Lost Oil Pressure - What to Do?

I was driving home and had pulled up in front of my house (at idle) and heard "rattle, rattle" (440 engine) & saw my oil pressure had dropped to zero, so I shut the motor off. Thank God I was in front of my house. It sounded like the valve gear rattling & not the deep "clunk, clunk" of a rod/main bearing (I'm hoping anyway). The engine did not seem to have any type of misfire.

These are the things that I can think of that could cause this problem.
1. spun main bearing
2. spun rod bearing
3. spun cam bearing (#4, right?)
4. leaking line going to the oil pressure gage
5. oil pump failure
6. REALLY low oil (was 1-1/2 qts. low per aftermarket dipstick). I don't think the pickup sucks air until about 3 qts. low (?)
7. Oil pump failure
8. sheared off the hex end of the oil pump/distributor gear

I'm afraid to even crank the motor until I find the problem. Obviously I don't want to pull the engine if I don't have to.

How do you guys suggest I go about fixing this problem? What order should I check everything? Can I see the hex end of the distributor/oil pump drive if I just pull the pump off? How can I tell if the pump went bad?

Any help is appreciated. Thanks in advance.

I'd start by pulling the distributor and intermediate shaft. If they look good then spin the pump with hex and drill while checking for pressure.

If none then I'd pull the pump and disassemble. I had a stuck pressure relief valve on a small block pump once so look at that portion carefully.

Had #8 happen to me once on a 360.

You can pull the pump, or pull the distributor and rotate the drive out. Easier to do on a 440 than a 360.

verify the drive, fill with oil and start!


On a big block I had a pump go bad, took out a crank, just that fast.

Relief spring stuck open because of RTV a previous owner had applied to valve covers, I do not use RTV, never have, never will.

Did you ever calibrate the after market dipstick to your oil pan? If not drain the oil pan now and look at the oil for shiny metal flakes and measure how much comes out and compare that to what the dipstick shows now before you drain it, that will answer your question on how much it has in it now.
While you have the drain plug out look inside at the pickup and see how far it is above the top of the drain plug hole or if it is sitting on the bottom of the oil pan like Ma Mopar suggests to set them up at in the factory service manuals
As far as what caused the loss of oil pressure may be answered by looking at the oil in the drain pan and the height of the oil pickup now If it is not a oil starvation problem due to oil level then take the oil pump off and remove the bypass plug and see if the bypass valve is free or stuck inside it, if stuck that is your problem, if not stuck see if the oil pump drive shaft tip is broken off and stuck in the oil pump gear drive hole
Do these things now and let us know what you find

Bent push rod.
Lifter popped out of it's bore.
Pull the valve covers.

I had that happen on a 400.

Damn, I'm a jinx

Do an oil change and cut the filter. Definitely start up top. Pull the dis. and int. shaft. Pull the valve covers and make sure everything is good. Spin the pump(counterclockwise). No pressure? Lastly pull the oil pump if all is well up top.

Cut the filter before anything. Look OK? Check to see if the hex broke on the oil pump drive? If so the pump rotors are are probably jammed, determin the source of the debris.
Doug

Do not forget the BB distributors / oil pump drives rotate CCW.
If you cannot get oil pressure, next step is to remove the valve covers and look for the potential problem. IE: broken rocker, other valve train issue that may have allowed a lifter to exit its bore. Next stop, Oil pump itself. DO NOT start the motor until the issue is identified. The drill motor is your friend

In 1975 my 383 pump failed just south of 80,000 miles, at startup, I let it run just a hair too long and developed terminal knock.

Robert

The first thing I'd do is pull the valve covers and look for a pushrod out of place. If there is one that's out of place, look to see if the lifter popped out...that will kill your oil pressure and probably not hurt the motor at all otherwise. Obviously you need to find out why the pushrod got loose...rocker adjuster issue, cam lobe going flat, etc.

If all is good under the valve covers, pull the distributor and check the oil pump driveshaft. It may be broken. If it is, pull the oil pump off and inspect it.

Then I'd drain the oil, check for glitter in it, and cut open the oil filter.

had a sticky valve cause this

I got VERY LUCKY.... thank you God. It was #6 & I shut the motor off in time.

6. REALLY low oil (was 1-1/2 qts. low per aftermarket dipstick). I don't think the pickup sucks air until about 3 qts. low (?)

The dipstick (aftermarket) was about 1 qt. off & I calibrated it when I changed the oil. I was at least 2-1/2 qts. low on oil (likely 3 qts. low) and the pickup sucked air for about 20 seconds.

what I do is have the car level. add 4 qts (for a std 4 qt sump pan) from scratch. mark the stick full at that point. this takes the filter out of the equation & this is with it previously primed so the passages everything is filled