Oil pressure gauge with single terminal warning light?

[Bronze Barracuda]

I want to add an oil pressure warning light to my dash. What type of fitting should I use to connect both the pressure fitting and the warning fitting to the single port on the engine? Will I need to relocate it? , and does it need to be a specific type of fitting? (ie; does the fitting need to have a narrow passage way, or can I just use some type of y plumbing fitting)
I'm pretty sure others have done this, any pictures?
Thanks.

 

[Kendog 170]

I started with an 1/8 NPT street tee. Your oil light fitting will screw directly in that. Then depending what fitting your gauge uses you may need an adapter fitting unless your gauge is 1/8" male.
https://www.amazon.com/SUNGATOR-Barstock-Fittings-Fitting-Pressure/dp/B0B9M4HKMT/?tag=fabo03-20

 

[MDchanic]

As Kerndog said, it's simple plumbing, just be sure to consider where all the parts, and their wires, physically end up, so they're not interfering with anything else.

Remember that you can't do this with the temperature sender, as the temperature will change along the course of your added pipes, whereas the pressure stays the same.

– Eric

 

[Professor Fate]

Just make sure you've got good continuity across all the joints from sender to block- especially if you use teflon tape. This is the sender's ground path and it will not work without a good ground.

 

[Dana67Dart]

's simple plumbing, just be sure to consider where all the parts, and their wires, physically end up, so they're not interfering with anything else

Also consider the lengths of the connections.

A mass on the end of a pipe and the vibrations of the engine can cause metal fatigue.

So keep things as short and stout as possible.

If this will fit into the block and allow the switch and sender to fit that is better than A length of pipe with a "t" on the end.

Many pipe and "T"s have been used with no issues but it only takes one broken pipe to ruin you engine.

 

[Oldmanmopar]

Oil Pressure Sensor Thread Adapter for Chevrolet Small Block 305/350

 

[MDchanic]

Oil Pressure Sensor Thread Adapter for Chevrolet Small Block 305/350

That's a neat little item.

Thanks,

– Eric

 

[Bronze Barracuda]

Curious on wiring a power source.
Should I pull power from the choke to the light and then from the light to the switch (pigtailed together?

 

[Professor Fate]

Curious on wiring a power source.
Should I pull power from the choke to the light and then from the light to the switch (pigtailed together?

Don't you already have a light in your instrument cluster?
If not, look at a wiring diagram and pull the power off the cluster the way the factory did.
Power->light->sending unit->ground.

 

[Vaanth]

I want to add an oil pressure warning light to my dash. What type of fitting should I use to connect both the pressure fitting and the warning fitting to the single port on the engine? Will I need to relocate it? , and does it need to be a specific type of fitting? (ie; does the fitting need to have a narrow passage way, or can I just use some type of y plumbing fitting)
I'm pretty sure others have done this, any pictures?
Thanks.

Chrysler produced a fitting for vehicles using both indicator light switch and pressure gauge sending unit for the small block V-8s and 225 slant six in the late 1970s.

The fittings are shown in the following diagram. Left to right: V-8 without vacuum advance, #3747433, V-8 with vacuum advance, #3747434, and 225, #3747432:

3747433:

3747433 fitting with original Chrysler Introl 3488609 sending unit and 2298882 switch:

3747433 fitting with original Chrysler Introl 3488609 sending unit and 3747431 combination choke control and pressure switch:

3747433 fitting with common aftermarket sending unit and switch:

The sending unit and switch can be in either fitting port. For A-bodies, F/M/J-bodies, and 1970-prior B-bodies, the arrangement as shown in the diagram fits better, depending on the distributor setup. In later B-bodies, C-bodies, R-bodies, and trucks, arrangement in the other picture, or the diagram, can fit okay. It is a little cramped for space either way though. On a big block, either arrangement can work, depending on the proximity to the firewall.

If using 3747433 with a vacuum advance distributor on a small block as arranged in the actual images, the sending unit can interfere with the vacuum canister. One or two 45 degree adapters.or a 90 degree adapter, can remedy this.

 

[Bronze Barracuda]

Don't you already have a light in your instrument cluster?
If not, look at a wiring diagram and pull the power off the cluster the way the factory did.
Power->light->sending unit->ground.

Nope. No existing light, I like the idea of a light with the gauge. I'm usually watching the road. I need a bright red light to get me back to reality sometimes!

 

[Professor Fate]

Chrysler produced a fitting for vehicles using both indicator light switch and pressure gauge sending unit for the small block V-8s and 225 slant six in the late 1970s.

The fittings are shown in the following diagram. Left to right: V-8 without vacuum advance, #3747433, V-8 with vacuum advance, #3747434, and 225, #3747432:
View attachment 1716396155

3747433:
View attachment 1716396160

3747433 fitting with original Chrysler Introl 3488609 sending unit and 2298882 switch:
View attachment 1716396156

3747433 fitting with original Chrysler Introl 3488609 sending unit and 3747431 combination choke control and pressure switch:
View attachment 1716396159

3747433 fitting with common aftermarket sending unit and switch:
View attachment 1716396158

The sending unit and switch can be in either fitting port. For A-bodies, F/M/J-bodies, and 1970-prior B-bodies, the arrangement as shown in the diagram fits better, depending on the distributor setup. In later B-bodies, C-bodies, R-bodies, and trucks, arrangement in the other picture, or the diagram, can fit okay. It is a little cramped for space either way though. On a big block, either arrangement can work, depending on the proximity to the firewall.

