LS oiling problem

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rebelrouser
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LS oiling problem

Post by rebelrouser »

I will ask for advice, if anybody has some ideas. Just did a 5.3 LS conversion for a 55 chevy. I built the engine from a doner 2002 chevy truck 5.3, stock rebuild just a small camshaft. Fired the engine, using Holley terminatorX system, got it running good in short order. Was sitting in the car looking at the lap top programing the transmission shift points, and looked up at the dash and it said zero oil pressure, no noises, no lifter rattling. Put a manual gauge on it and yes it has no oil pressure. I put the gauge on the cover plate above the oil filter where the oil cooler normally would go, the port behind the manifold is almost impossible to get to.

So next week I got to pull the thing out and figure it out. So my asking advice is what to look for? It has two pressure relief valves one in the Holley oil pan and one at the pump. I also read about issues with the plastic dumb bell in the oil passage at the back of the block. I remember putting a new O-ring on it, and it appeared in good shape. Never had something like this happen. Sometimes it sucks to be ME.
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Re: LS oiling problem

Post by BillK »

Jimmy,
I still think you need to pull the filter and crank it for a few seconds to see if it makes a mess. That would narrow it down quite a bit :) Forgot to ask, can you pull the pan with it in the car ?
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Re: LS oiling problem

Post by rustbucket79 »

Proper o ring on pickup tube?
Cup plug in oil gallery behind timing cover?
Oil cooler bypass above filter functions?

Did it have pressure at any point on fire up?
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Re: LS oiling problem

Post by rebelrouser »

BillK wrote: Thu Apr 29, 2021 9:43 am Jimmy,
I still think you need to pull the filter and crank it for a few seconds to see if it makes a mess. That would narrow it down quite a bit :) Forgot to ask, can you pull the pan with it in the car ?
It is just as easy to pull the engine, as to take the pan off in the car. I will try pulling the filter after I get it to the bay to pull the engine.
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Re: LS oiling problem

Post by rebelrouser »

rustbucket79 wrote: Thu Apr 29, 2021 10:04 am Proper o ring on pickup tube?
Cup plug in oil gallery behind timing cover?
Oil cooler bypass above filter functions?

Did it have pressure at any point on fire up?
Yes it had great pressure at fire up. Idle was 50lbs, and even 210 hot idle was 35 lbs. I drove it tuning on the lap top maybe 30 miles. O ring on the pickup was the one in the overhaul kit, the bypass cover over the filter is where I have my gauge hooked, I just drilled and tapped the cover for 1/8 pipe thread. I do that to most LS conversions, as they have only one oil port and it is not pipe thread. The cup plug behind the cover I will put on my list to check, quite possible it may have blew out. thanks for the idea.
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Re: LS oiling problem

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Re: LS oiling problem

Post by Racer71 »

It’s typically the O-ring on the pickup or if you had a issue with the cam retainer plate
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Re: LS oiling problem

Post by rustbucket79 »

You may want to start by cutting the filter. No plug in front results in no pressure but that coming out is unlikely. Pickup o ring ( apparently there are different sizes) would be a long term drop off or no or little pressure to begin with. Good luck!
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Re: LS oiling problem

Post by ProPower engines »

Did you install a NEW oil pump??
I know that some guys will disassemble and check the clearances etc. in the original pump if its for them self but they use a steel bypass valve in a aluminum pump body. Like many imports they suffer a similar affect they start up and have pressure then it goes away shortly after a stop and restart.

Is it possible the bypass is stuck. There was a load of BS about only using a Luberfinder oil filter on these engines of a no oil pressure thing would happen. Luberfinder make the AC Delco filters they come with from factory so that can't be it.

But the pressure relief jamming can be a real issue which would explain the no oil pressure thing.
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Re: LS oiling problem

Post by rebelrouser »

ProPower engines wrote: Thu Apr 29, 2021 9:00 pm Did you install a NEW oil pump??
I know that some guys will disassemble and check the clearances etc. in the original pump if its for them self but they use a steel bypass valve in a aluminum pump body. Like many imports they suffer a similar affect they start up and have pressure then it goes away shortly after a stop and restart.

Is it possible the bypass is stuck. There was a load of BS about only using a Luberfinder oil filter on these engines of a no oil pressure thing would happen. Luberfinder make the AC Delco filters they come with from factory so that can't be it.

But the pressure relief jamming can be a real issue which would explain the no oil pressure thing.
Yes I installed a new oil pump, don't really remember the brand, it was in the overhaul kit. I hope it is something simple like that. I just don't like the fact that I got to pull the engine to get to the relief valve.
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Re: LS oiling problem

Post by tblentrprz »

I agree with ProPower. If you started with oil pressure and it went away, most likely oil pump pressure relief valve stuck open in pump. If you measure pressure before oil filter at the LF engine galley plug (16mm x 1.5) you will likely measure some pressure (~3psi) due to filter restriction. Pull pump and spring. Relief valve should slide freely in pump bore when just tilting the pump body up and down. Verify pick up tube seal not damaged and tube/seal has slight resistance when inserting into pump. I would block pick up tube inlet, place large drain pan below engine and pressurize oil system through LF oil galley port to make sure you do not have any abnormal leaks anywhere.
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Re: LS oiling problem

Post by rebelrouser »

For those who answered my post, the issue was a small sliver of aluminum in the pressure relief valve. It appears that the outer bore is a little too tight, as the outer pump gear is stuck in the bore, I had to tap it out with hammer and punch. It looks like the bore is where the metal came from.

I pre-lubed the pump on assembly with Lucas engine assembly lube, as I usually do.

I guess I got lucky as the engine bearings have no damage.

I think the next LS pump will come apart and a closer check on clearances will be in order. Pump came in the master engine kit, not even sure what brand it was, box is long gone.
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Re: LS oiling problem

Post by FC-Pilot »

Thanks for getting back to us on what you found. All too often we hear the issue and never the cause.

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Re: LS oiling problem

Post by rebelrouser »

I am going to ask some advice on the LS oil pump. Got the replacement today it is a sealed power pump, which always was a name brand. I took it apart to check it and I get .005 rotor to bore clearance. I have a factory LS overhaul manual and they give no oil pump clearance specs, the text just says not rebuildable replace. Having dealt with automatic transmissions with these style oil pumps, the .005 is actually a little loose. I removing the rotor the edge is not polished smooth all the way across, and you can catch a finger nail on some of the machining marks. Hope the picture shows it. My plan is to polish the outside smooth, I don't think I would gain more than .001 extra clearance. does any body have some clearance specs, or just advice?
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Re: LS oiling problem

Post by engineman1642 »

I always take pump apart then mount loosely use 4 shims between rotor and pump housing to center it then tighten housing.have seen diy mechanics get it in a bind and burn up pump rather quick.
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