still low oil pressure after o ring swap?
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still low oil pressure after o ring swap?
Ok so i bought a shortblock LQ4 with 45k miles. This is my first time building an engine from a shortblock, well i bought a brand new GM oil pump for the build. I had a friend check the rod bearings and clearances and they all look good.. All the cam bearings looked good but the rear one looked a little worn out but went and put the cam in anyways. I checked the oil pick up tube with oil and it was clean.. So i had a o ring that was red but was faded green? So i put that in and when the engine was on the truck i went and started it up, the oil pressure went to 40 at idle and when the truck got to temperature it would drop down to around 20.. At that point i thought the oil pressure sensor was bad so i went and replaced it and still low.. wasn't convinced so i bought a manual gauge and it did the same thing. So i drained out the oil and it came out a little dirty, replaced with with rotella 15/40 oil with new filter hoping it would fix the problem.. still no. So i read on here that people were having trouble with green/blue O rings.. I got the GM part number to get the red one which is the good one. So i went and got it and it did look much thicker that the one i had put in, but i tried scraping it with my fingernail and the red would come off and under it was blue???? I put it in taking extra care that i wouldnt pinch it. So i did and again replaced the oil with the rotella 15/40 went and turned it back on and it would go to 40 and once it got to temperate it would drop to 20. I guess that did not fix the problem. The engine sounds very quiet at idle and works very good.. now im thinking what else would it be???? thanks for any help!!
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While I don’t feel like it is optimum, according to GM’s SI for a 2004 LQ4 6.0L (don't know what model yours is, but the info should be good), the Minimum Hot Oil Pressure is listed as:
6 psig at 1,000 engine RPM
18 psig at 2,000 engine RPM
24 psig at 4,000 engine RPM
I will say, as I’m sure you have heard as well is the old Hot Rod standard of 10 psig per 1,000 RPM is a good standard to go by.
6 psig at 1,000 engine RPM
18 psig at 2,000 engine RPM
24 psig at 4,000 engine RPM
I will say, as I’m sure you have heard as well is the old Hot Rod standard of 10 psig per 1,000 RPM is a good standard to go by.
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Ill check it tomorrow after a WOT pass, when i used the rotella i put a new K&N oil filter in there. actually today i checked it at WOT and its actually around 40 (when cold it goes to around 60 WOT) The engine is a 04, thats very good information about the PSI per RPM! When it comes down to around 20 at idle the engine feels a little shaky.. so would i be ok upping the boost to around 9-10 lbs and still live a normal life??
EDIT: Also i have both valve cover vacuum hoses disconnected, would that matter?? one intake vacuum goes straight to the BOV btw.
EDIT: Also i have both valve cover vacuum hoses disconnected, would that matter?? one intake vacuum goes straight to the BOV btw.
Last edited by blazinblue; 05-02-2010 at 11:48 PM.
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if you used 15/40 oil after o ring replacement then naturally the oil pressure will be lower because its thinner(im sure u know this)... try wut the cap calls for.. 5/30 and oil pressure will def be atleast a little higher... maybe even enough to make you happy...
just my .02
just my .02
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#8
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if you used 15/40 oil after o ring replacement then naturally the oil pressure will be lower because its thinner(im sure u know this)... try wut the cap calls for.. 5/30 and oil pressure will def be atleast a little higher... maybe even enough to make you happy...
just my .02
just my .02