Oil pressure. Should I be worried?

[WrenchWhore]

My stock oil pressure gauge has always been on the low side. Pretty much between the first line and N. Mileage on this used motor I put in is unknown. I just know it was an old U-Haul motor. Engine Compression is in the 400 PSI range when I tested. I replaced the oil pressure sending unit and it didn't seem to change much of anything on the stock gauge. Engine seems to run strong. I just put a screw on oil pressure gauge into the 093 turbo oil manifold before the turbo to get a oil pressure reading. Is this the best place to get accurate oil pressure readings? Here are my numbers after installing the oil pressure gauge.

Cold idle: 35 psi
Cold high idle: 39 psi

Hot idle: 6 psi
Hot @2500 RPM: 30psi

Do these numbers sound good to you? Should I be worried? Oil light came on recently after taking off in first and the RPMs dropped below idle hot (probably 300-400 RPM) Mind you this is a China gauge I got off amazon so take those measurements accordingly.

 

[DougBoy66]

I have almost that same set up under the hood. And I see similar results, maybe slightly higher on hot temps. Like 9-35

 

[DougBoy66]

My dash gauge only works when it has a notion to, so I also have a oil pressure gauge on the pillar. Seems like oil level effects it some if you get a little low, to me, it seems to make the pressure run on the lower side. I think even at 6 psi that pump is moving a bunch of oil around your engine

 

[Kdo58]

I seen a post on fb before, pretty normal, mine has all new rod and crankshaft bearing so mine is higher, high 40s cold and 10 hot at idle

 

[IDIBRONCO]

Keep this in mind. That oil port on the turbo is the highest point in the oiling system. It's also the farthest point away from the oil pump. That's the place where you should have the lowest oil pressure readings because the oil flow and pressure has been bled off by everything else in the entire engine by that point. If you take the pressure reading at a lower point, I'll bet that you'll see higher pressure. Ford probably used that spot simply because it was easily accessible after using the N/A oil sender location for the turbo oil feed line.

 

[ihc1470]

Rule of thumb in the heavy duty diesel world is 10 psi per thousand RPM so you should be OK.

 

[WrenchWhore]

Thank you guys so much for your words of wisdom. I'll sleep better knowing my motor isn't eating itself alive. @IDIBRONCO I kinda figured if the oil port is the highest point and the turbo being a restriction would cause pressure to be lower then the bottom end. All I know is the oil stays clean long enough that I don't worry about other components. I hope to send a sample off to Blackstone for an analysis just to be safe. If my motor decides go poo poo i've got the bump side swapped 460 waiting in the wings to supplement the IDI. My old 6.9 is on the engine stand waiting for some love. i've got some head studs waiting for it and a host of others if it all shakes out that way.

 

[DirtyWood]

My numbers were a hair higher using a digital gauge from Auber Instruments. With over 350k miles and at full 190F operating temp I always saw 14psi at idle and 38-40psi at 2000rpm.
I found list of specs for the 7.3 that has 10psi minimum at idle and 40-70psi at max. governed RPM.

 

[Greenie]

The oil pressure sensor is an on/off switch - the position of the gage needle means nothing other than that there is enough pressure to closed the sensor circuit. I replaced the factory sensor with an older Ford V-8 gas engine sensor (forgot the year and model but can look it up if you are interested). With the sensor replaced the gage needle shows an accurate reading - without an actual PSI number - but as a percentage of the needle's sweep.

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[IDIBRONCO]

(forgot the year and model but can look it up if you are interested).

Might as well look it up for us. My oil pressure gauge always reads toward the top no matter what. I've tried different senders. Not that I'll know what the pressure is, but at least it will move like it should.

 

[Greenie]

It's any large canister type sensor - the guy in the YouTube video says a Power Stroke sender - a check online would be any of these: 57-66 F100, F250 6cyl w/ gauges, 69-72 F100, F250 6cyl w/ gauges from serial #D96,001, 65-66 F100, F250 V8 w/ warning lights, and 69-72 F100, F250 V8 w/ gauges from serial #D96,001, and 73-79 F-Series V8 w/ gauges, and 82-83 F1003.8L w/ gauges, and 80-87 F-Series V8 w/ gauges.
The instrument cluster needs to be removed and a resistor jumped otherwise it's replacing the smaller switch with the larger pressure sensor.

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[DougBoy66]

https://www.amazon.com/Standard-Mot...ateway&sprefix=ford+oil+sender,aps,182&sr=8-5

This is the link in the video if helpful. Also I am not an Amazon sale representative

 

[WrenchWhore]

The sensor that came in the 093 turbo kit was the newer smaller switch type but I replaced it with my original factory 1987 sensor which had the larger variable type. The little post was wiggling on the OE Ford one so I just replaced it to make sure it wasn't the issue. The needle on the gauge does move up and down when RPM changes but it just sits on the bottom on the gauge most of the time. I'm thinking it might be worth getting another reputable gauge to test my oil pressure or possible testing in another port that isn't inline with something that "bleeds off" pressure like the turbo would.

 

[ROCK HARVEY]

I checked the service manual and the others are correct, minimum 10psi at hot idle:

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But the manual also recommends SAE 30wt oil if it’s above freezing outside. I bet you’re running 15w40, which would give a lower hot idle PSI. I’m not recommending a switch, just saying the oil viscosity might explain the difference. I think your engine is fine.

 

[WrenchWhore]

I am definitely running Mobile Delvac 1300 super 15w-40 (synthetic blend) with Cheap STP powerstroke blue filter. The oil probably has about 1500 miles on it. I mention it because I have seen slight drops in oil pressure once the oil has Had a few heat cycles put into it.