Tercel cooling system won't hold pressure

[babyjay8495]

94 tercel. I decided to finally flush the coolant on my old beater. I drained the radiator and blocked and hooked up my airlift coolant refill tool. It sucked the system down to 26 pounds, but would never hold steady pressure, would creep down. I didn't see any external leaks. I had to replace piston rings about a year ago, so the head gasket was replaced. Seems to cool fine and no other issues besides not holding pressure. Any reasons why it won't hold?

 

[The_Jeff]

Is that a vacuum exchange system? Maybe the hoses were collapsing?

I guess your next test is to (carefully) open the cap when it's warm to see if it makes any hiss.

 

[mechtech2]

A coolant system may leak from vacuum, but not pressure.
Or, visa versa.
26 is a lot either way, and you may have CAUSED a leak.

 

[StevieC]

I would fill it with liquid and keep and eye on the level. It's normal for it go down a bit over the first few days as the system works out any air, but then it should stay consistent. If it doesn't check the head gasket or for a cracked cylinder head if not leaking from under the car.

Being a '94 I would just keep topping it up and driving it and not worry about it unless it's in mint shape..

 

[highmilegeguy]

Originally Posted By: mechtech2
A coolant system may leak from vacuum, but not pressure.
Or, visa versa.
26 is a lot either way, and you may have CAUSED a leak.
Agreed. Testing pressure should be operating pressure arond 12-15. Pumping to 26 psi could easily burst a radiator tube or gasket somewhere.

Nothing like acting first and getting proper procedure second. Great way to inflict damage to a vehicle system.