Featured Technical Oil pressure dropped to zero on start up...

I started my car, the oil pressure gauge fluttered around between 40-50 & then dropped to zero. I immediately shut the engine off so it only ran for a second or two. I'm hoping it's the gauge. It's an electric Stewart Warner gauge. I have a gauge that I know is good. Would it be safe to put it in & start it? I could shut it off in seconds if there's no pressure. Although that wouldn't rule out the sending unit. If not, how do I check to see if the oil pump is working? It's a '57 Chrysler 392 with an 8:71. Thank you! Bill

 

First thing I’d do is check voltage to gauge and sender, then continuity of the wiring. If that checks out I’d disconnect the ignition so it doesn’t run and spin it on the starter motor. An analogue gauge would be best to check for pressure.

 

Or even safer, pull the distributor and use a power drill operated oil pump drive to spin it.

 

Like @Clydesdale said ,
I know the 426 Hemi that a common issues ,after installing Filter ,
Oil filter will get air locked ,
I do not know about 392

 

Pull the oil pressure sender and crank it on the starter. You will soon find out if it pumping oil.

 

I have seen similar symptoms from a collapsed oil filter.

 

Put a manual gauge in it, pull the coil wire and crank it over until you see pressure. If no pressure builds just cranking it over you know you have a pressure problem, not a gauge/sending unit problem.

 

I'd pull all 8 plugs before spinning it. takes the load off the bearings in case you actually lost the oil pump. Plus it'll spin faster.

 

Good suggestion.

 

This is the way. Do not turn the engine over until you have verified that you actually have oil pressure and it's not just a gauge/sender issue or trapped air.

Has this engine ran before or is this a first start up?

 

Pending your gauges you should be able to GROUND your wire at the sending unit and Max out the gauge with just turning on the Ign. switch momentarily.

 

I agree with all previous posts. Pull plugs and spin engine over with a known good mechanical gauge.
Also, you have a previous post about another gauge not working.
https://www.jalopyjournal.com/forum/threads/water-temperature-gauge-not-working.1135352/
Considering the time and effort of building a blown 392, I'd ditch the gauges and get a new set!

 

Not to mention the cost. A blown 392 deserves a set of the best gauges one can find, IMO.

 

A gauge AND a bright idiot light is probably best. The gauge to check what's going on in detail from time to time, and a light to scream DANGER DANGER DANGER when the pressure suddenly goes missing while you're busy looking at the road and have no idea what any of the gauges says.

 

You using the HH modified 340 oil pump? There are issues about mounting them up that they don't tell you about.

 

I've always used a mechanical oil pressure gauge. I also set it up with a "T" fitting that lights up the idiot light in the dash. A lot of good suggestions above.

 

Care to go into more detail about issues that you've had firsthand? I personally just purchased a fresh built 57 Dodge 355 loaded with HH parts and a total mess. Not saying the HH pieces are no good but defiantly installed with No builder skills at all. All I got with the Motor was folder full of receipts from H&H and machine shop receipts. One of many problems I found was a new Pump with a very rough spot when turning it by hand (Oil system was not yet primed) The adapter was bolted on the Main cap and one of the Pump housing to adapter bolts went through the adapter just far enough to bottom against the Main cap and NOT tighten the pump housing to adapter. Hardware looked to be what came with the Pump but not machined to do the job correctly. This is what the motor looked like when I bought it. Thank God the builder sold it before it went any further and I'm very pleased I didn't just decide to light it up and run it in before I dropped the Oil Pan to fix a Pin Hole in it. In Total what I found was hard to take.

 

I'd use a mechanical gauge on it. Remove the filter and fill it with a much oil as you can. Reinstall it. Take the spark plugs out and crank it over to see if pressure comes up.
Years ago I had an engine that was rebuilt I installed it in my car. It started and the oil pressure drop immediately, I shut in down and started searching for the problem. I pulled the engine dropped the oil pan and found an oil galley plug in the pan. Got another one installed it staked it in place and never had another problem.

