radiator pressure test questions (9 Viewers)

[landcruiser3DP]

gents,

new wrench here. bear with me please.

i just pressure tested my radiator with a snap on loaner from a local toyota tech.

as i recall instructions were heater to ON position, verify the heater control valve is fully to the left/DS (i double checked it). and then 17 PSI and see if it holds.

i’m used to motorcycle tires and i didn’t get much pressure on it but before i continued i checked the gauge it appeared to be up at 80 PSI so i stopped. quickly. i see now i was at kilopascals which is roughly 12 PSI which held fine.

two questions.

1. i had to /file/ some of the vertical edge surface of the cap off (seems fine since it seals at the interior) but it was still a super, super tight fit so i am a bit sketched about doing it again since i don’t want to bust the flange. i don’t know why the flange on my radiator is so damn tight. but i’m wondering if i need to retest. in which case i will probably take a little more off the flange.

2. i had a whole lotta coolant spurt out of the adapter when i pulled the pressure tester off of it. it /appears/ to have come out of the overflow reservoir. what is going on here? do i need to let it sit 20 minutes to let it flow back to the reservoir? should i have a pressure release on the gauge (doh!)?

someone mind clarifying the physics for me so i know how to do it properly next time?

honestly i was so focused on being gentle with that flange i didn’t quite catch what was what.

THANKS

jon

 

[Tools R Us]

The adapter takes a little more force to install than a cap, if it's the correct one, should not damage the radiator. The cap spec is 13psi, so test at that or slightly more, 14-15psi. The point is to see if it holds pressure, if there is a leak, make it leak with the motor cold, makes it easier to see, work on.

 

[landcruiser3DP]

The adapter takes a little more force to install than a cap, if it's the correct one, should not damage the radiator. The cap spec is 13psi, so test at that or slightly more, 14-15psi. The point is to see if it holds pressure, if there is a leak, make it leak with the motor cold, makes it easier to see, work on.

thanks man. i worked it for a week. no way the adapters (the correct ones) would fit. just some crazy oversizing on the radiator flange. i had to take like 1mm off the diameter with a file. then it barely fits.
so 12 PSI and no pressure drop is not enough and i need to see 14/15 i guess and can i just see that it HOLDS the PSI?
ALSO, did i somehow pump pressure into the reservoir with the cap on. then when i pulled the pressure tester the pressure escaped (along with coolant) out the adapter?!
i had a /geyser/ of coolant come out...

 

[Tools R Us]

Not sure what your goal is, but if it holds 12psi, it doesn't have a leak, is likely to hold 15psi. If there is air in the system, some liquid can be pushed out when the pressure is released.

 

[ToyotaMatt]

did your adapter come with a variety pack of thickness size rubber gaskets like shims ? gaskets

 

[landcruiser3DP]

did your adapter come with a variety pack of thickness size rubber gaskets like shims ? gaskets

yeah. the plastic (or whatever it is) flange is just like 1+mm oversized on the OD. kinda crazy. just no way it would fit the OD. i had to take a file to it. if i do it again i’ll take another 0.5mm off so it won’t be so sketchy this time. still a /very/ tight fit...

 

[ToyotaMatt]

like my snap-on tester has ?


my black toyota adapter is a MATCO brand

 

[ToyotaMatt]

those series of rubber gaskets are like shims , and too much or many would have made life hard installing the adapter

not enough and u will have a Leak Down

 

[landcruiser3DP]

Not sure what your goal is, but if it holds 12psi, it doesn't have a leak, is likely to hold 15psi. If there is air in the system, some liquid can be pushed out when the pressure is released.

thanks man. i really appreciate it. i just wanted to make sure nothing - like the heater core or radiator was leaking. pre-purchase inspection said the radiator was leaking and then when i got in there there was a bad hose spewing coolant on the ground, windshield was misted with coolant then the carpet was wet so it was all a bit hard to figure.
can i just ask the mechanics of the air in the system? i was wondering about that but couldn’t figure it out. air is in the system somewhere? i put pressure in the system and the air compresses more easily than the liquid and then it expands to expel the coolant?!
how does the air normally escape or does it just stay in there? or how did it even get in?
/also/ why was the overflow empty when the coolant was expelled? i guess it free flows back into the radiator to refill it when the radiator loses coolant?
sorry for the dumb questions (and i’m not even sure they are all explainable) i’m just curious how it works and to make sure i am taking care of it correctly...
THANKS

 

[CaptClose]

I am not near an FSM and maybe someone can confirm for me, but I think the system should hold pressure up to 20-21 PSI. Definitely check before you go that high, I could be thinking of another vehicle’s spec, or I could be high.

