Discussion-oil pressure - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


General GM Chat When starting new posts, please specify YEAR, MAKE, MODEL, ENGINE type, and whatever modifications you have made. Chat about all things GM (and related cars). Off-topic stuff should be in the Lounge, and all Model specific mechanical problems should be posted in the proper forum.

Reply
 
 
 
Thread Tools Search this Thread
Old 12-20-2006, 12:06 AM   #1
Junior Member
Thread Starter
 
Join Date: Aug 2002
Posts: 0
Thanks: 0
Thanked 0 Times in 0 Posts
Custom88 is on a distinguished road
Default Discussion-oil pressure

I noticed on my Aurora with the 3.5 V6 that its oil pressure has a very LARGE range. When the engine is cold and idling, I have seen as high as 115 PSI. On a warm idle during the summer, I have seen as LOW as 13 PSI!! Just curious if anyone has ever seen a car with such a huge range for the oil pressure. Does anyone have any reason as to why this engine might be that way? I sure don't!

Cold idle, oil pressure.
Name:  coldidlepressure.jpg
Views: 2
Size:  3.4 KB

Warm engine, crusing @ 55MPH
Name:  cruisewarmpressure.jpg
Views: 2
Size:  4.1 KB

and finally, warm engine, idling @ 550 RPM.
Name:  warmidlepressure.jpg
Views: 2
Size:  4.7 KB
Custom88 is offline   Reply With Quote
Old 12-20-2006, 05:20 AM   #2
Senior Member
Posts like a Camaro
 
Join Date: Dec 2005
Location: Clovis, CA
Posts: 851
Thanks: 0
Thanked 0 Times in 0 Posts
MACDRIVE is on a distinguished road
Default

I doubt those are the actual values. Have you hooked up a mechanical oil pressure gage to it yet? You might need a new sending unit, but there'* no way to verify the actual oil pressure without an external gage.
MACDRIVE is offline   Reply With Quote
Old 12-20-2006, 07:37 AM   #3
DINOSAURUS BOOSTUS

Expert Gearhead
 
BillBoost37's Avatar
 
Join Date: Mar 2005
Location: Enfield, CT
Posts: 41,391
Thanks: 0
Thanked 0 Times in 0 Posts
BillBoost37 is a glorious beacon of lightBillBoost37 is a glorious beacon of lightBillBoost37 is a glorious beacon of lightBillBoost37 is a glorious beacon of lightBillBoost37 is a glorious beacon of lightBillBoost37 is a glorious beacon of light
Default

While not knowing your engine well, Toasty had brought his Aurora 4.0 down one day and we were cruising around. He mentioned how the oil pressure at idle was 8psi and considered perfectly normal on this motor.

Being a baby version of the Northstar, I could understand that your 3.5 would have the same crazy looking readings that we are not used to seeing. I never questioned the top end valuves..
BillBoost37 is offline   Reply With Quote
Old 12-20-2006, 08:48 AM   #4
Senior Member
True Car Nut
 
toastedoats's Avatar
 
Join Date: Sep 2004
Location: Fitchburg Ma _ToastedRice_
Posts: 6,837
Thanks: 0
Thanked 0 Times in 0 Posts
toastedoats is on a distinguished road
Default

I know that the northstars run at almost freighteningly low oil pressure. Like Bill said, when warm and at idle, 8psi wasnt anything abnormal, however, i never saw anything close to 100psi, i think the highest i ever remember seeing was 50ish.
However, i could see if your maybe running a heavy weight oil in cold conditions at higher RPM, that 100psi might be perfectly normal aswell
toastedoats is offline   Reply With Quote
Old 12-20-2006, 12:08 PM   #5
Junior Member
Thread Starter
 
Join Date: Aug 2002
Posts: 0
Thanks: 0
Thanked 0 Times in 0 Posts
Custom88 is on a distinguished road
Default

