Oil pressure

[JHART]

I already asked the same question in another thread but i wanted to be more specific this time with pics.

Ok in the first pic you can see what the gauge is at when i am at idle just below 1k rpm.

The second pic is when i am driving at about 20-30 mph at or around 1200-1400 rpm.

Should i be worried? The motor sounds fine and performs fine.

[woodridge]

I wouldn't be if the guage is correct. Most likely a high presure pump.

[Texasdeere]

Are these readings with the engine oil at full operating temperature or hot?

[WorkinLonghorn]

Isn't there a relief valve on these oil pumps to relieve pressure over a certain amount at start-up? In any case,I would try another oil gauge.

[JHART]

Originally Posted by TexasC10

Are these readings with the engine oil at full operating temperature or hot?

I wouldnt say full operating temp ... it was running for about 15 mins.

[GREASEMONKEY72]

what weight oil are you running??

i run 20-50 and my gauge is in the middle at idle and 3/4 while driving at full temp

when i first start her up cold it sits at the 3/4 at idle

[Sport/Truck]

I wanted to start this in a separate thread, but I’ll ask here as it might help.
I read that the oil pressure sending unit is near the oil filter. I’m not sure what the oil path is on these, but my thinking is you need to read the pressure at the end of the line. So if you have blockage somewhere you won’t read high and think you are fine, also if your pump is weak, you will show less pressure.
Is the factory sending location in the beginning or at the end?
LMK
s/t

[Palf70Step]

These gauges are not that accurate, even when new. I suspect the gauge or sensor is the culprit. Cheaps and best way is to install an after market gauge and see what readings it provides. You can put a T on your mechanical pickup and have both gauges running for a comparison.

[Sport/Truck]

Originally Posted by Palf70Step

These gauges are not that accurate, even when new. I suspect the gauge or sensor is the culprit. Cheaps and best way is to install an after market gauge and see what readings it provides. You can put a T on your mechanical pickup and have both gauges running for a comparison.

So is the sending unit at the beginning or end?
I agree and disagree, here’s why. If you know what your gauge reads normally it wont matter. IE: lets say it 20psi one calibrated gauge, and you factory gauge reads 3/4. As long as nothing changes then there is no problem. Agree?
Here a problem with that statement. Does he know what it normally reads? Did it gradually get worse or did he change something and now it reads high? All theses questions need to be asked before we say it’s the gauge.
JMO
s/t

[brak]

These were mechanical gauges, and with any mechanical anything it can wear out over time.

the oil line leading to the gauge should connect at the top of the block (rear deck drivers side) directly behind the intake manifold.

Personally i would get a cheapo mechanical gauge (around 10 bucks or less), and check the pressure. directly off block (disconnect the stock line). If everything looks fine, reconnect the factory gauge and have a little peace of mind.

[Sport/Truck]

Originally Posted by brak

These were mechanical gauges, and with any mechanical anything it can wear out over time.

the oil line leading to the gauge should connect at the top of the block (rear deck drivers side) directly behind the intake manifold.

Personally i would get a cheapo mechanical gauge (around 10 bucks or less), and check the pressure. directly off block (disconnect the stock line). If everything looks fine, reconnect the factory gauge and have a little peace of mind.

Is the stock location at the oil filter?
s/t

[brak]

I don't think the factory location was by the filter, but then again, i've never seen a factory 67-72 chevy pickup.

The factory oil pressure location for every vehicle i've worked with is indicated in the picture below.

[Palf70Step]

That is the only place I remember seeing them on a small block also, back by the distributor.

[Sport/Truck]

The reason I say this, is in the thread about oil leaks, some one mentioned it was by the oil filter. Not sure what to think though. I have a sending unit in that location on my truck.
Do you think that is the end of the oil path? I want to upgrade from my oil idiot light.
s/t

[cooters]

there is a passage above the oil filter on a small block but i never seen it used except for the fuel injected trucks. The others had the copper line behind the distributer

[brak]

Originally Posted by Sport/Truck

The reason I say this, is in the thread about oil leaks, some one mentioned it was by the oil filter. Not sure what to think though. I have a sending unit in that location on my truck.
Do you think that is the end of the oil path? I want to upgrade from my oil idiot light.
s/t

I think i know the post you are talking about, and it was referring to the fact that some Small blocks had provisions for an external oil cooler, which connected to threaded ports by the oil filter. They are fairly large, 1/2" NPT i believe.

the Gen II engine in my 89 K-10 blazer had them, they came plugged from the factory.

