no oil pressure

[sleddyeddy]

i traded my atv for a 1998 gmc ext cab with a 350 on the drive home it ran great tranny had a hard shift and check engine light was on. when i got home the tranny compelty blew wouldnt shift just revved out hard then the motor died when i tried to restart the motor it didnt wanna turn over eaasy like it had a dead battery but it wasnt dead let it sit for a bit then it started whit a knock noticed no oil pressure shut it off i got the truck home now today i started it and it had oil pressure till it got warm then it dropped again but knock was gone. any ideas do you think motor is ******?

 

[am92]

Doesn't sound good, but check for metal shavings in your oil and then you'll know for sure

 

[badazzbulldog]

sounds like the oil pump pick-up screen is clogging up,i went thru this problem with our 99 silverado had pressure till it got warm then went to zero,poured a can of seafoam in ran it for 20 minutes did oil change got alot of sludge out,new filter and oil plus another can of seafoam ran it for a week great pressure changed again at end of the week clean as a whistle 60 psi at idle.

 

[MOBS]

When it drops, is it dropping to 0 oil pressure, or just dropping low and making a slight chatter sound?

I can't say anything for seafoam, never used it due to scary stories. But in my experiences, going from having oil pressure to absolutely none atall, has been oil pressure check valve sticking open. Going from high to low as engine warms up, has been excessive clearances in the bearings.

 

[sleddyeddy]

When it drops, is it dropping to 0 oil pressure, or just dropping low and making a slight chatter sound?

I can't say anything for seafoam, never used it due to scary stories. But in my experiences, going from having oil pressure to absolutely none atal, has been oil pressure check valve sticking open. Going from high to low as engine warms up, has been excessive clearances in the bearings.

it had none then cam back once warmed up it started fluctuatating but would hit zero if reved a little would come up.

 

[97SubMan]

it had none then cam back once warmed up it started fluctuatating but would hit zero if reved a little would come up.

with a low oil pressure issue, I would be willing to bet that revving the engine is a bad idea

 

[ChrisAU]

Sounds like you had a lovely first day with a GMT400.

Like taking a hot girl on a date and she ***** her pants in your car.

I have no useful insight right now, on the phone, I'll come back here in a couple hours.

 

[SAATR]

No knock is good news, but no oil pressure is obviously an issue. I would definitely drain the oil and pull the filter and look for chunks and/or metal flakes in both. If it looks like glitter is in the oil, then you are looking at a rebuild. If you have an engine oil cooler then I would check for oil in the coolant to rule out a leak into the cooling system causing your loss of oil pressure. It IS possible that you could have trash or sludge in the pan that is plugging the pickup tube or the oil filter, so an oil change with some cheap oil and a filter would be the first thing I would do if you find no metal in the pan and no oil in the coolant. Let us know what you find!

 

[outalne94z71]

Going from high to low as engine warms up, has been excessive clearances in the bearings.

this, once it was starved for oil originally it caused crank/bearing damage so now too big of a clearance when it warmed up, my mudder did the same thing and i hope to be putting the crank back in hopefully tomorrow

 

[copernicusd]

to the guy who said something about oil pick up screen clogging, could that happen after doing the head gaskets?
after i did mine, i started getting a bad tap, and no oil pressure, unless im driving, then it goes up a little, light says check gauges, i mean i adjusted the valves with the covers off, and it wasnt really throwing oil everywhere, i know the oil seems kinda thick, from the moly grease i guess, think its worth sea foaming it?