2008 GX470 using coolant
06-03-17, 09:47 AM
#32
Driver School Candidate
No need to have it at the low line when cold. Though it is good practice to leave a little room for expansion. You want to have as much coolant as you can in there so that it'll be full when at operating temperature.
That'll provide a little margin of error should a slow leak develop when you're on a trip and you need to get it home. When my water pump started seeping before I did the timing belt job, that was helpful. I had to go on a trip and just checked the overflow tank level every once in a while. Never needed to add any (though I did have a partial bottle of toyota coolant in the trunk).
Not entirely unusual for it to overflow a little if it started at the full line when cold. If expansion is more than an inch or so of coolant level in the overflow tank, usually that means your radiator cap is bad (less pressure in the system than there should be) or it's running a tiny bit hotter than it should be (thermostat). These items are good to replace when replacing the radiator or when doing a timing belt job because they're cheap and important.
That'll provide a little margin of error should a slow leak develop when you're on a trip and you need to get it home. When my water pump started seeping before I did the timing belt job, that was helpful. I had to go on a trip and just checked the overflow tank level every once in a while. Never needed to add any (though I did have a partial bottle of toyota coolant in the trunk).
Not entirely unusual for it to overflow a little if it started at the full line when cold. If expansion is more than an inch or so of coolant level in the overflow tank, usually that means your radiator cap is bad (less pressure in the system than there should be) or it's running a tiny bit hotter than it should be (thermostat). These items are good to replace when replacing the radiator or when doing a timing belt job because they're cheap and important.
06-04-17, 10:38 AM
#34
Driver School Candidate
It does irk me a little bit when I've got fresh, properly mixed coolant, a new toyota radiator cap, and a new toyota thermostat, and it's still expanding a lot.
Maybe someone has more input for troubleshooting? I had a 15 year old camry at one point which overflowed a couple of times despite extensive maintenance.
Possible causes:
Coolant - if its boiling point is not correct (too much water in coolant mix)
Pressure - radiator cap not holding to rated PSI
Temperature - a bunch of possible variables .. first one to service being thermostat
In our lexus GXs there's no temperature sensor controlling the radiator fan .. so what else could it be? I'm thinking: System has air in it (self fixing, shouldn't be the case for very long), radiator less efficient than designed (years of debris in fins perhaps), some sort of blockage (I've never 'flushed' .. only used the water pump to circulate distilled water and drain many times to get out old coolant), water pump defective (probably not likely). What else can be the culprit - does the heater core cause problems sometimes? Nobody ever talks about the heater core.
As a data point: My GX has been perfect, never much expansion.
Maybe someone has more input for troubleshooting? I had a 15 year old camry at one point which overflowed a couple of times despite extensive maintenance.
Possible causes:
Coolant - if its boiling point is not correct (too much water in coolant mix)
Pressure - radiator cap not holding to rated PSI
Temperature - a bunch of possible variables .. first one to service being thermostat
In our lexus GXs there's no temperature sensor controlling the radiator fan .. so what else could it be? I'm thinking: System has air in it (self fixing, shouldn't be the case for very long), radiator less efficient than designed (years of debris in fins perhaps), some sort of blockage (I've never 'flushed' .. only used the water pump to circulate distilled water and drain many times to get out old coolant), water pump defective (probably not likely). What else can be the culprit - does the heater core cause problems sometimes? Nobody ever talks about the heater core.
As a data point: My GX has been perfect, never much expansion.
Last edited by 2008; 06-04-17 at 10:41 AM.
06-04-17, 11:14 AM
#35
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I think you nailed it with thinking it had air in the system and is burping it. I have been watching it and drive it 3 hours straight yesterday in the he 90 degree heat and no more puking. Hopefully it was self correcting.
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