Oil pressure problems

Marco86gt

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May 11, 2021
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I have a 86 gt 5.0 ho and been having problems with the oil pressure. I was driving and I lost complete oil pressure but then I turned the car off as soon as it dropped and turned it back on after 2 mins and it went back to the “o” in normal. I put a new oil pressure sensor and a new cluster. What should it be oil pump or it’s just the cluster I put is bad because it’s used. But it’s weird how it lost it completely but got it back. Any suggestions what it could be?
 
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General karthief

wonder how much it would cost to ship you a pair
Mod Dude
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Install a mechanical pressure gauge, you can zip tie it to a wiper blade temporarily if necessarily, that way you can monitor the readings.
 
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7991LXnSHO

wanna catch the space herp
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An electrical gremlin is the most likely cause. But without verifying with a different gauge or at least testing the old components, you will never be sure.
were there any other symptoms of low oil pressure? For example, lifters soon collapse and the valve train gets noisy without oil pressure.
 

HemiRick

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if the engine truly had no oil pressure it would get louder as the lifters/rockers would start clicking/tapping.....
 
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Marco86gt

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An electrical gremlin is the most likely cause. But without verifying with a different gauge or at least testing the old components, you will never be sure.
were there any other symptoms of low oil pressure? For example, lifters soon collapse and the valve train gets noisy without oil pressure.
I had another cluster on it before and it never dropped like that. And the oil pressure to this time is on normal but on the “o” I turned the car on today and it was on normal for like 10 mins then it lost all pressure and I did turned the car off and then turned it back on and got the oil pressure back.
 

Marco86gt

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But for some reason it has oil pressure but it losses it then after I turn the car off and turn it on it comes back that’s what freaking me out. Is it the pump getting clogged or....????? Idk
 

7991LXnSHO

wanna catch the space herp
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1. What are the other gauges doing when this happens???
2. Is the 86 dash still the 4 eye style or the aero nose style? The early style and other Fox chassis cars seem to have more problems like this.
3. There is more to the circuit than the gauge and sender. The wires, circuit board and ground all need to be considered. Turning it on and off could even be the ignition switch, especially if the other gauges go bonkers.
 

Marco86gt

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May 11, 2021
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1. What are the other gauges doing when this happens???
2. Is the 86 dash still the 4 eye style or the aero nose style? The early style and other Fox chassis cars seem to have more problems like this.
3. There is more to the circuit than the gauge and sender. The wires, circuit board and ground all need to be considered. Turning it on and off could even be the ignition switch, especially if the other gauges go bonkers.
The 4 eye cluster. So I had the original gauge on it and the oil pressure was always on “o” in normal then I bought a new oil pressure sensor and it was on r and o for like 2 days never dropped them I got a used cluster because my rpms didn’t work on my original cluster and that’s when it dropped but came back. Still the 4 eye cluster but a used one for another car.
 

Marco86gt

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I’m put my old cluster back and see if the oil pressure drops with that one because since I had the car with the original cluster it never did that and since I put the other one that’s the first time it did it but I drove it like that to work and didn’t do it and on the way back it did it so It only did it once with the new cluster (new to me) and I drove it for a while. That’s why hat is weird. Cause if it was the cluster it will do it more often and it only did it once
 

7991LXnSHO

wanna catch the space herp
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Then likely possible problems, a weak connection, or a bad ground.
Do the other gauges go down or peg out at the same time?
 
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7991LXnSHO

wanna catch the space herp
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I have seen the multiple gauge problem in two 79 Mustangs, a Fairmont and an 87 Cougar. Most often when the gas tank was full, the other gauges would periodically start to head up to their maximum range. When the tank was near empty, the other gauges would head down. But it could happen at any time. This was before I knew about StangNet, or before this group was started.
The thing that sent the gauges back to normal, besides power cycling the key, was a Fonzie tap to the bottom of the dash above the right knee.
That’s why I suggest you check the connections at the dash and for loose grounds. The firewall to engine ground is also suspect.
 
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7991LXnSHO

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I see you are listed as 21. A Gibbs slap (NCIS) or a dope slap (Three Stooges) is similar to a Fonzie tap (Happy Days), but it fixed the jukebox and other electronics.

Sincerely, not a boomer, but I know many.
Les
 

Marco86gt

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May 11, 2021
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I see you are listed as 21. A Gibbs slap (NCIS) or a dope slap (Three Stooges) is similar to a Fonzie tap (Happy Days), but it fixed the jukebox and other electronics.

Sincerely, not a boomer, but
I see you are listed as 21. A Gibbs slap (NCIS) or a dope slap (Three Stooges) is similar to a Fonzie tap (Happy Days), but it fixed the jukebox and other electronics.

Sincerely, not a boomer, but I know many.
Les
?!
 

Marco86gt

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May 11, 2021
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Fortworth Texas
So I just drove the car for like 15 mins and i was gassing it and it never dropped pressure it went from o” in normal to r” but never dropped below normal. So that time it happen do yall think it was the oil pump getting clogged or just the gauge trippen out?
 

7991LXnSHO

wanna catch the space herp
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If you do not want to put on a mechanical gauge and check the wiring, you can pull the pan and see how much crud could be ready to plug the pickup. I know which two I would do. But if your oil pan is leaking, the extra work might be worth it - along with a new pump, pickup and ARP pump drive shaft.
 

Marco86gt

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May 11, 2021
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Fortworth Texas
If you do not want to put on a mechanical gauge and check the wiring, you can pull the pan and see how much crud could be ready to plug the pickup. I know which two I would do. But if your oil pan is leaking, the extra work might be worth it - along with a new pump, pickup and ARP pump drive shaft.
I’m put a mechanical gauge on it and run it for a while and see what happens.
 
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2000xp8

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I believe the 86 has a nice period correct looking gauge pod for the center console. Install real oil pressure and water temp gauges (preferably full sweep mechanical) and just leave them that way.
While i am no fan of aftermarket gauges, i think these 2 are necessary evils on foxes.
You will never have to worry about what the inaccurate factory gauges are suggesting ever again.
 
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OldManRiver

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Thought I'd add to this thread since experiencing same issue.Replaced oil pressure sender during rebuild even thou old one was working,just looked crusty.
With about 400 miles on rebuild had oil pressure drop to nothing on the factory gauge close to my destination,ended up checking the wire connection which didn't change anything, then tapped on the side of the sender and oil pressure came back.On the way home same thing,tapped on the side of the sender and gauge started reading correctly again.

With out knowing the internals of these senders I can't say for certain why tapping on the side of the sender body would make it work correctly,but since I don't throw anything out I will be installing the old crusty unit back in place.
 
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