Slow gauge

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dodgy

dodgy

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Hi there, i have a new mechanical Autometer oil pressure gauge that reads accurate but very slow to react, it's fed by a copper line that isn't kinked but seems to be smaller in diameter than the nylon tube supplied with gauge, i will change the feed line to check if it's the problem but just wanted to ask first if anyone has come across this before, i put an old test gauge to the same port and it reacts normal.
Link to slow gauge video

 
I would say there is a big restriction in the system some where, maybe even in the guage. It is acting like a thermal guage.
 
bad gauge , it should return to zero pressure when the car is turned off and it should build pressure as soon as you start the motor. Like the extra gauge you have. Oil feed line is OK.
 
I would suspect debri or a restriction in the copper line "for start" If you can get clear (white) nylon, buy a length of it and a couple compression ferrules and temporarily hook that to the gauge, even if you remove the gauge. Then you can SEE the oil back and forth in the tube.

Also some gauges have a restriction right at the gauge fitting, and maybe something plugged it or it is defective.
 
those oil preasure lines are curved brass tubes in the gauge that "unwrap" under pressure and are connected by a small gear that acts on the needle. if you can take the feed off the gauge and allow it to blow into a cup you can see if it just dribbles out or jets out. if it dribbles out, suspect a kink in copper line. if it jets, then maybe the gauge mechanism is rubbing on something. you can manually touch the sense tube in there and the needle should move with little effort but dont firce it as the tube will bend and the zero will be lost
 
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I haven't gotten back to it yet but have taken all the advice onboard and will troubleshoot it till i find the cause.
Thanks.
 
67Dart273 said:
I would suspect debri or a restriction in the copper line "for start" If you can get clear (white) nylon, buy a length of it and a couple compression ferrules and temporarily hook that to the gauge, even if you remove the gauge. Then you can SEE the oil back and forth in the tube.

Also some gauges have a restriction right at the gauge fitting, and maybe something plugged it or it is defective.
Click to expand...
I like the suggestion something might be blocking the line or inlet aperture of the gauge. I had an oil sender, which read alarmingly low. It turned out PO had used Teflon tape on the sender threads and a Teflon tape booger was blocking the sender inlet.
 
No tape on mine, compression fittings on both ends of the line and permatex 59235 on the npt at block.
I did have a look today at the other copper line kit i purchased with the other and it may be the problem, when looking at the ends it looks like they haven't opened up the copper tube before soldering the fittings on, I de soldered this one cut the ends off, cleaned it up and re soldered .
Hard to see and take pic off but end of line was terrible.

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All the gauge 1/8 oil lines I've used over the years were all compression fittings used for connections. I've never seen an oil line that had soldered fittings. If you used a line that has soldered fittings that could be your problem, if you get some solder on the end of the tube you will restrict the oil flow going to the gauge.

copper.jpg
 
Solder is no where near the end of tube. All good there.
d1970 said:
All the gauge 1/8 oil lines I've used over the years were all compression fittings used for connections. I've never seen an oil line that had soldered fittings. If you used a line that has soldered fittings that could be your problem, if you get some solder on the end of the tube you will restrict the oil flow going to the gauge.

View attachment 1715810848
Click to expand...
 
d1970 said:
All the gauge 1/8 oil lines I've used over the years were all compression fittings used for connections. I've never seen an oil line that had soldered fittings. If you used a line that has soldered fittings that could be your problem, if you get some solder on the end of the tube you will restrict the oil flow going to the gauge.

View attachment 1715810848
Click to expand...

Me neither. No solder.
 
67Dart273 said:
Me neither. No solder.
Click to expand...
just to clarify the oil line comes assembled with the ends soldered on, these are not the type that have the olives you slip over the tube and compress as you do the tube nut up. It was all i could get at the time.
 
This is after i refitted the ends. Anyhow getting away from the problem my soldering job is not it.

20211027_105931.jpg


20211027_105808.jpg
 
Cheap fuel pressure regulators are just turrets with graduated holes in them so your 'small hole' would make for a lazy gauge.
 
Yep just looking for my nylon tube to put that theory to rest
 
Ok so gauge is good , hooked up the nylon line and worked as should, i then hooked up the other copper line that i improved and symptoms came back , so anyone in Australia don't buy autobarn's copper line kit.
Thanks to all who gave their thoughts of what it could be.
 
I've used the plastic line for years with zero issues. I think the stories of them failing are exaggerated or mistakes made on installation.
 
4spdragtop said:
I've used the plastic line for years with zero issues. I think the stories of them failing are exaggerated or mistakes made on installation.
Click to expand...
Yeah me too , while in the local parts store i spotted the copper line and thought yeah why not--- well i know now, don't buy the cheap ones.
 
4spdragtop said:
I've used the plastic line for years with zero issues. I think the stories of them failing are exaggerated or mistakes made on installation.
Click to expand...

i betcha 90% of failures run the line to close to the exhaust and melt it more then they think
 
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