Low Oil Pressure when warmed up

ALS85GT · 10-15-2001, 03:51 PM

I have a nagging issue which is when my engine reaches normal temp, 180-190degrees, the oil pressure drops to about 8-10lbs. When cold it is around 40lbs. I have replaced the oil pres guage so that's not it. I have tried dif weights of oil, now using HD40. I have tried diff oil filters. I have an oil cooler on the car but can't use it cause I'll get 0 oil pressure???!!(when cold).- the oil pres will raise when reving the motor so I think the oil pump is working. Its also brand new.- Brief history on motor; 86 block, stock lower end, ie all bearings etc. Not sure on number of miles. Cam bearings looked used but not shot so those where retained. 85 rebuilt heads fm a carbed mustang.---I don't remember if the oil pump pickup uses a gasket between the pump and the filter? And I don't rem if I put one there. I think it should use one.
What do you guys think? Thanks for any thoughts.-one other thing. Even w/the low oil pressure, oil still gets to the top cause I checked it while running....

[This message has been edited by ALS85GT (edited 10-17-2001).]

stanger8172 · 10-15-2001, 10:36 PM

Do you still run the same stock electical gauge? Did you replace the sending unit?

------------------
'91 LX convertible , T-5,Centerforce Dual Friction, FMS adjustable cable w/quadrant, ported/polished/milled E7 heads, 1.6rr, 1.94/1.60 stainless valves, BBK 1 5/8" equal length shorties, 2 1/2" off road H-pipe, Summit 2 1/2" catback, March Performance Pulleys and A/C Eliminator

Fostang · 10-15-2001, 11:04 PM

I have exactly the same problem with my engine in the fastback. Even tried the same methods you mentioned. Nothing seems to help. I decided to leave it like that since the engine doesn't knock even on cold start ups.

------------------
67' Fastback-Mean Temper
67' Coupe Under Construction
70' Torino Cruiser
84' Svo Original

ALS85GT · 10-16-2001, 08:33 AM

I use AutoMeter guages. And I'm getting diff responces. Some says it's a pump issue(even though the pump is new), some say it's no big deal as long as you have about 8-10psi at 1000rpm(which it does when at 1000rpm).
The thing is that the engine runs fine, no noise what so ever, and the psi increases as the rpm increases. So this seems fine also. The engine is not new so I'm sure the old bearings have something to do with it.!??!I just want to be sure is all. Thanks...

PKRWUD · 10-16-2001, 09:38 AM

It sounds like routine wear and tear to me. You are right about your engines requirements: 10psi per 1k rpm minimum. As long as you don't fall below that, you'll be fine.

~C

------------------
Retired Moderator
MustangNet

My site: Peckerwoods Pit Stop

My teams site: Jim Porter Racing

RACECAR spelled backwards is RACECAR

HEY !!! Are you ASE Certified ??? If you are, ask me about iATN.

ALS85GT · 10-16-2001, 09:56 AM

OK, thanks for the responces. I'm not going to worry about it(too much). But what do you guys thing about the oil cooler? I made sure the oil reaches the "In" port on the adaptor. It's a Summit Oil/Trans cooler. I get 0 oil pressure when using this.
thanks again...

Stang_ROTY · 10-17-2001, 08:03 AM

If the engine is older than it's probably the bearings. My engine oil pressure drops after it warms up down to about 25psi from 60 and I only have 300 miles on my engine. But my thrust bearings need to be replaced due to a tranny overheat and is the main cause for my pressure drop.

Mach 1 · 10-17-2001, 09:06 AM

your oil pressure should drop when its warmed up, compared to cold. This is normal. remember, pressure is resistance to flow. warm oil flows better than cold oil, less resistance, less pressure..

------------------
1993 GT/AOD
'93 Mustang GT

Chevyguy · 10-17-2001, 12:49 PM

Mine drops to 15-25 at idle when warm from 50 - 75 while driving depending on how hot it is or how hard I was driving. This is with the stock gauge.

------------------
Frank W
90 5.0 LX Notchback Daily driver. MAC 2.5" cat back FMS aluminum driveshaft, MSD blaster coil, MAC shifter other stuff check out here user site

88 Notch 2.3L FOR SALE! My two Notchbacks
74 Chevy Laguna Type S-3 Warmed over 305 upgrading to 454 soon

ALS85GT · 10-17-2001, 01:43 PM

I understand that as an engine warms up the oil pressure will drop some. I just wasn't sure if 8-10psi was too low at idle when reaching operating temp... I appreciate the responses............I guess this may be ok for used motor w/some miles on it.

10-15-2001, 03:51 PM	#1
ALS85GT Registered Member Join Date: Aug 2001 Location: Miami, Fl, USA Posts: 69	Low Oil Pressure when warmed up I have a nagging issue which is when my engine reaches normal temp, 180-190degrees, the oil pressure drops to about 8-10lbs. When cold it is around 40lbs. I have replaced the oil pres guage so that's not it. I have tried dif weights of oil, now using HD40. I have tried diff oil filters. I have an oil cooler on the car but can't use it cause I'll get 0 oil pressure???!!(when cold).- the oil pres will raise when reving the motor so I think the oil pump is working. Its also brand new.- Brief history on motor; 86 block, stock lower end, ie all bearings etc. Not sure on number of miles. Cam bearings looked used but not shot so those where retained. 85 rebuilt heads fm a carbed mustang.---I don't remember if the oil pump pickup uses a gasket between the pump and the filter? And I don't rem if I put one there. I think it should use one. What do you guys think? Thanks for any thoughts.-one other thing. Even w/the low oil pressure, oil still gets to the top cause I checked it while running.... [This message has been edited by ALS85GT (edited 10-17-2001).]

