Big block oil pump removal

Posted By: Hotwheelsjr

Big block oil pump removal - 12/18/10 10:19 PM

Is it pretty easy in the car? Is it just the 4-5 9/16" head bolts or does the two 7/16" head ones need to come out too? Just dropped my son's 400 back in his '73 SSP yesterday (it was out so we could replace the torque converter, front tranny seal, and power steering gear box, to stop LEAKS!). Well, now that it's back in, it looks like the oil pump is leaking. Thought it was the new filter we had put on, but after replacing IT, I can see a steady drip off the back of the pump -- it's not coming from the filter. I'm about ready to douse the damn car in gas and light it on fire out in the desert -- but gas is too expensive to waste.

Posted By: torkrules

Re: Big block oil pump removal - 12/18/10 10:23 PM

4-3/8 bolts (9/16 heads). The two smaller bolts hold the cover on. You will need a replacement gasket and o ring for the stem. Come right off in the car. Worst case, you may need to pull the distributor drive.

Posted By: jvcuda

Re: Big block oil pump removal - 12/18/10 11:42 PM

Here's the needed gasket set

/oilpumpgasket.html oil pump gasket

Posted By: Commando1

Re: Big block oil pump removal - 12/19/10 12:23 AM

Quote:

Here's the needed gasket set
/oilpumpgasket.html oil pump gasket

He's right. Walk into any A-Z, Advance, etc., you'll ask for the gasket (!!!!) and they come out with an O-ring.

Posted By: Stanton

Re: Big block oil pump removal - 12/19/10 01:21 AM

Before pulling the pump, make sure its not leaking from the bypass fitting at the back of the pump. That would be a lot simpler fix than pulling the pump off.

Posted By: Hotwheelsjr

Re: Big block oil pump removal - 12/19/10 03:11 AM

Thanks all!

It's hard to tell where it's really coming from -- even though everything is clean, all I can see is a steady drip off the bottom of the pump. I've reached up under it and as far as I can tell it's wet from where the pump meets the block.

Posted By: Stanton

Re: Big block oil pump removal - 12/19/10 06:17 AM

Try snugging up all the bolts. The cover is sealed to the body with o-rings so there's little chance of doing any harm to the cover by "overtightening". It may just take a little more squeeze to get that pump-to-block gasket to seal.

Posted By: JohnRR

Re: Big block oil pump removal - 12/19/10 06:29 AM

new pump or old ? I just dealt with a brand spanking new melling that leaked , it was coming from between the cover and the body. I took it apart and it looked as though it had been surfaced on a rock but there was a cut on the o ring, I ended up lapping the cover and the body and new o rings and it doesn't leak a drop now.

Posted By: Hotwheelsjr

Re: Big block oil pump removal - 12/19/10 06:38 AM

Quote:

Try snugging up all the bolts. The cover is sealed to the body with o-rings so there's little chance of doing any harm to the cover by "overtightening". It may just take a little more squeeze to get that pump-to-block gasket to seal.

I already tried -- it's been on there for years and the bolts wouldn't budge.

Johndublr -- it's an old pump. Was on the motor when I bought it 3-4 years ago. Still works great (90psi cold, 30-40psi warm)...just leaks now. Not sure what changed to make it start leaking. I'll be pulling it off next weekend I guess.

Posted By: Von

Re: Big block oil pump removal - 12/19/10 06:43 AM

In the process of tearing an all factory 400 down. I couldnt get the dang oil pump to save my life. Beat it with a BFH and it still wouldnt budge. Finally, took the cover off, took the rotor and drove out the drive, the pump itself finally let go.

Posted By: BSB67

Re: Big block oil pump removal - 12/21/10 01:12 AM

Quote:

new pump or old ? I just dealt with a brand spanking new melling that leaked , it was coming from between the cover and the body. I took it apart and it looked as though it had been surfaced on a rock but there was a cut on the o ring, I ended up lapping the cover and the body and new o rings and it doesn't leak a drop now.

The newer Mellings that I've had are very poor in their QA/QC. Check the pressure passage alignment between the cover and the body too.