Mechanical oil pressure

[joe_db]

I'm ignorant but curious about this. If the balloon continues to expand, isn't some of the system pressure going toward strtching the balloon rather than pushing on the meter's sensor?

I'm curious because I can't see another explanation for my experience with the 4' hose, as stated in a previous post.

Question please: is anyone running at 180 with a longish non copper connection?

When the "balloon" is in transition the pressure will be off, but eventually it will either stabilize or pop
I have hooked up a number of oil pressure gauges and none of them ever needed bleeding. Pressure gauges on airplanes can have a lot of hose between the cockpit and an engine on the wing and they don't have bleeds. If there is 100 PSI oil at one end of a sealed pipe, it will move up the pipe until it meets 100 PSI air

[Marty Levenson]

pressure

When the "balloon" is in transition the pressure will be off, but eventually it will either stabilize or pop

...but isn't the hose ("balloon") steadily inflating as it gets hotter and hotter?

[toddster]

I think the gauge I got at NAPA came with 1/8-inch polypropylene tubing. (Not positive - could be PE or nylon, but I think PP is better with heat, oil, and pressure.) It came with quite a lot. At least ten feet. Maybe they have more at NAPA? Hardware stores tend not to stock the smaller sizes. I wouldn't use flex stuff like fuel line.

I use 1/8-inch PE up to 100 PSI for lab gases every day, at room temperature. Hot oil might be another story. I've got 1/16 PP tubing running at 2000 PSI liquid, but it does fail from time to time. Then there's PEEK, but that, and fittings for it, are expensive.

Anyway, my usual source for all that is Cole Parmer, except PE tubing can usually be had at Ace Hardware. May be cheaper to just buy a new NAPA gauge with tubing and fittings included.

Or heck, the whole mess is just sitting in my parts box. Could make you a great deal...

[JOHN COOKSON]

. May be cheaper to just buy a new NAPA gauge with tubing and fittings included.
...

I tried a mechanical oil pressure from a "boutique" auto parts store (Pep Boys).
It lasted ~ two years before it rusted out. A "marine rated" gauge would have lasted longer.

TRUE GRIT

[joe_db]

...but isn't the hose ("balloon") steadily inflating as it gets hotter and hotter?

It is open at each end. It would have to inflate pretty quick to make a noticeable change and it would then be popping and shooting oil all over. Slowly changing from 0.25 to 0.29 inches would do nothing on the gauge. I am talking something like 0.25 to 6 inches swelling rapidly The hose would pop before the gauge settles down.