No oil pressure!!
Thread Starter
Heel & Toe
Joined: Jul 2022
Posts: 20
Likes: 3
No oil pressure!!
Hi guys , I’m hoping someone can give me a clue as to what is going on . I’ve built dozens of small block chevys but never had this issue. I have a 383 gen 1 small block all new parts rebuilt. Engine in the car , I go to prime it and have NO OIL PRESSURE! I tear out the new oil pump and replace it still the problem persists. No oil is being forced out of the block anywhere. If I apply compressed air down the rear of the block where the sender goes it does move the distributor so I know there’s no blockage. It seems as though there is a plug missing somewhere in the system that won’t allow pressure to build . I’ve looked everywhere. Any ideas? Thanks .
Thread Starter
Heel & Toe
Joined: Jul 2022
Posts: 20
Likes: 3
Oil pressure
I have the rear hole where the sending unit comes out open. I have a line connection with no gauge, the line is open . I noticed the oil filter is full and when I changed the pump it had oil in it ! So I’m baffled.
Le Mans Master
Joined: Mar 2004
Posts: 7,493
Likes: 1,501
From: Little Rock AR
Leave the oil pump drive shaft out? Don't laugh, it happens.
There is a small hidden expansion plug that needs to be reinstalled in the rear of the block after the machine shop does the block work/cleaning. If you leave that out, you loose your oil pressure. Many shops install them as a matter of course but it could be left out. It's located (and installed) right under the rear main cap. It is directly below the top oil pressure tap at the top of the block where the gauge line or idiot light sensor would be threaded in.
There is a small hidden expansion plug that needs to be reinstalled in the rear of the block after the machine shop does the block work/cleaning. If you leave that out, you loose your oil pressure. Many shops install them as a matter of course but it could be left out. It's located (and installed) right under the rear main cap. It is directly below the top oil pressure tap at the top of the block where the gauge line or idiot light sensor would be threaded in.
Last edited by stingr69; Oct 16, 2025 at 02:10 PM.
Old Pro Solo Guy
Joined: Dec 2017
Posts: 8,079
Likes: 4,431
From: Marlton NJ
Hi guys , I’m hoping someone can give me a clue as to what is going on . I’ve built dozens of small block chevys but never had this issue. I have a 383 gen 1 small block all new parts rebuilt. Engine in the car , I go to prime it and have NO OIL PRESSURE! I tear out the new oil pump and replace it still the problem persists. No oil is being forced out of the block anywhere. If I apply compressed air down the rear of the block where the sender goes it does move the distributor so I know there’s no blockage. It seems as though there is a plug missing somewhere in the system that won’t allow pressure to build . I’ve looked everywhere. Any ideas? Thanks .
Without the correct tool, (or an old distributor), that includes a spacer by the distributor & camshaft hole. the top half of the engine never gets any oil due to the large internal leak by the distributor hole.
The upper tool does not work on gen 1 SBC or BBC.
The spacer in red completes the oil gallery passage, seals the internal leak.
This tool also lets you prime it before the engine ever rotates, and check the pushrod oil flow, with the valve covers off.
Last edited by leigh1322; Oct 16, 2025 at 11:52 PM.
Drifting
Joined: Jun 2025
Posts: 1,713
Likes: 597
^^^THIS^^^
On this very forum, a member was detailing his sbc build with many sharp photos. Including one of inverted lower end, Just as he was about to install pan.
An eagle-eyed member spotted Missing intermediate oil pump drive shaft. Eagle-eye sounded an alarm, builder got it and acted; even Before the gasket adhesive had cured.
On this very forum, a member was detailing his sbc build with many sharp photos. Including one of inverted lower end, Just as he was about to install pan.
An eagle-eyed member spotted Missing intermediate oil pump drive shaft. Eagle-eye sounded an alarm, builder got it and acted; even Before the gasket adhesive had cured.
Burning Brakes
Joined: Apr 2014
Posts: 877
Likes: 702
From: Oregon
# 26 of this thread...
https://www.corvetteforum.com/forums...e-at-home.html
The plug get left out of the oil galley under the rear main cap?
https://www.corvetteforum.com/forums...e-at-home.html
The plug get left out of the oil galley under the rear main cap?
