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LS oil pick-up tube

6872xtc

6872xtc

make mine modified
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So after finding that LS engines will have oil pick-up tube O-ring problems, I got to wondering why the factory parts have a restrictor plate on the bottom. Even the Melling replacement part has the restrictor. I have found that Milodon and a few others have an unrestricted screen, especially for the different styles of pans offered for swaps and cars.

Does anyone know why they would put a restrictor plate on a suction tube? The length of the tube impedes oil pick-up already, so why make it more difficult to get oil to the pump?

I ask because I have an oil delivery problem of some kind on and LQ9 that I just put a cam into, so I have to go back in and find out what happened. I did a new GM oil pump when it was out, but things aren't right and I wonder about opening up the pick-up for less restriction.

The picture is of the new Melling replacement part that just showed up.
20210723_152604.jpg
 
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The tube will only pull a limited volume. If the opening below is too big, the oil will start to cavitate at the opening and not flow smooth, creating pulses of oil into the system.








I have no idea why. But that made up reason sounded good. Just fake news.
 
Did you prime the pump from the top?
Put oil in at the plug in the block just above the pump on the passenger side.

It's important on the LS from what I read.
 
shady said:
Did you prime the pump from the top?
Put oil in at the plug in the block just above the pump on the passenger side.

It's important on the LS from what I read.
Click to expand...
I know of the galley plug. It has been running and the pressure was not what I expected, but then dropped some, developed a lifter tick that went away.

I have a diagnostic plan for tear down, there are a couple of things that I want to check, the cam retainer seal being one.

I am trying to understand why factory pickup tubes have a restrictor plate. Many aftermarket ones don't. Standard small and big block ones have a larger opening even though they have a shield covering part of it.

With what I know about hydraulic systems and pumps, I fail to understand why the suction tube would have this restriction on the end of the long tube. I am tempted to open it up, but I can't think if there is a downside that I am not seeing. I'm not real excited about trying something and having to drop the front differential and oil pan again if it has a problem that I couldn't foresee.
 
ktmoutfront said:
The tube will only pull a limited volume. If the opening below is too big, the oil will start to cavitate at the opening and not flow smooth, creating pulses of oil into the system.








I have no idea why. But that made up reason sounded good. Just fake news.
Click to expand...
I would have believed you if you would have told me that my blinker fluid was too low to maintain a zen level with the oil flow.
:D
 
Do you mean the wide round part that sucks up the oil? Potentially if it doesn't have the half moons on the side it can suction to the bottom of the pan
 
Just went looking through the GM service manuals for different years, gen 3 and gen 4 small blocks. There is nothing within the description and operation for the lubrication system for the restrictor in the oil pickup pipe.

Some engineer must have reasoned it was smart to put it in there, buy they don't list the reason why in the service manual.

I will say this though. I've seen thousands of trucks/SUVs come through with LS small blocks from new to 400,000 miles or more. Not once have I seen one of those engines fail due to starving for oil due to the restrictor. Run it out of oil? Sure. But if there is oil in the pan the pump is going to pull it. Plus it is only going to move as much oil as it can suck through the pipe anyway. So if the pickup is wide open or restricted it's really limited to what can flow through the pipe. That's my extent at knowledge on fluid dynamics at least.
 
I'd leave it. That opening will flow twice the volume the tube will.

I'd check and see if you spun a cam bearing. Even that hole your looking at won't cause a noticed change all at once.

To me, as an educated guess, I'd say the half moons are there to cause turbulence at the screen. That way if anything gets sucked in that could stick to the opening and just block it it would have swirling and such to move that stuff around.
 
Thanks @ZooMad75 . Yes, I have seen lots of them with tons of miles. I would assume that there was a reason why it was put on there by GM.
I have been around plenty of them that need a new O ring after lots of years and miles, so I wondered if less restriction would help. Obviously they pull oil through as is. Just using brain to think about things that I don't know.
@Firdaddy the tube is supported pretty well, so I don't believe that it could suck down to the pan.
@shady I wondered about the turbulence, but that seems counterproductive to fluid flow from what I have been taught. And I haven't tried to do the math on the area of the slot vs the tube diameter.
Sidenote: I don't know that a spun cam bearing would make a tick come and then go away in seconds, but maybe I am wrong.
 
