Cooling system question.

[captaingamez]

Alright I have a situational question. this is not a datsun question but would apply the same way I suppose. heres the situation. this is an 87 Toyota Supra with 7M N/A engine.

 

Cooling pressure remains after 9 hours and sometimes remains when the engine is cooled totally.

 

now before we go down the Blown Head Gasket road, I will say that the system has been tested for contaminates, and there is nothing, zilch, and nada. totally clean water.with no hydrocarbons or COs.

 

also leak down tested and No sign of a BHG.

 

Running just water wetter. and a 1.3 bar cap, radiator and lines all new or in excellent condition, new thermostat new water pump, pressurized reservoir with 1.3 bar cap. No actual problems with the car, nothing is wrong with it whatsoever, and it gets beaten hard, and sits in traffic for 2 hours and never overheats.

 

Obviously this isnt "normal" per say. but is it a cause for concern? especially if everything is known in excellent condition and theres no issues with the car?

[captaingamez]

bump

[Ratwagon1600]

Are you running what we call an expansion tank (auxiliary reservoir) and if so have you checked/replaced the cap on that tank?

 

Faulty cap on the expansion tank may? Cause cooling system not to depressurize after extended period.

 

Apart from that, FIIK.

[q-tip]

There will always be some pressure, its a sealed system. The over flow tank only captures coolant that has been bypassed by the cap because of too much pressure. If its popping the valve on the cap then you have so etching to worry about. If there is just a suction noise when you pull the cap off that's normal.

[captaingamez]

yes

 

Are you running what we call an expansion tank (auxiliary reservoir) and if so have you checked/replaced the cap on that tank?

Faulty cap on the expansion tank may? Cause cooling system not to depressurize after extended period.

Apart from that, FIIK.

yes were running an expansion tank, it has 1.3 bar caps on both tanks and both are new from the same company, so they should theoretically be in good condition.

 

as I said is it even a cause for concern? q-tip, your saying it should always have a little pressure in it, thats kind of what I thought too.

[q-tip]

Yeah, the cooling system is completely sealed when all the caps are on and there are no leaks so some pressure will be there just from the system heating and cooling

[]2eDeYe]

Bad cap would cause the system to over pressurize. The cap valve should be opening to relieve any pressure over its rating. The system will usually stay pressurized as it is a sealed system until the cap pressure is reached, any pressure loss below that would be due to the cooling of the coolant.

 

That just reads weird :lol: