Mechanical Oil Pressure Gauge, - does it need to be bled? Options

[Kansas 914]

I have a VDO oil pressure gauge in the center console gauge cluster. It is a mechanical gauge - oil line from the sending unit location on the top of the engine to the back of the gauge. I noticed this weekend the line near the gauge is full of air and only a little bit of oil in the line. Should I "bleed" the line somehow. If so how is that done?

Can I just open the line at the gauge and keep it higher than the sending unit area so the air will rise?

Thanks in advance!

[76-914]

Air is OK. Doesn't change the indicated pressure reading.

[00r101]

Air is OK. Doesn't change the indicated pressure reading.

Ahhh, My high school physics says that a gas is compressible but a liquid is not as much. So air in the line will be compressed a bit as oil pressure changes. But whether it will make a huge diff in the oil pressure reading I do not know. Air in the line will start off at 14.7 psi so how much it will compress at say 60 psi i might be minimal

[mikesmith]

Air is OK. Doesn't change the indicated pressure reading.

Ahhh, My high school physics says that a gas is compressible but a liquid is not as much. So air in the line will be compressed a bit as oil pressure changes. But whether it will make a huge diff in the oil pressure reading I do not know. Air in the line will start off at 14.7 psi so how much it will compress at say 60 psi i might be minimal

The pressure from the oil side in the line will be X psi. This will compress the air until the pressure from the air side is also X psi.

With air in the line, the gauge will move a little slower (since oil will have to flow up/down the line as the pressure changes), but once it's stable, the air pressure will match (precisely) the oil pressure.

This is also high-school physics. Remember the water column experiment?

[mgp4591]

Air is OK. Doesn't change the indicated pressure reading.

Ahhh, My high school physics says that a gas is compressible but a liquid is not as much. So air in the line will be compressed a bit as oil pressure changes. But whether it will make a huge diff in the oil pressure reading I do not know. Air in the line will start off at 14.7 psi so how much it will compress at say 60 psi i might be minimal

The pressure from the oil side in the line will be X psi. This will compress the air until the pressure from the air side is also X psi.

With air in the line, the gauge will move a little slower (since oil will have to flow up/down the line as the pressure changes), but once it's stable, the air pressure will match (precisely) the oil pressure.

This is also high-school physics. Remember the water column experiment?

Cartesian diver? (IMG:style_emoticons/default/popcorn[1].gif)