I just assembled my small-block Chevy 350 engine and also used a drill motor and an old distributor to pressure lube the engine before I fired it up. Unfortunately, it will not make oil pressure. I’m using a brand new Melling oil pump and I know I put all the oil plugs in the front and back of the engine. I even used a new oil filter adapter. I’m pretty sure the oil pump is working because I can feel a little bit of load on my drill motor but it won’t make any oil pressure. Do you have any suggestions?

T.M.

***

You’re not going to like what I’m about to tell you.

We’ve been there and made this mistake too—and it means removing the oil pan and the rear main cap. There’s a small press-in plug below the main cap that your machine shop removed to ensure proper cleaning of all the oil passages.

If you did not replace this oil plug, the oil pump will not push the oil through the oil filter but merely bypass it back into the engine. This is why spinning the oil pump feels like there is some load on it but not enough to create pressure.

The good news is that this is a rather simple fix.

You will need to drain the oil and remove the oil pan. Then you will need to remove the oil pump and the rear main cap. Underneath the rear main cap will be a hole on the driver side where the press-in oil plug must be placed. Note the photo to see where it goes.

stud and port near crankshaft in an engine block
The oil galley plug is located under the rear main cap. If you forget to install it like we did here, you will have to remove the oil pan and the rear main cap to install the plug. (Image/Jeff Smith)

Once the plug is pressed into place, it’s a simple process to torque the rear main cap in place, install the oil pump and oil pan and re-fill engine with oil. Of course you will still want to pressure lube the engine again once everything is reassembled.

We prefer to pressure lube the engine until all the rocker arms receive oil through the pushrods. This may take 10 or 15 minutes to get oil up to all the rockers. If there are a couple that do not, don’t fret. They will oil once the engine fires but it would be a good idea to check anyway just to make sure.

This should solve your oil pressure problem.

Keywords
Ask Away! , pre-lubing engine , small block Chevy
Share this Article
Author: Jeff Smith

Jeff Smith has had a passion for cars since he began working at his grandfather's gas station at the age 10. After graduating from Iowa State University with a journalism degree in 1978, he combined his two passions: cars and writing. Smith began writing for Car Craft magazine in 1979 and became editor in 1984. In 1987, he assumed the role of editor for Hot Rod magazine before returning to his first love of writing technical stories. Since 2003, Jeff has held various positions at Car Craft (including editor), has written books on small block Chevy performance, and even cultivated an impressive collection of 1965 and 1966 Chevelles. Now he serves as a regular contributor to OnAllCylinders.