PDA

View Full Version : Oil Pressure Problem...



Frank
07-06-2006, 02:05 PM
Ok, old Mellings pump used to put out a little too high of pressure... 90psi cold idle and 55psi hot idle pressure.... that old gauge could be off by 15psi. New Mopar unit reads 25psi cold... about 10-15 hot idle. It does get up to 50-60psi at about 4k rpms.

Is this ok???? I am nervious. She revs fast in the garage....


Frank

turbovanmanČ
07-06-2006, 02:13 PM
That is more than adequate, spec for minimum is 4 psi hot.

Una
07-06-2006, 02:22 PM
10psi per 1000rpm.. I usually get 12-13psi per 1000 in my worn out old engine (brand new oil pump), even when hot.

BadAssPerformance
07-06-2006, 04:58 PM
That is more than adequate, spec for minimum is 4 psi hot.

Well that is what the idiot light comes on at but if you only got 4psi at anything above idle, you'll soon have junk.

Frank, your numbers sound ok to me for a standard tolerance motor with a few miles on it.

Frank
07-06-2006, 05:01 PM
Ya well it barely has 300miles on it, and is a completely re done motor. When cruising at 2k rpms, it has about 25psi of oil pressure hot.

I still have my knock issues.... trying to figure that one out.


Frank

BadAssPerformance
07-06-2006, 05:04 PM
knock as in detonation, not as in rod right?

How tight was the engine built? What all was done to it?

Frank
07-06-2006, 05:23 PM
Knock as in #2 detonation, but its not detonating.... I think the cam maybe the problem.... since there is excessive noise from the head... probably off balance.

As for the engine, it is tight. Eagle H-Beam, Ross pistons, line bored, ARP, etc. The short block was assembled by a race shop.


Frank

crazy1eye
07-06-2006, 05:27 PM
With Mobil 1 15w50, stock T2 oil pump...
(HOT)
Idle = 18-20psi
3k+ rpm = 58-60psi

BadAssPerformance
07-06-2006, 09:09 PM
Knock as in #2 detonation, but its not detonating.... I think the cam maybe the problem.... since there is excessive noise from the head... probably off balance.

As for the engine, it is tight. Eagle H-Beam, Ross pistons, line bored, ARP, etc. The short block was assembled by a race shop.


Frank

What bearing clearance? Some race shops go loose cuz loose is supposed to make more power.

rhubbard
07-06-2006, 09:25 PM
With Mobil 1 15w50, stock T2 oil pump...
(HOT)
Idle = 18-20psi
3k+ rpm = 58-60psi


I need to pickup oil soon. is that a good viscosity to use? before my pressure was almost nothing with 5-30 synthetic, except at startup where it was great.

TurboJerry
07-16-2006, 09:40 PM
Sounds like loose bearing clearences to me. A HV pump on a stock engine with over 100,000 miles usually has 20-25 at hot idle if it wasen't abused it's whole life. 10 to 15 is still good though.

rhubbard
07-16-2006, 09:45 PM
how high is too high of an oil pressure at idle? I know something like 75 is outrageous, but what about 50?

puppet
07-16-2006, 10:22 PM
With Mobil 1 15w50, stock T2 oil pump...
(HOT)
Idle = 18-20psi
3k+ rpm = 58-60psiHoly balls Pat ... 15w50 ? Combine that weight and Canadian weather the oil must take what, a week to get into the head? :P

turbovanmanČ
07-16-2006, 10:52 PM
how high is too high of an oil pressure at idle? I know something like 75 is outrageous, but what about 50?

I would say 50 is too high.

BadAssPerformance
07-17-2006, 01:15 AM
I would say 50 is too high.

My Z idles cold at 80. Nice and tight motor.

turbovanmanČ
07-17-2006, 01:29 AM
My Z idles cold at 80. Nice and tight motor.


Wow, thats insane, :eek:

Tony Hanna
07-17-2006, 08:03 AM
I replaced the bearings in an old Toyota pickup I used to have and fooled with the oil pump a little. It would do well over 100 psi at anything over idle when the engine was cold. It would settle back into the 80-85 psi range warmed up though.
Frank,
How fast does the oil pressure come up as you rev the engine? If it jumps up pretty quick as you come off idle then I wouldn't worry.

