lickem

Don't know if right thread...but need help...oil pressure running at 40 to 45...after driving for a bit oil pressure drops at idle...almost to the red line....so was think oil pump..were is it located at..its a 5.7 TPI....just don't seam norm..like I said it don't do all the time..just if I drive for a long period of time....

camarosrock1989

iTrader: (1)

Bump, I hope you get some answers!

lickem

Iknow...driving me nuts...let's see if some one out there knows....

8t2 z-chev

A worn oil pump is one of the possible causes for the low
oil pressure-it's bolted to the rear main cap inside the
engine,you'll have to drop the pan to get to it...
A few other possible causes:
-bad pressure sender giving false reading
-oil level too high,causing the oil to foam up
-worn or out of position cam bearings
-oil getting too hot-an oil cooler is an important addition
to any high performance cooling system,some later 3rds
came with an oil cooler-if yours has one,check that it is
working good.

lickem

Right on...now I know were to start...is the oil cooler located close to the pump...im still learning each day about my car...sorry if I sound dumb..but not trying to...I went from a civic to my Z28....just don't know were some of the parts are at..time to get a manual.....

ymenic

iTrader: (1)

I would probably replace the oil pressure sending unit first. If it still low how mnay miles are on the car? over 125K probably time for a bottom end rebuild. I would first get a new oil pressure sending unit.

19camaro83

^^^ X2. I just ordered one from O'reily's for $4 for mine. Mine was spitting oil on the ground, however..

UnderCover89TBI

iTrader: (25)

Yeah. I would install AC Delco or Dealer ones I have had bad luck with aftermarket sending units.

camaronewbie

What year car? Year changes position of the oil pressure sending unit...

Earlier cars have 2 units - one on top of the china wall, rear of intake, just to pass side of distributor - that feeds the gauge - has a single wire. Other one just above oil filter on the block, that feeds the fuel pump circuit - that has 2 wires - if your car has both, then you want to replace the upper one (by distributor).

Later cars have just one, a 3 wire unit just above the oil filter.

As long as the oil pressure is always changing, you should be fine - it's like a gas gauge kinda - as long as the needle moves, you've got gas - same kinda theory - as long as the pressure changes (lower at idle, higher with accelleration), then your oil pump is pumping oil. It's when it falls and never comes back up that you have an issue with an oil pump or pickup.

19camaro83

Not to get too off topic, but my gauge was actually reading negative oil pressure (it would go counter-clockwise, past the "0"). And as for the after market stuff failing, I have not ran into any issues with any parts I have purchased through them. I do understand that there is a chance of it happening, as most of it is made in China, Taiwan, etc.. But so far I have had good luck, and at $4, I don't really have anything to lose there.

Mine is an 83, and I was unaware of the sending unit other than the one above the filter. Thank you for posting that information.

lickem

So as long as it still goz up in pressure when pushing the gas..then im good..see some times when car is started pressure will be at 60 then some days at 45 close to 50..never really the same pressure..but what had me werey was the fact that it would drop down to 20 or a little bit below it. The longer I drive..I had the oil pressure gage replaced not to long ago...I just don't want my engine taken a ****...
1991 Z28 5.7 TPI

19camaro83

Sounds like a normal engine with some miles on it. Nothing I would be too worried about.

lickem

Just a 182385 miles....lol not that much tho....could b worse

19camaro83

Thats not too bad pressure then, considering the oil PSI. I have a friend with a 92 C1500 4x4 with a 350 in it. He is around 196k miles, and he is HARD on that truck. He also experiments with the fuel injectors and all sorts of weird stuff... He is sitting at about 40 PSI WOT, and it idles around 5-10 PSI. You have nothing to be worried about

ASE doc

What weight oil are you running? Factory spec was 5w30 but over 100K you may need 10w40 to maintain oil pressure at lower revs. Also, be sure to use the largest filter you can. The OE used the short WIX 1085, if I remember my filter #s correctly. the WIC 1065, again if I have my #s right, will fit fine and is 1" longer with a higher filtration capacity.

lickem

Running 10w 30

lickem

Gunna chats pump to be on safe side....then run 10w 40 and see if im good....

camarosrock1989

iTrader: (1)

You might want to try some synthetic oil, with that TPI and those miles.
I heard that it is good for the high performance motors.

85z28kid

iTrader: (7)

well dont wanne break it to you but it deff sounds like a your main bearings are going bad thats normally what happens when they start to wear out a lot of motor guys will tell you the same thing oil pressure lose is normally do to bad mains. yes anything under 15 isnt that good. as i would nt run anything of mine under 50 to 60 at an idle aslong as you have 10 pounds for every thound rpms then you should be fine for now. yea 186k miles are a lot for a v8 specially in these kinda of cars you dont have these to go slow do we? lol

lickem

So true...do you think its worth a try though? Then see if pressure don't drop below 20... then if it does.....then ill check

85z28kid

iTrader: (7)

i would try it maybe thry a high pressure pump to see if that will help and thicker oil should be used to the reason you lose oil pressure is cuz the oils thick when first started then when it heats up the oil gets thinner example lost oil pressure happened to me it might just as easy to pull the motor out and fresshen it up with new rings and bearings should cost to much

lickem

Ok so I called and don't know if I need the high pressure pump or regular pump.....needs to know b 4 I buy

Apeiron

Forget about changing the pump. Change the oil pressure sender.

lickem

All read been dune...new sender

Apeiron

Then verify the gauge reading with a mechanical gauge, or replace the gauge.

lickem

So you saying that the sender could b bad and not pump..or the gage.....now im at a lost...please explane

Apeiron

I'm saying that the odds that you have low oil pressure due to a bad oil pump are about one in a hundred million, and that changing the pump is a waste of time.

Furthermore, the odds that you actually have dangerously low oil pressure are.... lets say one in a thousand.

If you have 10 psi of oil pressure for every 1000 RPM that the engine is turning, you have more than enough oil pressure for the bearings.

Your hydraulic valvetrain also makes a great backup low-pressure warning system. If you really had dangerously low oil pressure, the lifters would collapse and the valvetrain would be rattling and clattering.

Even if you really did have low oil pressure, the fix is a rebuild, not an oil pump.

lickem

So were u the one saying its like a gas gage...as long as it gos up at revealed then im good..I have a couple picks but this drone driving about for 15 min......_

lickem

This is from when I first started driving

lickem

And this from when I stopped at lights....some time it will get between the last red line and the 20 line....please tell me im fine

19camaro83

Your fine.. its an old engine with a lot of miles.. use some thicker weight oil and don't hammer on it as much as you normally do..

Apeiron

The reading on the gauge may have very little to do with the actual oil pressure.

grumpyvette

pressure is a measure of resistance to flow, thicker viscosity oil or a higher volume oil pump will increase the gauge pressure indicated but that may not be your problem, read thru these links





http://forum.grumpysperformance.com/....php?f=54&t=52

http://forum.grumpysperformance.com/...hp?f=54&t=2187

http://forum.grumpysperformance.com/...php?f=54&t=615

Toqwik

call gm tech line. they will tell you 5-7 lbs at idle is fine for lube of the bearings. Don't sweat it. you car has alot of miles. have fun with it, and worry when it dies. mine is just like yours, has 197000 on it. I quit looking at the guage. drive it and listen. If it goes tomorrow, oh well. been like that for years......

85z28kid

iTrader: (7)

Please listen to most people and the motor before she blows be a lot cheaper than if she blows