Coolant system question

[asexton]

I installed a low temp thermostat and drained a few gallons of coolant. I didn't drain the whole system cause it was done a few months back. I used the Uview 55000 and couldn't get more than 20psi due to the coolant in the system still. I used it and filled the system up. I just wanted to make sure 20psi is good enough to remove all the air from the system. I ran it and then topped off the coolant. Thanks for the advice!

Adam

[JFP in PA]

The level of vacuum produced in the system with the Uview tool is not affected by the amount of remaining coolant in the system; it is a function of the level of airflow available from the compressor used, and how tight the cooling system is. The bigger question that needs to be asked is did it hold 20 inches of vacuum for at least 5 min. before you opened the valve to fill the system? If not, you may have had a coolant system leak, which kept the system from reaching maximum vacuum.

[asexton]

It held 20psi for 5 minutes. I started to get coolant out of the tube on the uview after 20psi. Should I hook it up again and try to get 25psi?

[JFP in PA]

First of all, the Uview gauge reads in inches of vacuum, not PSIG. Secondly, vacuum should not move the liquid in the system, unless the liquid is being pushed by entrapped air behind it that is trying to get out. We use one of these systems just about daily, and the only time we have ever seen coolant liquid pulled by it is when there was air still in the system that was moving towards Uview unit. If that happens, you need to “throttle” the air pressure to the Uview unit so that the vacuum level comes up more slowly to allow the air pockets time to escape. We always pull vacuum until the system is at 25-27 inches, where we hold it to test for leaks.

Contrary to what I have seen published online; the Uview system is incapable of moving liquid unless the end of the Uview unit is actually submerged in the fluid, or there is an air pocket pushing the liquid.

[asexton]

Thanks for the info!

[BFeller]

Originally Posted by JFP in PA

First of all, the Uview gauge reads in inches of vacuum, not PSIG. Secondly, vacuum should not move the liquid in the system, unless the liquid is being pushed by entrapped air behind it that is trying to get out. We use one of these systems just about daily, and the only time we have ever seen coolant liquid pulled by it is when there was air still in the system that was moving towards Uview unit. If that happens, you need to “throttle” the air pressure to the Uview unit so that the vacuum level comes up more slowly to allow the air pockets time to escape. We always pull vacuum until the system is at 25-27 inches, where we hold it to test for leaks.

Contrary to what I have seen published online; the Uview system is incapable of moving liquid unless the end of the Uview unit is actually submerged in the fluid, or there is an air pocket pushing the liquid.

JFP in PA - thanks for posting this information. It just answered a question that interested me.