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High Oil Pressure?

Fordzilla80

Ranger Lariat
6,372
262
Narnia
I have a question. Ever since I first got the F100 it's had High Oil Pressure. I know some people say that it's not a concern, but there's a normal part of the gauge for a reason. What exactly could cause the engine to have to push the oil through at a higher pressure? I don't think the gauge is stuck because it always goes back down when the truck is off. I've always wondered about this, but kept forgetting to ask.
 

flareside_thunder

Florida Chapter member
7,812
246
The factory sending unit has no job to do other than read that there is oil pressure.....whatever that gauge says does not necessarily reflect the amount of pressure being fed.....best bet is a mechanical oil pressure gauge.
 

Fordzilla80

Ranger Lariat
6,372
262
Narnia
I'd imagine that when it pegs all the way to the right, it found something important.

I'm not into the whole ugly chrome gauges hanging below my dash or on the A-Pillar so the only time i'd ever consider a mechanical gauge is using one under the engine compartment to get an accurate reading. Anybody know of anything like that?
 
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LEB Ben

Arrogant A-hole At-Large
34,919
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outside your house
The factory sending unit has no job to do other than read that there is oil pressure.....whatever that gauge says does not necessarily reflect the amount of pressure being fed.....best bet is a mechanical oil pressure gauge.

Great description...tried to rep, but gotta spread it.

I'd imagine that when it pegs all the way to the right, it found something important.

I'm not into the whole ugly chrome gauges hanging below my dash or on the A-Pillar so the only time i'd ever consider a mechanical gauge is using one under the engine compartment to get an accurate reading. Anybody know of anything like that?

The factory dummy gauge could be the way it is because of an exposed wire, crimped wire, bad SU, etc...so many things that could be causing it to do what it does, it's not even funny.


As for the underhood gauge. Yes they're out there...seen it done that way several times. I dunno if it's just an adapted gauge, or if there's an actual kit. I always see them mounted on the firewall.
 

Fordzilla80

Ranger Lariat
6,372
262
Narnia
With the amount of oil that was on this engine when I got it, I wouldn't surprised if the wire/sending unit is screwed up.

What i'm looking for is something like a timing light. Something that you can just hook up, get a reading, and then disconnect and go on down the road. I don't want anything permanent.
 

1985 Ford F-150

Country Boys Can Survive
7,816
307
Tooele, Utah
Just put T fitting where the sending unit goes and screw the sending unit in one side and hook it up then get your mechanical gauge and put it in the other side. If thats too permanant then just unscrew the sending unit and put the mechanical gauges fitting in there see what your pressure is then swap it back. How long has it been runnin when ya look at the gauge? If your just startin it up after its been sittin and not lettin it get up to operatin temperature then its normal. Also what wieght of oil is in it and is it the right ammount? I personally wouldnt worry about high pressure its low pressure that ya really dont wanna have to deal with.
 
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Fordzilla80

Ranger Lariat
6,372
262
Narnia
Longest I ever ran the truck continuously was about 8 minutes. Any other time it was on, then off when I would move it around the yard.

As for oil weight, If I recall, it was 6 quarts of 10w40.

As long as High Oil pressure is okay, and doesn't mean something needs replaced, then i'm not too worried about it. But i'd still like to check it every once in awhile.

Does oil run through the sending unit only when the engine is running, or is there always a little excess in there even with the engine off? I don't want any surprises if I tried to remove the sending unit.
 
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1985 Ford F-150

Country Boys Can Survive
7,816
307
Tooele, Utah
That aint long enough to get it warmed up so its perfectly normal. Theres just a pin hole and I think a check ball in the bottom of the sending unit where it threads in when ya crank it over oil starts pushin against it and pit pushes on that little check ball the farther it goes in the higher the gauge will read and if theres any oil in it its only a drop or two. With a mechanical gauge there will be some left over in the line if you use one but its not much at all. Sounds like its perfectly normal and id only replace it if your gauge stops workin al together or it starts actin funny like peggin out one way or the other.
 

LEB Ben

Arrogant A-hole At-Large
34,919
1,124
outside your house
As Dan said...I'd rather have high pressure than low pressure. And 8 minutes isn't nearly long enough to get a 'warm reading'. Red and the Bronco can hold 60+psi for at least 5 minutes when starting from cold. If you're that worried about it, I'd replace the current SU and inspect the wire and see where it's at.
 

73F100Shortbed

That's how we roll!
5,937
320
NJ
My truck has 50psi when cold and won't drop until fully warm and that is usually more than 8 minutes. See what the gauge does when you leave it running longer than that.
 

Fordzilla80

Ranger Lariat
6,372
262
Narnia
Any further temps will have to come after I rebuild it. I have two popped freeze plugs and a bad radiator, so there's no chance of it running any time soon.

I just want the info for future knowledge because it's something i've never really understood and I keep forgetting about it. Thanks guys!
 
Hello everyone! Im new here and of course i have a question. Well i have an 86 f250 and put a used 87 302 into it and got everything working and running good i realized that my oil gauge is pegged out and gotit it home and saw that i had oil leaking out all of my gaskets pan main seal and the motor looks like it never had a leak before it was a very clean motor so my question is what would give me such high pressure like tha?
 

Fellro

Moderator
Staff member
The internal pressure has nothing to do with pan or valve cover gaskets leaking. If the truck sat for a while, the gaskets and seals may have dried out.
 

Fellro

Moderator
Staff member
bad sender, instrument cluster voltage regulator trouble, wiring troubles can make the reading high. In order to know that you truly have a high pressure, you need to verify with a good gauge. Do not trust the dash gauge.
 

SuperCab

Moderator
Staff member
10,068
547
Montana
Many dash gauges are simply what we call "idiot lights"


The original idiot light was just that, a light, but many of the gauges work the same way.

When there is oil pressure (over 15psi or something) the gauge shows normal, which could be anywhere from 40-80psi on your gauge, depending.

When there is no oil pressure, the gauge drops to zero. Therefore, it is no actual indication of what your oil pressure is. Only that you have some.
 

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