Yet ANOTHER No Oil Pressure 383 Tale of Woe and Bafflement

Gerald Morris

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This afternoon, I started to put down the street @ ~ 18 mph top speed, noting as often that the old 727 was taking its time shifting up. I then started to hear a little lifter chatter at a stop sign. "Odd, I just topped up w about 2 oz of 20-50W synthetic. Hmmmm" I turn. The chatter worsens. I look, see 0 psi oil pressure! Full stop! Motor switched off before car ceases rolling.

I get out, tap the body of the oil pump lightly w peen hammer in hope of jarring loose any possible crud there. I add an extra pint of 20-50W, crank the motor, and make the 3 blocks home sans any worse noises. I cut the ignition as soon as parked and it will stay OFF until this issue is resolved. (I dare not leave Mathilda on these streets! There are plenty folk with towing ability and she turns many heads even as she is...)

Seeing the previous thread on sudden, mysterious loss of oil pressure, I read through it, checked the distributor shaft and noted there is NO oil in the filter. The distributor shaft is intact, and likely the original if appearance informs me correctly. It IS nicked, but the end appears to be at factory hexagonal shape. The utter lack of oil in the filter and sudden onset of this rude surprise incline me to suspect the pickup is clogged.

Shall I drop the pan NOW, or have a look at my pump first? I normally got around 15-50 psi out of this pump between 500~3000 rpm, very seldom taking it over the modest 3 grand except for short hops on the interstate. I suspect an aged pump has lost its prime, though WHILE RUNNING seems unlikely, so I may well have a load of crap clogging the pickup. I KNOW the transmission filter was horribly neglected, and only within the past 2 weeks has that been corrected. I just HATE having to drop the pan, unless there is NO other option.

Have I any other option, aside from letting the car rust?
 
From what you describe, it is a possibility the pump could be the issue, that's n easy pull off and dismantle job, check the rotor for scoring and wear, and look at the check valve for crud and stickiness. If that shows no problems then yes go to the next job of dropping the pan, it may be a bit more work but it isn't that bad.
 
From what you describe, it is a possibility the pump could be the issue, that's n easy pull off and dismantle job, check the rotor for scoring and wear, and look at the check valve for crud and stickiness. If that shows no problems then yes go to the next job of dropping the pan, it may be a bit more work but it isn't that bad.

Right on bro. I know dropping the pan isn't as bad as say, one's own disembowelment party. The pump is an easy job, tho I might have to cancel my order for a pair of Mastercraft rubbers for the front. Ah well, little point in having them unless one is in motion. I think there are better than even odds the old pump has just sucked some crap into the check valve. If it indeed is original, as I've good reason to surmise, then it has done 50 yrs of service and a couple hundred kilomiles.

My puzzlement comes from the relative suddenness of this little crisis. Hell, I was just bragging on how NICE and SMOOTH old Mathilda was running after I apparently got the electrical issues straightened out for the time being. Oh how the 2nd Law bites us when we least expect it!
 
Suddenness tells me it is probably crud in some part, if the oil pump was worn then you would gradually lose oil pressure over time. The fact that it happened so fast is a good sign, its not something worn out by high miles which can affect the whole motor.
 
Suddenness tells me it is probably crud in some part, if the oil pump was worn then you would gradually lose oil pressure over time. The fact that it happened so fast is a good sign, its not something worn out by high miles which can affect the whole motor.

I've good reason to suspect crud. The tranny pan was about 1/8" deep in crap when I got it off. The previous owner admitted he was NOT a mechanic at all. I believed him then and doubly now. Oh sooner or later dropping the oil pan will be a MUST.

For now, my oil is clean and I use a good K&M filter to keep it so. I noted that my cam and visible lifter had a decent oil coating when I checked the intermediate shaft also, which comforted me a good bit. But a new pump was looming just over my Upgrade & Maintenance Event Horizon already, so if that will get Mathilda rolling right again, I'll be pretty damned happy.
 
I would say that for a the extra effort of dropping the pan... there is a whole lot of "extra" peace of mind. Regardless of cause, if the possibility of debris entering the pump is present, checking the pan is the only sure way to know.
 
Dropping the oil pan on a 60's big block is not a bad job at all. Bet you find pieces of worn cam gear blocking the pickup. If you do then replace the pick up tube also, (unless you have a compressor so you can blow out the line) When you reassemble the engine prime the pump and get the oil circulating thru the engine before you start it.
 
Dropping the oil pan on a 60's big block is not a bad job at all. Bet you find pieces of worn cam gear blocking the pickup. If you do then replace the pick up tube also, (unless you have a compressor so you can blow out the line) When you reassemble the engine prime the pump and get the oil circulating thru the engine before you start it.

There may be pieces of valve seals too. I have seen where the screens have torn, so replacing it may be necessary. If it were me, I'd probably change the oil pump too, just as insurance.

Finding pieces of the cam gear then leads you to replacing the cam gear/timing chain, if it hasn't be changed already.
 