There should be a little purge valve on your tester to depressure the system before disconnecting the tester. You’ll still get some seapage usually though, but not a geyser.

 

[landcruiser3DP]

those series of rubber gaskets are like shims , and too much or many would have made life hard installing the adapter

not enough and u will have a Leak Down




View attachment 1871401

thanks racingmatt. i think i caught that on another thread (thanks) and was too jammed up to answer.

i double checked. it is definitely the OD of the radiator flange in relation to the ID of all the adapters. the radiator cap will go on (obviously) but none of the adapters would fit over. i checked and rechecked. it was just simply too wide an OD to get the adapters over.

no one had ever heard of it. so i sat on it for like a week but i have to get this kit back. so i took about a mm off the OD and it goes over and gets down to seal. if i had to do it again i’d take off anouther 1/2 mm and not worry about ripping the flange off when getting the adapter off. it was still super sketchy getting that adapter off.

a bit bizarre but that’s what seems to be happening.

 

[landcruiser3DP]

I am not near an FSM and maybe someone can confirm for me, but I think the system should hold pressure up to 20-21 PSI. Definitely check before you go that high, I could be thinking of another vehicle’s spec, or I could be high.

There should be a little purge valve on your tester to depressure the system before disconnecting the tester. You’ll still get some seapage usually though, but not a geyser.

thanks man. i thought there might be something like that.
but...i guess the purge valve lets out the air in the gauge? if so, i’m starting to think a s***load of coolant would have still come out.
unless somehow popping the overflow cover off first would let air out. but not even sure the overflow would be getting tested.
anyway, i had to /refill/ the overflow. lot of coolant came out...

 

[Tools R Us]

...
can i just ask the mechanics of the air in the system? i was wondering about that but couldn’t figure it out. air is in the system somewhere? i put pressure in the system and the air compresses more easily than the liquid and then it expands to expel the coolant?!

If the system was worked on it likely has air in it, also pumping the tester puts air. The key is releasing the pressure slowly, I don't use the valve, just slowly remove the tester cap fitting.

... how does the air normally escape or does it just stay in there? or how did it even get in?
/also/ why was the overflow empty when the coolant was expelled? i guess it free flows back into the radiator to refill it when the radiator loses coolant?

Air gets in from leaks or work on the system. After working on the system, I run it with the cap off, heater on, watch the coolant level and keep it close to topped, until the thermostat opens, coolant circulates. When the level stabilizes, top it off and cap it.

The overflow should always have coolant in it. As the motor warms, some coolant is expelled into the overflow, when the motor is turned off, as it cools, coolant is sucked back from the overflow. Any air in the system will work it's way to the cap, the normal process will expel it through the overflow. After working on it, a couple of warm/cool cycles will remove any remaining air, just check the overflow level, fill as needed.

 

[Howard705]

I always make sure it is 100% dry- as in hosed off if I spilled any coolant the driven and warmed to dry are best.- preferable to test it cold so no expansion or contraction of coolant caused by temp change changing pressure- carefully installed- I always overpump pressure way up. - then leave it for an extended time and watch gauge ANY drops in pressure watch for seepage at connections- gaskets etc etc. if you have a couple houre while you do something else so much the better. big drops where you don't see coolant on the ground investigate HG etc- into cyl or oil.

 

[landcruiser3DP]

I always make sure it is 100% dry- as in hosed off if I spilled any coolant the driven and warmed to dry are best.- preferable to test it cold so no expansion or contraction of coolant caused by temp change changing pressure- carefully installed- I always overpump pressure way up. - then leave it for an extended time and watch gauge ANY drops in pressure watch for seepage at connections- gaskets etc etc. if you have a couple houre while you do something else so much the better. big drops where you don't see coolant on the ground investigate HG etc- into cyl or oil.

thanks.

