oil pressure gauge

[Vicus]

Hi folks

I have revised my 351 Cleveland completely and I'm now testing it on the streets.

After a 150 miles trip with some stops and some restarts without any issues, close to home I stopped at a gas station to refill my gas tank. After this stop, engine didn't start at the first turn of the key. Sounded like the starter wasn't hardly able to turn the motor. I stopped igniting and turned the key again after a few seconds. Engine starts and revs up without any hesitation. Then I noticed, that the oil pressure gauge only shows in the middle of the gauge. Before this, is shows close to maximum. I headed home (less than 2 mls), checked all the fluids and wiring; everything ok. Also no strange sound from the engine.

After two hours I started it again and the gauge was close to maximum again.



Today another 50 miles testdrive with several stops and restarts of the engine. After the third restart, gauge stopped again in the middle, close to the I from the OIL writing there. Again no strange noise from the motor, all fluids on correct level. All other gauges are working well. I also recognized, that the index needle is moving a little bit. It doesn't look like it is blocked internally.

Now I want to measure the voltage or better said the resistance of the sensor.

Can anybody provide me the figures, this sensor has to respond at different pressure conditions?

If I have to change the sensor, can I go with one from STANDARD, Rockauto is offering for less than 7 bucks, or should I opt for the Motorcraft sensor, offered for roughly 24 Dollars? Is it worth it?

Please let me know your thoughts.

Cheers

Frank

 

[midlife]

Hi folks

I have revised my 351 Cleveland completely and I'm now testing it on the streets.

After a 150 miles trip with some stops and some restarts without any issues, close to home I stopped at a gas station to refill my gas tank. After this stop, engine didn't start at the first turn of the key. Sounded like the starter wasn't hardly able to turn the motor. I stopped igniting and turned the key again after a few seconds. Engine starts and revs up without any hesitation. Then I noticed, that the oil pressure gauge only shows in the middle of the gauge. Before this, is shows close to maximum. I headed home (less than 2 mls), checked all the fluids and wiring; everything ok. Also no strange sound from the engine.

After two hours I started it again and the gauge was close to maximum again.



Today another 50 miles testdrive with several stops and restarts of the engine. After the third restart, gauge stopped again in the middle, close to the I from the OIL writing there. Again no strange noise from the motor, all fluids on correct level. All other gauges are working well. I also recognized, that the index needle is moving a little bit. It doesn't look like it is blocked internally.

Now I want to measure the voltage or better said the resistance of the sensor.

Can anybody provide me the figures, this sensor has to respond at different pressure conditions?

If I have to change the sensor, can I go with one from STANDARD, Rockauto is offering for less than 7 bucks, or should I opt for the Motorcraft sensor, offered for roughly 24 Dollars? Is it worth it?

Please let me know your thoughts.

Cheers

Frank

You could have a flakey connection which is adding resistance (lower reading) at times. You shouldn't be seeing that high an oil pressure reading on a stock engine, though...

I'd check your oil sending unit wire connection at the sending unit, the plug to the headlight harness near the firewall, and the plug at the gauge to see if all are clean and free of corrosion.  Of still flakey, I'd get a mechanical sending unit and tee it off to compare to the electrical unit.

 

[Vicus]

Hi folks

I have revised my 351 Cleveland completely and I'm now testing it on the streets.

After a 150 miles trip with some stops and some restarts without any issues, close to home I stopped at a gas station to refill my gas tank. After this stop, engine didn't start at the first turn of the key. Sounded like the starter wasn't hardly able to turn the motor. I stopped igniting and turned the key again after a few seconds. Engine starts and revs up without any hesitation. Then I noticed, that the oil pressure gauge only shows in the middle of the gauge. Before this, is shows close to maximum. I headed home (less than 2 mls), checked all the fluids and wiring; everything ok. Also no strange sound from the engine.

After two hours I started it again and the gauge was close to maximum again.



Today another 50 miles testdrive with several stops and restarts of the engine. After the third restart, gauge stopped again in the middle, close to the I from the OIL writing there. Again no strange noise from the motor, all fluids on correct level. All other gauges are working well. I also recognized, that the index needle is moving a little bit. It doesn't look like it is blocked internally.

Now I want to measure the voltage or better said the resistance of the sensor.

Can anybody provide me the figures, this sensor has to respond at different pressure conditions?

If I have to change the sensor, can I go with one from STANDARD, Rockauto is offering for less than 7 bucks, or should I opt for the Motorcraft sensor, offered for roughly 24 Dollars? Is it worth it?

Please let me know your thoughts.

