Got a good one for ya'll. My truck has always had low oil pressure it used to hang just under left white line when warm at idle and at 65 approx 1500rpms the pressure would set at approx 35psi which wasn't bad but i didn't like it. I was out at shiloh ridge in november going up helicopter hill when the oil pressure guage at idle started fluttering by the left white line then and the light came on but any throttle application would shoot it up to 30-35psi then when you let off it would settle down and start fluttering again and light would reappear. After i got up to the top we checked the oil and checked for any rock damage and found the oil level way perfect and there was no rock damage anywhere. when i went to get in the truck i noticed a lil smoke coming from the exhaust ( burning oil) i decided the hell with it and finished wheeling it that weekend and just bkept an eye on the oil I figured the oil pump was just going south and i had blown my plenum gasket. so in december i decided to install a mellings high volume oil pump, new oil pressure sensor, cloyes double roller timing chain set (just because i was in there), and ditched the keg for a hughes air gap intake. Fired it up and to my suprise it was still burning oil and the oil pressure was still the same not one bit of difference. been driving it around since then Approx 100 miles a day and it burns 3qts every day. in january it started doing this crap where whenever there is a decent load on the engine for example softly accelerating up a hill at 55 - 70 you start hearing what sounds like a pushrod rattleing then the truck will start shuddering and it will repetatively back fire through the intake and slowwly bog down the only way to stop it is to shift into 2 and pray it dont blow up. I'm thinking a valve or two is sticking. as for the oil pressure it tops out at 34 now and if rpms drop below 1200 the pressure falls completely off but there isn't any valvetrain noise to indicate low pressure. finally the smoke if you get on it on the highway my truck looks like a mesquito fogger ( blueish smoke with a little black). At idle and sitting still i can snap the throttle and a ploom of grey smoke pours out of the exhaust. also my exhaust is dumped before the rear axle so the whole under side of my bed and and axle on that side is pitch black. the motor has 215k on her and she has been wheeled basically her whole life so tons of abuse. this motor has out lived four transmissions, three rear axles, two transfer cases, and a rear driveshaft. so i assume the cam or main bearings could be worn to hell. I dont want to rebuild this block because the passenger side lower ear that bolts to the tranny is snapped off just trying to see if maybe i can slap a band aid on her till she finally dies. I already have a rebuilt long block sitting on the stand i just hate to send it to its grave while its still kicking. any ideas would help guys thanks in advance. sorry this is so long I was just trying to make sure i covered everything.

 

sounds like your SOL bud, rings sound very likely. how bout the PCV?

these engines are notorious for oil pressure heading south; likely due to worn mains or rods bearings. as long as you have good volume, which you will with the new pump. she'll keep kicking for quite some time

 

thats what I figured. The pcv valve was replaced in august whats your take on the back fire in the intake? it only does it when it wants too sometimes goes for days without doing it.

 

If you have a rebuilt there ready to go in, the only problem you have is putting it in.

 

I would swap in the new motor as soon as possible. You want to fix it when it is convenient for YOU, not when the current motor decides to blow up. (and you just KNOW it will pick the least convenient time to do so.....)

 

No guarantee that the engine is bad. Do a compression test and report the numbers of each cylinder...

 

Good compression does not a good motor make. He has other issues going on there as well.

 

Intake backfire could be a valve seating problem. Check valve springs/lifters. Throwing any codes?