Originally Posted by Califokie

The LS engines ( 4.8 and 5.3L) have had different issues what erratic oil press gauge readings.. If the engine sounds normal but the gauge reads low or sometimes even high the problem is probably a clogged screen that is under the Oil Pressure Sensor located on the left top of the bellhousing behind the Intake Manifold... This is a common failure and most people have at least heard about it..

Now with that being said, A customer left his 04 GMC Sierra with a 5.3L T code ( 8th digit of VIN) engine out in front of my shop the night before for me to change that screen to see if it would correct his oil pressure issues.. Well, I knew as soon as I started it the next morning and it rattle at me for about 5 seconds and then pumped the oil pressure up to about 30 to 35 psi as I pulled it into my shop, that this was NOT a dirty screen issue... The truck had 210K miles on it and the owner was ready to just call it wore out and find another truck.. The truck had been serviced regularly it's entire life and now here it was with low oil pressure issues, so he asked for my advice about if the truck was worth fixing.. My answer was ABSOLUTELY... In my opinion the LS motors are some of the very best engines on the road. Just like it's SBC predecessors, the engines are right next to being bullet proof..

This low oil pressure issue was caused by a weak design that was made when the engineers actually made the oil filter housing part of the oil pan.. The oil literally has to go through the oil pan gasket and oil pan to get to the filter.. The oil pan gasket has two O-rings built into it that seals the inlet and outlet to the oil filter. This design allows an o-ring to split and allow oil to escape the lubrication system and dump right back into the oil pan leaving no visible outside trace of an oil leak.. So a failed oil pan gasket can make you think that your engine is wore out... Another weak spot in the engine is another o-ring used on the pickup tube where it seals to the oil pump that hardens and allows oil to escape back into the pan there also..

To fix the truck I pulled the 4 bolts and dropped the crossmember, removed the oil pan, drilled out the rivets used to secure the oil pan gasket to the oil pan at the factory, pulled the pickup tube and replaced the o-ring on it and put the oil pan back on with a new gasket.. The truck now maintains 45-60 psi oil pressure and no longer rattles when starting up cold... Due to the fact that the oil pan bolts need to be torqued in sequence to prevent alignment problems I strongly suggest not doing this yourself.. However it is about a 4 hour job that is much cheaper than buying a new engine or truck.

Originally Posted by Califokie

The LS engines ( 4.8 and 5.3L) have had different issues what erratic oil press gauge readings.. If the engine sounds normal but the gauge reads low or sometimes even high the problem is probably a clogged screen that is under the Oil Pressure Sensor located on the left top of the bellhousing behind the Intake Manifold... This is a common failure and most people have at least heard about it..

Now with that being said, A customer left his 04 GMC Sierra with a 5.3L T code ( 8th digit of VIN) engine out in front of my shop the night before for me to change that screen to see if it would correct his oil pressure issues.. Well, I knew as soon as I started it the next morning and it rattle at me for about 5 seconds and then pumped the oil pressure up to about 30 to 35 psi as I pulled it into my shop, that this was NOT a dirty screen issue... The truck had 210K miles on it and the owner was ready to just call it wore out and find another truck.. The truck had been serviced regularly it's entire life and now here it was with low oil pressure issues, so he asked for my advice about if the truck was worth fixing.. My answer was ABSOLUTELY... In my opinion the LS motors are some of the very best engines on the road. Just like it's SBC predecessors, the engines are right next to being bullet proof..

This low oil pressure issue was caused by a weak design that was made when the engineers actually made the oil filter housing part of the oil pan.. The oil literally has to go through the oil pan gasket and oil pan to get to the filter.. The oil pan gasket has two O-rings built into it that seals the inlet and outlet to the oil filter. This design allows an o-ring to split and allow oil to escape the lubrication system and dump right back into the oil pan leaving no visible outside trace of an oil leak.. So a failed oil pan gasket can make you think that your engine is wore out... Another weak spot in the engine is another o-ring used on the pickup tube where it seals to the oil pump that hardens and allows oil to escape back into the pan there also..

To fix the truck I pulled the 4 bolts and dropped the crossmember, removed the oil pan, drilled out the rivets used to secure the oil pan gasket to the oil pan at the factory, pulled the pickup tube and replaced the o-ring on it and put the oil pan back on with a new gasket.. The truck now maintains 45-60 psi oil pressure and no longer rattles when starting up cold... Due to the fact that the oil pan bolts need to be torqued in sequence to prevent alignment problems I strongly suggest not doing this yourself.. However it is about a 4 hour job that is much cheaper than buying a new engine or truck.