Cheers

Frank

You could have a flakey connection which is adding resistance (lower reading) at times. You shouldn't be seeing that high an oil pressure reading on a stock engine, though...

I'd check your oil sending unit wire connection at the sending unit, the plug to the headlight harness near the firewall, and the plug at the gauge to see if all are clean and free of corrosion.  Of still flakey, I'd get a mechanical sending unit and tee it off to compare to the electrical unit.

Randy

Thank you very much for your comment. I will check with a mechanical gauge and revert.

Regarding the high pressure reading, the engine is completely revised and got a new Melling oil pump, but standard volume and standard pressure. Still too much reading?

Cheers Frank

 

[jpaz]

I have a recently rebuilt 351 4V  Cleveland engine with a Melling standard volume oil pump too. I did have an aftermarket electric oil gauge with matching sender and was getting some weird oil pressure readings. I guess the sender went or is going bad? Anyway I just add a mechanical gauge and it isn’t doing any of the weird readings anymore. But, it does read about 80 psi @ cold idle, then as low as 30 psi @ hot idle. I’m around 45-50 cruising around town. I do feel more reassured having the mechanical gauge and as long as you have at least 10 psi per 1000 rpms then you’re good to go.

 

[Stanglover]

I have a recently rebuilt 351 4V  Cleveland engine with a Melling standard volume oil pump too. I did have an aftermarket electric oil gauge with matching sender and was getting some weird oil pressure readings. I guess the sender went or is going bad? Anyway I just add a mechanical gauge and it isn’t doing any of the weird readings anymore. But, it does read about 80 psi @ cold idle, then as low as 30 psi @ hot idle. I’m around 45-50 cruising around town. I do feel more reassured having the mechanical gauge and as long as you have at least 10 psi per 1000 rpms then you’re good to go.

 John, I'm curious. This might also be helpful to Frank as well. We both have the same Melling oil pump and I don't think our motors are so much different. What I see on mine is about 75 hot at idle and only drops to 60 running. I have never seen it drop anywhere near 30 or even 45 psi.

So why the difference? Your new mechanical gauge is a Bosch I believe, so even though the face is different, the parts inside ought to be at least similar. I would think that the readings on the two gauges would be close to each other unless there are factors I'm not realizing.

 

[jpaz]

I have a recently rebuilt 351 4V  Cleveland engine with a Melling standard volume oil pump too. I did have an aftermarket electric oil gauge with matching sender and was getting some weird oil pressure readings. I guess the sender went or is going bad? Anyway I just add a mechanical gauge and it isn’t doing any of the weird readings anymore. But, it does read about 80 psi @ cold idle, then as low as 30 psi @ hot idle. I’m around 45-50 cruising around town. I do feel more reassured having the mechanical gauge and as long as you have at least 10 psi per 1000 rpms then you’re good to go.

 John, I'm curious. This might also be helpful to Frank as well. We both have the same Melling oil pump and I don't think our motors are so much different. What I see on mine is about 75 hot at idle and only drops to 60 running. I have never seen it drop anywhere near 30 or even 45 psi.

So why the difference? Your new mechanical gauge is a Bosch I believe, so even though the face is different, the parts inside ought to be at least similar. I would think that the readings on the two gauges would be close to each other unless there are factors I'm not realizing.

I don’t know why the difference, but that’s what it says. I do have a Bosch mechanical gauge. You have 75 hot idle and 60 cruising? That doesn’t sound right, you must mean the the other way around.

Sorry Vicus, not try to hijack your thread.

 

[Hemikiller]

Check your grounds. Coupled with the difficulty starting, you might have a loose, bad or missing connection in the battery -> fender apron -> block ground cable.

 

[machattack]

With that much invested wouldn't a copper tube mechanical gauge be the ticket for accuracy?  My engine isnt in yet but I already run a copper tube and mounted a mechanical oil presure gauge. I also have the center console 3 gauge pack. So, I have 2 gauges checking oil presure.

Just sayin.

 

[Vicus]

With that much invested wouldn't a copper tube mechanical gauge be the ticket for accuracy?  My engine isnt in yet but I already run a copper tube and mounted a mechanical oil presure gauge. I also have the center console 3 gauge pack. So, I have 2 gauges checking oil presure.

Just sayin.

Rod

Y adaptor to connect two sensors is already purchased. At first I will go with a temporary solution to  get back the trust in my own work. Final installation of a mechanical oil pressure gauge will follow but I will opt to a CuNiFe10 tube.

Cheers Frank

 

[Vicus]

Check your grounds. Coupled with the difficulty starting, you might have a loose, bad or missing connection in the battery -> fender apron -> block ground cable.

Very good idea! I will check and revert.

