Oil pressure gauge install information for disconnect.
 

I'm putting in a new oil pressure gauge on my 72 C10. I was reading about the disconnect Union just outside the firewall on the engine side to make it easier I guess if the engine is pulled?

What exactly is the purpose here and what parts would I need?

Is there a way to put a tee in it to have the oil pressure light light up as well? Or even run a disconnect for the ignition if there's a loss of oil pressure.

Re: Oil pressure gauge install information for disconnect.
 

Tagging for info. Fittings are odd size. I want to put in braided line for ease of gauge/bezel removal.

Re: Oil pressure gauge install information for disconnect.
 

Don't mess with the union. Instead, put a T right off the block and on one arm of the T, put the existing oil gauge tubing. On the other arm, put the idiot light sensor.

Re: Oil pressure gauge install information for disconnect.
 

I agree, leave the union as-is and put the T fitting right off the block. I think the union was there just to make things easier on the assembly line. The two pieces of tubing connected with a union were easier to install compared to trying to fish a long piece of tubing through a relatively small hole in the firewall.

Yes, the factory oil lines use a compression sleeve nut fitting ... basically has the compression ferrule built into the nut instead of being a separate ring. Replacement nuts are available as Weatherhead #6100x2 or Edelmann #111200. And the connector that goes into the 1/8" NPT threads in the block is Weatherhead #6200x2 or Edelmann #112220. Although some of the factory ones on small block V8s used a longer connector since it fits in close behind the rear edge of the intake manifold.

Re: Oil pressure gauge install information for disconnect.
 

I want to install one of those stainless braided lines from the engine to the factory gauge. The engine is 1/8th NPT I believe and I already have the adapter to AN on that end.

At the gauge I need something that adapts from the compression sleeve nut female fitting on the back of the gauge and convert to 4 AN or is it -4 AN?

Would you know of such an adapter?

Re: Oil pressure gauge install information for disconnect.
 

I'm not aware of any adapters like that. A few options I can think of:

(1) You might be able to find a gauge with NPT threads. I have seen one or two of these in some early square body (73 to 75 or so) medium duty trucks. They have an adapter (like on the engine) that goes to the sleeve nut fitting that could be removed and replaced with an NPT to AN adpater. I don't think these gauges are very common though and I'm not sure if they used them at all in 67-72 or not.

(2) You could make up a short section of tubing with a compression sleeve nut on the end that threads into the gauge and a regular compression to AN adapter on the other end.

(3) I remember taking a gauge cluster out of a truck and finding that a previous owner had adapted a standard compression fitting onto the gauge. It looked like they just took a male pipe adapter and threaded it into the back of the gauge with some thread sealer. I think the stock sleeve nuts have 5/16" threads, which is about the same OD as 1/16" NPT so the size is pretty close despite the thread pitch differences. Kind of a hokey fix but it seemed to have held okay.

Re: Oil pressure gauge install information for disconnect.
 

Wouldn't it be easier to run the light off the fitting/plug right above the oil filter and leave the gauge line alone.

Re: Oil pressure gauge install information for disconnect.
 

If I can find a compression sleeve nut to AN adapter that is what I will/would do. All the old good auto supply houses are gone around here and the chain places all have that guy from the rock auto commercial. Even the NAPA isn't any good?

Re: Oil pressure gauge install information for disconnect.
 

Slightly off topic question, but I have, in the past, had a plastic line going to the gauge (changed to copper now) and noticed air in the line. Would this affect the oil pressure reading on the gauge, or should the line be bled somehow. Thanks in advance.

Re: Oil pressure gauge install information for disconnect.
 

I bought the necessary parts at NAPA today.

https://i.postimg.cc/FFM2G12s/IMG_20..._102928421.jpg

https://i.postimg.cc/cLZPy2xp/IMG_20..._102934649.jpg

Re: Oil pressure gauge install information for disconnect.
 

Thats what I am thinking of doing. I am worried about the Tee and such being too tall back there by the HEI.

Re: Oil pressure gauge install information for disconnect.
 

That looks good. Where did you come through the firewall at?

Re: Oil pressure gauge install information for disconnect.
 

Since the air will compress to whatever the oil pressure is, it won't throw off the gauge. Where it is a concern is in a dynamic system (think brakes or clutch) where the air compresses and the fluid doesn't, and you need something to move. The only thing bleeding it would do for you is get you correct readings more immediately.