Losing oil presure
05-24-2007, 10:27 AM
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Losing oil presure ****Updated with pics***
Just got down swapping my ls1 into my 94. Ran great all weekend while on vacation and on my return home, the oil pressure gauge started bounching all over the place between 20 and 40 psi at normal cruising speeds. Befor putting the motor in the car, i put on a portes ls6 which created excellent pressure. I figured that their must be something wrong with the sending unit because of how eratic the readings were. We pulled over, listened to see if there was any knock, checked the connections, ect. Everything seemed fine. After some more driving it seemed to start to steady out at 35-40 psi when crusing but when I got on it to pass somebody it would dip down to 20 psi. Once back, we hooked up the mechanical gauge and saw that the gauge in the cluster was really telling the truth. Changed the oil and filter to see if that would help, and it didn't, same issue. After cutting the filter open, their appeared to be some red, blue, and yellow makings which later turned out to be some markings that are made by comp on the cam. Also was some metal shavings but no more then we had ever seen in any filter that was breaking in some new parts (new lifters, timing chain, springs, push rods, cam, and rod bolts). So pulled the motor and trans out, pulled the pan down and saw nothing in it. The screen on the pick up tube had some items on it, looks like pieces of the oil filter elements. But still their really wasnt enough for it to impeed the flow of oil that drasticaly. We thought that some of the particles may have gotten past then screen so we decided to check out the oil pump. Thought that maybe some junk had caused the spring/valve to get stuck. After inspection, it looked perfect, no problems at all. So we then decided to spray some brakeclean down the oil inlet passage of the block. All that came out the filter inlet was just some oil and breakclean. So we replaced the oil pump and the pickup tube. Still in the process of getting it together but wanted to run it buy you guys here to see if you had any input. We think it may be a spun bearing but I always thought knock/noise accompanied that issue.
Just got down swapping my ls1 into my 94. Ran great all weekend while on vacation and on my return home, the oil pressure gauge started bounching all over the place between 20 and 40 psi at normal cruising speeds. Befor putting the motor in the car, i put on a portes ls6 which created excellent pressure. I figured that their must be something wrong with the sending unit because of how eratic the readings were. We pulled over, listened to see if there was any knock, checked the connections, ect. Everything seemed fine. After some more driving it seemed to start to steady out at 35-40 psi when crusing but when I got on it to pass somebody it would dip down to 20 psi. Once back, we hooked up the mechanical gauge and saw that the gauge in the cluster was really telling the truth. Changed the oil and filter to see if that would help, and it didn't, same issue. After cutting the filter open, their appeared to be some red, blue, and yellow makings which later turned out to be some markings that are made by comp on the cam. Also was some metal shavings but no more then we had ever seen in any filter that was breaking in some new parts (new lifters, timing chain, springs, push rods, cam, and rod bolts). So pulled the motor and trans out, pulled the pan down and saw nothing in it. The screen on the pick up tube had some items on it, looks like pieces of the oil filter elements. But still their really wasnt enough for it to impeed the flow of oil that drasticaly. We thought that some of the particles may have gotten past then screen so we decided to check out the oil pump. Thought that maybe some junk had caused the spring/valve to get stuck. After inspection, it looked perfect, no problems at all. So we then decided to spray some brakeclean down the oil inlet passage of the block. All that came out the filter inlet was just some oil and breakclean. So we replaced the oil pump and the pickup tube. Still in the process of getting it together but wanted to run it buy you guys here to see if you had any input. We think it may be a spun bearing but I always thought knock/noise accompanied that issue.
Last edited by MeanGreenLT1; 05-27-2007 at 07:54 PM.
05-24-2007, 01:21 PM
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Pumps are difficult to asess with a visual inspection of the pump gears and housing. These LSx factory oil pumps are known to be of a poor design with recurring issues. what about hte o-ring - another poor design IMO?
...when in doubt, replace them and never look back.
...when in doubt, replace them and never look back.
05-24-2007, 03:33 PM
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Originally Posted by robertbartsch
New oil pumps are under $100, new engines are significantly more!
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05-24-2007, 05:20 PM
#9
when i put it together the first time, i put in a new oil pump and used the same pickup tube. Then last night i took that pump out, put another new one in and on top of that a new pick up tube as well.
o rings usually cause problems right out the box. Not run perfect for a while and then start messing up.
- MeangreenLT1
o rings usually cause problems right out the box. Not run perfect for a while and then start messing up.
- MeangreenLT1
05-24-2007, 09:46 PM
#10
My guess would be a spun bearing. Fluctuating oil pressure is usually a tell-tale sign, especially since you know the sending unit is working and the o-ring wasn't pinched. I supposed it could have just been something with the pump, but I wouldn't bet on it.
05-25-2007, 12:17 AM
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yeah must be a bearing. Just put in a second new pump and a brand new pick up tube, and the problem is still there.
