low oil pressure??
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Senior User
Joined: Aug 2001
Posts: 194
Likes: 0
low oil pressure??
ok i need some help...when i first bought my truck almost a year ago the mechanic said the oil pressure sending unit was bad, but i couldnt get the damn thing out, wrenches were too long, and i couldnt figure out how to get it out, its at the back of the manifold and the firewal is really close to it.
my questions iare, 1. what causes low oil pressure? and what will happen if it get too low, besides the engine getting really messed up or seized..? 2. how can i change that stupid sending unit, i hate how my gauge tries to peg to the low side, but i know it had oil pressure or else wouldnt the valves or sumthing be making noise??
thanks...
1977 F250 460
C6 B&M transpak
K&N, MSD 6A box,
Hedman Headers
dual 40 series flowmasters
and yes less than 90,000 original miles on entire truck, an NO RUST!!
my questions iare, 1. what causes low oil pressure? and what will happen if it get too low, besides the engine getting really messed up or seized..? 2. how can i change that stupid sending unit, i hate how my gauge tries to peg to the low side, but i know it had oil pressure or else wouldnt the valves or sumthing be making noise??
thanks...
1977 F250 460
C6 B&M transpak
K&N, MSD 6A box,
Hedman Headers
dual 40 series flowmasters
and yes less than 90,000 original miles on entire truck, an NO RUST!!
Lead Driver
Joined: Nov 2000
Posts: 6,625
Likes: 342
From: Albuquerque
low oil pressure??
Go buy a cheap open end wrench of the proper size and saw half of it off. It works for me. If it's tight you may be able to hook another box end wrench around the short handle and get more torque. You might consider adding a tee fitting and an after market gauge while your in there so you be sure of the pressure.
1977 Ford F-100
400m/c6/4:11/Gear Vender O.D.
Crane hydralic roller, forged, ported polished,Deamon,Edlebrock, yada, yada, yada
280,000 miles
Stock on the outside
modified/rebuilt everything
1977 Ford F-100
400m/c6/4:11/Gear Vender O.D.
Crane hydralic roller, forged, ported polished,Deamon,Edlebrock, yada, yada, yada
280,000 miles
Stock on the outside
modified/rebuilt everything
Senior User
Joined: Jan 2001
Posts: 380
Likes: 1
From: Meriden USA
low oil pressure??
low oil pressure could be worn main bearings or a worn oil pump. id put a mechanical gauge on it most of em have low oil pressure it would usually tick if its too low.
Anthony DiPietro
79 F150 Ranger
Anthony DiPietro
79 F150 Ranger
Junior User
Joined: Oct 2001
Posts: 93
Likes: 0
low oil pressure??
I have had this low oil pressure reading on my 78 F-150 Ranger for a couple of years and have not replaced the sender because it is so difficult to get too.The oil pressure reading tends to bottom out when idleing in the hot summer months.If I rev the engine a little the oil pressure comes back up.I know it was risky but I blamed it on a faulty sender and just ignored it the best I could. Because I don't have in mind keeping my truck 100% original I plan on installing a set of underdash gauges "one of these days".
Freshman User
Joined: Aug 2001
Posts: 48
Likes: 0
From: san diego
low oil pressure??
Big ford engines are famous for low oil pressure. i don't know why? i have a stock 400m with a 97,000 original miles. i thought i had a bad stock sender (easier to get to with the carb removed.) so i replace with a mech gauge. the stock one would drop to low mark when warm (a real eye opener!!) i still got only about 12lbs at a warm idle. i was told by an reputable ford engine builder that if it hit 9psi or lower, beware!! my engine didn't rattle but i went ahead and changed my oil pump, and main and rod bearings. i have good compression and the rest of the engine was in good shape too. so i did it in place. the bearings i pulled showed brass coloring, but even wear. Also the oil pump pick-up was clogged too. i changed my oil pump to a mellings hi-volume,...don't know if it was a good idea or not, but my oil pressure is now about 60psi at a warm idle and it seems high now but the engine runs like a champ and no leaks or rattles.
i wish i could say the same thing about the tranny????
i hope this helps
dads77
f-250 custom
2wd 400m
my dad was the original owner
i wish i could say the same thing about the tranny????
i hope this helps
dads77
f-250 custom
2wd 400m
my dad was the original owner
Elder User
Joined: Aug 1999
Posts: 910
Likes: 0
low oil pressure??
I had 302 in my 79 that would get down to between 5-10 at idle when engine was hot. It didn't give me rod knock but I didn't care for the low reading. I then got a junkyard 360 engine for my 76 that when I got running had terrible pressure. When warm, it would idle at less than 5lbs and after 20min of running, you'd start to here lifter clatter and rod knock. This was unacceptable to me and I got the wrecking yard to give me a 390 to replace it (the 360 was sold to me as a 390 anyway so that was another reason to get exchange). This 390 Idles at 20lbs when warm and with little RPMS shoots right up to 40-45. Oil Pressure comes with tight bearing clearance, mostly from the Main bearings although w/ FE motors, the Cam bearings are involved as well since the oil goes there first before the Mains. Excessive wear= excessive clearance and lower oil pressure.
BBT
BBT
Senior User
Joined: Oct 2000
Posts: 219
Likes: 0
From: Richmond USA
low oil pressure??
" my questions iare, 1. what causes low oil pressure? and what will happen if it get too low, besides the engine getting really messed up or seized..? 2. how can i change that stupid sending unit, i hate how my gauge tries to peg to the low side, but i know it had oil pressure or else wouldnt the valves or sumthing be making noise??"
Besides getting really messed up or seized !, there is nothing left to happen.
