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Mr. Mac
New User
Oct 30, 2008, 8:04 PM
Post #1 of 4
(1867 views)
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YES I HAVE A 1997 HONDA ACCORD, AND I AM HAVING PROBLEMS WITH IT GETTING HOT , I HAVE RECENTLY REPLACED THE RADIATOR AND THE HOSES AND THERMOSTAT , AND JUST YESTERDAY IT OVER HEATED AND MELTED THE RADIATOR CAP ANY ANSWERS THANKS
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Oct 30, 2008, 9:05 PM
Post #2 of 4
(1865 views)
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Fan(s) working? Are you sure all air is purged out when you fill the system?
From there it's going to be determining head gasket issues if all else is right,
T
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Mr. Mac
New User
Oct 31, 2008, 10:28 AM
Post #3 of 4
(1858 views)
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HOW DO YOU GO ABOUT PURGING THE SYSTEM
THANKS
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Oct 31, 2008, 11:14 AM
Post #4 of 4
(1851 views)
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Purging Cooling systems in motor vehicles
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That's a $40,000 dollar question. Vehicles differ in the ways you would do that and most would do it over several cycles by themselves if not allowed to boil in between cycles of cool/cold to full warm ups with thermostat open as it's a plug between whatever is in engine and what is on radiator side of a system. When cold it's shut of course and open when hot. The idea is for systems to push air/gasses out to recovery tanks which goes in thru the bottom and return just liquid in the expansion and contraction of warming up and cooling down.
When a system is low for any reason you need to know that it's truly full and some only give you a recovery tank to watch which is fine but isn't the whole story till all is known purged - then it means something.
When found low or after an overheat that loses coolant you fill where you can when engine is cool. Some will have bleeder plugs (plumbing plugs) at or near thermostats and some don't. Some you may need to unhook the highest hose and fill from there and allow several cycles or warm ups and cool downs - observing temps, pressure build up and loss when cooling noting heater can throw heat and temp needles stay stable. That's a good sign that the air is out.
When air/gasses are recurrent then a problem may exist with combustion gasses getting into the engine side which doesn't transfer heat well - causes late thermostat reaction and is constantly overwhelmed with air that just can't cool the engine and symptoms include.... heat not working, fast rise at recovery tanks and pressure building up sooner than normal from just expansion as it warms. When a system is opened and warm it shouldn't build up pressure so fast and if so the gaskets (head and intakes sometimes) can be the fault.
When dealing with a system with a cap on the radiator you would fill it as much as possible when cold - wait as it will drop some, fill again, then start till it warms to open thermostat with rad cap off (spills can happen and always use commons sense with warm/hot coolant AND note pressure as flash boiling can occur if not real careful) - and then coolant level will drop - sometimes out of sight and slow refill with engine running in that type usually finishes the job - cap can be put back on and let the rest purge out thru the cycles or warm and cool - observed over several cycles - heater running too as an indicator an helps to get air out when flowing.
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Some vehicle just behave the first round and that the end of it and some are a real pest. Some so difficult that you can have to jack up the vehicle such that the fill cap is the highest possible so air will go to the top from where it hides.
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There are other things that confuse the issue too: Fan(s) electric or by fan clutch must operate, debris must be clear for air thru radiator and of course the components must all be good.
Some rare problems include pumps that impellers are weak and some are strong and can collapse input hose from radiator - those subject to that usually put a spring inside that hose which prevents that.
So - the air needs to be known out for further diagnosis if a problem still exists. Each vehicle is a little different on how to properly fill them up and know it so there's no good "one size fits all" description for all cases. It takes time and patience to fill a system and rushing it isn't in order for this. It can help to take vehicles for a run around a block - stopping, starting up, steering left and right which swishes the coolant around inside to get the air in place to escape out thermostats to recovery tanks to not return again. The only thing we can count on is that air will rise to the top of it's area and as said at the beginning could be trapped inside engine by a shut thermostat. Hope that helps you understand how this is such an issue to at least rule out before more can be diagnosed if needed,
T
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