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Oil Pressure concern

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Old 05-28-2005, 11:35 PM
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Default Oil Pressure concern

I installed the new 6.0 a few weeks ago with a 244/248 cam and it started right up on the first try. The oil pressure was about 45 at idle and everything seemed fine. Now, when I start it up I get the same 45 psi at idle and i get great cruising pressure (~ 60 psi) but that only lasts for about the first 20 min. of driving. After that, when I'm sitting at a light I am getting about 30psi at idle and sometimes a bit lower (due to the fact that the car is still untuned and drops below the 800 idle every so often) and when I'm cruising i get about 40-50psi. I'm just wondering if I should be concerned about this. The lowest I get at idle is 30 for the most part, but sometimes it does hit 25 when it is dropping idle trying to learn. I don't think it's a bad oil pump b/c it is a ported ls6 with only 1500 miles on it (at least that's what I was told and didn't touch it). Any ideas or reasons I should (or shouldn't) be concerned?
Old 05-28-2005, 11:51 PM
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a good rule of thumb is 10 psi / 1000 rpms. not sure, why you're seeing a drop, but you should be fine.
Old 05-28-2005, 11:58 PM
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Well I just switched to 5w30 from 10w30... I'm not sure if it would make that much of a difference from what I'm used to though.
Old 05-29-2005, 12:22 AM
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It will make a little difference, but not much. I wouldnt be concerned about it unless it is low at high RPM's.
Old 05-29-2005, 12:25 AM
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I just did a swap also, and am running a 244/244. My oil pressure runs about the same as yours. 50-60psi at start up. 40-50 at cruise after 10 mins. and 25-35 at idle after car's been running awhile. I was nervous too. Is this okay?
Old 05-29-2005, 12:37 AM
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Its fine, the oil is thickest when its cold. As it heats up it will thin out some. Just like calongo said as long as you have 10psi per 1000 RPM its OK.
Old 05-29-2005, 01:22 AM
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Originally Posted by Dustin 98TA
Its fine, the oil is thickest when its cold. As it heats up it will thin out some. Just like calongo said as long as you have 10psi per 1000 RPM its OK.
Exactly! As the oil gets hot the pressure will drop somewhat as the clearances on the aluminum block open up AND the oil thins out.
Old 05-29-2005, 03:26 AM
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Originally Posted by racer7088
Exactly! As the oil gets hot the pressure will drop somewhat as the clearances on the aluminum block open up AND the oil thins out.
I've got an iron block 6.0 though... just my heads are aluminum.
Old 05-29-2005, 08:44 AM
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Iron expands with heat too, just takes a little longer. Did you install a new O-ring on the pick up tube? This is a common cause for low oil pressure
Old 05-29-2005, 12:16 PM
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Originally Posted by ArcticZ28
I've got an iron block 6.0 though... just my heads are aluminum.
HMMM! Well that's a little stranger but you will always lose some oil pressure as the oil gets hot. I talk to people on here with only 10 psi at idle and yet only like 30 psi at higher rpm so at least you aren't that bad off. You might have something holding your oil pump pressure relief valve open a bit like a small piece of retainer or spring that came off when the springs and cam were new and were breaking in. It seems like a lot of people on LS1tech have that problem after changing cams and springs. Just keep an eye on it in case it drops lower otherwise you could change the pump but it may do nothing.
Old 05-29-2005, 01:07 PM
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Originally Posted by TAQuickness
Iron expands with heat too, just takes a little longer. Did you install a new O-ring on the pick up tube? This is a common cause for low oil pressure
The engine came assembled as a shortblock with 1300 miles on it that was used in a project car by Ron at GMMG. I didn't touch any of the internals. I just swapped it in and bolted some new LQ9 heads on with a PRC dual spring kit.
Old 05-29-2005, 01:34 PM
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Originally Posted by racer7088
HMMM! It seems like a lot of people on LS1tech have that problem after changing cams and springs.
I noticed that also. I often wonder if it's the aftermarket cams we install. Maybe they are slightly smaller and are causing more play in the cam bearing which leads to lower oil pressure. Of course it's hard to tell since everyone changes oil pumps when installing a cam, so maybe they are installing the o-rings incorrectly. Who knows.
Old 05-29-2005, 01:46 PM
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Everybody's probably right and it's not a problem, but it's the kind of thing that can bug ya ... I would try an oil with a high cst like Mobil 1 0W-40 and see if that helps, just to take the edge off.
Old 05-29-2005, 03:10 PM
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It will definitely bug me, but I can live with it if it won't cause harm.
Old 05-29-2005, 03:15 PM
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I think the problem with this LS1 oil problem is not realy a oil issue. At least in the cars that did not come with oil coolers from the factory. As you build more HP and the engine becomes less efitiant at idle, the heat the engine builds incresses. The coolant in the Jacket Water system only cools the heads and Cyl walls. Most of these cars have radiators that are bearly able to cool a stock engine. The oil also cools the engine. It cools all the bearings, the lifters, the valve train. All this extra friction from bigger cams/springs, and the extra heat generated from higher HP engines will incress the oil temps. The LS1 seems to have a problem with trapping heat in the oil. My owners manual states to run synthetic oil do to the higher heat.

I had the same issue with mine, I installed an external oil cooler and dropped the oil temps. We have hit a couple of 100 degree days last week and I did notice that my oil pressure stayed normal even with lots of intown driving. It would not do that on the 90 degree days we had before I installed the oil cooler.

Install an iol cooler on the engine and I bet you will see the symptom disapear.
Old 05-29-2005, 03:35 PM
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Don't forget that a ported oil pump will flow more volume but also have less pressure. If you install a ported pump, then you should shim it.
Old 05-29-2005, 03:43 PM
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I didn't install this one, but I have installed a ported ls6 before. What do you mean by shimming?
Old 05-29-2005, 10:34 PM
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I am having a problem to with my Oil pressure. I just put my new motor in last Friday. And, at start up idle it is at 40psi and steady drops and stays at 20-25 psi. I been worried about driving it. When get on it it goes up to 35-40psi
Old 05-30-2005, 01:05 AM
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Sometimes if you're not careful enough sliding a cam out or in, you can scar a cam bearing or 2 which can contribute to larger clearances and lower oil pressure. Alot of LT1 guys have run into this before too on cam swaps. But those motors are harder on cam bearings because of the cam driven water pump.

Jason




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