Well that was fun, almost two years to get everything together and get it in there, and only two days to destroy it.
Well that was fun, almost two years to get everything together and get it in there, and only two days to destroy it.
05-25-2007, 03:42 AM
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where the spring is on the oil pump there should be a spacer, check it. when u slide the tube into the pump make sure O-ring and inside of pump where tube goes in has oil to aid installation. 
05-25-2007, 08:06 AM
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Originally Posted by cowboysfan
where the spring is on the oil pump there should be a spacer, check it. when u slide the tube into the pump make sure O-ring and inside of pump where tube goes in has oil to aid installation.
05-25-2007, 08:41 AM
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Originally Posted by bjamick
WHat about your sensor, a sensor going bad will do this same thing, so dont go and build a new motor now just bc someone told you it has a spun bearing.. Change the sensor out 1st then go from there 
05-25-2007, 08:43 AM
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Originally Posted by 01slowbird
hate to repeat....but probably spun rod bearing...sorry man
05-27-2007, 01:30 AM
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And it just continues to become increasingly odd
Started taking everything off today and ran into some surprises. After taking off the intake, there was heavy rings of oil around intake port/gaskets 1,3,6, and 8. There was some on the others as well but not as bad. I also noticed some oil sitting in a few of the areas where the head studs are at the top of the heads near the valley cover. I have no clue where the oil is coming from because there is no PCV system, just filters on the covers. Also the back of the throttle blade and the intake also had oil in it. The walls of the intake ports are oil colored but for the most part dry. As it progresses down to the actual valve, the oil colored walls dissipate and look normal which leads me to believe that the oil is going from the intake down into the intake port. Also was a little small bit of oil on the intake valve but not much at all. After pulling the heads it looked like their was oil on the pistons and they were covered with carbon deposits and i guess burn oil. I'm not sure how quickly it takes for these deposits to forum, but the car has only been together for about 300 miles or so.
After pulling the lifters, some of them looked vertically scared on the bottom portion near the roller. Also looked like some slight scaring on a few of the cam journals as well.
I couldn't continue the tear down because i didn't have my puller for the crank pulley, but going to take the rest apart tomorrow.
There are two many things not adding up here though. I thought that I would have seen some copper or gotten some kinds of noise if it was one of the bearings, but haven't seen any sighs of copper in the filter nor it is generating any abnormal knocking noises.
Also, how the hell am i getting oil into the intake when the pcv isn’t hooked up to it? I could see maybe their could be a chance that a valve sear or guide was bad it would let oil into the intake, but its way heavier in the actually intake, and it looks perfectly clean in the intake valve housing?
Also, I never saw any blue smoke come from the car at all. You would think that with all this oil moving around the inake and combustion chamber, it would create some visible sigh of smoke. I rode around with friends all weekend, and they said that no smoke ever came from my car. Somebody was even following me all the way home after the gauge was giving the irratic readings and they said it never smoked either.
I also already relpaced the valve seals.
Started taking everything off today and ran into some surprises. After taking off the intake, there was heavy rings of oil around intake port/gaskets 1,3,6, and 8. There was some on the others as well but not as bad. I also noticed some oil sitting in a few of the areas where the head studs are at the top of the heads near the valley cover. I have no clue where the oil is coming from because there is no PCV system, just filters on the covers. Also the back of the throttle blade and the intake also had oil in it. The walls of the intake ports are oil colored but for the most part dry. As it progresses down to the actual valve, the oil colored walls dissipate and look normal which leads me to believe that the oil is going from the intake down into the intake port. Also was a little small bit of oil on the intake valve but not much at all. After pulling the heads it looked like their was oil on the pistons and they were covered with carbon deposits and i guess burn oil. I'm not sure how quickly it takes for these deposits to forum, but the car has only been together for about 300 miles or so.
After pulling the lifters, some of them looked vertically scared on the bottom portion near the roller. Also looked like some slight scaring on a few of the cam journals as well.
I couldn't continue the tear down because i didn't have my puller for the crank pulley, but going to take the rest apart tomorrow.
There are two many things not adding up here though. I thought that I would have seen some copper or gotten some kinds of noise if it was one of the bearings, but haven't seen any sighs of copper in the filter nor it is generating any abnormal knocking noises.
Also, how the hell am i getting oil into the intake when the pcv isn’t hooked up to it? I could see maybe their could be a chance that a valve sear or guide was bad it would let oil into the intake, but its way heavier in the actually intake, and it looks perfectly clean in the intake valve housing?
Also, I never saw any blue smoke come from the car at all. You would think that with all this oil moving around the inake and combustion chamber, it would create some visible sigh of smoke. I rode around with friends all weekend, and they said that no smoke ever came from my car. Somebody was even following me all the way home after the gauge was giving the irratic readings and they said it never smoked either.
I also already relpaced the valve seals.
Last edited by MeanGreenLT1; 05-27-2007 at 01:38 AM.
