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Installation Water/Oil guage

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Gadwhite

Senior Member
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Hi All
I am installing a new Water temp /oil pressure gauge in my wife's 64 AH 3000 Mk3. My one question is do I need to prime /make sure the line from the engine to the back of the gauge is full of oil? I am curious if there is air in the line if it would cause a false reading. The motor is a new rebuild so I was planning on first making sure I was getting oil out through the flex line from the block, then connecting it to the hard line that goes through the firewall. I would then crank the motor over until I got some oil coming out the other end of the line before connecting it to the back of the gauge. Anyone done this, or have any opinions? The new gauge didn't come with any information.
 
This is subject to some debate (which we'll surely get here ;)). I've done this several times, and all I did was hook up the pipe and crank the engine. You actually want a little bubble of air at the end of the line as it acts as a damper on the pressure readings and, no matter what you do you'll get a small one anyway. Oil is not compressible but air, of course, is, but when the the air in the line is compressed to the pressure of the oil you get an accurate reading without a lot of fluctuation. Also, when you shut the engine down the oil passages get at least partially filled with air anyway.
 
I agree with Bob, I've never made any effort to 'bleed' the oil line to the gage and I've never noticed any erratic or odd readings.
Dave
 
i think the only time i read about bleeding the line was to use it when priming the oil pump. otherwise i can't see a need for it. i know i changed my gauge at least twice in my old TD and never pumped oil up the line.
besides if you just removed the gauge, at the gauge, there is probably oil still in it.
 
Ive had my gauge disconnected one or two times to install a Low Oil Pressure sender and never reprimed the tube to the OP head, just hooked it back up and everything was fine.
 
I'm with the rest of the team, had mine out for several months whilst rebuilding the engine and renewing electric etc and never bothered to try and prime - did not even think about it actually.

:cheers:

Bob
 
Yeah me TOO, just hook up N GO!
 
Yes My wife and I are members. We almost always attend the Golden Cove British cars meet meets and the Peninsula Coffees and cars.
 
Gadwhite said:
Yes My wife and I are members. We almost always attend the Golden Cove British cars meet meets and the Peninsula Coffees and cars.
Click to expand...

Great! : cuz you can just walk or coast down the hill to get there .---:congratulatory:
 
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