Low Oil Pressure ?'s

[Deuling]

Ive got an 85 K5 with a 305 and when i start it up the oil pressure is up nice around 45 or so, but when the oil warms up, its at about zero at idle. Every old chevy i have ever seen does this. I just wondered if its somthing they just do, or if theirs something i can do (besides pulling engine or any other big fixes) to fix it or look for. Im running quaker state 5w30. Should i try a thicker oil possibly? I just dont like running thick oil when its cold out because of how thick it gets when its really really cold. Or would an oil additive help or hurt.?

 

[K5_Fla]

what is "rear nothing" at warm idel ? Nothing at all ...?

 

[Deuling]

what is "rear nothing" at warm idel ? Nothing at all ...?

I meant when the oil gets to temp, without hitting the gas the pressure is basically zero. At 55 its only at like 15. I guess i just didnt know if its normal or not. My van does the zero at idle too, but its more like 35 at normal driving speeds.

 

[K85 Octane]

if it's possible, check with a mechanical gauge
you may have a bad sending unit or worse, pump, crap in the pump screen, or pressure spring in the pump
but I have never dealt with this before

 

[Deuling]

if it's possible, check with a mechanical gauge
you may have a bad sending unit or worse, pump, crap in the pump screen, or pressure spring in the pump
but I have never dealt with this before

Well if thats the case i guess ill get a pump and a new oil pan gasket. Should be able to get the pan out without removing tranny or raising engine right???

 

[chulisohombre]

i wouldnt ever put anything less than 10w30 in my engine.i run 10w40 4 quarts and a bottle of lucas. right now and even warmed up it stays around 20 psi.startup is around between 45 and 50 til it warms up a lil.5w30 is way thin oil and should only be ran in ricers in my opinion.you can try lucas but you would have to take out some of the oil you have in there now.

 

[Deuling]

i wouldnt ever put anything less than 10w30 in my engine.i run 10w40 4 quarts and a bottle of lucas. right now and even warmed up it stays around 20 psi.startup is around between 45 and 50 til it warms up a lil.5w30 is way thin oil and should only be ran in ricers in my opinion.you can try lucas but you would have to take out some of the oil you have in there now.

ok good idea, i just thought it would be the best for the cold starts in the -15 degree temps weve been having lol.

 

[TexasSilhouette]

Well if thats the case i guess ill get a pump and a new oil pan gasket. Should be able to get the pan out without removing tranny or raising engine right???

Check the oil pressure with a mechanical gauge before you start throwing parts at it.

Oil pumps rarely go bad, they are the best lubricated part of your engine.

Find out if it is really dangerously low or if it just seems to be, then take measures to locate the actual cause.

 

[Deuling]

I know on my bronco their was a little plastic piece on the timing chain that was known for breaking and clogging oil pumps and destroying engines. Took the pump out and sure enought the screen was full of plastic chunks. I just dont know if their is something like that on these or not. Had to take the tranny out to get the stupid oil pan off tho that sucked

 

[TexasSilhouette]

I know on my bronco their was a little plastic piece on the timing chain that was known for breaking and clogging oil pumps and destroying engines. Took the pump out and sure enought the screen was full of plastic chunks. I just dont know if their is something like that on these or not. Had to take the tranny out to get the stupid oil pan off tho that sucked

I fixed a bunch of those, some we got to too late and a piece of the timing gear made it through the screen and locked up the pump, twisted off the drive rod and killed the engine.

Plugged pickup screens can be an issure but not from a nylon timing gear issue.

 

[ryoken]

i like 15-40 here in joysey... and Quaker State sucks...

 

[Deuling]

i like 15-40 here in joysey... and Quaker State sucks...

Lol yah yah, they used to have it with the slick-50 additive in it which i put in my van that burned a good quart an oil change when i got it. They were using valvoline, and now the oil looks golden brown with 3000 miles at almost full. Idk just like to stick with one thing

 

[1980]

If it jumps up when you rev it up, it indicates main bearings going bad.

 

[Deuling]

If it jumps up when you rev it up, it indicates main bearings going bad.

