283 V8 looses oil pressur at driving temperature - The 1947 - Present Chevrolet & GMC Truck Message Board Network

oleguy · 12-13-2013, 11:09 PM

I am about to acquire a 283 out of a 66 chevy pickup.To put in my 67 C10. It was recently (overhauled) by a previous owner. The oil pressure is good at low to medium temperature, but at running temp. it drops to near zero. My thoughts are #1. Main bearings to much clearance. #2. Cam bearings to much clearance. #3. I don't know if the oil pump was replaced or even checked. I will tear the engine down and check these items. Any further ideas on the the cause of this problem will be appreciated. Thanks in advance.

Rod Run · 12-13-2013, 11:13 PM

Sounds like a possible bad pump. whatever it is, I would stay away from it unless you are buying it under the idea that it is going to need an immediate rebuild? Must be priced accordingly. free?

cool68 · 12-13-2013, 11:14 PM

what are you relying on to give you correct pressure reading? what are the pressure readings?

swamp rat · 12-14-2013, 03:00 AM

Quote:

Originally Posted by oleguy

I am about to acquire a 283 out of a 66 chevy pickup.To put in my 67 C10. It was recently (overhauled) by a previous owner. The oil pressure is good at low to medium temperature, but at running temp. it drops to near zero. My thoughts are #1. Main bearings to much clearance. #2. Cam bearings to much clearance. #3. I don't know if the oil pump was replaced or even checked. I will tear the engine down and check these items. Any further ideas on the the cause of this problem will be appreciated. Thanks in advance.

Could be all the above, and it could be the wrong weight oil too. Ask the guy if the mains were plasti gauged when rebuilt and see what he says, i cant remember the clearance off hand but i think about .001 to .0015? If he rebuilt it doesn't know then he has no business rebuilding an engine in the first place. If he has no answer on the plasti guage he could have probably just slid a new cam into the old bearings too. I don't know the guy obviously but this is what i'd be thinking.

Andy4639 · 12-14-2013, 08:55 AM

As stated see what the real pressure is and it's normal for oil presssure to drop off after reaching running temperature. Mine reads high when first cranked up but after she is running it will drop off a bunch around 25-40PSI. Get a good trusted reading yourself.

5lbs of oil pressure is not un common at idle.

Eddie H. · 12-14-2013, 10:39 AM

Most every small block chevy I have ever owned showed low oil pressure at idle after they are fully warmed up. As long as you have at least 5-10 psi, I wouldn't worry about it.

Sammy · 12-14-2013, 12:03 PM

If it is actually zero that isn't good. I wouldn't install anything with that low of pressure. Too easy to investigate that and figure out a reason while it is out. Likely it is just the pickup screen on the oil pump too high to suck up the oil.

cwilkie · 12-14-2013, 12:27 PM

Try a different oil filter. One of my engines had extremely low oil pressure after it was rebuilt. It had a Fram filter on it. It switched to an ac delco and the oil pressure remained high ever since.

Sammy · 12-14-2013, 04:41 PM

Quote:

Originally Posted by cwilkie

Try a different oil filter. One of my engines had extremely low oil pressure after it was rebuilt. It had a Fram filter on it. It switched to an ac delco and the oil pressure remained high ever since.

I have heard that before.

myyamr7 · 12-14-2013, 08:27 PM

I remember the machine shop telling me a small block only needs 5psi of oil pressure per 1000 rpm.
I have a new GM goodwrench 350 in my truck and it has 65psi when cold started, stays about 50 when warm and driving, but drops down to 10 at idle when it's hot

oleguy · 12-27-2013, 12:43 AM

I have been off of the computer for a while, but I want to thank all of you for the help. I will mic. the main and rod journals as well as plasti gague them. I will replace the cam bearings. I will check the oil pickup screen and height, and replace the pump. Once again thanks for the info.

Grip · 12-27-2013, 02:29 AM

In the circle track racing world, the rule of thumb is 10lbs per 1,000 rpm. I think you are fine. Clearances are just a little loose.

oleguy · 12-30-2013, 03:54 PM

OOps. I just reread my original post and neglected to mention, at highway speed (75 mph. on turnpike & 65 mph on secondary Highways ) when the engine warms to normal temp. the oil pressure drops to near zero. Thanks again for all of the input.

67 chevelle · 12-30-2013, 04:25 PM

Quote:

Originally Posted by oleguy

OOps. I just reread my original post and neglected to mention, at highway speed (75 mph. on turnpike & 65 mph on secondary Highways ) when the engine warms to normal temp. the oil pressure drops to near zero. Thanks again for all of the input.

not good at all

zeldman · 12-30-2013, 11:37 PM

Ok,different problem. Check the oil return galleys and make sure they are not sludged up and restricting the oil returning to the pan. Have you tried checking the pressure with another gauge?

12-14-2013, 08:55 AM	#5
Andy4639 Old member Join Date: Jan 2002 Location: Liberty, & Garden City S.C. , U.S. Posts: 19,945	Re: 283 V8 looses oil pressur at driving temperature As stated see what the real pressure is and it's normal for oil presssure to drop off after reaching running temperature. Mine reads high when first cranked up but after she is running it will drop off a bunch around 25-40PSI. Get a good trusted reading yourself. 5lbs of oil pressure is not un common at idle. __________________ 1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs.

