Low oil pressure in rebuilt motor...PT 2
02-01-2009, 04:21 PM
#1
Low oil pressure in rebuilt motor...PT 2 I previously started a thread about my freshly rebuilt LS2 404 having hardly any oil pressure. Well it turned out it was a cam bearing that was installed to far foward and was letting oil bybass the cam bearing, and there for loosing almost all oil pressure.
Well lets fast foward about a month...I had a "tool" made to pull the bearing back into place, and it was pulled into place. It took a fairly good bit of force to pull the bearing back into place.I would say that the bearing was probably almost a 1/2" from where it's supposed to be. So like I said the bearing was put back to where everything lined up. I reinstall all the engine covers, cam, rocker arsm, ect. Everything to get it to running status, sans water pump, accesories, ect. So I fire the car up, and instatly get 60psi(previously was way below the 20psi mark on the guage). I let it run for a few minutes to get warm, then I reved the motor up to around 3500-4500k, and it rose up like normal, almost pegging the guage. Then it would drop back down to idle and the guage would hover around 45-50psi.
Hoping that everything was going to work, I started reassembling the car, to get it drivable. So this past Friday, I finally get to take it out for a drive. I let the car warm up to operating temperature, and take off down the road. As I'm driving I keep the rpms around 2k for about a mile or so. Then I roll into it a little bit and take it up to around 3.5k. All the time I'm watching my pressure and its staying around 50psi while cruising. But as soon as a I take it up to 3500k and let it go back to cruising rpms I notice the pressure DROPPED to around 35psi. The exact some thing it done last time....So needless to say I am highly pissed at this point. I push the clutch in and rev it up to see if the pressure would climb. I take it up to around 6k and the pressure never went above 40psi, and actually started falling. After that it would only hold 20psi at 1500k. So I get to the nearest store and pull off and go get my truck and trailer and tow it back home.
I havent taken it back apart yet, but I am aobut 99% sure its going to be that same cam bearing that has moved again. What I want to know is if there is anyway this jackass who built my motor could have put a size to small cam bearing in there, and its to loose? I'm just looking for ideas of why it keeps doing this ****. My car has been down for almost 5 months now. And I spent $2800 to have this motor rebuilt. Not to mention, it took him almost 3 months just to get the motor back to me, and my own time I have had to waste trying to diagnose the problem, pulling trans, cam, and everything that comes along with this.
Sorry for such a long post, just venting some I guess...
Well lets fast foward about a month...I had a "tool" made to pull the bearing back into place, and it was pulled into place. It took a fairly good bit of force to pull the bearing back into place.I would say that the bearing was probably almost a 1/2" from where it's supposed to be. So like I said the bearing was put back to where everything lined up. I reinstall all the engine covers, cam, rocker arsm, ect. Everything to get it to running status, sans water pump, accesories, ect. So I fire the car up, and instatly get 60psi(previously was way below the 20psi mark on the guage). I let it run for a few minutes to get warm, then I reved the motor up to around 3500-4500k, and it rose up like normal, almost pegging the guage. Then it would drop back down to idle and the guage would hover around 45-50psi.
Hoping that everything was going to work, I started reassembling the car, to get it drivable. So this past Friday, I finally get to take it out for a drive. I let the car warm up to operating temperature, and take off down the road. As I'm driving I keep the rpms around 2k for about a mile or so. Then I roll into it a little bit and take it up to around 3.5k. All the time I'm watching my pressure and its staying around 50psi while cruising. But as soon as a I take it up to 3500k and let it go back to cruising rpms I notice the pressure DROPPED to around 35psi. The exact some thing it done last time....So needless to say I am highly pissed at this point. I push the clutch in and rev it up to see if the pressure would climb. I take it up to around 6k and the pressure never went above 40psi, and actually started falling. After that it would only hold 20psi at 1500k. So I get to the nearest store and pull off and go get my truck and trailer and tow it back home.
I havent taken it back apart yet, but I am aobut 99% sure its going to be that same cam bearing that has moved again. What I want to know is if there is anyway this jackass who built my motor could have put a size to small cam bearing in there, and its to loose? I'm just looking for ideas of why it keeps doing this ****. My car has been down for almost 5 months now. And I spent $2800 to have this motor rebuilt. Not to mention, it took him almost 3 months just to get the motor back to me, and my own time I have had to waste trying to diagnose the problem, pulling trans, cam, and everything that comes along with this.
Sorry for such a long post, just venting some I guess...
Last edited by blk00ss; 02-01-2009 at 04:27 PM.
02-02-2009, 09:32 PM
#4
This is not an oil weight issue here. I've lready had the exact same problem and it was a cam bearing that had walked. I know this is what's happened again. I just want to know if it's possible to have a wrong sized cam bearing in there or something similar.
02-02-2009, 10:00 PM
#5
The cam bearings are different sizes and need to be installed in the proper order in the block. If they a not correctly installed it is possible for them to walk or cause the cam to walk. The bearings are numbered on the backside and come with instructions to tell you what order they go in, but if the bearing has spun you probably won't be able to see the number.
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02-03-2009, 09:35 PM
#10
Unfortunately the only thing to do now is check the bearing again. If it has moved again you need to pull it out and measure the bearing and the cam bore to see if they are in spec. If you find the bearing has been installed in the wrong place you really should replace them all, because you can't just install one wrong. At this point I agree with you that the bearing has slipped again and there isn't much you can do other than tear down and check it out.
02-03-2009, 10:31 PM
#12
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if you have a cam bearing spin, you can have the cam journals aline bored, and have over sized cam bearings installed. sorry to hear about this, but i have seen journals expand for some reason. it preaty common for a ls series engine for this to accoure, the cam bearing like to walk. also if the bearing is just walking, you can take a center puch to the cam journal and raise it up so that it expands and holds the bearing better. i hope this information helps.
02-04-2009, 01:36 AM
#14
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Sorry to hear that man! Same thing happened to me after my cam install, while tuning the car, it was showing low oil pressure but it was continued to be driven and consequently spun a bearing. That forced me to rebuild the motor! Be very careful, don't get anxious and take your time cuz u definitely don't want to mess up your freshly rebuilt motor! Already cost way too much $$$$$$ 
02-04-2009, 07:42 AM
#16
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The same thing happened to me with a shortblock from a "reputable" builder in Texas. The front bearing walked back. Consequently, all my bearings were damaged. This is why the motor is out of my car right now. Sorry Man. Get a local builder that will warranty his work.
02-04-2009, 07:58 AM
#17
that's what I've done. It's just the fact I waited almost 3 months for him to get done and then I get it installed and a brand new bearing walks?! Also I spent $2800 on a rebuild with new pistons and rings. For the money and time it took I SHOULD not be having these problems.
02-04-2009, 10:07 AM
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Cam bearings walking is a common problem with these motors? First time i am hearing about this. I will be paying special attention when doing my build.
