oil pressure concerns...

fiveoho

15 Year Member

Apr 28, 2005

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Nov 28, 2012

#1

• Nov 28, 2012

• #1

my 90 gt shows solid oil pressure on a cold start (factory gauge). the needle is smack dab in the middle of the gauge. the warming the car gets, the more the needle falls - even while cruising. its always in the "normal" range but not by too much - resting on the 1st mark above the "red mark L". i'm aware the factory gauge is more of a dummy light than anything. i hooked up a mechanical gauge but i want to be sure the numbers i got are decent.

at hot idle, the car makes 17 lbs. at 2500 rpm, it makes 37lbs.

is this safe?

 

tca7291

I can see your wieners.

5 Year Member

Sep 1, 2011

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Raleigh, NC

Nov 28, 2012

#2

• Nov 28, 2012

• #2

Sounds a little low, probably had a lot of hard miles on her, but I wouldn't be too concerned, I used to have a chevy 350 that would hot idle at about 6-8psi with running 20w50 oil, and she never blew up.

 

fiveoho

15 Year Member

Apr 28, 2005

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Nov 28, 2012

#3

• Nov 28, 2012

• #3

actually i think the car has been driven pretty easy. when i bought it from the 2nd owner, it was bone stock - right down to the mufflers and airbox. auto with a 2.73 rear. i dont think you could purposely abuse it with that combo. 139,000 miles.

 

95Vert383AOD

15 Year Member

Jun 10, 2008

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New Bedford, MA

Nov 28, 2012

#4

• Nov 28, 2012

• #4

What filter are you using?

 

fiveoho

15 Year Member

Apr 28, 2005

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Nov 28, 2012

#5

• Nov 28, 2012

• #5

FL1A

 

fiveoho

15 Year Member

Apr 28, 2005

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Nov 30, 2012

#6

• Nov 30, 2012

• #6

bump

 

2000xp8

SN Certified Technician

Aug 8, 2003

8,035

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NJ

Dec 1, 2012

#7

• Dec 1, 2012

• #7

You're fine.
Rule of thumb is 10 psi per 1000rpm.

Stangnet members seem to over inflate their oil pressure and gas mileage numbers.
If you were 10 and under at idle i'd be concerned.
I've had a mechanical oil pressure gauge since i pretty much owned the car, when in proper working order hot idle always hovered around 20psi.

If it's on your mind, just make sure to change your oil every 3000 miles.

How many quarts are you going through between oil changes?

 

fiveoho

15 Year Member

Apr 28, 2005

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Dec 4, 2012

#8

• Dec 4, 2012

• #8

sorry for the delayed response...

i actually have only had the car long enough for 3 oil changes. the 1st was the initial one when i got it. the other two have been very quick ones - 1500 miles and 700 miles. the intake valley was fairly sludgy and did have some carbon build up. my mechanic cleaned it out best he could but he suggested i do a few short oil changes to help flush things out. the last oil change ( yesterday ), i swapped over to 10w 40 and have noticed a little increase in pressure. i didnt want to go any thicker than that as i do not want to impede oil flow.

so far, the car does not burn any oil.

thanks for your response btw.

 

fiveoho

15 Year Member

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Dec 4, 2012

#9

• Dec 4, 2012

• #9

edit...

post above should say -lifter valley-

editing feature doesnt seem to be working or very delayed.

 

Dino Dino Bambino

15 Year Member

Jun 13, 2007

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Dec 4, 2012

#10

• Dec 4, 2012

• #10

fiveoho said:

at hot idle, the car makes 17 lbs. at 2500 rpm, it makes 37lbs.

is this safe?

Click to expand...

Those numbers are a little low and are indicative of a high mileage engine, but there's still plenty of life in it yet so I wouldn't be concerned at this stage. Sounds like the previous owner didn't change the oil as often as he should have.

 

Maryland Stang

Active Member

Aug 21, 2002

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Greenville, NC

Dec 4, 2012

#11

• Dec 4, 2012

• #11

The pressure sounds good for an engine that has had questionable maintenance done. Sludge buildup is a for sure sign that the maintenance was questionable. The one thing that really worries me is the condition of the timing chain. It's unfortunate that there isn't a good way to check the chain without tearing the front off of the engine. I have 148,000 miles on the chain on my 5.0 1995 F150 but I know the history of my truck and the oil changes have been done at 3,000 miles with high quality oil. I may think about changing the chain at 200,000 if the water pump doesn't need to be replaced before then.

 

fiveoho

15 Year Member

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Dec 5, 2012

#12

• Dec 5, 2012

• #12

i know some of the history on the car. the doctor that had it for the majority of its life lived 10 minutes from the hospital. he drove it to work every day but being such a short distance, the car never really got up to operating temperature much. which would probably explain the sludge in the lifter valley. it wasnt terrible but more than what needed to be there.

no worries on the chain. when i got the car, a GT40 intake and e cam were put in place - along with a frpp double roller chain.