This is the one from my 6.0 that spun out, and ended up getting into the edge of a lifter.
I'd guess it made a ticking sound a few times before it got bent enough to just stick to the cam and not contact the lifter anymore. I had to lightly pry it off the cams bearing surface.
Looked like it had been back and forth on the bearing surface of the cam a few times. These are stock though.
Not sure if yours are. Aftermarket ones stay put better due to their design.

Screenshot_20210724-120257~2.png

Screenshot_20210724-120305~2.png
 
That's not really a restriction compared to the tube or the outlet. I'd just leave it, and make sure to use loctite on the pickup bolt.

Moroso makes a clamp that uses two bolts to attach the pickup, or some of their pickups have both bolts on the flange already. Then you have half the chance the bolt will come out. I can get them for you if you want, extra insurance....

www.moroso.com

PICKUP FLANGE REINFORCEMENT, GM LS

GM LS Oil Pump Flange Reinforcement
www.moroso.com www.moroso.com




24890inst_part.png
 
Thanks @folkenheath I have Melling 's version of that with their new pick-up tube and a new pump.
I apologize for not ordering things through you, I get in the habit of looking on Summit as I usually get things in 2 to 3 days from Nevada.
I do appreciate your knowledge!
 
I think you need to find the problem that went wrong to cause the issues, it seems you are trying to find a solution when you don't know the problem yet.

Are you using a FRAM filter? I avoid them at all costs, even brand new ones don't flow any oil sometimes, then it just goes through the bypass if it can flow enough.

Did you change the cam and that's it before this issue started?

What are your bearing clearances?

What oil are you using?

Mow much oil in the pan and what pump?
 
@folkenheath , yes I plan on doing some diagnosis. The truck got sidelined for a while due to other things. Which led my brain to think when I have a minute.

I refuse to use Fram as well.

My son and I drove the Escalade for close to 2K miles before we pulled it. No issues with the oil system previously. 228K when pulled, one owner vehicle.
So while it was out, new cam, GM oil pump and timing chain. So mostly just a cam change. I wasn't concerned after being around several LS engines with lots more miles.

The front and 2nd cam bearings looked really good for those miles, so I didn't get a scope to look farther back. Didn't look at rod or main bearings because of how well it responded on cold starts in the teens after days of sitting.

We put semi synthetic Schaeffer's in it when we got it, after a cleaner shot in the old oil. Still has Schaeffer's in it. Lots of people will 2nd guess this oil since they don't know it, I have been around their products for lots of years. I have been able to see the improvements in several applications with their products.

And keep in mind, after first start in this truck, oil pressure wasn't quite what I expected, but different sender and gauge than before. The loss of 5 PSI or so after 300 miles and the tick that came and went away twice is what made me park it.
So I got to wondering about the pick-up tube design. I have been around hydraulics somehow since 1988, so I had a thought about what I saw as a restrictor plate on the pick-up tube.

I want to get digging into this, but other things took priority.
 
Schaeffers is fine, good quality stuff, have used them before, I was more asking about the viscosity.

Could just be an old worn lifter too.

Is this tick only when cold or anything like that? At a certain RPM or temperature?

It sounds like you have it under control I was just saying, don't fix a problem you don't have is all.

Heck the tick could be an exhaust leak? Are you sure its in the engine? Lifter ticks and small single cylinder exhaust leaks sound so similar its not even funny.

Good luck man, I don't think I would of parked it for that but maybe there is something else we don't yet.
 
Well I don't believe that it's an exhaust leak because it was quiet cold, then did it after getting just almost to temperature, then went away. It did this the first time after driving 4 miles towards town, and also after about 3 miles on the way home at the end if the day. I didn't tell you that it sounded as if it rattled all of the lifters when I fired it up to come home, then got quiet when it got oil pressure.

If I open it up, I will check the cam bearings like @shady suggested.

I am using 5W-30 oil since they seem to call for it. I know some use 10W-30.

I have several trucks, so leaving this one sit until I can check it out isn't a problem. I am just driving the '01 4.8 2wd that has 300K on it. I rattles the lifters on first start since it needs a new O ring on the pick-up tube. (Don't park it nose high!) It has more pressure according to the gauge than the LQ9 does. It has 5W30 in it and the delay in oil pressure was worse when I got it and it had 10W30 in it.

Or I have my 3 older trucks to drive...

Thanks again for the input.
 
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