If the oil pressure jumps??? Like goes up super fast? It seems to go up with rpms alright, not like random

 

[1980]

If the oil pressure jumps??? Like goes up super fast? It seems to go up with rpms alright, not like random

Yep, goes up with rpms. Thats been my experiance, but that is just an indication of one possibility. Hopefully some others have other ideas that aren't so depressing.

 

[4X4HIGH]

Check the pressure with a known good mechanical gauge. It takes 15 psi minimum for the hydraulic lifters to work so unless you hear lifter clatter you have at least 15 psi. It IS NOT normal for the gauge to give you such low readings unless there is a problem somewhere. My gauge reads 60 psi at idle when cold and 50ish when at normal operating temps (I have verfied with a mechanical gauge as well) this is also on an engine with less than 6K miles since I built it (standard oil pump)

 

[63chevyll]

try a differnt oil.......and save some $$$ for an engine when the time comes.

Just dont want to be caught off guard

 

[diesel4me]

Oil pumps DO wear out after a lot of miles,and many get damaged by metal filings,nylon timing gear teeth fragments,and cracked valve stem seals--the screen on the intake can and will actually pull away from the housing during a cold start when oil is thick and let crud get inhaled too,especially if the screen is clogged up badly..I've found everything from those items to the steel c-clips that go in the valve lifters get into oil pumps and booger the gears up...the oil pressure releif valve springs can weaken with age and heat after a long time and drop pressure too.

.a new stock oil pump is less than 20 bucks for a SBC,and a steel driveshaft collar for it is only another 5-10 bucks,a good investment to replace the crap nylon POS stock one...I dont beleive in "Hi-Volume" or "Hi Pressure" pumps,seen them cause more grief tan good in a stock engine,they need certain mods to make them compatible ..

But,I'd do as suggested frst,and put a good mechanical pressure gauge on the engine in place of the stock sending unit and see exactly what pressure you have both cold and hot..and maybe try another oil pressure tap on the engine in case the one for the sending unit has become restricted with sludge...chances are if your lifters aren't clattering there is sufficient pressure and its just the gauge or sending unit leading you to beleive you have a problem when none really exists..

I'd also run thicker oil if its a high mileage engine--10W-30 is the thinnest I'd use unless its below zero where you are very often--or use the thicker oil with a block heater...usually if bearings are loose,you'll hear a woodpecker type clatter upon starting a cold engine for several seconds until oil pressure builds up...

I've had certain oils lose viscosity when hot and let oil pressure droop as the engine heats up..the worst ones were Quaker State and Penzoil,I had best results with Castrol GTX 20W-50 in my old engines that had the oil pressure drop off after they got fully warmed up,but you may not be able to use that till summer comes,it gets too stiff below 20 degrees...

 

[jekquistk5]

buy a cheap set of gauges. My factory gauges did that but I ended up ditching it for mechanical setup.

 

[Deuling]

Ok thanks for the input. I wanted to also add that their is, only when warmed up, and idling 550rpm, not a ticking sound but more like a deep clunk, idk im gonna guess with the bearing issue, but wouldnt it continue once i hit the gas??? It goes right away as soon as its revved up a bit.

Every old vehicle i have ever driven does the low at idle and goes up as you hit the gas, wouldnt it make sense for pressure to increase as rpms increase??? Im not saying that its not the case here because with that noise it most likely could be, but if the oil pressure is supposed to stay constant, your saying all these older motors are shot??? Idk if i can buy that. My van does the same thing and that thing runs amazing. No rough idle, doesnt burn a drop of oil, tons of power for a 350.

I guess ill just have to treat her nice till summer gets here and i can get old red out of the barn and start lookin into this thing more. 350/260 crate motors on summit for $1500. SHould be gettin tax money soon lol. I would love to drop a brand new engine in a truck. Never done it before.

If it dies it dies i guess and ill find a new motor. I would rebuild one if i had the time and some help from somebody who knows what their doing. If i hadnt been lookin for one of these for so long and finally found one that wasnt a rust bucket for a decent price i would just sell it now. But i like it and wanna see what i can do with it.