off
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Phoneguy
Cometic HG stress tester
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- Aug 27, 2002
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- 6,880
Just the purge before the thermostat opens, nothing to worry about unless you are losing fluid or you are constantly overheating. How was the flow when it opened?
Bryan
Bryan
When I saw it over flowing I shut it down. The coolant was already a quart low. My mechanic had replaced the front cover recently as I blew out the seal and lost coolant. He said my headgaskets were fine. Found out the Walbro was bad and only 2 years old! This was after replacing the bad 169 pump. Replaced it with Red's XP pump this time. Well, I'm losing coolant again and car was running hot (fans didn't come on, for some reason). I checked the fans and they do work. I replaced the temp sensor on front of intake but that didn't help. So I pressurized the radiator and found coolant coming out from front cover where it meets with oil pan, near oil filter. Since there shouldn't be coolant there i'm thinking maybe bad water pump? The water pump was replaced with the front cover. Maybe coolant was running down from water pump and it just "looks" like it is coming from front cover? So now mechanic wants to check for hydrocarbons in the coolant. I did a compression test and found 150 psi in all cylinders (except for #6 where I couldn't get the tester threaded into the spark plug hole). Mechanic said that is not a true test of a blown HG. So in summary, coolant overflowed big time from radiator with cap off, fans don't stay on and car runs hot, coolant ran out big time from front cover area (when cap was on radiator), compression test is good.
novaderrik
Well-Known Member
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- May 12, 2004
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- 8,076
it's normal for the coolant to overflow like that after it warms up if the radiator is filled all the way to the top when it's cold.. the coolant expands when it gets warm, which pushes a bunch of it out of the filler neck. this is why you have an overflow tank, and why older cars that didn't have an overflow tank had a "full" line in the radiator tank 3-4 inches down from the top...
how fast does it warm up and build pressure in the cooling system with the cap on? if it overheats in a couple of minutes and the hoses get rock hard, then you are looking at a bad head gasket and/or a cracked head. the pressure is from combustion gasses, and it gets hot because of all the air pockets that the gasses cause.
how fast does it warm up and build pressure in the cooling system with the cap on? if it overheats in a couple of minutes and the hoses get rock hard, then you are looking at a bad head gasket and/or a cracked head. the pressure is from combustion gasses, and it gets hot because of all the air pockets that the gasses cause.
The coolant was down several inches when cold...that is why I suspect a bad thermostat. Could the coolant fill the radiator from the bottom hose but then not enter the block from the top hose because the thermostat is stuck closed? Or does it flow the other way?
mikestertwo
Well-Known Member
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- Sep 13, 2006
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- 5,249
Fill the cooling system and put the cap back on. Your scenerio is normal.
groumoutis
Active Member
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- May 1, 2009
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Do you have a reliable temp gauge in the car and do you know what degree thermostat is in the car as well? Either you can pull the thermostat and boil it in a pan of water while you monitor what temp it opens or you can tell by the temp gauge in the car when the thermostat opens while you have the radiator cap off. When the thermostat opens you will see the level drop like a rock and it will drop fast. The temp shouldn't get over 200 since the factory thermostats were under 200. I have a 160 thermostat and according to the scanmaster the thermostat is fully open at 162.
If you do pull the thermostat out here is a great tip for you.... Pry the thermostat open and wedge a aspirin between the sealing surfaces so the water car flow through the system to purge out all the air. This works very well and the aspirin dissolves in a minute or so.
If you do pull the thermostat out here is a great tip for you.... Pry the thermostat open and wedge a aspirin between the sealing surfaces so the water car flow through the system to purge out all the air. This works very well and the aspirin dissolves in a minute or so.
