I had a recent oil change on my 1995 F250 with 180,000 miles, 4wd with 460 gas engine. Since then, my oil pressure gauge flutters at idle after 30 minutes of warmup, and even drops to zero until I rev above 1,000 rpm. I decided to try letting it idle for a few secs with no pressure on gauge, but engine runs and sounds normal. After checking for proper oil level, I decided to replace oil pressure gauge sending unit since it doesn't cost much to eliminate that possibility.

Only problem is, I can't find the damn thing. Online research suggests two locations....near the oil filter, where you would expect it, at lower right front of motor, and top of engine block behind intake manifold at firewall. A thorough inspection with mirror and flashlight turned up nothing.

Any ideas? A picture would be even better. Thanks in advance for your help.

 

here is a pic of the back of my 460 in a 95 f350. you can see the sending unit just above the bellhousing in the center of the block

 

The oil pressure sender is in the rear of the engine behind the intake manifold on our 88 460 in an F350.
There is also a pluged hole above where the fuel pump would be on a carbed engine. Looks to me like the PS pump would have to be removed to access.
I expect either one could be used for oil pressure testing.
Bad news is that neither can be easily accesed when the engine is in the truck.
The easy way would be to put a T in the oil cooler line if you have the external air cooler.

 

The gauge sender is at the top, center, back of the block.
The oil pressure sensor (used to control the fuel pumps on carbureted trucks) is on the side of the block.
I'm not sure if there is a pressure sensor on your '95...

Here you can see the sender location at the back of my carbureted engine. It's nestled in a notch at the back of the intake, with the thermactor crossover pipes pointing towards it.

 

Thanks very much for your help and photos. After finding a larger mirror and laying on top of my motor for several minutes, I did find the sending unit at the top of the block at the firewall. A sheet metal hose bracket helped to hide it from view.

Michael