Frustrating oil leak

[Sagesurfing]

I swear for the past 12 years I have had an oil leak from the oil pressure sending unit. It’s a Chevy 350z I’ve swapped out units. I’ve swapped out engines. I’ve tried with Teflon, without Teflon. I make sure to cute the tubbing each time. I’ve tried tightening more and tightening less. It always, always, always ends up leaking right from where the copper tubbing goes into the unit. What am I doing wrong at this point? And please don’t tell me to use plastic or some other material. This system should work. I just swapped to a longer unit so it’s easier to access. I use the ferrule correctly, it comes with the unit. I want to know what I’m doing wrong 🫤

[Richard]

I would guess it is the tubing. To my knowledge copper is not used on automobiles. The stock sending line is steel. An argument could be made that it is not used because of cost. Then there is that copper is more malleable. It can bend and fatigue easier in the automotive environment.

[HO455]

Can you post a photo of the whole oil line? It may be the engine vibrations/movement is causing the leaking.

It also appears you are using an aftermarket fitting on the factory tubing. Maybe that is the problem. I know the factory ferrule is a different design from what you posted.
How snug is the ferrule your using on the tubing?

[Sagesurfing]

[QUOTE=Richard;9385812] I’m sorry, I think it’s actually brass.

[Sagesurfing]

Hey HO455

It also appears you are using an aftermarket fitting on the factory tubing.

When I google the fitting for a 1972 this is exactly what comes up 🤷*♂️

How snug is the ferrule you’re using on the tubing?

It seems to fit properly. It just never seems to fully seal somehow 🫤

[HO455]

This thread has some information as well as a photo of what the GM fitting looks like. (Google lied) It may be that the fitting and ferrule you are using aren't the correct size to seal the factory steel tubing.

http://67-72chevytrucks.com/vboard/s...d.php?t=644302

[Grounded63]

With the non GM fittings. The ferrule needs to fit the factory tube pretty closely. If there is daylight between the tube and ferrule. It's too loose, and may not be able to compress/seal fully. Is the ferrule swagged on to the factory tubing, after tightening ? You should not be able to remove the nut. Without cutting the tube. Or cutting the ferrule.

[LockDoc]

Originally Posted by Richard

I would guess it is the tubing. To my knowledge copper is not used on automobiles. The stock sending line is steel. An argument could be made that it is not used because of cost. Then there is that copper is more malleable. It can bend and fatigue easier in the automotive environment.

You are correct on the copper line being more costly to produce. You are partially correct on the bending and fatigue statement. That depends on the type of copper tubing used. The copper oil pressure lines I sell are made from 1/8" refrigeration copper that is designed for installation in areas that are subject to heat, cold, vibration, and high pressure. Most of the original lines were mild steel tubing and some of them had a piece of vacuum type hose over the line, I presume to help dampen vibration. Also, some of them were one piece and some of them were two piece with a coupler at the firewall.

Everyone needs to do what they feel comfortable with. I have used the copper oil lines on all of my builds since 2004 with no issues. That would be 6 trucks and 2 Hot Rods......

Originally Posted by Sagesurfing

I swear for the past 12 years I have had an oil leak from the oil pressure sending unit. It’s a Chevy 350z I’ve swapped out units. I’ve swapped out engines. I’ve tried with Teflon, without Teflon. I make sure to cute the tubbing each time. I’ve tried tightening more and tightening less. It always, always, always ends up leaking right from where the copper tubbing goes into the unit. What am I doing wrong at this point? And please don’t tell me to use plastic or some other material. This system should work. I just swapped to a longer unit so it’s easier to access. I use the ferrule correctly, it comes with the unit. I want to know what I’m doing wrong ��

Here is a thread I posted with information on the stock GM fittings.

https://67-72chevytrucks.com/vboard/...d.php?t=613238

The compression sleeve nuts are the only fitting that will work in the back of the gauge without leaking....
.

[Blue Tank]

To me it looks like the nut is bottoming out on the fitting in the first pic. It should look more like pic of the one from Advance auto when it's tight. That means one of the 4 items isn't compatible. I would go with the line from Lock Doc or one of the junk auto stores might carry the Autometer copper tube kit. The factory "Bundy" tube is a little different size. I can measure it this weekend and see.

[Blue Tank]

I checked the stock Bundy tubing and it measures .103". A normal ferrule would never clamp tight on that and stay round. You might need to go to a Corvette supplier to get a ferrule that would fit. Probably easier to swap over to copper tubing and then it won't be an issue down the road.