Oil pump rotors under the cover spin; is that normal?

[Opusx56]

Hello! First post, but I've been reading here for many years (since I got my '88 Jimmy in 2011). Thank you all for providing much-needed help for so many years! Sorry if this post is in the wrong section. I'm having some trouble finding answers regarding the standard SBC 350 oil pump... as I was disassembling it to clean it up and replace the pickup I noticed I was able to spin the rotors under the cover, with the distributor fully seated. Is this normal? I appreciate any help.

Dave

 

[dyeager535]

Hello! First post, but I've been reading here for many years (since I got my '88 Jimmy in 2011). Thank you all for providing much-needed help for so many years! Sorry if this post is in the wrong section. I'm having some trouble finding answers regarding the standard SBC 350 oil pump... as I was disassembling it to clean it up and replace the pickup I noticed I was able to spin the rotors under the cover, with the distributor fully seated. Is this normal? I appreciate any help.

Dave

You are saying the oil pump is assembled, bolted to main cap, and the distributor and oil pump driveshaft are also bolted up/in place, camshaft is in place, and you can spin the oil pump?

You should definitely not be able to rotate the oil pump if everything is assembled properly and in proper working order. The cam has to rotate to drive/allow the distributor to drive the oil pump.

 

[Blue85]

It sounds like you have the oil pan off and the pump cover removed. The oil pump should basically only turn when the engine turns. Crank--> timing chain --> cam --> distributor --> pump shaft --> pump. You may have the wrong shaft or something was damaged in disassembly. Or the distributor isn't actually seated correctly.

What has changed since it was running? Here's some information on how it all fits together: https://garage.grumpysperformance.com/index.php?threads/oil-pump-drive-shafts.123/

 

[Opusx56]

It sounds like you have the oil pan off and the pump cover removed. The oil pump should basically only turn when the engine turns. Crank--> timing chain --> cam --> distributor --> pump shaft --> pump. You may have the wrong shaft or something was damaged in disassembly. Or the distributor isn't actually seated correctly.

What has changed since it was running? Here's some information on how it all fits together: https://garage.grumpysperformance.com/index.php?threads/oil-pump-drive-shafts.123/

Thank you very much for the reply, and thank you @dyeager535 for your reply as well. It turns out that I did, in fact, destroy the nylon keeper that connects the intermediate shaft to the drive gear in the pump and one of the ears was annihilated. I didn't want to pull the oil pan again, but it kept nagging me; the condition of the oil pan, pump, pickup and general filthiness of it before cleaning had me thinking "it's worth the time and effort to pull it again and check it all out thoroughly." Pulled it, saw there was damage done and replaced the intermediate shaft with a new Melling one with steel keeper and a new pickup. Oil pressure has never been better. You're correct: it should not spin! Now that's done right, the only thing left for now is figuring out why it's running so cool, or if my temp sender/gauge are lying.

Dave

 

[Blue85]

Glad you found it. Better than scratching your head with no oil pressure trying to figure it out, which could have been much worse.

Sometimes just sounding ideas off of others helps the process.