Accelerated and lost all oil pressure.

Hi all!! Well the other day I took out my 72 skylark custom 350 out for a drive. I went to pass another vehicle and as soon as I stepped on it, I lost all oil pressure. Dummy light went on and gauge dropped to 0. Thankfully I was able to pull over and shut it off ASAP. No leaks, oil levels are all good still. No idea why this happened. I was getting good oil pressure before, on start up 40-60psi (I thought this was kinda high) then around 20 when warm. I’m running 10w/30 oil. Ordered new gear set, booster plate, shim kit and adjustable regulator. Hopefully didn’t cause any damage.

 

First thing you should check is the roll pin for the distributor gear it may have broke, and you caught the zero oil pressure and shut it off as soon as possible.

 

Will check that tomorrow, very thankful I caught it.

 

If the roll pin breaks, the car stops running in my experience. The distributer and the oil pump turn together, so if one stops, the other does too.

 

Hope you caught it before it caught you!

 

Unless the sudden acceleration caused the pickup to lose oil, which is quite possibly what happened, then something probably broke - Maybe the end of the pump shaft? Hopefully you caught it in time (fingers crossed) - I think you did fwiw!

I'd pull the distributor (noting position of the rotor and housing) & first look at the end of the shaft, the gear, etc. Then tirn the pump by hand w/a long screwdriver and see how feels. If everything seems ok, turn the pump w/a drill (I use an old distributor w/no gear/guts & attach the drill to the dist. shaft) and see if you get pressure. If so, then the pickup lost oil.

Alternatively, remove the pump cover & turn the engine by hand & see if the pump turns. Then pull the driven gear and inspect the end, gears, housing, etc. for damage. If nothing obvious, pack 'er up in case the pump lost prime & then do the above.

 

Need more info on engine.
Stock original never opened?
Rebuilt?
Oil pump/timing cover ever monkeyed with?
Oil pressure before this happened, hot idle, and cruising pressure at what RPM?

 

It’s been opened it’s a 350, with a top end rebuild. TA-112 Cam. New timing gears and chain. Oil pressure at cold start 40/60psi, hot idle 20psi. Pressure would go up +10psi per 1000 rpm maxing out at 60psi. No pressure issues or leaks for last 300+ miles def think it’s the roll pin. I never changed that and it’s the factory one as far as I know, have work today will take off distributor tomorrow and spin by hand to see it I get any pressure.

 

Wouldn't sheared roll pin kill eng immediately. No spark.

 

The pin is at the base of the distributor gear, if it breaks the distributor still spins but it’s no longer turning the oil pump gears. So pressure would drop to zero but motor will still be running. Like how you can turn it with a screw driver.

 

Just take the cap off have someone hit the starter and see if the rotor moves if it doesn’t move, you found your problem.

 

I had this happen to me in 2018 with my 455. It was a broken rocker arm shaft, which is pretty easy to inspect under the valve cover. A new rocker arm, new shaft and all new plastic retaining pins and I was back in business. Hopefully yours is a simple issue.

 

If the roll pin breaks it shuts everything down, ignition AND oil pump.
The distributor shaft drives the oil pump, the distributor drive gear attaches to the distributor shaft via the roll pin, if the roll pin breaks (not typical) the distributor gear will just spin on the shaft NOT turning the distributor OR the oil pump.
CHECK to see if the pressed in RIGHT SIDE oil galley plug popped out, that happens quite often if they’re not staked in properly.
You’ll have to remove the timing cover to see.
OOOOR remove distributor, spin oil pump with drill and look thru distributor hole and see if you have oil pouring from the right front of engine.

 

Yes

 

I might be calling it the wrong name, The pressure relief spring that is inside that big bolt. I had one go bad on my 68 GS 400. Zero oil pressure. Bought a new spring and it worked perfect.

 

This is wrong. The gear is held to the bottom of the distributer shaft by the roll pin.

If the pin breaks, the car no longer runs. At least that is how the 350's I have worked on are set up ('68-'69).

Take a look at this thread:
https://www.v8buick.com/index.php?threads/1976-buick-350-oil-galley-plug.260519/

 

BBB's are the same, the distributor gear is one tooth different between the two (and curves). I used my 350 distributor and replaced the gear (roller cam/bronze gear).

 

The engine will turn over, however zero pressure. Opening it up tomorrow for a better look.

 

How the heck would a busted rocker arm shaft make for zip oil pressure?