The Stovebolt Site Forums The Shop Area Engine Shop Oil pump defective?

1956 Chevy 3100 pickup, 235 engine:
Got everything back together, engine, transmission, and driveshaft. Filled the engine with oil both in the pan and the filter. Decided to do a quick test on pumping oil. Inserted large flathead screwdriver into distributor opening and turned the oil pump using a drill. No oil along rocker arm shaft. Only oil came out of the gauge connection fitting I mistakenly forgot to close off. Plugged it and tried again. No oil showing up. Decided tomorrow to hook a gauge up to that same oil gauge connection and see what kind of pressure I'm getting when running the "drill" test. Otherwise, I plan on dropping the pan and checking out the oil filter. I don't understand what could go wrong with the oil pump as I had taken it apart and thoroughly cleaned, along with the pan, etc. when I had the engine out of the frame and on an engine stand.

What's the likelihood of the oil pump going out? Before I started the teardown I had fired up the engine for a very short period. It sounded good and the dash gauge read 40 lbs pressure. My b-i-l said using a drill probably is not enough to pump oil and the engine needs to start up.

Anyone's thoughts are so very welcome. I don't look forward to pulling the pan. Thanks!

This may seem pretty obvious, but are you turning the pump in the correct direction? If you reverse the drill, does more or less oil then come out?

If you run the drill in the wrong direction, no oil will be pumped. A gear type pump is essentially a positive displacement pump, but until there's oil in the pump itself, it'll be trying to pump compressible air. When I did the same driving the pump with a drill, it took quite a while for oil to come out at the rockers. I was wondering if I was going the wrong direction and reversed the drill, but then went back to forward and got oil coming out. This was with a 216 with modified oil pump (a Melling M29) that has higher capacity than the original.

I think if you keep at it with the drill, you'll get oil to the rockers (unless there's a problem with the supply tubing.)

I have a 1962 235. With the rocker cover off and the engine idling, I don't see a lot of oil weeping out all over the place. Don't expect to see oil gushing out; if you do, you have a problem.

When priming Pontiac engines I build for customers, a 1/2 electric drill will pump 70 psi pretty easy. The drill will get hot and about rip out of hands if not paying attentions.

The drill should spin easy if you go real slow, then speed it up and you should feel it pull down. If it doesn't pull down even a little, then something is letting the oil out of the system or the pump is air locked. Even a worn pump will still make pressure. Remember, the cam is running half speed of the crank, and the oil pump might not be running cam speed, depends on the gearing from cam to pump, so a 1800 rpm drill motor make plenty of oil pressure.

DO NOT TRY AND START THE ENGINE, it won't effect how the pump is working or not working. If you can, use a hand pump oil can and pump some into the pressure port, it might run down to the pump and help it pick-up prime.

If oil is coming out of the pressure port in the main gallery the pump is working. Plumb a gauge to that port and be sure you're spinning the pump clockwise from the distributor hole. If you use a digital watch or a cell phone to tell time, get an oldtimer to explain what "clockwise" means. If the engine has an oil filter, it might take a couple of minutes of pumping to get the system to come up to full pressure.

Getting more than a slow seep from the rocker arm weep holes could also take a while. The volume of oil going to the rocker shaft can be very low on some engines, as the oil passages can have restrictors to limit volume to the top end. That's a feature, not a bug, as stovebolts are engineered to sacrifice the rockers if necessary to save the bottom end in case of a low oil pressure situation. On 216s and spray-oiler 235s, the rockers get no oil at all until pressure at the main bearings exceeds 15 PSI.

Even with a brand new pump (and definitely a used one) I always remove the base plate and pack the gear chamber with vaseline. That assures that the pump will self-prime quickly, and the vaseline dissolves as soon as the oil gets to it. DO NOT use wheel bearing grease!
Jerry

1/2" plug-in drill is a must have for this task. A side handle is needed as well because you will build up speed before the oil system becomes fully primed, then suddenly rip the drill out of your hands if you're lucky. Without the side handle, the half inch plug-in drill will get you wrapped up in your work once that elevated speed gets converted to raw torque. Sudden torque is what will break your wrist.

Thanks so much for the advice. We will run the plug in 1/2" drill way longer than we did. We didn't run it nearly long enough. We'll also put the handle back on the drill 52 Carl. Good advice since my son and I have enough damaged body parts as it is.

It could be the oil suply line which goes across the push rods under the side cover. The line goes from a metering orifice in the block. As I understand it either the orifice and/ or the oil line can become clogged from build up.

https://www.stovebolt.com/techtips/engines/261%20rebuild/images/d-top-end-3a.jpg?crc=4177595665

It's not uncommon for that line to break, or to get a hole rubbed into it by coming in contact with a pushrod. The oil recycles back into the pan, rather than leaking to the outside.
Jerry

Jerry,
Would the broken/ clogged oil supply line affect oil pressure?
If so could it be enough to give a false "bad oil pump" indication?
Chris

I doubt it. I just took my side cover and valve cover off and discovered the oil line broken in half - cleanly cut where it rubbed on the edge of the passageway to the head. It had been that way for quite some time as evinced by the dried out rockers at the rear of the engine.

Oil pressure gauge always reads 14-15psi on the highway and 8psi idling. 20-30 on startup.

Great news!! Not going to have to drop the pan to check the oil pump. I took ya'lls advice and pumped oil into the oil line in the middle of the rocker shaft back down into the pump. Then we, my son and I, did the drill routine again in the distributor downhole. Ran it at mid-speed for a minute or so and the pump started feeding across all the rocker shaft. We just hadn't run it long enough nor had it primed enough. So happy the pump is working like it should. Plus, a small meter I installed where the gauge line connects jumped up and went between 40 and 60 lbs while using the drill.

All is good on this end, thanks to you guys' great advice!!! Have a great week.