Water flow slows down during extraction - Page 2

[erics]

Well, if you still have the OPV out, try simply blowing into the inlet. There should be zero flow. If there is any "air" leakage from the small port where the very flexible line slips on, you need to look further for why's and wherefor's of this leak.

If no leak, then OUCH! I am bewildered.

[CTurner]

All,

This morning I tried using the machine, but the overflow valve into the drip tray ran water steadily when I tried a few preliminary flushes through the group.

Opened up, there is a small leak between the OPV and the pump, at the crease where they join. Figured I hadn't tightened enough and went in again. Tightened all down really well. Also screwed in the OPV screw a bit--I had left it most of the way up, as when I got it.

Still getting a leak--a drip, steady--at the OPV/pump crease.

Craig

[erics]

Craig -

The threading on the snout of the Ulka pump is 1/8"-28 BSPP female (straight threads); the threading on the OPV end which screws into the snout is 1/8"-28 BSPP male (straight threads).

That leak is perfectly normal (but not right) for all that you have done. The "production" solution on the factory floor is to apply a small amount (2 matchheads) of thread sealant to the OPV threading prior to assembly.

Your solution will be to wrap two turns of teflon tape around the threads of the OPV in a CW direction. You would also want to wrap two turns around the 90 degree fitting that screws into the OPV. Hopefully you've noticed that the snout of the Ulka pump can be rotated freely after screwing in the OPV valve. This is to allow you to orient the OPV in the desirable direction.

Take this opportunity to once again (I know its frustrating) inspect the OPV and make sure that the orientation of the plunger is correct as per the pictures in the OPV article I linked to earlier. Blow through the end that screws into the Ulka pump while holding your finger over the outlet. There should be zero flow through the barb fitting that the return hose attaches to.

[CTurner]

Dear Eric and All,

Events have overtaken this thread. I decided that it was not worth my time to continue working on the machine. Also, I had for some time been looking at the QuickMill Anita. Some urging support from my wife and I have ordered a new machine and upgrade grinder and sold the Expobar to someone who wants to work on it.

It's forums like this that have provided so much information and support to fans of espresso like me. I want to thank everyone once again---and especially you, Eric--for all the help and advice. But I simply lost interest in tinkering at a level I couldn't be completely confident about.

I have asked the new owner to pass on his results with the machine, so maybe we'll get to the bottom of whatever it was!

Best to All and Thanks,
Craig