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Oil pressure problem?

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Old Jul 17, 2008 | 09:39 PM
  #1  
chas0218's Avatar
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From: Corning NY
Car: 86' IROC
Engine: 388
Transmission: Built 700r4
Axle/Gears: 3.08 non-posi
Oil pressure problem?

When im driving the car it runs about 30 psi when it idles it drops to 10psi...it idles at 800 rpms...when i accelerate it does go up but i just want to be sure that the pressure is supposed to drop this low...this is my first V-8 so bare with me...

thanks chas
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Old Jul 18, 2008 | 10:21 AM
  #2  
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From: Southern IL
Car: 88 GTA "Cocaine"
Engine: 350 tpi
Transmission: 700r4
Axle/Gears: 3.27
Re: Oil pressure problem?

standard oil pump-normal
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Old Jul 18, 2008 | 12:15 PM
  #3  
Theking's Avatar
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From: Sweden
Car: 1989 IROC-Z
Engine: 350 TPI
Transmission: Th700R4
Axle/Gears: 3.27
Re: Oil pressure problem?

As long as you arent in the RED zone on the gauge you will be fine. And if the pressure rises with throttle/rpm dont worry.
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Old Jul 18, 2008 | 01:27 PM
  #4  
89RsPower!'s Avatar
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Joined: Apr 2002
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From: New Jersey
Car: 86 Corvette, 89 IROC, 1999 TA
Engine: 350, 350, LS1
Transmission: 700r4, 700r4, T-56
Axle/Gears: 3.07, 373, 4.10
Re: Oil pressure problem?

Where are you getting the reading from? Factory gauges are known to be very inaccurate. If you want a reading you can trust hook up a known good mechanical gauge. Rule of thumb is 10psi per 1k rpm's, but in my mind that's the absolute lowest I'd want to see. For example I just pulled my 305 because it had a rod knock, it had 15 psi at idle once it warmed up. If you engine is running well and noise free at 10psi I'd put my money on a bad oil pressure sending unit before I'd bet on worn bearings.
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Old Jul 18, 2008 | 02:33 PM
  #5  
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From: Bedford Tx
Car: 1991 Z28 1LE
Engine: 370CID GenIII
Transmission: 4l60e
Axle/Gears: 4.33 Moser 9inch
Re: Oil pressure problem?

Originally Posted by 89RsPower!
Where are you getting the reading from? Factory gauges are known to be very inaccurate. If you want a reading you can trust hook up a known good mechanical gauge. Rule of thumb is 10psi per 1k rpm's, but in my mind that's the absolute lowest I'd want to see. For example I just pulled my 305 because it had a rod knock, it had 15 psi at idle once it warmed up. If you engine is running well and noise free at 10psi I'd put my money on a bad oil pressure sending unit before I'd bet on worn bearings.
one thing to add my general rule is 10 psi per 1000rpms pluse an extra 10psi margin. so at 1000rpms 20 psi at 2000 rpms 30psi and so foth is how i like it....
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Old Jul 18, 2008 | 09:47 PM
  #6  
chas0218's Avatar
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From: Corning NY
Car: 86' IROC
Engine: 388
Transmission: Built 700r4
Axle/Gears: 3.08 non-posi
Re: Oil pressure problem?

its an auto meter 3 1/2" gauge so im guessing its right on...i have to change my oil its pretty dirty but normally it runs higher when dirty...but it gets up to 60 and flucuates down to 10...this isnt the stock motor its a 350...at what pressure should i start to worry about it?
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Old Jul 19, 2008 | 01:14 PM
  #7  
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From: Bedford Tx
Car: 1991 Z28 1LE
Engine: 370CID GenIII
Transmission: 4l60e
Axle/Gears: 4.33 Moser 9inch
Re: Oil pressure problem?

if i were u i would start saving up for a rebuild. the motor will probably last a while still sbc are tough but this way when it does go ull be ready...
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Old Jul 20, 2008 | 10:54 PM
  #8  
chas0218's Avatar
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Joined: Jun 2008
Posts: 660
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From: Corning NY
Car: 86' IROC
Engine: 388
Transmission: Built 700r4
Axle/Gears: 3.08 non-posi
Re: Oil pressure problem?

All is good im running about 15-20 psi at an idle after my oil change...im thinking he was running a lighter weight oil than 10w-30 b/c im having no problems at all and all of the pistons are within 8psi in compression of each other and it was rebuilt 5k miles ago so i think i am good....thanks for the help guys!
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Old Jul 21, 2008 | 01:19 PM
  #9  
89RsPower!'s Avatar
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Joined: Apr 2002
Posts: 3,552
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From: New Jersey
Car: 86 Corvette, 89 IROC, 1999 TA
Engine: 350, 350, LS1
Transmission: 700r4, 700r4, T-56
Axle/Gears: 3.07, 373, 4.10
Re: Oil pressure problem?

Originally Posted by chas0218
All is good im running about 15-20 psi at an idle after my oil change...im thinking he was running a lighter weight oil than 10w-30 b/c im having no problems at all and all of the pistons are within 8psi in compression of each other and it was rebuilt 5k miles ago so i think i am good....thanks for the help guys!
unless its was built with extremely loose tolerances it should be a bit higher than that if it only has 5k on it, somewhere around 30-35psi at idle when warm seems about right for a fresh sbc.
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