12-14-2013, 10:39 AM	#6
Eddie H. Registered User Join Date: Mar 2001 Location: Paradise TX USA Posts: 1,200	Re: 283 V8 looses oil pressur at driving temperature Most every small block chevy I have ever owned showed low oil pressure at idle after they are fully warmed up. As long as you have at least 5-10 psi, I wouldn't worry about it. __________________ "Negative people always seem to have a problem for every solution"

12-14-2013, 12:03 PM	#7
Sammy Registered User Join Date: Apr 2000 Location: Bonne Terre, Mo Posts: 3,005	Re: 283 V8 looses oil pressur at driving temperature If it is actually zero that isn't good. I wouldn't install anything with that low of pressure. Too easy to investigate that and figure out a reason while it is out. Likely it is just the pickup screen on the oil pump too high to suck up the oil. __________________ '69 Chevy Long Fleet & '71 GMC Short Step & Project "ODD BALL" "You can wash a pig, soak it in most expensive perfume. In the end it is still just a pig." ODD BALL build thread http://67-72chevytrucks.com/vboard/s...d.php?t=478629"

12-14-2013, 12:27 PM	#8
cwilkie Chance Join Date: Sep 2001 Location: Belcourt ,ND, USA Posts: 750	Re: 283 V8 looses oil pressur at driving temperature Try a different oil filter. One of my engines had extremely low oil pressure after it was rebuilt. It had a Fram filter on it. It switched to an ac delco and the oil pressure remained high ever since. __________________ 1968 Chevrolet Stepside BB 396 w/TH400 1972 Chevrolet 3/4 Ton 4x4 BB 496 w/TH400

12-14-2013, 08:27 PM	#10
myyamr7 Registered User Join Date: Dec 2012 Location: Providence, RI Posts: 211	Re: 283 V8 looses oil pressur at driving temperature I remember the machine shop telling me a small block only needs 5psi of oil pressure per 1000 rpm. I have a new GM goodwrench 350 in my truck and it has 65psi when cold started, stays about 50 when warm and driving, but drops down to 10 at idle when it's hot __________________ Mark 71 C10 Cheyenne 12 Aprilia RSV4

12-13-2013, 11:09 PM	#1
oleguy Registered User Join Date: Sep 2013 Location: Broken Arrow OK Posts: 39	283 V8 looses oil pressur at driving temperature I am about to acquire a 283 out of a 66 chevy pickup.To put in my 67 C10. It was recently (overhauled) by a previous owner. The oil pressure is good at low to medium temperature, but at running temp. it drops to near zero. My thoughts are #1. Main bearings to much clearance. #2. Cam bearings to much clearance. #3. I don't know if the oil pump was replaced or even checked. I will tear the engine down and check these items. Any further ideas on the the cause of this problem will be appreciated. Thanks in advance.

12-13-2013, 11:13 PM	#2
Rod Run Registered User Join Date: Oct 2013 Location: Massachusetts Posts: 777	Re: 283 V8 looses oil pressur at driving temperature Sounds like a possible bad pump. whatever it is, I would stay away from it unless you are buying it under the idea that it is going to need an immediate rebuild? Must be priced accordingly. free? __________________ ______________________ www.northeastrodrun.com

12-13-2013, 11:14 PM	#3
cool68 Registered User Join Date: Oct 2013 Location: Stockton, CA Posts: 475	Re: 283 V8 looses oil pressur at driving temperature what are you relying on to give you correct pressure reading? what are the pressure readings?

12-27-2013, 12:43 AM	#11
oleguy Registered User Join Date: Sep 2013 Location: Broken Arrow OK Posts: 39	Re: 283 V8 looses oil pressur at driving temperature I have been off of the computer for a while, but I want to thank all of you for the help. I will mic. the main and rod journals as well as plasti gague them. I will replace the cam bearings. I will check the oil pickup screen and height, and replace the pump. Once again thanks for the info.

12-27-2013, 02:29 AM	#12
Grip Registered User Join Date: Mar 2009 Location: Conyers, Ga. Posts: 121	Re: 283 V8 looses oil pressur at driving temperature In the circle track racing world, the rule of thumb is 10lbs per 1,000 rpm. I think you are fine. Clearances are just a little loose.

12-30-2013, 03:54 PM	#13
oleguy Registered User Join Date: Sep 2013 Location: Broken Arrow OK Posts: 39	Re: 283 V8 looses oil pressur at driving temperature OOps. I just reread my original post and neglected to mention, at highway speed (75 mph. on turnpike & 65 mph on secondary Highways ) when the engine warms to normal temp. the oil pressure drops to near zero. Thanks again for all of the input.

12-30-2013, 11:37 PM	#15
zeldman Registered User Join Date: Oct 2013 Location: Rt 66 Gallup, NM Posts: 527	Re: 283 V8 looses oil pressur at driving temperature Ok,different problem. Check the oil return galleys and make sure they are not sludged up and restricting the oil returning to the pan. Have you tried checking the pressure with another gauge? __________________ 2005 GMC K2500HD D/A 1993 GMC K1500 2011 Subaru Legacy. 2013 Subaru Outback 1970 C-10 2WD, SWB stepside, 292, TH350, PS, more rust than anything. God is my pilot.



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