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Ls1 Rebuild has Zero oil pressure

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Old 08-11-2024, 09:31 PM
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Default Ls1 Rebuild has Zero oil pressure

Just rebuilt, my 1998 LS1 out of my F-Body Camaro. Has forged rods and pistons, cam, 243 Heads the works etc. After fighting with some wiring issues, I got the car to turn over and had no oil pressure on the dash. When just cranking it over with fuel pump disconnected. No oil is coming up to the heads and no oil was found in my oil filter.

My first thought was the pick up tube no having any suction. I pulled the oil pan with the engine in the car and slid a new black O-ring onto the pick up tube. I have a melling high-pressure oil pump and it worked fine before the rebuild probably has 1000-4000 miles on it.

After replacing the O-ring, still no oil pressure. I then removed the alternator removed the oil galley plug, and manually filled the oil pump with oil. With a 3/8 line and a funnel. Filled up the oil filter with oil. And started it again still with no pressure.

My next guess is to takeoff all the front accessories and replace the oil pump which was in working condition before the rebuild.

I made sure to install a metal barbell fitting into the rear cover. I believe the front cover has a cap in the oil galley and is not normally removed. My only other guess would be when I was removing the rear pilot bearing. I pushed out the oil cap behind the pilot bearing near the center of the rear crankshaft trying to use bread to remove the bearing. I made sure to install the cap back in with red lock tight all around it. And I believe it’s still in working order.

Any guesses why I’m getting zero oil pressure when cranking the car over. I don’t want to pull the engine out of the car if I don’t have to. I have to pull it out of the top because I don’t have a lift. My next guess is replacing the oil pump and getting a new pick up tube possibly that one could be clogged somehow. But removing the pick up tube is going to be an effort in itself in the car. Any suggestions will help.

Old 08-12-2024, 06:13 AM
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Put a mechanical gauge on it and crank it maybe 6-8 times and you should start to see oil pressure. Unless the bypass valve is stuck in the oil pump I don't see it being the issue. Is the OP sender in good working condition and connected? I'd light the cylinders up and If I didn't see OP right away shut it down.
Old 08-12-2024, 10:21 AM
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If you filled the lower Galley the Oil Pump is primed, I'd start it and see what it does.
Old 08-12-2024, 01:18 PM
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Going to try manually filling the oil galley again, this time with some type of threaded attachment and fittings. So oil doesn’t pour back out around the rubber hose.
Old 08-13-2024, 12:18 PM
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I made sure to install a metal barbell fitting into the rear cover. I believe the front cover has a cap in the oil galley and is not normally removed. My only other guess would be when I was removing the rear pilot bearing. I pushed out the oil cap behind the pilot bearing near the center of the rear crankshaft trying to use bread to remove the bearing. I made sure to install the cap back in with red lock tight all around it. And I believe it’s still in working order.


Two things jump out at me here:
  1. Is the Barbell new and installed the correct way? This would explain why no oil in the filter...
  2. It sounds as if you reused the crankshaft plug because you sealed it with red lock tight...This should be replaced with a new one that is pressed fit into the crankshaft.
Also, I'm hoping that a thorough cleaning of all of the oil passages was completed. What you are describing sounds like a complete block of the oil passage or oil being bypassed either in the oil pump or out the back of the crank.
Old 08-13-2024, 05:07 PM
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I didn't read that one the first time. Yea, definitely a new Freeze Plug. Never use an old one.
Old 08-13-2024, 11:06 PM
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Key-tip. The starter does not make enough oil pressure to send oil to the top of the rockers. Or show any reading on the dash.

I attached the fuel pump relay, and the car gained oil pressure once started.

Rather I’d been be safe than sorry. I did lift the front of the engine. Take apart the oil pan and replaced the O-ring for no reason and contemplated with it over almost another week. But just another learning lesson.

I did replace rear oil cap with red lock tight. Still worried as those are usually not removed. Though I will be keeping an eye on it as I am going to upgrading clutch hopefully in the winter. Wasn’t in the budget yet for McLeod twin disk and flywheel. Stock clutch still has some life left.

23years old and built from the bare block a running and driving forged piston cammed Camaro in 1 week. (After it sat empty for while I acquired parts, takes a little more time than you think) With no mechanical background besides changing oil at a dealership at an old job. Hopefully this gives some of you at home some inspiration know you can do it. It’s just nuts and bolts people.

