[bobby35ny]

Originally Posted by Dixie ZL1

The pump assembly is comprised of three main sections 1) outer housing that bolts to the front of the block and holds the assembly together, 2) middle section that effectively creates the housing the impeller rides inside of to create pressure and holds the pressure relief mechanism, and 3) the impeller that is keyed to the crank and creates pressure as the crank rotates within the static outer assembly bolted to the block.

What actually fails is the middle section, the interior circumference of which allows the impeller to create pressure, and also holds the pressure relief assembly.

Question is - how does the middle section break into multiple pieces in a rotating assembly if the inside and outside are circularly symmetric and concentric? I don't believe it will unless a force pulls the impeller into the middle section of the pump.

I've been thinking about this a lot and have a theory.......

The Gen V LT1 and LT4 use exactly the same pump and yet only the LT4 has experienced failure - the only difference is the blower that is also driven by the crank shaft.

My unproven theory is some engines will have a tolerance stack up issue where the crankshaft bearing clearance is on the loose end of the spec, say .004' (.002" up / down) and the oil pump impeller to inner housing clearance is less (say .001" - .0015") such that under heavy loads the crank is pulled upward by the blower pulley creating contact internal to the pump, resulting in the failure.

Its just a theory and one can also point to the quality of sintered metal
components, casting imperfections, or stress risers in the design around the alignment pins, but none of those potential causes explains why only the LT4 and not the LT1 with exactly the same pump over the same timeframes.

We might never know, but this is my guess.

This thread is in the ZL1 section. Its not only us. The SS guys are breaking oil pumps too.

[Dixie ZL1]

Didn’t realize LT1’s were also experiencing pump failures, but in a weird way it makes me feel better.

[Chutzpah]

Originally Posted by Dixie ZL1

Didn’t realize LT1’s were also experiencing pump failures, but in a weird way it makes me feel better.

Can someone point me in the direction of a post here, or elsewhere, showing that the LT1 is losing oil pumps as well? I’ve done some searching, but can’t find any info...

[Dixie ZL1]

Can a moderator move all the oil pump failure threads into the 6th Gen general forum?

[Dixie ZL1]

Originally Posted by crossroaddemons

The only counter to that theory is the blower is driven by a serpentine ribbed belt which has a tensioner so the amount of perpendicular force theoretically applied to the centerline of the crank is likely insufficient to do so. Transmission of vibration under load however is entirely possible in my opinion.

Your theory is also reasonable. It’s also possible for the vibration frequency to have a resonance that creates sufficient displacement to allow contact.

Assuming this is a ZL1 only issue I think there’s something to this discussion. If LT1’s are also losing pumps it’s something different.

[Les7311]

Originally Posted by Dixie ZL1

Build date?

Repairs completed today

Build date is 4/17

[Les7311]

Originally Posted by Les7311

So more things discovered..... still on the lift.

gM cost is $2300 for this repair
Out of warranted would be $2600

[Dixie ZL1]

Originally Posted by Les7311

Repairs completed today

Build date is 4/17

Congrats getting it back.

[Les7311]

Originally Posted by Dixie ZL1

Congrats getting it back.

Thank you sir!

I don’t feel the punch when I floor it, and uncertain if related to the tear down, 98 degrees and humidity, or just .....???

Would this repair affect performance?

[Dixie ZL1]

Originally Posted by Les7311

Thank you sir!

I don’t feel the punch when I floor it, and uncertain if related to the tear down, 98 degrees and humidity, or just .....???

Would this repair affect performance?

The repair should not affect performance. Did you have a tune on it? If so they may have flashed the most recent OE tune. Also possible they didn’t bleed the blower coolant system.

[Les7311]

Originally Posted by Dixie ZL1

The repair should not affect performance. Did you have a tune on it? If so they may have flashed the most recent OE tune. Also possible they didn’t bleed the blower coolant system.

Am 2nd owner since March and uncertain if tuned

will check dealership if the BC needed bleeding from these repairs.

Feels more “laggy”...

[Dysan911]

Originally Posted by Chutzpah

Can someone point me in the direction of a post here, or elsewhere, showing that the LT1 is losing oil pumps as well? I’ve done some searching, but can’t find any info...

I asked the exact same thing earlier and also could not find anything where LT1's were experiencing pump failures like the ZL1's are on this forum and there's a hell ton more SS's than ZL1's here.

[dbb143]

Originally Posted by Les7311

gM cost is $2300 for this repair
Out of warranted would be $2600

My engine swap will be well over $20k. Will have been over 5 week ordeal. God i pray there is no performance detraction!!!!

[Chutzpah]

Originally Posted by Dysan911

I asked the exact same thing earlier and also could not find anything where LT1's were experiencing pump failures like the ZL1's are on this forum and there's a hell ton more SS's than ZL1's here.

Yep, that’s my point... owned an SS from late 16 till a month ago. I don’t remember seeing a single SS post on an oil pump failure. Pick up tube issues early on in 2016, yes that was an issue.

It’s possible I missed something though, so waiting on confirmation....