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Oil Pressure Very low on new setup!!!	Z28EATR	Windsor Power	17	09-16-2003 04:03 PM
Fuel pressure question - HELP!	Stang_ROTY	Windsor Power	30	05-30-2003 08:20 AM
Rising Fuel Pressure with Rising RPM?	StreetStang37	Windsor Power	1	05-21-2002 03:49 AM
Please Help...Fuel pressure keeps moving.	Dark_5.0	Windsor Power	2	04-06-2002 01:31 AM
fuel pressure and bad injectors???	wrathchild	Windsor Power	1	10-02-2001 06:40 AM

10-15-2001, 10:36 PM	#2
stanger8172 Registered Member Join Date: Nov 2000 Location: Milwaukee,Wisconsin Posts: 380	Do you still run the same stock electical gauge? Did you replace the sending unit? ------------------ '91 LX convertible , T-5,Centerforce Dual Friction, FMS adjustable cable w/quadrant, ported/polished/milled E7 heads, 1.6rr, 1.94/1.60 stainless valves, BBK 1 5/8" equal length shorties, 2 1/2" off road H-pipe, Summit 2 1/2" catback, March Performance Pulleys and A/C Eliminator

10-15-2001, 11:04 PM	#3
Fostang Registered Member Join Date: Feb 2001 Location: Stockton, Ca Posts: 599	I have exactly the same problem with my engine in the fastback. Even tried the same methods you mentioned. Nothing seems to help. I decided to leave it like that since the engine doesn't knock even on cold start ups. ------------------ 67' Fastback-Mean Temper 67' Coupe Under Construction 70' Torino Cruiser 84' Svo Original

10-16-2001, 08:33 AM	#4
ALS85GT Registered Member Join Date: Aug 2001 Location: Miami, Fl, USA Posts: 69	I use AutoMeter guages. And I'm getting diff responces. Some says it's a pump issue(even though the pump is new), some say it's no big deal as long as you have about 8-10psi at 1000rpm(which it does when at 1000rpm). The thing is that the engine runs fine, no noise what so ever, and the psi increases as the rpm increases. So this seems fine also. The engine is not new so I'm sure the old bearings have something to do with it.!??!I just want to be sure is all. Thanks...

10-16-2001, 09:38 AM	#5
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	It sounds like routine wear and tear to me. You are right about your engines requirements: 10psi per 1k rpm minimum. As long as you don't fall below that, you'll be fine. ~C ------------------ Retired Moderator MustangNet My site: Peckerwoods Pit Stop My teams site: Jim Porter Racing RACECAR spelled backwards is RACECAR HEY !!! Are you ASE Certified ??? If you are, ask me about iATN.

10-16-2001, 09:56 AM	#6
ALS85GT Registered Member Join Date: Aug 2001 Location: Miami, Fl, USA Posts: 69	OK, thanks for the responces. I'm not going to worry about it(too much). But what do you guys thing about the oil cooler? I made sure the oil reaches the "In" port on the adaptor. It's a Summit Oil/Trans cooler. I get 0 oil pressure when using this. thanks again...

10-17-2001, 08:03 AM	#7
Stang_ROTY Registered Member Join Date: Feb 2001 Location: Berkshire County - Massachusetts Posts: 735	If the engine is older than it's probably the bearings. My engine oil pressure drops after it warms up down to about 25psi from 60 and I only have 300 miles on my engine. But my thrust bearings need to be replaced due to a tranny overheat and is the main cause for my pressure drop.

10-17-2001, 09:06 AM	#8
Mach 1 Registered Member Join Date: May 1999 Location: Georgia Posts: 3,866	your oil pressure should drop when its warmed up, compared to cold. This is normal. remember, pressure is resistance to flow. warm oil flows better than cold oil, less resistance, less pressure.. ------------------ 1993 GT/AOD '93 Mustang GT

10-17-2001, 12:49 PM	#9
Chevyguy Backyard Mechanic/Chemist Join Date: Feb 2001 Location: Acton MA USA Posts: 435	Mine drops to 15-25 at idle when warm from 50 - 75 while driving depending on how hot it is or how hard I was driving. This is with the stock gauge. ------------------ Frank W 90 5.0 LX Notchback Daily driver. MAC 2.5" cat back FMS aluminum driveshaft, MSD blaster coil, MAC shifter other stuff check out here user site 88 Notch 2.3L FOR SALE! My two Notchbacks 74 Chevy Laguna Type S-3 Warmed over 305 upgrading to 454 soon

10-17-2001, 01:43 PM	#10
ALS85GT Registered Member Join Date: Aug 2001 Location: Miami, Fl, USA Posts: 69	I understand that as an engine warms up the oil pressure will drop some. I just wasn't sure if 8-10psi was too low at idle when reaching operating temp... I appreciate the responses............I guess this may be ok for used motor w/some miles on it.