BRZ overheating

[86kahl]

Air bubble. You gotta jack up the drivers side and run it with the heater on

[Poodles]

Originally Posted by justatroll

So a car's cooling system will not work when first started up because it is not under pressure.... got it.

Living up to your name, got it.

Originally Posted by justatroll

He is overheating in just 10 miles. That is NOT due to ONLY a pinhole leak,
Like I said:

10 miles is long enough to get up to operating temp, so yes it could be that issue.

Originally Posted by justatroll

it could only be caused by a pinhole leak which caused another problem, like a bubble in the system.

This is like arguing that you didn't kill a guy because he died from blood loss because you shot him... Cause and effect, learn it.

Originally Posted by justatroll

My Point was that the system does not need to be pressurized before water starts moving through it.
If his car is overheating in 10 miles it is NOT because of a pinhole leak UNLESS the pinhole leak CAUSED A BUBBLE.
Which was precisely what I meant in my first post:


I guess that English reading comprehension is not your strong suit.

10 miles and it's up to operating temp which means you'd easily have localized boiling in the heads if the system isn't pressurized. It's a self regulating system, and even goes into vacuum when it's cooling down. This all happens at once, heat = pressure.

Originally Posted by Notso

update. On Monday I went to Autozone to rent a pressure tester, and the cap for the pressure tester didn't fit my radiator. I even asked him if there was additional caps, he said it would be fine.
Anyways I got fed up and just installed a new waterpump. The leak is now completely gone, thought it's still overheating. not to the extent it was, and I can drive longer distances, about 15 miles before it overheats (and people when I say overheat, I mean like 3/4 on the gauge, I'm obviously not driving it around redlined with the check engine light on)
So the past 3 nights i've been burping (bleeding) the cooling system, with minimal bubbles coming up, but some. I guess i'm going to keep bleeding it, and if that doesn't work i guess find a pressure tester that fits my cap... any other suggestions? Thank you

There is a adapter for the pressure tester for asian cars. He apparently didn't know that.

You're just changing things without knowing the issue. You also keep driving it when the more you overheat, the more likely you are to blow a headgasket or something...

[Notso]

Originally Posted by 86kahl

Air bubble. You gotta jack up the drivers side and run it with the heater on

why the driver side? i figured jacking up the passenger side where the radiator is so the air bubbles would naturally go to the highest point

[justatroll]

Originally Posted by Poodles

Living up to your name, got it.
..

Ok, I give up.
If you are so certain of your statement than you can explain WHY a closed loop system "requires pressure" to operate.

If it is so simple, Please.

[86kahl]

When bleeding coolant put the thermostat as high up as possible

[Poodles]

Originally Posted by justatroll

Ok, I give up.
If you are so certain of your statement than you can explain WHY a closed loop system "requires pressure" to operate.

If it is so simple, Please.

Because it's NOT a closed system. Even if it was, it builds it's own natural pressure!

Of course that is unless you go with a waterless coolant that doesn't expand with temperature, but that's beside the point.

[steve99]

There is a bleed valve in the top heater hose at rear of engine its in the 90 degree connector. Use that to bleed system , have heater on full hot setting

When you driving turn the heater in car on full with fan running for heater on full. Does it blow rearly hot air when car is hot, if not the coolant is not circulating, check for blocked radiator or hoses or the thermostat is in backwards. you have already replaced pump.

[Notso]

So, it seems to be getting better each time I bleed it, but it still doesn't like to be idle at a stop light, or going over 50, even in 6th low rpms. Casual town driving 35mph it seems to be doing fine though, about half temp on the gauge. The hottest it gets now is just under 3/4 on the gauge, still not comfortable with that. I'm hoping it's just a really pesky airbubble. I've jacked up the car, both sides at different times, squeezed the radiator hoses. Used the air bleed valve, revved the engine while bleeding, heater on etc...

Originally Posted by steve99

There is a bleed valve in the top heater hose at rear of engine its in the 90 degree connector. Use that to bleed system , have heater on full hot setting

When you driving turn the heater in car on full with fan running for heater on full. Does it blow rearly hot air when car is hot, if not the coolant is not circulating, check for blocked radiator or hoses or the thermostat is in backwards. you have already replaced pump.

The front and lower radiator hoses are both hot when the car is up to running temp.. the heater doesn't blow really hot air but it's hot, the thermostat isn't in backwards, the jiggle pin is facing to the back of the car

[mav1178]

Originally Posted by Notso

So, it seems to be getting better each time I bleed it, but it still doesn't like to be idle at a stop light, or going over 50, even in 6th low rpms. Casual town driving 35mph it seems to be doing fine though, about half temp on the gauge. The hottest it gets now is just under 3/4 on the gauge, still not comfortable with that. I'm hoping it's just a really pesky airbubble. I've jacked up the car, both sides at different times, squeezed the radiator hoses. Used the air bleed valve, revved the engine while bleeding, heater on etc...