[Longhorn Man]

the stock location for the guage, is as indicated in the photo. I am 99% sure the dummy light is the same. I have never noticed a small block with either of these located in any other location, new, old, or anything in between.
That guage should be rated for 60 PSI, which, is where the bypass valve should be rtated also.
There is no sending unit for a mechanical guage. For a dummy lamp, or a later electrical guage, the sending unit would be on the spot indicated in the photo.

[clay68c10]

Is this a fresh rebuild? Are you running 20-50 oil?
With good bearing clearances and a high pressure or high volume oil pump you'll see the gauge peg like that. As long as the pressure isn't causing your rear main to leak I wouldn't worry about it. Better to have high oil pressure than low.

[JHART]

Originally Posted by clay68c10

Is this a fresh rebuild? Are you running 20-50 oil?
With good bearing clearances and a high pressure or high volume oil pump you'll see the gauge peg like that. As long as the pressure isn't causing your rear main to leak I wouldn't worry about it. Better to have high oil pressure than low.

Well i dont know what oil the guys used when i bought. i can say this though. I had the truck out on the highway doing well over 100mph and she didnt even hick-up so i dont think my oil pressure is the problem.

Thank you all for the great tips and awesome response. I didnt think i would get this much help. You all kick a** in my book. Man i am glad i found this site.

So i have decided to go pick up a new gauge and try that. Also i am pulling out the tranny today and getting it ready for rebuil

Thx guy again everyone!

-Hart

[powell72]

Originally Posted by JHART

So i have decided to go pick up a new gauge and try that. Also i am pulling out the tranny today and getting it ready for rebuil

I would be happy to have oil pressure like that, I certainly wouldn't waste any money buying another gauge. Save your money for your trans.

[st1x10]

What grade of oil should be run in these trucks?

[piecesparts]

On a lot of engines there is an oil pressure sending unit down by the oil filter. These, in most cases were used for switching items on and off (Example: ignition circuit of the power to an electric choke assembly). this sender connection is just after the oil filter in the flowpath and is at the front of the oil pressure galleys. The GM V-8 motor has an oil pressure tap on top of the block (as pictured above) just behind the intake manifold. This is the standard oil pressure indication connection. This takes pressure from the top end of the engine and the final galleys that oil goes to, so it is considered the END of the flowpath.

With ANY question on oil pressure, always go to the tried and true method--CONNECT a mechanical gauge and read it outside of the cab, then compare it to the ones in your dash. Go from there, know what you have, it may save your engine some day. The factory installed gauges are ususally off a fair amount, but you can compensate.

What grade of oil do you want? That depends on what each person desires and likes. A lot of people are now looking at the Rotella-T oil for the protection to their camshafts since the newer oils are missing a lot of the zinc based additives. The weight depends on what you want and where you live--COLD as Hell, a lower weight will work better---HOTTER than the cold place, the weights can go up.

GM always recommended a 5W-30 oil, but I have used 10W-30 weight for years. The important thing is to look at what the oils carry for additives and on a new motor from the car lot, you match the recommended items (warranty issues there).

[BLACK AND BLUE 67-72]

I don't see any problem with that reading, mine runs there all the time. If it was running that far to the L or LOW side THEN I would be worried!!!! I run 10w30 in mine.

[Longhorn Man]

I had the truck out on the highway doing well over 100mph and she didnt even hick-up so i dont think my oil pressure is the problem.

What problem are you trying to locate?

[cableguy0]

oil pressure like that is nothing to be concerned about.if it was reading really low i would worry but each line on that gauge is 15 psi 60 max. most of the relief springs are set at 80psi