1967 442 - 400 motor was rebuilt about 10 years ago and has less than 500 miles since then. Was driving the car yesterday and the oil pressure suddenly just dropped to single digits and car died. Car now won’t start and there’s zero oil pressure (pressure gauge doesn’t move). Changed the oil and filter, no change. Distributer rotor turns when cranking the car.
Advice and help needed.

 

Mechanical pressure gauge or electric with sending unit?

 

1st, check for spark and fuel
2nd, check the gauge, or remove the fitting at the front of the motor, crank, and see if oil spurts from the pressure port
3rd, pull the distributor and see if the oil pump driveshaft is still intact and engaged with the oil pump
4th, cut open the old filter and check for metal in the filter material
5th, plan on pulling the motor to check the oil pump

 

Mechanical gauge.
Would loss of fuel or spark cause the oil pressure to drop to nothing?
Will pull the distributor to make sure it’s still engaged to pump.
Can the engine be hoisted up a little bit for the oil pan to come off or does the engine have to fully come out?

 

Not to be a jerk, but are you sure it's mechanical? Because, if it's electrical, you lost ignition power, and that's the only problem.

Mechanical means there is a hose of oil coming into the passenger compartment that pressurizes a mechanical gauge with a needle and there are no wires there. It does not mean "a gauge with a needle." Most oil pressure gauges are electric and analog. An electric, analog gauge will go to zero immediately with loss of power. A purely mechanical gauge will not drop immediately to zero unless your car is literally barfing oil on the ground (which you would have noticed and told us about.)

A loss of spark or fuel will not cause an immediate loss in oil pressure. It will stop the engine from running, but your oil pressure will coast down to nothing, not plummet.

 

Dollars to donuts you have an electrical issue.

 

If your gauge set includes an amp gauge, check to see that the connections are tight. That would cause loss of all power if it is installed correctly and loses connection.

 

If no odd noises/taps/knocks and it has oil on the dipstick X2 on it"s electrical, not mechanical.

 

1- Please treat me like an idiot because this is new to me. So No comment is a bad comment.
that said, Koda, you are correct, it is electrical (has a small sending unit).
Gauge set includes temperature, oil pressure and amps. Oil pressure was the only one to drop, the other two remained working.
My dad has some crazy wiring going on so electrical problem makes perfects sense. However, I have no idea where to start looking…

 

Get a known good mechanical oil pressure gauge. My money is on the current gauge, sender, or wiring. As noted, a loss of oil pressure like that would immediately cause the lifters to start clattering.

 

Hey Joe,
Where is the sender located? I don’t see it around the top of the engine so must not be in an obvious spot. To me at least.
I assume it wouldn’t really matter if the gauge doesn’t work since it’s informational. (?)
Definitely sounds like an electrical problem, however, not sure what electrical to look at.
I looked by the oil filter and I don’t see a sender there either. Is it possible I don’t have an oil sender (I’m aware that might be a very stupid question)?

 

How do I put this delicately? Bah, nevermind.

First test for spark. Get one of these: OTC 6589 Electronic Ignition Spark Tester white https://a.co/d/h9QFDpR

Secondly, the engine has to be running to have oil pressure. So, did it die before or after you looked at the gauge?

Third, are you sure it has fuel?

 

Lol, no need to be delicate here!! I’m literally wondering if I have way too low of fuel in there!! Gawd help me if that’s the case, but looooord I hope it is!! Damn fuel gauge is Never accurate so would just be my luck!!

 

There is only one oil pressure port on an Olds motor, on the front driver side of the block. This particular photo shows a non-factory tee fitting feeding both the original idiot light switch and a tube for a mechanical oil pressure gauge.

 

Got it. On mine all I have is a mechanical oil pressure line.

Should I also tee in an oil sender? It’s never had one since the engine was rebuilt a decade ago.

 

Yes, that is a mechanical gauge oil pressure line, not electrical.