 

32blownhemi, Clydesdale posted the only single answer to your question. The rest is good input but may not have been what you're looking for. To add to his information, you should know the rest of How to do that. Once the Dist is removed you must also remove the intermediate drive shaft and gear. That unit is engaged in the Camshaft gear, passes through the Bronz bushing in the block and drops into the Oil Pump output shaft. Next you need the Oil Pump primming shaft made by several suppliers. HH has one and their part number is 21901. It locks into the Oil Pump, fits correctly in the bushing in your block and is long enough to get up above the Block so you can connect a drill motor. A common thing Not to do on a rebuild is replace that bushing. Also a lot of builders don't know how to check proper shaft to pump thrust clearance. It's really easy to destroy an oil pump when it doesn't have this set up properly.

 

The way I see it, if I’m dealing with a very expensive or complex part, I want to take the least risk possible.

Hence my suggestion, Pist-n-Broke filled in the specifics, thanks fella.

 

I don't recall exactly, it had to do with the pump mounting, I'll have a look this evening, I remember taking photos of the problem.
Good thing you have an inquisitive streak.

 

I will say it pays to pay attention to the small things. I had removed the Valve Covers after mounting the motor in my project just to check the valve settings prior to priming the system. I was told it had adjustable pushrods and it did. Lifting the cover off this jumped right in my face.

Now I've blown up a lot of Motors but never have I broken one of these rocker stands and never would I consider welding one back together, especially the one that oils the rocker assembly. This was a screaming Yellow Light!
So with Oil now in the pan I noticed an oil spot growing on my floor under the Motor. Wasn't there when I started. Checked the drain plug and it was tight. Wiped the pan and got a little off the direct back side. On closer inspection it was leaking through the Pan itself. It was easy to remove the motor to drop the pan for repair. On doing that This was visible on top of the pickup screen, and it is Magnetic! Now mind you, this motor has never had a starter engaged in the Ring Gear sense being assembled.

Looking down into the empty Pan I couldn't believe my eyes. I removed this with a Magnet. At this point I was a little Sick and it all went downhill from there.
Fresh bore with new pistons, fresh Racer Brown cam and lifters, reground Crank with new bearings. Some salvage in it but quite a bit we just will not reinstall because of the actual parts even though they "FIT" in place. To me this is yet another lesson that just because you own a wonderful Tool Box and know the place where all the parts go does not qualify you to do the Job. This motor would have eaten itself up in short order.

 

Hmmmmmmmmm...sounds like a Ford !
6sally6

 

Thank you for all the replies! History on it is It's a Big Al's Toy Box crate engine. It's been in the car for 13 or so years. Got it new but probably only have a couple thousand miles on the motor. Not sure what oil pump Big Al used. When I first got the car it had a small block Chevy in, it was the only car I had for 2 1/2 years & I put like 20,000+ miles on it. When the SBC blew up I should have put another SBC in it!
I just ordered an Auto Meter mechanical gauge & a braided stainless hose from Summit. I'll pull the plugs & coil wire & turn it over. I don't want to pull the distributor & use a power drill to turn the pump. The distributor goes into a hole cutout in the firewall with an 1/16" clearance between the distributor & blower. No room whatsoever. And I like the idea of hooking up an idiot light. Not sure how to check the voltage to the gauge & sending unit. I'll see if I can figure it out. Thanks again everyone! Bill

 

It's probably safe to say it's not an assembly issue. You don't need to know the actual voltage at or for the gauge. Just use a test light and check for Batt power at the gauge positive post, then with a jumper wire ground the other post and watch the gauge needle. If it goes up the gauge is ok. Then go to the sender unit and take that jumper wire and ground the terminal post there, again watch the needle. If the gauge needle doesn't move it's probably the gauge or lack of power to it.

 

Explain please…

 

Thank you!

 

I just got to thinking, you don't suppose you blew the fuse that powers your gauges, do ya? That would probably be too simple.

 

Welp....most SBF engines...when they get a couple hundred-thousand miles on them have a habit of oil pressure dropping down low enough (at idle) the oil light will flicker on/off. Doesn't seem to hurt them because as soon as ya giv'em a little gas the pressure jumps back up to 10-20 psig !
SBF are designed so well they don't need hi-pressure/hi-volume oil pumps like a Shivel-lay or others !
6sally6