Cheers Frank

 

[Stanglover]

I have a recently rebuilt 351 4V  Cleveland engine with a Melling standard volume oil pump too. I did have an aftermarket electric oil gauge with matching sender and was getting some weird oil pressure readings. I guess the sender went or is going bad? Anyway I just add a mechanical gauge and it isn’t doing any of the weird readings anymore. But, it does read about 80 psi @ cold idle, then as low as 30 psi @ hot idle. I’m around 45-50 cruising around town. I do feel more reassured having the mechanical gauge and as long as you have at least 10 psi per 1000 rpms then you’re good to go.

 John, I'm curious. This might also be helpful to Frank as well. We both have the same Melling oil pump and I don't think our motors are so much different. What I see on mine is about 75 hot at idle and only drops to 60 running. I have never seen it drop anywhere near 30 or even 45 psi.

So why the difference? Your new mechanical gauge is a Bosch I believe, so even though the face is different, the parts inside ought to be at least similar. I would think that the readings on the two gauges would be close to each other unless there are factors I'm not realizing.

I don’t know why the difference, but that’s what it says. I do have a Bosch mechanical gauge. You have 75 hot idle and 60 cruising? That doesn’t sound right, you must mean the the other way around.

Sorry Vicus, not try to hijack your thread.

 Yes, apologies to Frank, but the numbers could be useful to him for when he gets his mechanical oil gauge. 

I took a screen shot off my video. It's not too clear, but shows around 75 at (almost) hot idle. I didn't get a shot of the gauge when wifey was driving, but I know it was at 60 psi. When I installed the gauges, I somehow managed to get the Temp and Oil switched around, which makes the oil gauge a bit harder to see. It is what it is now though. However, now I'm getting curious so I may get another gauge and double check my numbers.



Running at 2700rpm, needle is between 50 &75, so around 60 looking straight on at it.

 

[goodnigh]

The stock electric gauge on my 351C-4V always runs 90% of scale

and will sometimes drop to 80% but never lower.

I use 10W/30 Valvoline VR-1 racing oil with a K&N filter.

The type of oil and filter being used could affect oil pressure readings.

mike

 

[Stanglover]

The stock electric gauge on my 351C-4V always runs 90% of scale

and will sometimes drop to 80% but never lower.

I use 10W/30 Valvoline VR-1 racing oil with a K&N filter.

The type of oil and filter being used could affect oil pressure readings.

mike

Good point on the filter choice. I think 80% of scale would be about equal to the 60 psi I see that never drops below.

I use Castrol 10W/30 with (usually) a Motorcraft FL1A filter. I use this more for looks, but Purolator make good filters and meet Ford specs, so as I only drive 1500 miles a year, I'm not worried about it. However it is due for an oil change, so I'll try another brand and see if there is any difference. 

If there is, I'll repost.

 

[jpaz]

The stock electric gauge on my 351C-4V always runs 90% of scale

and will sometimes drop to 80% but never lower.

I use 10W/30 Valvoline VR-1 racing oil with a K&N filter.

The type of oil and filter being used could affect oil pressure readings.

mike

Good point on the filter choice. I think 80% of scale would be about equal to the 60 psi I see that never drops below.

I use Castrol 10W/30 with (usually) a Motorcraft FL1A filter. I use this more for looks, but Purolator make good filters and meet Ford specs, so as I only drive 1500 miles a year, I'm not worried about it. However it is due for an oil change, so I'll try another brand and see if there is any difference. 

If there is, I'll repost.

I’m using Joe Gibbs 10w/30 and a wix filter.

 

[Vicus]

Folks

The oil pressure was never gone, the sensor wasn't able to read the right pressure rates. 

I found the culprit. 



This little piece of motor silicone has worked its way into the hole in the sensor.

Now the gauge shows again high pressure within the limits. Nevertheless the already ordered mechanical oil pressure sensor and gauge will find its way into my car during summer.

Cheers Frank

 

[machattack]

"WEW" I bet your relieved...... HUH.

Best to have 2 gauges reading at the same time. I had this happen once to my Mechanical oil gauge. Got stuff in the gauge. Looked more like Oil sludge. Glad you figured this out!

Rod and Sally

 

[jpaz]

Ya that’s a big relief. Thanks for showing us what happened and glad that’s all it was!

 

[tony-muscle]

The OEM pressure gauges are also very slow to react. When I start my engine it takes a while for it go up. I dont think the actual pressure would take that long.

Sent from my SAMSUNG-SM-G930A using Tapatalk

 

[Hemikiller]

Might want to look to another brand of oil filter, the one you're using is bypassing and allowed that to get into the main oil galley.