Quote:
Originally Posted by MACDRIVE
I doubt those are the actual values. Have you hooked up a mechanical oil pressure gage to it yet? You might need a new sending unit, but there'* no way to verify the actual oil pressure without an external gage.
A failed sending unit would read pegged out at 120 most of the time. The value of my oil pressure on the in-car gauge follows engine temperature and engine RPM exactly as it should. I don't think a bad sender would read both high, and low. Aaron, the odd thing is, I run 5W-30 year round. And you're right about it being considered 'normal,' the service manual states that the "low oil pressure" warning doesn't come on until 5 PSI. I just wonder why these engines run so low. Hmmm. Forever shall remain a mystery.
Custom88 is offline   Reply With Quote
Old 12-20-2006, 12:55 PM   #6
Senior Member
True Car Nut
 
toastedoats's Avatar
 
Join Date: Sep 2004
Location: Fitchburg Ma _ToastedRice_
Posts: 6,837
Thanks: 0
Thanked 0 Times in 0 Posts
toastedoats is on a distinguished road
Default

Quote:
Originally Posted by Custom88
Quote:
Originally Posted by MACDRIVE
I doubt those are the actual values. Have you hooked up a mechanical oil pressure gage to it yet? You might need a new sending unit, but there'* no way to verify the actual oil pressure without an external gage.
A failed sending unit would read pegged out at 120 most of the time. The value of my oil pressure on the in-car gauge follows engine temperature and engine RPM exactly as it should. I don't think a bad sender would read both high, and low. Aaron, the odd thing is, I run 5W-30 year round. And you're right about it being considered 'normal,' the service manual states that the "low oil pressure" warning doesn't come on until 5 PSI. I just wonder why these engines run so low. Hmmm. Forever shall remain a mystery.
have you asked around at ACNA? i thought i remember reading a discussion over there about it????
toastedoats is offline   Reply With Quote
Old 12-20-2006, 02:10 PM   #7
Junior Member
Thread Starter
 
Join Date: Aug 2002
Posts: 0
Thanks: 0
Thanked 0 Times in 0 Posts
Custom88 is on a distinguished road
Default

we've talked about how they have low oil pressure, but nobody seems to know why they do. I was hoping that someone would have some insight on what would cause an engine to have low pressure, and why it would be designed that way? I don't know enough about engine design/engineering to know why it would be that way, nor do I know possible causes, either. I was hoping someone would have an idea of why it'd be so low. It'* nto really a technical problem, it'* more of a discussion more than anything else.
Custom88 is offline   Reply With Quote
Old 12-22-2006, 01:06 AM   #8
Senior Member
Posts like a Camaro
 
Join Date: Aug 2004
Location: Chi-Town
Posts: 1,116
Thanks: 0
Thanked 0 Times in 0 Posts
Boreas is on a distinguished road
Default

Since your engine is similar to a Northstar, it may be best to ask around in a Cadillac forum. I know the oil pressure in our Cadillac is low as well.

http://www.cadillacforums.com/forums/
Boreas is offline   Reply With Quote
Old 12-22-2006, 04:53 AM   #9
Senior Member
True Car Nut
 
Join Date: Feb 2006
Location: Somewhere different on the globe every month....
Posts: 2,896
Thanks: 0
Thanked 0 Times in 0 Posts
Cheetah is on a distinguished road
Default

My dad'* '02 3.5 Aurora has the same readings.
Cheetah is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
MLB 05 Discussion. BonneMeMN Lounge 11 04-05-2005 06:56 PM
Tire discussion (Nokian?) Rogue General GM Chat 23 11-23-2004 06:55 PM
Discussion of body parts Geez SSEi General GM Chat 17 07-06-2004 01:40 AM
Bigger TB discussion. BonneMeMN Performance, Brainstorming & Tuning 9 04-25-2004 09:13 PM
EXHAUST PIX and some more disCUSSion... BusMaster007 Performance, Brainstorming & Tuning 33 06-03-2003 03:32 AM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 04:50 AM.


We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.