[updated:LAST EDITED ON 22-Oct-02 AT 08:50 PM (EST)]Oil pressure gage gets pegged,then goes back to normal.
Is this a sensor prob. or more? Much Obliged, Paul

 

the gage is fake,above something like 4.5 pounds it reads normal below that it reads zero. so its something with you connection

96 Bronco, Eddie Bauer, 351w, auto

 

Thank you Sir, I'll take alook at the connections.
Much Obliged, Paul

 

There is a 20 ohm resistor on the back of the gauge cluster to center the oil pressure needle. It must be shorting somehow to peg the needle on H.

Jim

 

[updated:LAST EDITED ON 23-Oct-02 AT 02:57 PM (EST)]Thank you Sir, I'll be sure to look at that also.
Much Obliged, Paul

 

i dont believe the resistor is there to center the gage at all. i think the resistor is ther to stabilize the gage so dumd consumers dont think they have oil pressure problems. if you look at a GM product oil gage it registers oil pressure quickly as engine speed increases and decreases. this resistor on the ford lets this oil gage respond more slowly and smoothly. the same goes for the gas gauge fords are slow and smooth where GMs are fast and jumpy.

 

I'm afraid you missed the point. Ford had a "better idea" starting about '87 to give you an idiot sender that is just an on-off switch at about 5psi. The only valid readings are pegged-at-L or mid-range. The resistor is so that it does not peg at H. Any other reading is an electrical problem. If you don't believe me, look at a factory service manual.

Yes, GM and others, including Toyota, have fast-acting real indicators. Toyota is scary because normal pressure at idle is almost zero, but it comes up immediately above idle.

Jim

 

>I'm afraid you missed the point. Ford had a "better idea"
>starting about '87 to give you an idiot sender that is just
>an on-off switch at about 5psi. The only valid readings are
>pegged-at-L or mid-range. The resistor is so that it does
>not peg at H. Any other reading is an electrical problem. If
>you don't believe me, look at a factory service manual.
>
>Yes, GM and others, including Toyota, have fast-acting real
>indicators. Toyota is scary because normal pressure at idle
>is almost zero, but it comes up immediately above idle.
>
>Jim

If it's an 'electrical problem', how can it be corrected? My truck read about 25% at all times, sometimes climbs upto the N in Normal. The needle definitely moves (fluctuates) depending on its mood. Is it just a bad ground?

 

hey jim

so what you are saying is the sending unit is just a pressure activated switch? so in reality all you would have to do is change the sending unit to one that gives a variable short to make the gage operate as a real oil gage. does this mean a pre say 1987 sending unit would do this? thanks for setting me straight but its not that i didnt believe you it was just the way i thought it was.

 

[updated:LAST EDITED ON 25-Oct-02 AT 10:04 AM (EST)]You are close. To make the "idiot" gauge into a "real" gauge, pull the instrument cluster out and replace the 20ohm resistor with a piece of wire, then change the sending unit to an earlier design that is a variable resistance unit. You could leave the 20 ohm resistor in, but your gauge would be off on indication. I think that other's have used a 1986 sending unit with good results.

 

How can I just make the guage act like the idiot it's supposed to? In other words, I'm tired of seeing it read like I have only 25% pressure, when my other Bronc shows about 60%. Is it just a bad ground?

 

we need validation of this tech article; I know some pals here have performed this mod to their Broncos/F series in recent past.

 

>How can I just make the guage act like the idiot it's
>supposed to? In other words, I'm tired of seeing it read
>like I have only 25% pressure, when my other Bronc shows
>about 60%. Is it just a bad ground?

The connection at the sending unit is not very positive. I would look there first. Next would be the connections at the gauge cluster.

AIM,

Thanks for posting that link. The only difference for a gas V-8 is the location of the sending unit. Due to the much larger size of the "real" sending unit, it is a challenge. A 1/4 NPT pipe nipple and elbow are reqired to clear the oil fiter for the gas engine installation.

Jim

 

Had a similar problem on my 87 with 302 gas engine.
Oil pressure had 'seemed' to very slowly drop over 6 months, until was very close to low. Strangely, the 'pressure' went lower with higher revs- not what you'd expect.
I cleaned the terminal & connector to the sender, and crimped it a bit with pliers to get a tighter fit, now oil 'pressure' back in the middle. At least it stops the paranoia of low oil pressure worries!

 

[updated:LAST EDITED ON 28-Oct-02 AT 10:17 PM (EST)]Ok, stupid question number 9,683,245. If the newer oil pressure gauge is just an "idiot" sensor that pushes the needle then why on my '92 when I replaced the 302 did the exact same gauge read higher in the "normal" range after the engine swap. Thats right, the new engine reads higher oil pressure than the old engine on the factory "idiot" gauge!

Oh and please don't come back with something cryptic, like I'm the idiot. I know what the gauge read then and what it reads now. the readings are different.