It won't hurt to just replace the oil pump and manually prime the system. At least you'll know if it's the pump or not. Was the filter put on dry....? It's a good practice to fill the filter before installing it.
If over 70/80K on the engine then now would be a great time to replace the original timing gear set and clean the pan and pickup. If you do find traces of old oil seals then it's time for those too. Some preventive maint now will save some headache's down the road.
None of these procedures are hard to do.
 
No oil press gauge in the cockpit I assume?
Oh there is a mechanical pressure gauge in the "cockpit" rest assured. I installed mechanical oil pressure and temperature gauges within the first week of owning this wonderful antique, as I expected this kind of fun and games for summer. Popped a heater hose last week, right on schedule as it was. Fortunately, nothing got over thermostat temperature then as I was parked at a Circle Jerk when I saw a puddle starting neath the motor after coming out. Just pulled off the defective hose and looped the decent hose back to the pump, no problem. Lost under 2 litres H2O then.
 
It won't hurt to just replace the oil pump and manually prime the system. At least you'll know if it's the pump or not.
Was the filter put on dry....? It's a good practice to fill the filter before installing it.
If over 70/80K on the engine then now would be a great time to replace the original timing gear set and clean the pan and pickup. If you do find traces of old oil seals then it's time for those too. Some preventive maint now will save some headache's down the road.
None of these procedures are hard to do.

Yes, I plan to prime the whichever pump I bolt back on to the engine. I expect I'll pack it with petroleum jelly, as that is what I have.

Yes, the filter was installed dry, save for the seal, which I coated with a bit of oil to make it go on evenly. The motor ran nicely and got plenty lubrication top side for the 3 months I've driven it since then, but yes, it will be better practice henceforth to pre-fill the filter before screwing it on.

This motor very likely has 200k+ miles on it. The intermediate shaft is of the old sort, and while still intact and apparently at the OEM length, shows clear signs of being the original. I guess it had a valve job done at some point circa 1980, but aside from that and the more obvious bolt-on peripherals I suspect the bottom end has seldom, if ever seen daylight since it rolled off the line.

Oh yes, I KNOW it needs much care down under, as well as topside. All I need are a few thousand more greenbacks than what I have, so I can then buy another B block mill, drop it in for driving, then take care of all the needful tasks on this one in the proper way.

But as an aged junky with an infant daughter and young wife to care for, I must budget VERY CAREFULLY. Even an oil pump means the Mastercraft rubbers will have to wait another month...

Yes, I sure as **** am likely to drop the damned pan very soon. IFF I can diddle the old pump back into functioning with a scrupulous clean-up, then I may even keep it. I'm now reasonably sure that debris caused this problem, so I reckon more cleaning is in order in a big way.
 
I would say that for a the extra effort of dropping the pan... there is a whole lot of "extra" peace of mind. Regardless of cause, if the possibility of debris entering the pump is present, checking the pan is the only sure way to know.

I've two young ladies here who regard me more as Gandalf-with- a-wrench than not, so I have to account for their attitude in my peace of mind cost/benefit analyses. I NEEDS DOING tho... so I just had better get on with it.....
 
Oh there is a mechanical pressure gauge in the "cockpit" rest assured. I installed mechanical oil pressure and temperature gauges within the first week of owning this wonderful antique, as I expected this kind of fun and games for summer. Popped a heater hose last week, right on schedule as it was. Fortunately, nothing got over thermostat temperature then as I was parked at a Circle Jerk when I saw a puddle starting neath the motor after coming out. Just pulled off the defective hose and looped the decent hose back to the pump, no problem. Lost under 2 litres H2O then.
all goes with the territory
 
Gerald, most of us old timers have been where you are at today. Hell I remember working at the dealership during the day, a trucking company at night, and personal customers cars on the weekend. That is one of the reasons we give you the advice, so you don't spend the money we did.
 
Gerald, most of us old timers have been where you are at today. Hell I remember working at the dealership during the day, a trucking company at night, and personal customers cars on the weekend. That is one of the reasons we give you the advice, so you don't spend the money we did.

I dig. C-body lovers are a Certain Sort, and we appreciate the rugged elegance and SIMPLICITY of these old classics. Today, I saved $90-100 by tightening the relief valve, which had worked loose to FINGER TIGHT, after removing the pump, cleaning and inspecting it. I packed it full of vaseline, re-installed, used the starter to prime the rest of the motor w the ignition disconnected, reconnected and ECCE! I got my 50 psi cold oil pressure back!!! I STILL shut down quick tho, as I've a nasty lifter clatter persisting on the right side. Will remove the valve cover when the outside temperatre drops below lethal feverish (~105F). Believe me, I APPRECIATE THE ADVICE!!! What I can't use at once, I file away for use later, if/when relevant.
 
You probably now have a stuck lifter. Since you now have your oil pressure drain approximately 1 quart of oil out and put in 1 quart A.T.F. let the engine idle for a while, the detergent in the fluid will help unstick the lifter, after it is gone change the oil and filter again and you will have one of the cleanest internal engines around.
 
Lifter can be dry and it may take a while to stop making sounds. Could start it and rev few times to 2-3k rpm, usually idling doesnt remove lifter tapping noise. In worst case scenario... you already have a wiped cam lobe.
 
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