Hey guys,
I have a 1987 Ford F250, 6.9 IDI. When I drive for over 10 minutes, the oil pressure on the gauge slowly drops to the point that it reads empty, and the red warning light turns on. But when I pull over and check the dipstick, the oil level is fine, and I don’t see any leaks.
You should try using a real oil pressure gauge and get some actual psi readings. The factory gauges aren’t very reliable.
A new sending unit is pretty cheap, but you’re better off with a real gauge. I prefer a mechanical gauge, but an electric one like Auber Instruments sells can work too. I’ve had good luck with that setup. The hardest part is routing the wires and mounting the gauge.
I read that newer Dodge diesels had more accurate oil pressure gauges, but people kept calling in to report problems because the pressure fluctuated. So they redesigned the gauge to show a steady reading all the time. Makes you wonder if the gauge is the dummy or if it’s us!
That’s not an oil level gauge; it’s an oil pressure gauge. Oil level can affect pressure, but they’re not the same thing.
If you’re not hearing strange engine noises, it’s probably a bad oil pressure sensor. But don’t ignore it—if you’re actually low on oil pressure, you could be doing serious damage to the engine.
My 7.3 oil pressure gauge always shows the same reading, whether it’s at a cold start or warmed up. Feels like it’s a dummy gauge.
That doesn’t necessarily mean it’s a dummy gauge. It could be that your engine is just always running at the maximum pressure allowed by the pressure regulator. Most International diesels run at a regulated pressure all the time.
Good to know! I’m always watching for low pressure, so hopefully it’s still running healthy.
I’ve noticed GM engines and some older gas V8s don’t have pumps big enough to always run at max pressure. I’ve seen some Duramax engines with low oil pressure at idle that goes up when revved. But on the 6.9 or 7.3, you shouldn’t see much fluctuation unless something’s wrong.
Oil pressure absolutely fluctuates on a 7.3 IDI. It’s usually around 18 psi at idle and about 38 psi at 2000 rpm. My 7.3 has 383k miles, and I get 15 psi at idle and 37 at 2000 rpm. The oil pumps rarely fail on these engines. I added a real gauge, and it’s been much more accurate than the factory dummy gauge.
Just because the gauge isn’t fluctuating doesn’t mean it’s at maximum pressure. It could just be showing that there’s ‘some’ pressure, but the actual oil pressure might be fine regardless of what the gauge says.
Looks like you’re losing oil pressure.
The factory gauge isn’t great. These engines only need a few pounds of pressure at idle. Mine does the same thing, minus the red warning light.
You could replace the sensor, but others are right, these gauges aren’t great. Don’t just ignore it, though.
If the red warning light is coming on, you’re likely experiencing low oil pressure. That could mean serious engine damage if it hasn’t happened already. You might need a new oil pump or there could be debris stuck in the bypass valve. There are two valves: one in the oil cooler and one in the oil pump. The oil pump can’t be accessed without removing the oil pan, and the pan can’t be removed without lifting the engine. Just to clarify, the gauge shows oil pressure, not oil level—hopefully that’s clear now.
I don’t know what everyone’s talking about—on these trucks, the oil pressure gauge is basically a switch. It’s either on or off. As long as it’s on, you’re good, and the position doesn’t mean anything. If it’s moving, it could be a voltage issue. These trucks are getting pretty old now.
Edit: If the engine has oil and isn’t knocking, it’s probably fine. Once you lose oil pressure, the engine’s toast. At that point, you’d need a rebuild, but these engines aren’t worth a full rebuild. You’re better off finding a used one for $500 on Marketplace.
Your oil pressure will drop as the oil heats up and thins out. When I start mine on a cold morning, the oil pressure is around 50 psi, but once it’s warmed up, it drops to about 15 psi at idle. The IDIs are low-pressure, high-volume engines. Some people shim the regulator to increase oil pressure slightly, but it’s usually not necessary.