Expansion Tank Levels

Bill UK · 09-07-2008, 10:19 AM

Probably a bit paranoid about the coolant expansion tank levels, like most of us who have had their fair share of BHG`s. I haven’t found any information relating to what should be the normal increase in level after an average journey, (if there is such a thing). So lets say the thermostat, water pump, radiator, rad cap, fan etc are all working correctly, what would you expect the level to be increased by from a cold start up to the end of 40 mile trip. This obviously depends on county, climate, altitude and driving conditions. In theory water expands with temperature the nearer the boiling point the larger the increase in volume. Can anyone give me some increase in levels on their Supra?

fienloco · 09-11-2008, 03:22 AM

Say there. I noticed the same thing you are concerned about today on my 87 MKIII. I just did a HG. Went for about a twenty mile drive got home looked at the expansion tank it was high let her cool down and she dropped down to its normal level. If that helps. My gauge does not read hot either. So Im guessing it is somewhat normal. So do you know what the beginning of a clutch failure feels like?

Bill UK · 09-11-2008, 06:57 PM

Thanks for the info, that sounds reassuring. Like you I've just done a HG replacement, no gurgling noise behind the dash at start up,the expansion tank coolant rises about ? to ? of an inch after a 40 mile trip (with moderate boost) Left over night and the coolant is sucked back into the system as it should. I put the expansion tank in the dishwasher to give it a good clean and marked the max level with black marker pen, probably should have left it dirty then I wouldn’t have noticed the level increase. Your question about the clutch; one way to test a slipping clutch is to drive up a hill and accelerate hard and see if the speed increase in relation to the rev`s, or on a flat road put it into say 4th about 30 miles per hour and accelerate hard, if its slipping the revs will increase but the speed will marginally increase. If you smell something burning it will most defiantly be the clutch.

09-07-2008, 10:19 AM	#1
Bill UK AEM EMS Join Date: Jul 2006 Location: UK Posts: 891	Expansion Tank Levels Probably a bit paranoid about the coolant expansion tank levels, like most of us who have had their fair share of BHG`s. I haven’t found any information relating to what should be the normal increase in level after an average journey, (if there is such a thing). So lets say the thermostat, water pump, radiator, rad cap, fan etc are all working correctly, what would you expect the level to be increased by from a cold start up to the end of 40 mile trip. This obviously depends on county, climate, altitude and driving conditions. In theory water expands with temperature the nearer the boiling point the larger the increase in volume. Can anyone give me some increase in levels on their Supra?

09-11-2008, 06:57 PM	#3
Bill UK AEM EMS Join Date: Jul 2006 Location: UK Posts: 891	Thanks for the info, that sounds reassuring. Like you I've just done a HG replacement, no gurgling noise behind the dash at start up,the expansion tank coolant rises about ? to ? of an inch after a 40 mile trip (with moderate boost) Left over night and the coolant is sucked back into the system as it should. I put the expansion tank in the dishwasher to give it a good clean and marked the max level with black marker pen, probably should have left it dirty then I wouldn’t have noticed the level increase. Your question about the clutch; one way to test a slipping clutch is to drive up a hill and accelerate hard and see if the speed increase in relation to the rev`s, or on a flat road put it into say 4th about 30 miles per hour and accelerate hard, if its slipping the revs will increase but the speed will marginally increase. If you smell something burning it will most defiantly be the clutch. Last edited by Bill UK; 09-11-2008 at 07:52 PM.

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09-11-2008, 03:22 AM	#2
fienloco Intake Join Date: Apr 2008 Location: Pueblo,CO Posts: 33	Say there. I noticed the same thing you are concerned about today on my 87 MKIII. I just did a HG. Went for about a twenty mile drive got home looked at the expansion tank it was high let her cool down and she dropped down to its normal level. If that helps. My gauge does not read hot either. So Im guessing it is somewhat normal. So do you know what the beginning of a clutch failure feels like?