 

[landcruiser3DP]

If the system was worked on it likely has air in it, also pumping the tester puts air. The key is releasing the pressure slowly, I don't use the valve, just slowly remove the tester cap fitting.



Air gets in from leaks or work on the system. After working on the system, I run it with the cap off, heater on, watch the coolant level and keep it close to topped, until the thermostat opens, coolant circulates. When the level stabilizes, top it off and cap it.

The overflow should always have coolant in it. As the motor warms, some coolant is expelled into the overflow, when the motor is turned off, as it cools, coolant is sucked back from the overflow. Any air in the system will work it's way to the cap, the normal process will expel it through the overflow. After working on it, a couple of warm/cool cycles will remove any remaining air, just check the overflow level, fill as needed.

thanks a lot. this all makes sense.

so, it sounds like the overflow container is basically being tested in some way? or i guess 17 PSI is too low to force any fluid through to the container i suppose?

the thing i am missing in this case though is what happened. i had the overflow topped off at full line. and removing the gauge resulted in a constant 2’ high /stream/ of fluid out the hole in the adapter.

the overflow is topped off now. and obviously the radiator is topped off.

no need to crack the cap open a little and ride it like that to vent air out the radiator cap? or maybe i need to crack the overflow cap and try to see if air can get expelled through it?

either way i guess i will give it another test here while i have the kit. this time i make sure car is cold. overpressurize slightly and let the gauge sit for awhile.

/appreciate/ it.

 

[ZackR]

When cold the overflow should be closer to the low line. As the coolant warms up and expands it will also increase the level in the overflow tank so you need space for it to go. During cool down after the engine is off coolant will be sucked back into the radiator as it contracts.

 

[landcruiser3DP]

When cold the overflow should be closer to the low line. As the coolant warms up and expands it will also increase the level in the overflow tank so you need space for it to go. During cool down after the engine is off coolant will be sucked back into the radiator as it contracts.

thanks zack. yeah i think i got this. i wasn’t sure if just keeping it at full when cold mattered. when the radiator heats up it still has plenty of room to go upward in the tank.
also, it seems simpler this way somehow. just fill to fill when cold and call it a day.
the thing that is bugging me is why i has a freaking geyser after testing a cold engine. i’m guessing there is air in the system that compressed, the i removed the gauge and it skewed out the adapter. i even let some of it sit in the adapter 10 minutes and it still didn’t go down.
i’m guessing there is air back in the system that can’t get out or hasn’t gotten out?

can i run it with the red cap cracked and hope it works it’s way out? i guess i need to run it with the heater on and until it got hot enough for the thermostat to open the path to the heating system or something?!

do i need to make sure the thermostat is open to run the pressure gauge test somehow?!

either way i will probably try a retest today.

 

[Tools R Us]

No need and don't see the point of pressure testing with the thermostat open, coolant warm.

Not sure what problem you are looking for, but a correctly working system will eject any air with a few heat/cool cycles. Better if done with the heater on, fan isn't needed, low is better than hi.

The overflow tank doesn't hold pressure, vents to atmosphere, so no way or need to pressure test.

If the system held pressure, why are you testing again?

 

[landcruiser3DP]

No need and don't see the point of pressure testing with the thermostat open, coolant warm.

Not sure what problem you are looking for, but a correctly working system will eject any air with a few heat/cool cycles. Better if done with the heater on, fan isn't needed, low is better than hi.

The overflow tank doesn't hold pressure, vents to atmosphere, so no way or need to pressure test.

If the system held pressure, why are you testing again?

i just had it on for a couple of minutes and it didn’t move at all. but also i wasn’t sure if the ~12 PSI was sufficient. would have run it to 17 if i didn’t get clutched misreading the gauge like a dope.

also, if i have the gage i may as well use it before returning it.

so, “heat/cool cycle” implies running the vehicle with the heat control slider set to hot and low fan? i didn’t quite follow that.

but i’ve run the car quite a bit with both AC and heat on so i am a tad confused why i would have air in the system expelling coolant i guess...