[arpad_m]

Originally Posted by articblueSS

My 2018 SS was just diagnosed yesterday with an oil pump failure. The car has just over 20k miles on it. The only symptom i had was a strange humming/buzzing noise from the front of the engine that would change pitch with the rpms. I never lost oil pressure tho. GM is replacing the pump under my power train warranty.

That sounds like a different failure mode, though. Rotational speed specific noise plus no oil pressure loss are clearly different symptoms from those of the typical cracked housing and gradually (abruptly) letting go that all those LT4 oil pumps experienced.

[articblueSS]

Originally Posted by arpad_m

That sounds like a different failure mode, though. Rotational speed specific noise plus no oil pressure loss are clearly different symptoms from those of the typical cracked housing and gradually (abruptly) letting go that all those LT4 oil pumps experienced.

I just got the car back this evening. I was told that the tech did indeed find a crack in the oil pump housing. I’m curious how much longer it would have survived if I didn’t stop driving it. Anyway, it appears that my oil pump failure seems to be an anomaly when compared to others which have failed completely. All told, the repair cost for the pump replacement would have been $2700 if it wasn’t covered by the powertrain warranty.

I was also told by another GM tech who works at that very same dealership that they do see this from time to time on LT1 cars (Corvettes included).

[ctrlz]

Wish you had the pump or a picture of the crack.
If it's the stator crack it may not separate the housing until low pressure mode is commanded. That shift will probably open the crack and then maybe the pump can throw a vane. This would explain why some pumps show drop in pressure but not (obvious) total failure.

[Canyonero]

Does this happen to dry sump LT1 Corvettes too?

[ctrlz]

Originally Posted by Canyonero

Does this happen to dry sump LT1 Corvettes too?

Not sure, but LT4, yes.
Nice graphic. This thing breaks where it says "slide pivots about pin"
https://www.corvette-web-central.com/LT1oilpump.html

[articblueSS]

Originally Posted by ctrlz

Wish you had the pump or a picture of the crack.
If it's the stator crack it may not separate the housing until low pressure mode is commanded. That shift will probably open the crack and then maybe the pump can throw a vane. This would explain why some pumps show drop in pressure but not (obvious) total failure.

I wish I had gotten pictures too. Unfortunately, I got there after service had closed for the day and the dealership isn’t exactly close to me. I will reach out to the service writer to see if she is willing to snap a pic for me. Probably not, but it is worth a shot. I’ll see what I can do.

[N Camarolina]

Originally Posted by ctrlz

Not sure, but LT4, yes.
Nice graphic. This thing breaks where it says "slide pivots about pin"
https://www.corvette-web-central.com/LT1oilpump.html

Thanks for that link Ctrlz. The bottom of that linked page contained a graph of pump pressure output vs engine RPM, which is what I've been searching for. It clearly shows a large boost that kicks in at 5700 RPM, which is consistent with the PDR data that mentioned earlier in this thread.

[ctrlz]

Originally Posted by N Camarolina

what I've been searching for. It clearly shows a large boost that kicks in at 5700 RPM, which is consistent with the PDR data that mentioned earlier in this thread.

Happy coincidence! And I just liked the picture!