BadAssPerformance
07-17-2006, 08:14 AM
Wow, thats insane, :eek:

LOL... not sure about insane, but it probably does rob some power. I like it tho, seems to e pretty durable (knock on wood) btw, it it is Moparboyy's old bottom end.

rhubbard
07-17-2006, 08:59 AM
The reason I ask is because I would get almsot 0 pressure at idle when I had 5-30 synthetic, so I switched to 20-50 or 20-40 and it's at 50 psi cold idle. I'm not sure what it does when it gets warm though cause it hasn't ran that long and I don't know when warm is cause I need a new sending unit for my water temp.

turbovanmanČ
07-17-2006, 12:50 PM
Sounds like you have a bearing issue. Switching to a thicker oil shows you have some loose bearings.

89ShelbyGuy
07-26-2006, 10:07 PM
Yea...i get 60 at cold and 10-11 at warm/hot.

u used 5w30 in the beginning but then the idle pressure was dropin too low on my new gauge, but no dummy light..i drained the oil and it was like water consisty...then i switched to 10w30 and its perfect!

Tom

puppet
07-27-2006, 05:06 PM
Yea...i get 60 at cold and 10-11 at warm/hot.

u used 5w30 in the beginning but then the idle pressure was dropin too low on my new gauge, but no dummy light..i drained the oil and it was like water consisty...then i switched to 10w30 and its perfect!

TomIt's still 30 weight oil. The 5w or 10w before it doesn't change the (30) ... only difference should be when dead cold.

jre97
07-27-2006, 06:28 PM
It's still 30 weight oil. The 5w or 10w before it doesn't change the (30) ... only difference should be when dead cold.
I think you're backwards. The 15w stands for a 15 weight oil and the 30 means it won't thin more than a 30 when it's hot. Hence the multiviscosity 15w30. I read this somewhere I'll try to find it.

puppet
07-27-2006, 07:22 PM
I think you're backwards. The 15w stands for a 15 weight oil and the 30 means it won't thin more than a 30 when it's hot. Hence the multiviscosity 15w30. I read this somewhere I'll try to find it.It's not backward .. my point was that 5w*30 and 10w*30 are still *30 weight when hot. The only difference between the two oils will be when dead cold ... 5w vs 10w. Once the oil reaches a certain temperature the first numbers (5w and 10w) mean nothing.

Una
07-27-2006, 08:41 PM
Yeah, in theory that's how they are supposed to work.. But it never really does..

89ShelbyGuy
07-27-2006, 10:19 PM
maybe its cause i used that lucas stablizer for the oil in place with one quart of oil....but seriously, i was running psi between 1-4...too low for me....once i changed to 10w30 from 5w30, it is 10-11 hot..hot...but whatever...long as its good for me...i use it...

Tom

turbovanmanČ
07-28-2006, 03:04 AM
Yeah, in theory that's how they are supposed to work.. But it never really does..

I agree, I have drained 5w30, 10w30 and 10w40 hot, and the 5w30 is like water, it was scary. :censored:

TurboJerry
07-29-2006, 12:30 AM
The first no# indicates the "hot" weight. The 10 in 10W30 is the hot #. Which is why you get more oil press with 10 insted of 5........ That's why 5W50 usually has way low oil press at idle, but flows well at sub zero temps. Another weird thing I noticed is the big Aux. shaft bearing has a groove to the side of the bearing. It is big enough to cause a pressure loss. This could be a problem for those who have the low oil press issue......

Mario
07-29-2006, 12:53 AM
....and the second number is for the oil at 100 degrees Celcius, or 212 F.


I agree, I have drained 5w30, 10w30 and 10w40 hot, and the 5w30 is like water, it was scary. :censored:

Yes. That also depends on if it's synthetic or not as well, because with time, petro based oils lose their viscosity properties, due to the added polymers burning off. I hope none of you do, but running non synthetic 10w40 is a bad idea. Petro based oils with that wide of a viscosity range are more prone to viscosity and thermal breakdown because of the higher polymer content of them.