oil pressure on stock 5.0

GhettoPop · 12-30-2003, 01:14 PM

Ques on oil pressure on a stock 5.0. Stock gauge will read about 1/2 when cold at idle or under load. Once warm, the gauge reads 1/2 when driving, but when at idle, gauge will drop down to about 1/4. (2nd line from the bottom i believe.) Is this normal? I know the stock gauges are sh*t, just wanted some input. This is the case with my 90Gt, as well as a friends 91 GT conv. Thanks.

Dark_5.0 · 12-30-2003, 04:52 PM

No that is not normal. I would check with a mechanical oil pressure gauge for sure.

84LX89GT · 12-31-2003, 04:16 AM

My oil pressure gauge now stands a bit over 1/2 all the time after installing a new crank, bearings and oil pump. It used to read 1/4 at idle and 1/2 under load, and although some of the bearings didn't look too good it never knocked or anything. I'd say it's normal. If you look at a chiltons book it says something like 40-60 psi at 2000 rpm. If you're getting down to 15 psi or so at idle your engine might be getting worn on the bottom end.
If you're concerned you can always add "liquid bearings"

(15W40 oil or 20W50 oil) to take up the clearances a bit and get pressure back up.

Hethj7 · 01-05-2004, 02:35 AM

My gauge stays around the halfway mark, but when I hit 5th gear it drops off some

. It has done this ever since I can remember. I know the guage is pretty useless but am not sure why it only changes in 5th gear.

420nitro · 01-05-2004, 08:59 AM

Quote:

Originally posted by GhettoPop
Ques on oil pressure on a stock 5.0. Stock gauge will read about 1/2 when cold at idle or under load. Once warm, the gauge reads 1/2 when driving, but when at idle, gauge will drop down to about 1/4. (2nd line from the bottom i believe.) Is this normal? I know the stock gauges are sh*t, just wanted some input. This is the case with my 90Gt, as well as a friends 91 GT conv. Thanks.

Yes, it is normal. When I used to work for Ford and a car would come in for a low oil pressure, Ford says to check pressure with a mechincal guage and check. Just because the needle was low did not indicate the oil pressure was dangerously low. If it is in the "normal" range then you were OK. It sucks, but what you going to do. You should check the oil pressure with a mechincal one to make sure. Technically all you need is 10 psi of oil pressure per 1,000 rpms . I still would not feel comfortable with less then 20 psi at idle. If it is lower then that, you can also get a thicker oil.

420nitro · 01-05-2004, 09:14 AM

Now that I think about it, I believe it was 1991 was the first year they came out with the guages having "normal" written in the guages. I could be wrong but don't remember. Your second line would be the "n" on normal on the newer cars. That's one of the reasons why they had "normal" written on the guages. To many compliants about "this being to high" or "to low", etc, etc.

GhettoPop · 01-13-2004, 06:25 PM

how much does a mechanical gauge cost?

Hethj7 · 01-13-2004, 07:52 PM

Quote:

Originally posted by 420nitro
Now that I think about it, I believe it was 1991 was the first year they came out with the guages having "normal" written in the guages. I could be wrong but don't remember. Your second line would be the "n" on normal on the newer cars. That's one of the reasons why they had "normal" written on the guages. To many compliants about "this being to high" or "to low", etc, etc.

Mine's a 90 and it has normal written on the gauge.

12-30-2003, 01:14 PM	#1
GhettoPop Gimme a Drink! Join Date: Dec 2002 Location: NYC Posts: 694	oil pressure on stock 5.0 Ques on oil pressure on a stock 5.0. Stock gauge will read about 1/2 when cold at idle or under load. Once warm, the gauge reads 1/2 when driving, but when at idle, gauge will drop down to about 1/4. (2nd line from the bottom i believe.) Is this normal? I know the stock gauges are sht, just wanted some input. This is the case with my 90Gt, as well as a friends 91 GT conv. Thanks. __________________ 1990 GT,stock T-5,K&N w/o air silencer,March underdrives,FMS wires,timing@14,PA Perf 130amp alt,Steeda Tri-Ax Shifter,Steeda adj quadrant/clutch cable/firewall adj,Centerforce II clutch,o/r x-pipe,Magnaflow SS catback,g-load brace, subframes,Bilstein struts/shocks,Autometer gauges, 136k and running strong!

12-30-2003, 04:52 PM	#2
Dark_5.0 Registered Member Join Date: Apr 2001 Location: Staging lane Posts: 4,337	No that is not normal. I would check with a mechanical oil pressure gauge for sure. __________________ 92' LX-Big brakes, Lots and lots of suspension, GT40X heads, Ported cobra intake, stock cam, Vortech SC trim. 00' Lightning-Stock 88'CRX-13 second ego killer

12-31-2003, 04:16 AM	#3
84LX89GT Mustangs Join Date: Jul 2000 Posts: 1,938	My oil pressure gauge now stands a bit over 1/2 all the time after installing a new crank, bearings and oil pump. It used to read 1/4 at idle and 1/2 under load, and although some of the bearings didn't look too good it never knocked or anything. I'd say it's normal. If you look at a chiltons book it says something like 40-60 psi at 2000 rpm. If you're getting down to 15 psi or so at idle your engine might be getting worn on the bottom end. If you're concerned you can always add "liquid bearings" (15W40 oil or 20W50 oil) to take up the clearances a bit and get pressure back up. __________________ 2005 Suzuki Hayabusa GSX1300-R 1980 Ford Thunderbird - 255 V8 ported heads, 5.0L ported stock headers, O.R. H-pipe and Flowmaster 2-chambers, dual roller timing chain hi-po Mack Truck hood emblem 1985 Mustang GT 5.0L T5, F-303, GT40p, headers, off-road h, flowmasters, MSD stuff, etc. Sold 02/06/04 1989 Mustang GT ET: 13.304@102.29 mph (5-24-03) Sold - 1998 Mustang Cobra coupe, 1/4 mile - street tires: 13.843@103.41 (bone stock)

01-05-2004, 02:35 AM	#4
Hethj7 Mizzou Tigers Join Date: Apr 1999 Location: weston, MO United States Posts: 1,455	My gauge stays around the halfway mark, but when I hit 5th gear it drops off some . It has done this ever since I can remember. I know the guage is pretty useless but am not sure why it only changes in 5th gear. __________________ 2006 Mustang GT 1990 LX GT-40 motor 262 horsepower, 307ft-lbs (sold but forever loved) 1998 Contour SVT Rice Haters Club Member #244

01-13-2004, 06:25 PM	#7
GhettoPop Gimme a Drink! Join Date: Dec 2002 Location: NYC Posts: 694	how much does a mechanical gauge cost? __________________ 1990 GT,stock T-5,K&N w/o air silencer,March underdrives,FMS wires,timing@14*,PA Perf 130amp alt,Steeda Tri-Ax Shifter,Steeda adj quadrant/clutch cable/firewall adj,Centerforce II clutch,o/r x-pipe,Magnaflow SS catback,g-load brace, subframes,Bilstein struts/shocks,Autometer gauges, 136k and running strong!

01-05-2004, 09:14 AM	#6
420nitro Registered Member Join Date: Nov 2003 Location: Rockford Posts: 596	Now that I think about it, I believe it was 1991 was the first year they came out with the guages having "normal" written in the guages. I could be wrong but don't remember. Your second line would be the "n" on normal on the newer cars. That's one of the reasons why they had "normal" written on the guages. To many compliants about "this being to high" or "to low", etc, etc.

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