Last edited by LSX.Tom; 08-13-2024 at 11:28 PM.
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Old 08-14-2024, 05:05 AM
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That's why I said start it, the starter rolling it over won't do anything
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Old 08-15-2024, 07:10 PM
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If an lube tech guy can do it…..so can anyone else folks….get out there and finish your swaps!!!!
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Old 08-15-2024, 08:38 PM
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Originally Posted by the_merv
That's why I said start it, the starter rolling it over won't do anything
I disagree. Turning the engine over with the starter should be more than enough to get oil pressure. It may take a few turns to build pressure, but even at starter speed the engine should build pressure. If it doesn't you'd never have pressure at slow engine speeds like idle.

If the engine was completely dry inside, it will take time turning the engine to build pressure. Thank about it, the oil pump is in the front and oil pressure sending unit is in the back.

Assuming you assembled the engine with assembly lube on the mains and on the cam, pushrods and rockers, you should be able to just fire it up and you should see oil pressure in a few seconds if everything is alright.

The plug in the rear of the crankshaft has nothing to do with oil pressure but you do need to make sure you have a plug snuggly installed there, otherwise you'll be potentially introducing dirt right into the crankcase and introducing oil right onto the clutch.
Old 08-15-2024, 09:01 PM
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Freeze Plug out of the Crank will mess with the PCV also.

Have you see the oil flow diagram of an LS Engine or tried to prime one with rolling it over with the Starter? Just wondering...

Two of us said the same thing here in the post for a reason.
Old 08-15-2024, 10:09 PM
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Every engine I've ever built was assembled with the proper assembly lubes on all the moving and contact parts and a primed oil pump and I have used the starter to turn the engine with the plugs out to build initial oil pressure and prime the engine before firing. I've never had an issue getting initial oil pressure using the starter to turn the engine.
Old 08-16-2024, 05:06 AM
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The recently rebuilt LM7 sitting in front of my Catalina got oil primed up to a manual oil pressure gauge with the starter. It took a while and took a very healthy battery to do it but that oil pressure gauge eventually settled on 47 PSI with a vigorously spinning starter. You can watch the oil move up the plastic tube while its cranking.

Rick
Old 08-16-2024, 07:19 AM
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There is a video somewhere out there of a guy tuning an LS by hand with a gauge connected to it. He zooms in with his cell phone and it has good oil pressure, every time he turns it. That video was popular around here years back, every time this topic came up.
The starter turns the LS about 450ish rpm…it will build pressure if you’ve got the time, and a good battery. Me….I say Prefill the filter, and fire it. You’ll see pressure in 2.4 seconds. GM doesn’t prime anything on the assembly line. Those engines seem to last ok…jus sayin.
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Old 08-16-2024, 08:05 AM
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Well I guess I've never tried the Starter method because I didn't want to waste the battery. All the ones I did I primed the Pump, filled the Galleys and touched it off.

I wonder if GM still does the same rapid break-in procedure they used to do on Engines.
Old 08-16-2024, 08:22 AM
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We pressure lube ours....
Old 08-16-2024, 08:07 PM
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Originally Posted by Old Buzzard
We pressure lube ours....
Call me crazy but I never have. The very first LS I ever assembled back in 122 BC, I used a HD drill to spin the engine over until I got oil out of the pushrods. It took me 30 minutes and a lot of setup. I 86’d that quickly. Every build since, I’ve simply pre-filled the filter and fired it off. Never had an issue ever.
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Old Yesterday, 07:47 AM
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Talking My story and I'm....

Scott,
Our "builds" usually sit for anywhere 6 mo's to 2 yrs before starting.
Both of us are in our 80's, and as such, are in "tortoise mode", most of the time.
We are at the "fossilizing" point, so we try to COA and not rely on the assy lube we "think" we used.
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Old Yesterday, 02:52 PM
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Originally Posted by Old Buzzard
Scott,
Our "builds" usually sit for anywhere 6 mo's to 2 yrs before starting.
Both of us are in our 80's, and as such, are in "tortoise mode", most of the time.
We are at the "fossilizing" point, so we try to COA and not rely on the assy lube we "think" we used.
Gotcha!! Don’t blame you one bit for pressurizing an engine that’s sit for a while. That’s the right way to do it knowing this is the case. Keep getting after it sir…you’ve got a long way to go still. 😜
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