The only thing left to do (after you've ruled out mechanical possibilities) is to get a reader that can read engine coolant temps from the ECU. The possibility of normal coolant temp(s) and a faulty sensor is there, we just haven't ruled it out.

-alex

[WolfpackS2k]

Originally Posted by Notso

So, it seems to be getting better each time I bleed it, but it still doesn't like to be idle at a stop light, or going over 50, even in 6th low rpms. Casual town driving 35mph it seems to be doing fine though, about half temp on the gauge.r

Okay that seems pretty odd. Does the BRZ's engine have really bad airflow? Because even a halfass semi non-functional cooling system should be sufficienct when you're cruising above 50 mph in high gear from natural airflow (unless it's like 100°+ outside). I know from experience

[Notso]

Originally Posted by WolfpackS2k

Okay that seems pretty odd. Does the BRZ's engine have really bad airflow? Because even a halfass semi non-functional cooling system should be sufficienct when you're cruising above 50 mph in high gear from natural airflow (unless it's like 100°+ outside). I know from experience

it was only mid 80's

[justatroll]

Originally Posted by Poodles

Because it's NOT a closed system. Even if it was, it builds it's own natural pressure!.

Part of this discussion keeps revolving around some misconceptions obout HOW these systems work:

You stated the following:

Originally Posted by Poodles

BS. Cooling system works because it's pressurized. Lose the pressure and it causes localized boiling, massive over pressure, and very rapid overheating. Pinhole leak is all it takes to lose pressure.

When talking about a cooling system, there are TWO kinds of "pressure".

The system may (or may NOT be) under an increased absolute pressure with respect to atmospheric pressure. The system is (by definition) "Closed" as it is allowed to have an absolute pressure that is different than the atmosphere. It is also "closed" due to the fact that the system's water pump does not have to pump against any "head" (there is no uphill vs downhill). Another condition of a "closed loop" system is that it's working fluid volume remains constant during operation (if you let any coolant escape, it doesnt get replenished).

The system most definitely MUST have a differential pressure which is completely different than absolute pressure.

For the system to provide cooling it requires differential pressure (provided by the water pump) to circulate the water through the cooling passages and through the heat exchanger (radiator).
No differential pressure, no flow, no cooling.

The fact that the system pressurizes due to the water reaching boiling temperature has absolutely nothing to do with the operation of the system EXCEPT: If the system did not maintain a CLOSED LOOP SYSTEM during steady state operation, the coolant would boil away and leave you with no working fluid.

So does the system need to be "pressurized" wrt to atmospheric pressure to operate?
NO.

Now what are we talking about wrt burping and why can the system stop "pumping" and overheat badly?

What can stop the cooling system from operating?
1 - The heat cannot move from the heat source (engine) to the working fluid
2 - The heat cannot move from the working fluid to the heat exchanger (radiator)
3 - The heat exchanger cannot transfer heat to the heat sink (atmosphere).
4 - The working fluid cannot move from the heat source to the heat exchanger (pump not pumping)

So now that we have that cleared up, we can refer to the 4 conditions above when trying to figure out why the system stopped working.


And lets not forget that there are three possibilities occurring in the OPs case:

A - The Engine is fine except the cooling system is malfunctioning
B - The Cooling system is fine but the engine is producing too much heat and the cooling system cannot handle the heat load.
C - The engine is not really overheating but the temperature indicators are malfunctioning.

OR....
Has anyone suggested checking for:
Oil in the water?
Water in the Oil?
Inability of the cooling system to maintain pressure under a pressure test?

Because any of those things could indicate a blown head gasket.

Or you could just stick your HEAD IN THERE and LOOK for a blown head gasket.....

Originally Posted by extrashaky

LOL. Let's start with this:
In your quest to make this easy diagnosis as complicated as possible, you're missing the simple fact that it isn't necessary to heat up and cool off the motor to poke your noggin under the car and visually inspect for leaks of not-invisible coolant.

And YOU are too dense to realize two simple facts (no really they ARE FACTS, but extra will work overtime to say otherwise):
some leaks (such as a blown head gasket) will only present themselves when the system is under pressure
it is infinitely easier to stick your head in an engine bay and look for coolant leaks when the engine is not running and cold as opposed to running and HOT.

[extrashaky]

Nah. Never mind. This guy obviously didn't pass middle school earth sciences class, so arguing with him is pointless.

[justatroll]

Originally Posted by extrashaky

Nah. Never mind. This guy obviously didn't pass middle school earth sciences class, so arguing with him is pointless.

The guy that builds, tests, and flies interplanetary probes for NASA.
.. earth science class.....
Riiiiight...... Got it.

You clearly WERE going to say something but thought better of it.
Because you are out of YOUR class maybe?

Oh and what can cause #4 above (pump not pumping)?
How about 'cavitation'? You might want to look that up.