As long as you have the 1/8" MPT plug taped up it shouldn't be leaking at all, and I had a tech inspect these Check Valves and they all open and close/seal without a problem.

I wanted to make sure the Check Valves wasn't going to bottom out when threaded into the 3166 1/2" FPT x 3/8" MPT adapter, and it does not. You would really have to crank the check valve for it to bottom out when open. The check valve threads only need to be threaded in with 2, maybe 3, revolutions. If you thread it in to the adapter any more than then it's possible it will bottom out when it opens to allow air in the tank.

The problem is that it can be difficult to diagnose these symptoms remotely.

Let me know what you find out after you tape the threads on the plug, we'll get to the bottom of this.

- MTR

Sorry for the delay but yes, if you could upload a clip of the problem that would greatly help.

We'll get this taken care of, I promise you that.

- MTR

Thanks for posting the video, it looks like you did a great job on the install. Also, the compressor looks like new!

It's hard to say where the squeal is coming from, you're right, and not being there it's all the more difficult to say. Have you used a soapy water solution and sprayed down the area? Any leak will cause form bubbles so you at least know where the leak is originating from.

It's just hard to say, but if we knew where the leak was coming from it would certainly narrow it down and single out the problem. Let me know and we'll go from there.

- MTR