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Low oil pressure and shudder at low rpm

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Old Oct 21, 2011 | 08:07 PM
  #1  
evilstuie's Avatar
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From: Brisbane, Australia
Car: 1985 Pontiac TransAM
Engine: 400SBC 24x conversion
Transmission: T700r Stage2 Shiftkitted
Axle/Gears: 2.77 9 Bolt
Low oil pressure and shudder at low rpm

Hey guys,
It's been a bad week for my car, hopefully someone can offer some hope for it here

1) Low oil pressure - Sits at about 20-25 at cold start, then drops off to 0 once it's warm and idling. Will hit about 30 at 3500rpm but i don't want to go over that. I'm thinking blockage or oil pump is on it's last legs maybe?

2) Car won't start all the time. Sounds like starter motor.

3) Dipstick tube is loose and spraying oil all over my headers and starter motor (may be the issue with starting)

Can anyone confirm any of this, or more importantly point me in the right direction for changing these parts?

It's a 85 bird with 350 tpi, converted to Right hand drive.



Edit: Also is there any hope for the engine or will i have to rebuild / replace, the shuddering at low revs has me very worried it's a mechanical issue that cannot be undone.
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Old Oct 21, 2011 | 09:40 PM
  #2  
Apeiron's Avatar
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Joined: Jan 2000
Posts: 20,981
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From: Mercedes Norte, Heredia, Costa Rica
Car: 1984 Z28 Hardtop
Engine: 383 Carb
Transmission: 4L60
Axle/Gears: 3.54 Dana 44
Re: Low oil pressure and shudder at low rpm

Originally Posted by evilstuie
1) Low oil pressure - Sits at about 20-25 at cold start, then drops off to 0 once it's warm and idling. Will hit about 30 at 3500rpm but i don't want to go over that. I'm thinking blockage or oil pump is on it's last legs maybe?
Check the oil pressure sender.

Originally Posted by evilstuie
2) Car won't start all the time. Sounds like starter motor.
Check the starter

Originally Posted by evilstuie
3) Dipstick tube is loose and spraying oil all over my headers and starter motor (may be the issue with starting)
Check the PCV system.
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Old Oct 21, 2011 | 10:23 PM
  #3  
evilstuie's Avatar
Thread Starter
Senior Member
15 Year Member
 
Joined: Feb 2009
Posts: 874
Likes: 18
From: Brisbane, Australia
Car: 1985 Pontiac TransAM
Engine: 400SBC 24x conversion
Transmission: T700r Stage2 Shiftkitted
Axle/Gears: 2.77 9 Bolt
Re: Low oil pressure and shudder at low rpm

Originally Posted by Apeiron
Check the oil pressure sender.
how do I check it?

Originally Posted by Apeiron
Check the starter



Check the PCV system.
Thanks for the tip, but i was more after a tutorial or step by step.
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Old Oct 22, 2011 | 01:44 AM
  #4  
evilstuie's Avatar
Thread Starter
Senior Member
15 Year Member
 
Joined: Feb 2009
Posts: 874
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From: Brisbane, Australia
Car: 1985 Pontiac TransAM
Engine: 400SBC 24x conversion
Transmission: T700r Stage2 Shiftkitted
Axle/Gears: 2.77 9 Bolt
Re: Low oil pressure and shudder at low rpm

oil changed, filter changed, 4L oil put back in, adjusted dipstick and doesn't seem to be spitting oil. cleaned the connectors for the starter motor and solenoid with hexane to remove all the gunk.

Seems to start first go now, the oil pressure starts at 30 and drops to 15 after warm, but when i rev it, it maxes out at around 35. i gave it a bootfull and kept it in low for about 40secs @ 4000rpm and still wouldn't go above 30-35.

Didn't blow up, but still not sure, I only took it around the block so didn't have enough time to check if it was overheating...
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Old Oct 22, 2011 | 12:36 PM
  #5  
grumpyvette's Avatar
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Joined: May 2002
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From: loxahatchee fla
Re: Low oil pressure and shudder at low rpm

sounds like oil pump pick-up may be loose and you've got symptoms that might be a cracked head or bad head gasket or bad intake gasket, if your smart youll pull the engine ,disassemble and inspect its components before further damage is done
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Old Oct 23, 2011 | 02:28 PM
  #6  
evilstuie's Avatar
Thread Starter
Senior Member
15 Year Member
 
Joined: Feb 2009
Posts: 874
Likes: 18
From: Brisbane, Australia
Car: 1985 Pontiac TransAM
Engine: 400SBC 24x conversion
Transmission: T700r Stage2 Shiftkitted
Axle/Gears: 2.77 9 Bolt
Re: Low oil pressure and shudder at low rpm

The engine hasn't been all that great for a while now, had a stuffed thermostat, and then a clogged cat and a lot of blowby, so it's time for a new engine anyway.

I'll take the sump off and have a look this weekend and replace the pump and pickup and see if that fixes the pressure issue, but anything more than that is a waste of money if I'm putting a new motor in.

Thanks for the info.
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