oil pressure

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Rushman04

New Member

Aug 11, 2003

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May 1, 2008

#1

• May 1, 2008

• #1

hey, i have a 86 mustang with a 5.0 that i rebuilt and the oil pressure is dropping. Here is the situation, when i start the car up the oil pressure is sitting in the middle of the gauge and over a twinty min. period it lowers down to low. Iam trying to figure out wether or not if i should get a new oil pump or if it is a bearing.Is there any tests i could do to narrow down things.

 

cenok is family

15 Year Member

Jun 25, 2003

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Norman, Ok

May 1, 2008

#2

• May 1, 2008

• #2

are you sure your gauge is accurate? stock fox gauges are almost worthless. regardless, it sounds like the pump is going out. how many miles are on the motor?

 

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Rushman04

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Aug 11, 2003

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May 1, 2008

#3

• May 1, 2008

• #3

the miles on the motor are 30 since the rebuild, the oil pump i didn't get a chance to replace during the rebuild. the oil pump has appox. 90K on it. Maybe i will get a gauage at autozone this weekend and double check the oil pressure

 

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91foxbod50

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Sep 26, 2007

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May 1, 2008

#4

• May 1, 2008

• #4

sending unit

 

Jaswir

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Mar 31, 2005

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Orlando, FL

May 1, 2008

#5

• May 1, 2008

• #5

wow that is one of the most import things to replace on a rebuild... get a aftermarket gauge and hook it up and see what kinda of pressure you really have!

 

cenok is family

15 Year Member

Jun 25, 2003

1,409

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Norman, Ok

May 1, 2008

#6

• May 1, 2008

• #6

Rushman04 said:

the miles on the motor are 30 since the rebuild, the oil pump i didn't get a chance to replace during the rebuild. the oil pump has appox. 90K on it. Maybe i will get a gauage at autozone this weekend and double check the oil pressure

Click to expand...

im going to say the pump. you should have replaced it man! they're cheap!

 

Fast63

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Sep 20, 2007

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May 2, 2008

#7

• May 2, 2008

• #7

are you wondering why it's going from middle to low after 20 minutes? Because the oil warms up, gets thinner, and you get less pressure.

If you're just wondering why your oil pressure is low, it's because your bearings are worn, but I second the idea of getting an aftermarket gauge on it because the stock gauges are junk on your 86. So are the ones on my 85.

 

bloopbloob

Member

Sep 27, 2006

578

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Alberta

May 2, 2008

#8

• May 2, 2008

• #8

yup! i'm with the pump or bearings crowd. since it's rebuilt, that puts me on the pump crowd's side. only time i ever had oil pressure drop was when my bearings went. and i replaced them, and the oil pump (cheap insurance when doing a rebuild!!!) when it was rebuilt. no problems ever since.

 

mustangfan1990

New Member

Jul 17, 2005

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Lenoir, North Carolina

May 2, 2008

#9

• May 2, 2008

• #9

I think bearings. Pumps dont go out often they are simple piece of metal that is turned by the oil pump driveshaft that connects to the bottom of your distributor. I wouldnt think that it is the oil pump even though when you pull the motor you change it good or bad cause you dont want to have to pull the oil pan off with the engine in the car ( BIG BIG BIG BIG BIG PITA) and you dont want to pull the engine just to change the oil pump. I would say the engine need a rebuild OR you could be low in oil lol

 

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Rushman04

New Member

Aug 11, 2003

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May 5, 2008

#10

• May 5, 2008

• #10

hey i finally got to play around more. the oil gauge will drop to low then if i rev the engine up alittle the pressure comes up but then will go down shortly after i brought the pressure up.

 

ninety15.0

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Mar 10, 2004

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May 5, 2008

#11

• May 5, 2008

• #11

i would get a real gauge on there. Mine was doing something similar after my rebuild. It wasn't responding to revving the motor. The pressure seemed to just always been just below half. I put a mechanical autometer on there. And viola 25psi hot idle and 50psi cruising.

The stock gauge is inaccurate and the stock sending unit can be a problem as well. If the oil pressure is low when the motor is at a hot idle thats ok. Then it should rise when you rev it. I would get a real gauge on there.