If using 3747433 with a vacuum advance distributor on a small block as arranged in the actual images, the sending unit can interfere with the vacuum canister. One or two 45 degree adapters.or a 90 degree adapter, can remedy this.
View attachment 1716396157

View attachment 1716396161

Wasn't a fitting like that also used when the vehicle was equipped with a factory oil cooler (cop/taxi)? I seem to remember that it teed off at the pressure sender port, went through the cooler and returned through a hollow fuel pump bolt.
Just thought it might be another source/part number for a similar fitting.

 

[Vaanth]

The fittings for engines with the oil cooler were partially similar. The 1/8 inch NPT threads at the block end became a flare fitting at the hose/line end with multiple adapters. There were two types (early and late) for small blocks and differences for body lines. The F-bodies and early type R-bodies connected the sending unit and switch inline. The late type, #4140371, was a three port fitting, but has an internal check valve to prevent oil drain back. #0105404 pipe nipple is required to connect the fitting to the block.

Big block applications did not use dual light/gauge originally. The sending unit threaded into the standard location. The engine output oil cooling line connected via a long hex adapter, with check valve, that threaded into the coarse threaded port that is usually plugged.

Both my 1978 Fury 440 police and 1977 Fury 400 police use the long hex pipe. Following is my 1977 Fury 400. It's rough looking, but has 380000 miles on the un-rebuilt engine. I did touch up the paint a few decades ago and got paint on the adapter pipe which is bare zinc coated. It will get a refresh later this year.

 

[Dana67Dart]

Nope. No existing light, I like the idea of a light with the gauge

better yet a buzzer

 

[Dana67Dart]

it seems like taping off the oil pressure port would change the oil pressure the sensor reads?

measuring pressure in a static line vs a flowing line.

it looks like it dumps the oil back into the crankcase through the oil pump bolt hole.

 

[halifaxhops]

I would T it as said above. BUT I used a sending unit from a 87 318 truck with both. You do need the pigtail also just had it.

 

[Bronze Barracuda]

Don't you already have a light in your instrument cluster?
If not, look at a wiring diagram and pull the power off the cluster the way the factory did.
Power->light->sending unit->ground.

Ok just to visualize, I'll pull power from choke lead to warning bulb then send it back to the sending unit via pigtail. It'll be grounded through the block at no bring surface. I bought the 192 socket off Amazon it has a negative wire so I just need to cut that wire off then?

Thanks again.

 

[Professor Fate]

Ok just to visualize, I'll pull power from choke lead to warning bulb then send it back to the sending unit via pigtail. It'll be grounded through the block at no bring surface. I bought the 192 socket off Amazon it has a negative wire so I just need to cut that wire off then?

Thanks again.

View attachment 1716396508

View attachment 1716396509

You're feeding power THROUGH the light, so no- you don't cut any pigtails off.
Power goes into the light via the pos. wire (red) and exits the light via the black wire and goes to the sending unit.

 

[Bronze Barracuda]

You're feeding power THROUGH the light, so no- you don't cut any pigtails off.
Power goes into the light via the pos. wire (red) and exits the light via the black wire and goes to the sending unit.

Ok!!
Thank goodness I asked. Would have been a drag to have to pull it apart again.

 

[Dana67Dart]

You can get the keyed 12v pos from the cir board or other under dash sources

If your cir board looks like this...

If not post a photo of the cir board.

All 3 points are 12v switched (12v when key is in run or ACC)

The arrow "12v pin" is the 12v input to the cir board. If you tap into that wire that will provide the switched 12v you need to feed your oil pressure light.

 

[Bronze Barracuda]

It's actually an 81 Ramcharger I'm working on at the moment, but I was thinking of doing something similar to my Barracuda. I read somewhere on FABO (IIRC) where someone put a small led in the faceplate of the oil pressure gauge. It's what got me going down this path. I had a parts truck for my RC that did not have a gauge, just the warning light. So I took the little warning light decal thing that goes in front of the bulb and replaced the one in my 81 that had an engine service light (the one no one uses, I think it was just some light for emissions) So it had a natural place to go in the dash to compliment the gauge. I've got an led bulb in the hole now which is positive and negative specific. I have the red wire hooked to positive and the black to negative. Both are now fed through the firewall waiting to be connected under the hood. So I guess I'm finding a keyed positive under there now. Probably the choke, although I do have an auxiliary fuse panel with 4 free spots available.
Thanks for the help, I have a little more knowledge when I start on the Barracuda.

 

[Dana67Dart]

Cheap and no cluster modification

https://www.amazon.com/dp/B09H7RYFQ6?tag=fabo03-20

 

[BillGrissom]

A side note for those changing an oil pressure switch, consider a 3-terminal switch (1970's Chevy?) which is wired to disable an electric fuel pump if oil pressure is lost, for safety. I did that in my 1964 & 65 A-body. One terminal goes to the Starter Solenoid ("S" terminal) to run the pump ("P" terminal) while cranking. Once running, "P" is powered via the ignition wire ("I" terminal) if oil pressure is up. From memory, but google for much info and PN. Same 1/8" NPT thread. BTW, the slant six oil port is 1/4" NPT as I recall, requiring a reducing bushing (or correct sender PN).