Oil Pressure Drops, Temp Rises, Loss Of Power

Josiah36

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Apr 12, 2017
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Brought a 91 mustang gt (302HO) about a month or two ago. Car runs good when cold but when it warms up (about 30mins of driving) the oil pressure starts to drop. When driving at a steady speed the oil pressure will maintain its self (but the tempature guage goes up almost to L on NORMAL and fluctuates back in forth to the M AND L ) when I come to a stoplight or any complete stops the oil pressure drops way below the red line, and goes back up when I accelerate. It also seem like my car loses power when this occurs. HELP PLEASE I'm tired of dealing with it.
 
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Josiah36

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Apr 12, 2017
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Brought a 91 mustang gt (302HO) about a month or two ago. Car runs good when cold but when it warms up (about 30mins of driving) the oil pressure starts to drop. When driving at a steady speed the oil pressure will maintain its self (but the tempature guage goes up almost to O on NORMAL and fluctuates back in forth from O To R) when I come to a stoplight or any complete stops the oil pressure drops way below the redline reading low, and goes back up when I accelerate. It also seem like my car loses power and wants to die when this occurs. HELP PLEASE I'm tired of dealing with it.
 

Blandnuts

I don't swallow; I only swoosh
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I would get real gauges on the car. It might be a voltage issue due to the car dropping in rpms during idle conditions.

What are the idle rpms and do they fluctuate too?

What modification do you have? Alternator? Pulleys? Radiator?

Is the air deflector installed under the front bumper?

Has the car had a tune up and what was done?
 

Josiah36

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Apr 12, 2017
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I would get real gauges on the car. It might be a voltage issue due to the car dropping in rpms during idle conditions.

What are the idle rpms and do they fluctuate too?

What modification do you have? Alternator? Pulleys? Radiator?

Is the air deflector installed under the front bumper?

Has the car had a tune up and what was done?
When you say vault issue, is that something to do with the battery? Because it, it does have a little corrosion on the positive connection. I don't have any modifications except a aftermarket airfilter. It hasn't had a tune up since I brought it but the plugs and wires seem to be good. the rpms only drop when at a complete stop. I've done a oil change, valve cover gasket, belt, and pvf since I owned the car.
 

90sickfox

I didn't really have an issue with the stink...
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We need a little more info. Is your car a 5 speed or automatic ? Between the o and r is normal for our cars. Before that temperature certain sensors aren't talking to the computer...like the o2 sensors. There are a couple threads around the internet about pulling codes on a fox mustang.

Pull the codes and let us know what they are.
 

Josiah36

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Apr 12, 2017
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We need a little more info. Is your car a 5 speed or automatic ? Between the o and r is normal for our cars. Before that temperature certain sensors aren't talking to the computer...like the o2 sensors. There are a couple threads around the internet about pulling codes on a fox mustang.

Pull the codes and let us know what they are.
It's an automatic
 

foxbobby

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Apr 6, 2017
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As 5.0's age it's not necessary uncommon for the oil pressure to drop off at idle but it sounds like yours is extreme. Fresh oil with some additive may be a good investment then proceed to idle frustration.
 

General karthief

wonder how much it would cost to ship you a pair
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A place to start.
Get some cheep aftermarket mechanical gauges and see what your real temp and oil pressure is, you can zip tie them to the wiper arms temporarily.
Do some stuff like changing the thermostat with a quality 190' stat. Check to see that radiator is flowing good and temp is consistent top and bottom.
Check your plugs wires cap and rotor, fuel filter and check fuel pressure, timing and air filter
Does the car have any blowby or smoke out the exhaust?
 

mikestang63

SN Certified Technician
Aug 27, 2012
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The first thing you need to to is fix the overheating/high temp problem. For that, you need to post more information. It could be anything. You havent said if the car is stock, how many miles, stock fan, radiator, etc. have you done any work to it lately.

  • how many miles on the motor- is it burning or using oil
  • high oil temperature can cause low oil pressure- which you have already said the car runs hot
  • a worn oil pump also will cause low oil presure at idle
 

mikestang63

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People have already tried to help you in your last thread. Did you answer and do all of the recommendations...?
wait- you mean I've been hoodwinked? scammed? taken advantage of?wasted my knowledge, time and valuable resources in providing advice to someone who has previously ignored others on SN?:pirate:
 
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