Fresh big block with low oil pressure at idle.

[bucket]

No, I agree that the lifters are needed to have oil pressure. How much one lifter can cause the pressure to drop is beyond me.

 

[chevyk10]

Everywhere there is a clearance that the oil flows through adds too or takes away oil pressure.


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[bobkyle2]

You should be able to create oil pressure without the lifters in the block.

I wouldn't do anything till i put a mechanical gauge on it. Even if you just put the gauge under the hood and start it and watch it.. If the oil pressure don't come up, then you infact do have a problem...

 

[HotRodPC]

You should be able to create oil pressure without the lifters in the block.

I wouldn't do anything till i put a mechanical gauge on it. Even if you just put the gauge under the hood and start it and watch it.. If the oil pressure don't come up, then you infact do have a problem...

Zactly, and I even said, put a cheap mechanical under the hood and leave it. You can do it with brass fittings and don't even have to use the flex line ****. Believe it or not, you'll use it alot more than you think. And as much as you like to 'Feel the Power" and burn off tires, trust me, you're going to be working on this thing more often than you think.

 

[Irishman999]

You should be able to create oil pressure without the lifters in the block.

I wouldn't do anything till i put a mechanical gauge on it. Even if you just put the gauge under the hood and start it and watch it.. If the oil pressure don't come up, then you infact do have a problem...

I dont see how its going to create oil pressure with oil gushing out of the holes in the lifter bores. From everything I have read and looked at on my block the oil goes in the block straight to the cam shaft area, from there it goes through galleys to the cam bearings and another circuit goes over to the lifter bores. The oil flows to cam bearings and also down into the main bearings, through main bearings into the crank and finally flowing into the rod journals.

As far as I can tell the other oiling circuit goes to the lifter bores, through the lifters and up the pushrod ending at the rocker arms. The galley holes in the lifter bores are pretty big, if a single lifter has a problem and is gushing oil somehow I think thats a pretty big leak in the oil system. Think of the spigot analogy mentioned before, that one spigot is stuck wide open and I think thats where the pressure is going.

Just to be clear, its got great oil pressure. This problem happens after you have been driving around alot and the oil is really warm, at idle its teetering where the check gauges light is on, about 15 pounds or so. If you let it sit there for a while idling it shows zero.

 

[SlickGTP]

If you were measuring oil pressure from the front top side of the engine then the spigot analogy would work, but since the gauge is set up right close to the pump you're actually measuring the oil pressure as it leaves the pump, not throughout the system. Thinking through it I would presume a pretty hefty pressure drop by the time you get to the ends of each of the oil galleys.

If you have a lifter gushing oil, then I'd be worried about the oil to the components down the line from the lifter, but it wouldn't affect how the gauge reads as it sees the flow from the pump, not the flow at the end of the system.

 

[SlickGTP]

Just read your last paragraph too... When the oil warms up it becomes thinner... At a cold idle my gauge reads pretty high, but after she warms up the gauge reads closer to 30psi...

It's normal and I'm guessing that the gauge on your truck is just far enough out of wack that it reads low and cuts out. Just my guess though.

 

[Irishman999]

If you were measuring oil pressure from the front top side of the engine then the spigot analogy would work, but since the gauge is set up right close to the pump you're actually measuring the oil pressure as it leaves the pump, not throughout the system. Thinking through it I would presume a pretty hefty pressure drop by the time you get to the ends of each of the oil galleys.

If you have a lifter gushing oil, then I'd be worried about the oil to the components down the line from the lifter, but it wouldn't affect how the gauge reads as it sees the flow from the pump, not the flow at the end of the system.

So what your saying is my oil pressure sending unit thats screwed into the front of the block on the bottom drivers side is actually measuring FLOW coming from the the oil pump in the back of the engine?

Is there a check valve I missed between the two main oil galleys on a big block? This is the second time I have herd I can have oil pressure regardless of back pressure from the valve train. I had this crazy idea that oil kinda flows like water or electricity always flowing in the path of least resistance.

I guess my main question here is how can the system pressurize like its supposed to with any part of the system having a leak? Is the oiling path for the top end of the engine completely separate somehow from the camshaft and bottom end?