 

So you have a MECHANICAL gauge, not an electric one? Kinda makes it difficult to provide useful info if we don't know what is on your car. How about a photo of the actual gauge as well. The only reason to run the tee fitting is if you want to retain the idiot light in addition to the gauge.

 

Follow that line and see where it goes.

I also wonder what the heck that line in the red nut is doing.

Sorry, another dumb question, but did you disconnect that line for the photo? If you just took a picture, that line fell off, and you did lose some oil pressure.

 

Mechanical temp gauge.

 

In the midst of my frustration I was looking originally at the temperature gauge which is the line that goes to the red nut.

I disconnected the oil pressure line to make sure it was mechanical and took a picture while it was disconnected.

 

If you still have to old oil filter, use a pair of tin snips to cut it open. Look for metallic debris inside the filter pleats. If the filter is clean, that more than likely rules of catastrophic engine failure.


Check for spark next. You don’t NEED a fancy spark tester, but it is nice to have. Pull a spark plug wire, find a screwdriver that fits the terminal of the plug. Wrap the handle of the screwdriver with a rag, wear some heavy gloves and carefully hold the screwdriver about an 1/4 inch over a solid piece of metal, something like the alternator or power steering mounting bracket. Have a helper crank the engine while you look for spark.

No spark? Remove the distributor cap. Crank the engine, hopefully you see the rotor moving. If not, now you know why you have no spark, and no oil pressure. Time to pull the timing cover for timing chain inspection.

 

Why are we looking for spark and fuel if it's been established that the gauge is mechanical? In my experience, you can usually get a good bump on the gauge just off the starter motor whether the engine fires or not.

In OP's defense, he did state that it was a mechanical gauge before we tried to convince him otherwise.

 

Thanks to all that followed my thread and told me to check the obvious first!
I’m not too proud to admit that I’m a moron! As it turns out, the damn fuel gauge was stuck so registered I had a half tank of gas when in reality I ran out of fuel!!
So ya, went and got some gasoline and the damn thing started back up (with oil pressure).

Sincerely,
the idiot with a bad fuel gauge

 

I suggested looking at spark because the engine had no oil pressure while cranking, and it wouldn’t run.

Since both the fuel pump, oil pump and distributor are all driven off the camshaft, a timing chain issue would cause the car to not drive any of them.

While no fuel would definitely result in a “crank but won’t start” complaint, it doesn’t explain the no oil pressure while cranking.

Hopefully the engine hasn’t cranked long enough to register oil pressure, and everything is good now.

 

Glad you got it, man. I put an aftermarket fuel gauge in.

My 468 won't show oil pressure while cranking with a Powermaster 9510. It shoots up when it starts.

 

Jeez isn't it nice to have someone report a simple successful solution to a scary sounding situation - I feel better even though it isn't my personal trouble or problem - Like a cool rain falling on parched earth. Sort of like a ASMR vicarious Oldsmobile experience. In through the nose, out through the mouth.

 

Definitely next on the list!!

 

Lol, major stress relief!!

 

You're not the first to have a faulty fuel gauge send you off on a goose chase, I had a similar situation with a diesel truck. Glad it worked out.

 

that damn fuel gauge is going to be the death of me Lol

 

But, Bullwinkle, that joke never works!

I though that mech temp gauges didn't work too well since the sensor is not in the hot coolant flow.

Excellent. the check for fuel should be with the air and spark in the future. Remove air cleaner, look down primaries, hit acclerator pump with engine off, and you should see twin streams of gasoline spurting. If not, there's a fuel issue of some sort.

 

Lesson learned !

 

The sensor is long enough to extend past the fittings and into the coolant flow.

 

Oh, I remember what it is now.

You can T an oil pressure port and run idiot light and gauge. You can't T a temp sender for idiot light and another for gauge because the senders are not in the flow anymore. That's what you can't do, not not run a mech temp gauge.

I've run a mechanical temp gauge before with a separate gauge package, but I had to use a different port.

 

You have a couple PMs