Hey all im once again reaching out with a 5.3 issue. So a few months back I started having low oil pressure in my daily (2012 Chevy Tahoe LTZ 5.3), I went ahead and changed out the oil pump and pick up tube o-ring to no avail. I had a 09 PPV 5.3 on a stand at the house so in an effort to keep my daily on the road I went ahead and started building it. Full BTR DoD/AFM delete, BTR Truck Norris Cam Shaft, did the tower plugs with the michigan motor plugs and the valley cover plate with the orings, i did the oil pan valve delete as well. All this being said my oil pressure was still low so I opted to go to a higher pressure oil pump if im correct it was the mellings 10295 pump. The day I was going to swap the pumps I heard a loud pop and lost pressure after tearing it down the pump had literally blew apart. After inspecting this pump (that was gave to me by a friend) I found a pick up tube bolt hung in it however my bolt was still holding the tube in place so must've been in there when it was installed bad oversight on my part ill admit. So I proceed to thoroughly clean the motor and replace the pump. Still low oil pressure so I sent it to a local shop where they recommended 15 weight oil and running the copo spring, I did let them change that and while on start up it was good pressure at operating temp it was back down to 7-10 psi however, it ran fine for a couple of months and then on my way to work "pop" another oil pump so once again took apart cleaned and replaced this time no extra bolts hung in it. That pump lasted a week and once again it blew up. I checked to see if my crank was bent, it was not. I checked crankshaft thrust it was .007 I figured thats not too bad. So im at a lost on what to do ive debated sending out my original bolt for cleaning and replace it with the dod delete kit and reinstall but I dont want to have the same issue im having now. Also wanted to note I was following mellings recommended install process when installing the oil pumps.

 

Does the pump slide onto the timing gear smoothly?

Ive never installed one using the feeler gauges method...always just throw them onthere loosely turn crank few times and torque it down...never had a failure of any sort

 

Yes always slides on smoothly and I have installed them both with filler gauges and by putting it on loosely and spinning the engine by hand before tightening it to final torque

 

Probably had bearings that are too loose on tolerances causing the low oil pressure...

And IDK about the oil pump exploding, but likely the fragments of it coming apart sent through the oil galleys destroyed the bearings/journals anyways. It was either defective or not installed correctly?

 

If he's running a good oil filter, there shouldn't be any fragments past the oil filter. I know, SHOULDN'T be. As for a shop recommending 15w oil.....I've never seen any V8 successfully use oil that thin. GM tried that, recommending 20w. Didn't work out well. Going with even thinner oil.....Not me. I know the oil doesn't know the number of cylinders or their configuration. But I know I'd never run oil that thin in my LS7. FWIW.....

 

And there are millions of motors running 20w without issues for years and years

 

When the pump was installed, was the timing chain still on the engine? Was the pickup bolted on before it was torqued. Have you ever used an oil pump alignment tool?

 

The timing chain was still on yes and no I tend to wait until after the pump is torqued to install the pick up tube. I did you the shim method

 

The shim method is a waste. Your crankshaft isn’t centered in the bearing with zero oil pressure, which is what you have as the engine is coming to a stop. The crank is only ever centered in the bearing while the engine is at RPM. I’ve had conversations at length with engineers at Melling about this, and I’m speaking truth. The shim method is a joke…don’t waste your time.

 

What do you mean by that? The oil pump goes on after the timing chain... am I missing what youre saying or something?


You typed that backwards im assuming...

 

I did indeed…wow
long day here. Appreciate the catch.

 

Please name the GM V8s that are successfully, and have been running 20w successfully, for years and years. I'm assuming LS1 Tech is all about GM V8s. I dont know, or care, what other manufacturers V8s are running. If they're designed to run oil that thin, then yeah, they are probably successful. We're talking GM V8s here......

 

My concern is on an assembled engine, valve springs can apply force through the chain and lift the crank. As Scott mentioned, pending on oil clearance, is the crank down? When you assembly a short block . Just the cam, gear and chain are in place. Are they holding the crank up or does it hang in the middle? Depends on the brand and how much the chain and gears wear in. Theory is getting real deep. Let’s see the blown up pumps. See the damage and work back from that instead of all the guessing. I prefer the oil pump locating too over the shims. They use the V head bolts to the pump face to locate the back. The hole in the front is machined so the pump can be centred to the crank and can be torqued. Same like locating the cam cover plate. Now show us the blown up parts!

 

Here is one of the pumps I dont have a picture of the most recent but they all have the same damage.

 

This specific pump was mounted using mellings recommended way of installing the pump hand tightening the bolts spinning the motor over and the torque the bolts down

 

OP "That pump lasted a week and once again it blew up. I checked to see if my crank was bent, it was not."
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I can assure you: LS Oil pumps are not fragile. If you have a large fleet, or drive 75,000 miles per year you MIGHT, MAYBE see an oil pump failure once in a decade, but you probably WON'T. IF you have TWO oil pump failures inside one week YOU DO have something very fucked up in your installation.
My best recommendation is to get a cheap JunkYard take out motor, slammed in there to get you running, and then learn how to assemble engines carefully and without time pressure..
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...... I can assure you: Melling oil pumps are NOT grenading everywhere else.

 

Ok, I see the rotor but not the ring around it. Was the ring scraping the aluminum housing? Did the ring seize to the housing? Then the rotor pushed the ring out and that shattered the housing. Is there any debris in the bottom of the pan? Doesn’t seen likely, but if a chunk was sucked up into the pump. That could have caused the interference between the rotor and the ring. Any debris marks on the pump rotor?

 

So the outer ring is in multiple pieces at the bottom of the pan I have not inspected to see if there are wear marks on the inside of the housing thats something I have been overlooking

 

I re-read your original post. Did you shim or change the oil pump bypass springs can apply? It looks like something blocked off the oil system and the pressure went sky high in the pump until it exploded. The bypass area looks intact. Is there any debris piston seized? Might also cut open the oil filter to see if any blockage there too.

 

On the very first pump I did find an oil pick up tube bolt in the housing. That was my fault for allowing a buddy to offer me a pump he had instead of purchasing a new one. The 2nd pump I had was a m365 pump that I had the copo spring put in that one I could see the piston hanging up and it over pressurizing, under 2k rpms it would see pressure of 60lbs sometimes higher but at idle and op temp it would fall to about 7lbs. This 3rd pump however was a mellings 10295 and it wouldnt even make it to 40lbs under throttle.