Fresh big block with low oil pressure at idle.

[Irishman999]

I have a suspicion of whats going on here, just wanted some other opinions on it.

All bearings spec'd out, fresh cam bearings and a brand new oil pump. It has good oil pressure after start up, its only when the engine warms up that the gauge reads low and the light comes on. Its the same thing the last engine was doing which is why I built a new one.

One of the rocker arms was hitting the inside of the valve cover, coincidentally it was also gushing oil like a geyser. All the other rockers just had a little oil flowing through them onto the valve spring but this one rocker is just hemorrhaging oil!

My thinking is that is where the oil pressure is going, either there is a problem with the hydraulic lifter or something is bent. I have no idea, I was just wondering if anyone had experience with this?

Im going to go pull it apart and check some stuff out, if its not the problem should I just try running thicker oil? Its got 10-30 in it right now with a Napa premium filter.

 

[J Knight]

Have you ever changed the oil pressure sending unit or check oil pressure with another gauge?

 

[chevyk10]

Hi

They didn't leave an oil galley plug out did they? If it was line bored with the right bearings then that shouldn't be a problem. Sometimes the cam bearings. Maybe the lifters if they were foreign made. Check lifter bore clearance.

 

[89Suburban]

They didn't leave an oil galley plug out did they? If it was line bored with the right bearings then that shouldn't be a problem. Sometimes the cam bearings. Maybe the lifters if they were foreign made. Check lifter bore clearance.

That's what happened to me one time I installed a reman angine, but I don't think it would show any pressure at all if that was the case. At least it didn't show any for me.

 

[Irishman999]

Have you ever changed the oil pressure sending unit or check oil pressure with another gauge?

I checked it the last go around, still have the mechanical gauge all ready to go. I had it hooked up during initial breakin. If my rocker fix does not work im going to suspect the gauge again because the free bigblock I gave away had a nearly perfectly new bottom end according to the dude I gave it too. If it did not have oil pressure it would have looked much worse.

My personal method of engine building is not re-use old parts, especially those that are known bad. If I'm spending the time and the money, then I spend the time and the money.

And no, thicker oil is not a solution.

Replace the failed parts, and you may need to plastigage the rods and mains if it's been run with the oil light on. Clearance is only .0015" so a lack of oil quickly strips the lead babbit off bearing shells, destroying them and gouging crank journals.

Im not sure what you read but I didnt build ****, I dont build engines at all.... I assembled a big block . The only way this thing is coming back out is if rods are sticking through the block. Its a big block chevy, not an artificial heart.

As a engine builder what is your opinion on my rocker arm theory? The more I think about it the more it makes sense, im willing to bet cash that there is some problem with either the rocker, pushrod or lifter and once its resolved the oil pressure will read at least 20 on the factory gauge. I just dont see how it can have normal pressure with such a big place for the oil to escape.

They didn't leave an oil galley plug out did they? If it was line bored with the right bearings then that shouldn't be a problem. Sometimes the cam bearings. Maybe the lifters if they were foreign made. Check lifter bore clearance.

I installed all galley plugs, nothing is leaking. Cam bearings are new, got a tool and installed them myself. Lifters are all brand new comp cams lifters and everything spec'd out.

Oil flows through a port in the side of them, from a circuit directly connected to the circuit that lubricates cam bearings. Oil goes through the lifter to pump up the plunger and a little bit squirts through the pushrod into the rocker arm. From the rocker arm it kinda trickles down onto the valve spring and helps keep them cool. From the spring it pools up in there and flows back down to the oil pan through the front or the back of the head.

So if all 16 rockers have normal oil flow and one is just a gushing fountain of oil do you guys think that would effect oil pressure at idle? Thats my main question, I think YES and im about to go find out.

 

[Swims350]

ok first off what is low?

exact psi numbers? anything over 7 psi or so is usually ok with a stock pump.

yes usually new motors have more.

some is better then none of course.

use the mechanical gauge and see what it has. I run all my small blocks off the back at the intake rear, top of the block ds.

now did the cam bearings oil holes line up right when installing them?

run a brush thru all the oil holes everywhere to clean them out when it was rebuilt? maybe it had crap trapped in one before and still does.

new push rods or old? run anything thru them or even compressed air to make sure they were clean and clear?

I never trust stock gauges. or lights.

just some thoughts or questions I wondered on since I didn't build it.

you can build engines bro it's not hard. If I can do it you can too.

 

[Irishman999]

ok first off what is low?

exact psi numbers? anything over 7 psi or so is usually ok with a stock pump.

yes usually new motors have more.

some is better then none of course.

use the mechanical gauge and see what it has. I run all my small blocks off the back at the intake rear, top of the block ds.

now did the cam bearings oil holes line up right when installing them?

run a brush thru all the oil holes everywhere to clean them out when it was rebuilt? maybe it had crap trapped in one before and still does.

new push rods or old? run anything thru them or even compressed air to make sure they were clean and clear?

I never trust stock gauges. or lights.

just some thoughts or questions I wondered on since I didn't build it.

you can build engines bro it's not hard. If I can do it you can too.

Its showing zero on the gauge at idle when warm. Light turns on if it drops below 15, I would like the factory stuff to work like it did in 1990 so factory gauge is staying.

Yes the cam bearing holes lined up when I installed them.

No crap in oil galleys unless it produced its own and plugged itself up.

Not only are they new comp cams magnum pushrods but they were ordered in custom lengths using a length checking tool, all those bases were covered.

Again, did not build ****. Building an engine requires modifying parts to fit that were not specifically designed to fit. I assembled this engine and not its not rocket surgery.

Before anymore spitballing would someone read through what I said and give an opinion on weather or not a rocker arm gushing oil could effect oil pressure at idle. That is what I am really after, if I come back inside and have to discuss oil filters im just going to say **** U **** U **** U **** U.

 

[Swims350]

well sounds like you might get plenty of help then.

 

[J Knight]

NO! Absolutely NOT! CANT HAPPEN! ZIP, ZERO, NADA!

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A rocker arm wont effect oil pressure.

 

[Irishman999]

NO! Absolutely NOT! CANT HAPPEN! ZIP, ZERO, NADA!

You must be registered for see images attach

A rocker arm wont effect oil pressure.

Tell me what you really mean

What about a hydraulic lifter stuck open?

 

[SlickGTP]

No such thing unless you blew it apart... Even then it may or may not have an effect on oil pressure, but you'd definitely tell that the engine wasn't running right.

I'd verify the gauge first before diving into the engine...

 

[Old77]

What about the oil filt.....oh wait

 

[chevyk10]

I definitely agree with the no on a rocker dropping oil pressure. Rereading your posts: So how much oil pressure did you have with the gauge at break-in? If it was good then then you should have your answer.

 

[HotRodPC]

To the best of my knowledge only things that affect oil pressure, is the pump of course, and bearing tolerances. I guess it's possible that lifters to loose in the bores could too, but past that every thing else is above where the oil pressure is already decided. I do know cam bearing alignment can be important also. As far as oil galleries being clogged, unless it's the one to the oil pressure port itself, shouldn't affect the oil pressure, but will affect oil volume. There is certainly a difference of oil pressure and oil volume. Be sure not to confuse the 2.

 

[chevyk10]

Let us know what you find out.


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