Coolant Pressure Tester results
Thread Starter
Burning Brakes
Joined: Jan 2015
Posts: 875
Likes: 76
Coolant Pressure Tester results
When you connect a coolant pressure tester to the radiator and the engine is cold. What should the needle do as you let the car idle on up to operating temp?
I noticed after the thermostat started opening, that the needle started working it's way up and got to 20 psi. Then the radiator fan turned on, and the needle dropped down to 9-11 psi when the fans turned off, then the needle worked it's way back up to 20 psi until the fans turned on.
Wondering if that's normal?
I assume if the radiator cap was on there, then the pressure would only get to 16 psi and the rest would bleed off into the overflow tank?
I noticed after the thermostat started opening, that the needle started working it's way up and got to 20 psi. Then the radiator fan turned on, and the needle dropped down to 9-11 psi when the fans turned off, then the needle worked it's way back up to 20 psi until the fans turned on.
Wondering if that's normal?
I assume if the radiator cap was on there, then the pressure would only get to 16 psi and the rest would bleed off into the overflow tank?
Safety Car
Joined: Aug 2002
Posts: 3,842
Likes: 230
From: SANTA CRUZ CA
What I learned from the following link: lubricate tester gasket, pump to 20 psi....read the rest:
https://www.corvetteforum.com/forums...um-tester.html
https://www.corvetteforum.com/forums...um-tester.html
Last edited by don hall; May 12, 2015 at 10:16 PM.
Thread Starter
Burning Brakes
Joined: Jan 2015
Posts: 875
Likes: 76
The test I was doing is seeing if the system was over pressurizing while running. I'm thinking I've read over pressurizing would show up while the engine is cold and running. i.e. psi shoot up shortly after starting up if I remember correctly.
I replaced the original OEM radiator a year or so ago. And the aftermarket radiator recently started leaking. Don't know where, but dripping out the passenger drain hole same as where the OEM was dripping out of.
So replaced the aftermarket radiator with a Harrison and after that the heater core started leaking.
Did a block leak test a couple of years ago, so will redo that. Wanted to check that out before putting in a new heater core.
I replaced the original OEM radiator a year or so ago. And the aftermarket radiator recently started leaking. Don't know where, but dripping out the passenger drain hole same as where the OEM was dripping out of.
So replaced the aftermarket radiator with a Harrison and after that the heater core started leaking.
Did a block leak test a couple of years ago, so will redo that. Wanted to check that out before putting in a new heater core.
Safety Car
Joined: Aug 2002
Posts: 3,842
Likes: 230
From: SANTA CRUZ CA
The following link has suggestions for sources:
https://www.corvetteforum.com/forums...or-1988-a.html
Race Director
Joined: Apr 2003
Posts: 17,700
Likes: 1,667
From: moraga ca
If you have a 17 lb radiator cap, the pressure won't get over 17 lbs. the cap can be tested off the radiator. I'm not sure what you were doing sealing off the system and running the motor. You could have blown a hose or the radiator
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Thread Starter
Burning Brakes
Joined: Jan 2015
Posts: 875
Likes: 76
Sounds like a new heater core is in order.
The following link has suggestions for sources:
https://www.corvetteforum.com/forums...or-1988-a.html
The following link has suggestions for sources:
https://www.corvetteforum.com/forums...or-1988-a.html
Though the heater core could have had a slow leak and finally went. As in the past I would think sometimes I'd smell coolant inside briefly, but the carpet would be dry.
Thread Starter
Burning Brakes
Joined: Jan 2015
Posts: 875
Likes: 76
The psi only reached 20 psi. I was watching it and would have shut it off before going into the red. Looks like from what I've read the system is rated at 20 psi max. So shouldn't have done any harm.
Melting Slicks
Joined: Aug 2008
Posts: 2,082
Likes: 50
From: Palmdale CA
[QUOTE=colter;1589618899]Was just checking to see if there was an apparent over pressurizing condition. Had read of hooking the coolant pressure tester up and running the engine to see if the psi quickly spiked.
The psi only reached 20 psi. I was watching it and would have shut it off before going into the red. Looks like from what I've read the system is rated at 20 psi max. So shouldn't have done any harm.[/[QUOTE]
This time!
Your Radiator cap is an pressure relieving device, without it you have "0" safety margin.. I personally watched an upper Radiator hose burst on a Hot engine at 18 years old, I suffered from 3rd degree Burns.. Now I have a dislike for Mustangs, and Hot water
The psi only reached 20 psi. I was watching it and would have shut it off before going into the red. Looks like from what I've read the system is rated at 20 psi max. So shouldn't have done any harm.[/[QUOTE]
This time!
Your Radiator cap is an pressure relieving device, without it you have "0" safety margin.. I personally watched an upper Radiator hose burst on a Hot engine at 18 years old, I suffered from 3rd degree Burns.. Now I have a dislike for Mustangs, and Hot water