Pitot/static ports

[andynoiseboy]

Does anyone know if the pitot and static ports on EFIS's (any model) are airtight?
Sounds like a stupid question but I was using a U-gauge manometer to check the accuracy of a steam gauge ASI and found that it leaked pressure. I then tried the same test and found that all the ports on an MX1 leaked too.
To clarify:
1. The pressures used were well within limits and at no point exceeded ASI maximums.
2. I double-checked tubing for leaks, to a point where I was directly connecting to the ports from the manometer with a short length of new tubing.

Scratching my head here....
TIA

[sparxfly]

They normally don't leak, but best to use silicon rubber tube (the stuff model aircraft guys use as fuel tube) with a small cable tie sealing it off behind the barb on the nipple.
The seal can be easily broken if you use stiffer tube with any bending force on the nipple.

[andynoiseboy]

Thanks for the response...
I'll have to try again, but I know that the tubing itself was airtight. It could only be the union of pipe-to-port or the port itself, but the pipe did seem to fit tightly to the port stem.
I'll try some softer silicone tube....