Strange sound when priming oil pump
 

I was using a heavy duty drill on an old Merc distributor with the gear removed to prime the oiling system on my BBC tonight. I was getting oil to all the rockers, but when I turn the drill off I hear a strange sound, almost like air bleeding out of somewhere as the oil pressure bleeds off. It sounds like it's coming from the front of the engine around the timing cover. I know that the front oil gallery plugs have small holes drilled in them to allow oil to get to the timing chain. Should I be hearing anything from this? Starting to wonder if my pump is sucking air. Don't have a gauge on it right now, that will probably be the next step, but I must be building pressure for it to make it up through the pushrods. I also noticed that it is barely coming out of the rocker holes - was expecting a steady spurt of oil here.

Do I have a problem here, or am I just being paranoid? Don't ever remember hearing anything like this before when I primed engines this way.

For the record, it is a Melling Select 10778C pump, stock pickup brazed all the way around, stock 8-quart GM pan with about 5 quarts in it. Maybe my level is too low, but I would think the pickup should be fully covered.

I would put the other 3 quarts in. Also do you rotate the engine while the drill is running? I tether the drill in the on position, and then put a wrench on the front pulley. Don't know if it helps or hinders.

Rookie, I turned it one full revolution between runs of the drill. It's a big ass drill, and I wouldn't feel comfortable just letting it run by itself without having someone else there to hold it. Would probably just spin around unless I had some kind of sturdy jig to hold it with.

I have primed several engines, and don't ever remember hearing anything like this. Leave it to this problem child to have all the weird issues.

I was going through a mental checklist, and specifically remember putting the o-ring back in under the rear main cap. Don't remember having any gallery plugs left over either.

Mine have done that. I just assumed it was the oil pressure bleeding down as soon as the drills stopped

I've heard some funny noises as my engines have bled down but thought it was more in the lifter galley area.

That bleed down noise you are hearing is normal. Oil will not squirt up through the pushrods with any force, while priming with a drill. As long as you are getting oil up to all of the rockers, even just a trickle, its all good.

Do you have an oil pressure gauge on it while priming?

Going to put one on it today. I was mainly just watching for oil flow up at the rockers. Thanks for the replies, guys. This motor has made me paranoid with all the funky issues I've had with it. :party-smiley-004: It's turning me into a "hydrochondriac". :)

im not sure why you put 5 qts in an 8 qt pan but you need to put the other 3 qts in it ,add a pressure gage and reprime it.would you run it 3 qts low in the boat?the noise you are hearing is probibally the pump sucking air instead of oil.

It's not my motor, so I say run it ! LOL.

On a serious note, I have a mechanical guage installed, look fo proper psi and look for oil out of all rockers. Oil flow thru rockers can take some time and some motors I have to rotate crank while priming for the oil to come up all of them.

Can't tell thru desciption if you weird noise is something wrong or not by description. Air entrapted in fluid purging thru small holes can make some good noises. Usually more like vagina farts. LOL.