Anyway the sending unit is a pain to get to but a thin wrench will take it off. Also install a mechanical gauge to read real pressures. Don't assume that if you don't hear any tapping that everthing is OK.
Low oil pressures can come from large clearances in the Main, Rod, and Cam bearings, as well as a clogged pickup screen, bad pump.
On my 460, Cold pressure run around 75-80psi.
Hot pressure run around 20-25psi Iding @ 650rpm.
Dre'
1978 F-150, 460ci(750cfm,Edelbrock Performer,Dynomax Ceramic Coated headers,etc.)Auto-C6,3:70.1 - 9" Posi.
Besides getting really messed up or seized !, there is nothing left to happen.
Anyway the sending unit is a pain to get to but a thin wrench will take it off. Also install a mechanical gauge to read real pressures. Don't assume that if you don't hear any tapping that everthing is OK.
Low oil pressures can come from large clearances in the Main, Rod, and Cam bearings, as well as a clogged pickup screen, bad pump.
On my 460, Cold pressure run around 75-80psi.
Hot pressure run around 20-25psi Iding @ 650rpm.
Dre'
1978 F-150, 460ci(750cfm,Edelbrock Performer,Dynomax Ceramic Coated headers,etc.)Auto-C6,3:70.1 - 9" Posi.
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Elder User
Joined: Apr 2001
Posts: 997
Likes: 0
From: texarkana, tx
low oil pressure??
Jeez, Dre...my 460 runs the same pressure cold (near 80 poundz), but warm, he idles near 40.....iz your engine "well used", Dre?
The LaptopGeek -----
1974 White F100 Custom Fleetside
460 bored .040 over & C-6 automatic 2WD
Lunati cam, L&L Headers / mounts
Holley Avenger 770CFM & Edlebrock RPM
Plush black leather 40-20-40 bench seat
38 gallon JC Whitney fuel tank
The LaptopGeek -----
1974 White F100 Custom Fleetside
460 bored .040 over & C-6 automatic 2WD
Lunati cam, L&L Headers / mounts
Holley Avenger 770CFM & Edlebrock RPM
Plush black leather 40-20-40 bench seat
38 gallon JC Whitney fuel tank
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Senior User
Joined: Oct 2000
Posts: 219
Likes: 0
From: Richmond USA
low oil pressure??
Yes, is has about 100K on the stock block.
But specs. calls for 40-60 @ 2000rpm hot. Which it does get to.
The bearings doesn't require a lot of oil pressure at idling.
10-15psi is good.
Dre'
1978 F-150, 460ci(750cfm,Edelbrock Performer,Dynomax Ceramic Coated headers,etc.)Auto-C6,3:70.1 - 9" Posi.
But specs. calls for 40-60 @ 2000rpm hot. Which it does get to.
The bearings doesn't require a lot of oil pressure at idling.
10-15psi is good.
Dre'
1978 F-150, 460ci(750cfm,Edelbrock Performer,Dynomax Ceramic Coated headers,etc.)Auto-C6,3:70.1 - 9" Posi.
Elder User
Joined: Apr 2001
Posts: 997
Likes: 0
From: texarkana, tx
low oil pressure??
Thanks Dre...she does have some miles, doesn't she?!? Mr. Harrison has 4'000 on his 3 month old rebuild with fresh crank and bearings through-out....I guess that must be the explanation.
Just look for the white blur....
The Laptop Geek
1974 White F100 Custom Fleetside
460 bored .040 over & C-6 automatic 2WD
Lunati cam, L&L Headers / mounts
Holley Avenger 770CFM & Edlebrock RPM
Plush black leather 40-20-40 bench seat
38 gallon JC Whitney fuel tank
Just look for the white blur....
The Laptop Geek
1974 White F100 Custom Fleetside
460 bored .040 over & C-6 automatic 2WD
Lunati cam, L&L Headers / mounts
Holley Avenger 770CFM & Edlebrock RPM
Plush black leather 40-20-40 bench seat
38 gallon JC Whitney fuel tank
Posting Guru
Joined: Jul 2001
Posts: 1,613
Likes: 2
From: Gainesville, FL
low oil pressure??
Gentlemen,
Let's recall that there are no numbers on these factory gauges and for good reason, they're not calibrated. It makes sense that a motor requires oil pressure to run. Yet i have run my 302 for years with little to no oil pressure at the light, I doubt it. there are distinct advantages to having a gauge in the truck but when an idiot light comes on, calibrated or not, its time to shut her down. When your old ford starts to show her age start putting the thick oils in. 40 or 50 weight is pushing it, but you can get away within in the summer. Changing you oil pump is not any fun but, a high volume oil pump can save you a rebuild for years, let me tell you, I'm still counting them. Beartracks had the classic suggestion to put in a TEE and run two gauges the odds of both of them lieing to you is slim. There is a special socket that fits the oil sending unit and this may explain why your having difficulty.
Good Luck, have Fun,
KingFisher
Let's recall that there are no numbers on these factory gauges and for good reason, they're not calibrated. It makes sense that a motor requires oil pressure to run. Yet i have run my 302 for years with little to no oil pressure at the light, I doubt it. there are distinct advantages to having a gauge in the truck but when an idiot light comes on, calibrated or not, its time to shut her down. When your old ford starts to show her age start putting the thick oils in. 40 or 50 weight is pushing it, but you can get away within in the summer. Changing you oil pump is not any fun but, a high volume oil pump can save you a rebuild for years, let me tell you, I'm still counting them. Beartracks had the classic suggestion to put in a TEE and run two gauges the odds of both of them lieing to you is slim. There is a special socket that fits the oil sending unit and this may explain why your having difficulty.
Good Luck, have Fun,
KingFisher