**** this, im calling my machinist.

 

[SlickGTP]

Okay, I was thinking of things the way they are on my Mark IV... The sending unit is right above the oil filter boss and is pretty much the fist thing the oil hits before going through the block.

Where exactly is the sending unit on the later versions? Pic?

 

[Irishman999]

I just herd back from BTM custom machine-

He said the lifter thing mentioned before could have been caused by the ends of the pushrods getting wore down and making the hole bigger letting more oil through. That makes perfect sense considering the valve cover was stopping it from going all the way up and putting a ton of pressure on the pushrod. Chances are thats what I will find happened.

He also said he did not think it would be enough to cause a drop in oil pressure Im still going to try it out.....

Right when I was about to ask about oil viscosity he asked what weight oil I was running. He suggested I run 20-50 in my big block. So there is the plan.

 

[Irishman999]

Okay, I was thinking of things the way they are on my Mark IV... The sending unit is right above the oil filter boss and is pretty much the fist thing the oil hits before going through the block.

Where exactly is the sending unit on the later versions? Pic?

Gen VI engines had oil system revisions.

The factory sending unit is down on the bottom of the block on the front on the drivers side. There is also a threaded port on the top of the bellhousing on the drivers side which is where I connected the mechanical gauge when I was breaking it in.

No matter where you put the sending unit it should read similar, its a pressurized system meaning the back pressure should be the same and the back pressure is what your sending unit is reading. Your right though, it could be different depending on where you put it on the oil system and how close it is to an exit.

 

[HotRodPC]

I would also run 20-50 in that one. Not because it's a big block, but because you polished the crank and used standard bearings. Had you used .001 oversize, or had the crank turned and had tighter tolerances I don't think I'd run 20-50. Oil viscosity suggestion by manufactuers are usually determined by the rotating assembly tolerances. LS motors for example, very tight tolerances and usually 5w-20 is suggested or 5w-30. Thinner oil for tighter tolerances. Heavier oil for loose motors.

 

[HotRodPC]

Thread kinda needed spiffed up a bit. Did the new gauge arrive yet? Enjoying that AZ weather while everyone else is getting froze over? At least when you get it, you'll be able to work on it without having to dress up like a fuggin mummy to keep warm.

 

[chevyk10]

An oil pressure sending unit is NOT measuring how much pressure the oil pump is making it's more a measure of resistance. Did you pull the oil filter off and look for shavings or a magnetic drain plug? How did the lifters get worn that much from the pushrods? You shouldn't need 20-50 on a street engine. We use that more for a race engine because the clearance are a bit looser.


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[Irishman999]

An oil pressure sending unit is NOT measuring how much pressure the oil pump is making it's more a measure of resistance. Did you pull the oil filter off and look for shavings or a magnetic drain plug? How did the lifters get worn that much from the pushrods? You shouldn't need 20-50 on a street engine. We use that more for a race engine because the clearance are a bit looser.


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If you read back there was a rocker hitting the inside of my valve covers I got to clear aftermarket rockers, nothing is an exact science. Something will always give you problems.

What my machinist suggested is that the resistance wore our the posh rod tips making the little hole big enough to flow the **** out of oil like I saw. Im still the only person to think that could be a problem considering how much oil was coming out but im getting ready to take it apart and get a final verdict even if it means taking it apart down to the lifter valley.

Im going to pull the filter when and change oil in the next couple days, I was planning on checking out what it looked like. Hopefully I have that cloudy aluminum bearing material and thats it.

As far as oil viscosity, I did put it together slightly on the loose side. Its still in specs but I could have gone with over sized bearings on some of the journals. 10-30 does turn into water when it gets warm and there is alot of weight rotating in there. The machinist I got the engine from drove home the point that we live in Arizona and he runs thick oil in his big blocks. I ignored advice from a guy that deals with this **** day in and day out and decided to go with 10-30.

I dont think there is any damage done, it runs like a raped ape with absolutely no engine noise. It teeters on 15 pounds at idle most of the time when decently warm so a little thicker oil might solve that. If I am wrong **** it, I will just tear it back apart and build a stroker this time.