acsX

Hello, I'm currently doing a coolant flush but ran into a problem. With my Uview 550000, I can only draw the vacuum to a max of 16 psi. It reaches 10 psi quickly, but past that takes a bit longer. However, when I close the valve, it stays steady and does not leak. All the cooling hoses are sucked in when drawing a vacuum and I'm not able to hear any leaks. There is a little bit of coolant at the very bottom of the coolant tank.

okie981

What vacuum are you trying to reach? A vacuum of 16 psi would be absolute vacuum I believe because standard atmospheric pressure is 14.7 psi, IIRC.

acsX

The recommended/suggested 24-26 psi

MrMoose

The gauge is in inches of mercury vacuum. So 30 is full vacuum.

Anyway, what pressure compressed air are you using? The Uview needs a minimum of 90 PSI. If you have a small compressor, you may need to close the valve on the Uview to hold vacuum in the system and then disconnect the compressed air line to let your compressor build up pressure again. If your compressor's really small you may need to do that a couple of times.

acsX

I've been using 120 psi for the compressed air (goes all the way up to 165)

okie981

You may have a leak between the shutoff valve of the UView and the vacuum created by the venturi effect nozzle, or your compressor isn't flowing enough air. It takes sufficient air flow, not pressure, to enable the venturi nozzle to do its thing. You need CFM flowing out of your air compressor, not just one with ability to create high pressure.

MrMoose

It's holding 120 or is it dropping below that as you vacuum the system? Like I said, if the pressure in the tank falls below 90 you'll probably need to stop to let the compressor catch up.

Also, you're pulling vacuum at the overflow tank in the engine bay, right? Not the fill port? At least on a 987.2 Cayman the latter won't work as the cap on the overflow tank has vacuum relief.

acsX

I do feel air around the venturi effect nozzle when it is running. Not too often, some water or liquid drips out of the side in which I have the air nipple attached to. The air compressor I'm renting out is rated for 2.6 SCFM at 90 psi. How much air flow is recommended?

I didn't look, although I probably should've. I do not have much experience with air compressors. I am running it from the overflow tank, yes.

MrMoose

So that's a smaller compressor but it should work...mine's the same SCFM rating (3 gallon Craftsman) and it was able to do the job.

Try this: evacuate the system and get the vacuum as high as you can. Then shut the valve to hold vacuum in the car, disconnect the air line, and let the compressor run until it stops again. Now try to evacuate again: if the pressure goes down further then you've solved your problem, just repeat this process until it's in the green.

Jim981CS

^ this
I think this sounds like the best solution with a small compressor. I have a 60 gallon compressor with 11.5 SCFM @ 90 psi and it has no problem pulling 25 inches of vacuum with the air lift when I installed my center radiator. I seem to recall that the more complete the drain that the easier it is to pull the 25 inches of vacuum.
Jim

acsX

Thanks, it worked!
Also is there any difference between these two caps?
https://www.suncoastparts.com/product/99610644704.html
https://www.autohausaz.com/pn/99610644704
Besides one is blue and the other is black? Same part #

MrMoose

Cool, then your problem was just that your compressor was a tad undersized for the job. Cycling it manually is a way to get around that.

I believe the caps come in different colors depending on who manufactured them. There were a few revisions to the cap, if I recall, but I'd assume everyone is now carrying the latest P/N.

acsX

Yeah, not all good news though. I didn't have the cap on the coolant tank tight enough and leaked coolant :c. I got that refilled and taken care of. Doesn't stop there. Apparently I didn't have a hose in all the way when I put the connector ring back on. So on test drive it got loose and leaked enough coolant to trigger a warning light. I got that fixed and filled up. Went for a second test drive and still overheated. No drips until a couple minutes later and that was underneath the coolant tank area. Tighten and fixed the gasket for the coolant tank lid. On top of that, I now have message "failure indicator" so I have to get that fixed now.

acsX

So from what I've gathered, I have an air pocket in the system after that hose got loose. Past 175 on the temperature gauge, the radiator fans turn on and the temperature gauge keeps rising 175. Do I need to use the airlift again to pressure it properly or just need to burp it?