mac_in_mt

Hi all,
I have a 1996 Chevy k1500 with the 5.7 L V8 which I am having low oil pressure issues. I am wondering if the main bearings and rods can be replaced through the oil pan on this vehicle?

THanks,
mac

chevyboy1993

only way to do it that way is to completely drop the front diff, i'd recommend pulling the motor but dont be too quick on bearings. i worked on a 96 tahoe with 5.7 vortec that was running 5psi at idle and 20 at 2000rpm and i dropped the pan to replace oil pump and then replace the oil pressure sensor. now it's at 25 idle and 45 at 2000. in order to get the pan out we had to drop the diff and the truck had a 4" lift kit on it.

mac_in_mt

Both the oil pressure sensor and the oil pump have been replaced and I am still having very low oil pressure (according to a manual gage) at idol. While the oil pan was off to replace the oil pump, would it have been easy to check the bearing clearances? I am having a mechanic do most of the work and I am having second thoughts about his abilities....even though they are much better than mine!

chevyboy1993

to check the clearance you need to buy some plastigauge, really cheap don't know where to get it though, and pull the caps off and place the strip in perpendicular to the surface, torque the caps down and remove them again and take the reading off of the plastigauge. should be 0.001"-0.004" of clearance

MDTAHOE

It would have been very easy to pull the main caps and rod caps to look at the bearings. Problem should have been obvious. Most of the time low oil pressure is not cause by a bad pump. If you went from good oil pressure to not oil pressure in a blink of an eye then it could be a failed pump. In order too order the correct bearing size you must plastiguage the clearances. Yes the bearings could be rolled in from the oil pan. If the engine has a knock at all the rods are most likely no longer round (egg shaped) rolling bearings in will only be a short term fix.

mac_in_mt

There appears to be no knocking as of this point. My mechanic also indicated that he is not hearing any knocking. If there is no knocking noise, would I be okay to roll in bearings from the bottom or am I asking for trouble? I am taking the truck to a different mechanic tomorrow and would like to have a preferred direction. Everybody I have talked to says that if the main bearings are worn, I will need a rebuild, which nobody seems to do. Everyone orders crate engines from some big factory several states away. Seems too expensive to me.

chevyboy1993

i just remembered this from when i was in auto class in school. if you drop oil pressure the most probable reason would be the cam bearing not the crank or rod bearing. most of the oil has to travel through the cam area to get up into the top end of the motor through the oil passages. i would consider pulling the cam. just my opinion