Oil Pressure

[The_Green_Bean_59]

I was wondering if anyone would be able to tell me what the average Oil pressure is on a 1959 Willys Truck with a 6-226 "Super Hurricane" 16 L Head Motor in it is. Running and idle pressures would be great if able, but idle pressure is more important. Thanks much.

[bmorgil]

Here you go TGB, https://www.kaiserwillys.com/tech-guide/l6-226-engine-specs.

When using these numbers to determine the engines condition, a good measuring instrument needs to be installed. I have had gauges on the dash read no where near what the actual number was when hooked to a testing quality gauge.

Trouble with the oil pressure TGB?

[LarrBeard]

I'll ask the question that everyone else is too shy to ask. In the spec sheet, it says:

Maximum Safe Oil Pressure 20 lb. @2000 rpm. (35 mph.)
Normal Oil Pressure 35 lb. @ 1700 rpm.

How can the "Maximum Safe Oil Pressure" be lower than the "Normal Oil Pressure".

And, yes - do get a good mechanical gauge to check the oil pressure down at the block where the sensor mounts. Dash gauges are "FOR REFERENCE ONLY".

[bmorgil]

It does need to be a little more specific. The "Safe" oil pressure is indicative of "How Low it can Go" safe being clarified as do not operate below this number. What is interesting is although they are giving you the "Safe" number, it is at 2000 rpm or (35 mph). This is a sign of the times. Oil pressure on the motors varied wildly under 2000 rpm due to manufacturing tolerance capabilities. When you wanted to see if it had good oil pressure you revved it a bit to get the pump to spin up. Low oil pressure at idle was common and as long as there was some, it wasn't usually a concern unless things were "Knocking" at idle. Oil pressure under load is much more important.The clearances in the engines were very loose by today's standards. There was significant "splash' lubrication going on in the crankcase. Now with the advent of hydraulic lifters things changed. If you don't have enough oil pressure at idle with hydraulic lifters, the lifters will collapse and not function properly.

[LarrBeard]

So, at 2,000 RPM, I need at least 20 PSI, but I should have about 35..?

It might better have been called "Minimum Safe Oil Pressure at 2000 RMP"

I think I understand better now. Thanks Doc Dana ...

[The_Green_Bean_59]

Unfortunately, I'm not yet at the point of running condition. But I believe I am close and I was told by a friend that I need to find out what the minimum oil pressure is at idle so when I start the truck it doesn't blow something.

Just for context, I have received the truck from my grandmother and through no fault of her own, the truck was left to sit outside in the conditions for about 15+ years. Everything on the outside of the engine seems to be in good condition, but I still want to make sure that I have as much information about the operating specs as I can before I fully commit to starting it.

Thank you for the information - TGB59

[LarrBeard]

Here is our standard advice about waking up an old vehicle:

Startup Best Practices


It is not unusual for folks who have just found a barn Jeep or who are starting to work on Grandpa’s CJ3 to ask what to do to get the engine running. While coaxing an old Jeep back to life isn’t all that difficult a job, doing it in too big of a hurry can turn what could have been a pretty good engine into a basket case pretty quickly. Several of us who have gone through our repairs and restorations have come up with some things that will cover a lot of the issues that you will find trying to wake up that old engine. Thanks to Forum contributors Gmwillys, LarrBeard and Pelago for their suggestions.

A good starting place is to check the engine oil level, and oil condition. Go ahead and pull the drain plug. If the oil is milky, then the odds are that the head gasket was likely the cause of the Jeep to be parked. A Willys L or F-head has an oil capacity of about 4 quarts. (The Super Hurricane 6 holds 5-quarts). If a lot more than 4 or 5 quarts comes out, there is a possibility that the block is cracked and coolant has leaked into the oil pan.

Take this opportunity to check the coolant. For initial checkout, it’s not a bad idea to pull the thermostat. When you get to the point that things run, you don’t want a stuck thermostat to blow off or split a hose and give you a hot water shower! If it is clean and green, then there should not be any issues with the head gasket. If there is no coolant in the engine, add water (about 11 or 12 quarts) and see if water leaks out the oil pan drain plug – not a good sign. Radiator leaks and leaky hoses show up about now as well. Resist the temptation to pour stop leak in the radiator. It will usually cause more problems than it solves.

Next, pull the spark plugs and put in a few ounces of engine oil/transmission fluid and a good dose of penetrating oil into each cylinder. Do this before attempting to turn the engine by hand. A word of caution; place a shop towel over the exposed spark plugs holes to catch any oil from running down the side of the F head and you don’t want stuff falling down in spark plug holes in an L-head. Let the engine sit with the concoction for a half hour or so, in order for the penetrating oil to seep into the rings. There could be twenty years of crud in there that will bind the rings to the cylinder wall. If the mixture seeps past the rings, it will just drain into the crankcase and out the drain plug.

While you wait, remove the tappet cover on the driver's side, and lube the cam shaft and tappets. Everything in there is going to be dry and dirty. Inspect for broken springs, or damaged valves. At this time, adjust the fan belt to where it is snug in the water pump and generator pulleys.

Use the fan to carefully rock the engine back and forth. Resist the urge to use a breaker bar on the crankshaft pulley. If it takes that much effort to turn the engine, there are problems. If the engine turns freely, then continue to turn the engine through several times until both the compression and exhaust strokes have been completed. Pay special attention to any noises or a feel of something hanging up the rotation. On the F head engines, pull the valve cover to ensure that the intake valves are cycling fully. Oil the top end well because it’s going to be dry after sitting all that time.

Once you are convinced that the engine is loose and lubricated, it’s time to look into the wiring. Inspect the wires leading from the ignition switch to the coil for mouse damage or just plain old wear and rot. Repair any damage found to prevent a fire hazard. If things are in bad shape, it may be easier to just jury rig a wire from the battery to the coil and another to the starter solenoid to bypass a bunch of wires that may have issues. Remember to disconnect the old wires!

Once all the wires are cleared for electricity, it will be time for a battery. It would be helpful to have a helper when checking the starter for proper operation, in order to pull a cable off the battery in case the starter sticks engaged. If all checks out to this point, then it will be time to check for spark.

Pull the distributor cap, and check the points to ensure that the contacts are clean (they probably won’t be), and are adjusted correctly. It wouldn't be a bad idea to hook up a tach and dwell meter to the distributor to adjust the points, at this time.

Check the cap for cracks and clean the contacts, then reassemble the distributor. When you get to the point of cranking the engine, check for spark at the plugs. Check every plug – this is the easiest place to find an open spark plug wire. A helper is really a bonus for this step!

If you have gotten this far with no major issues, it’s time to add fresh oil. Changing the old oil is a very good idea because you have no way of knowing just what is in that crankcase! For both L and F-134 engines, straight 30W, non-detergent is what the book calls for. New and improved isn’t necessarily better.

It would be prudent at this time to run a compression test to determine if all cylinders will support the engine running. If the compression is right, and there is spark, then reinstall the spark plugs, (a clean used set would do, since there might be a chance of fouling a good set). Or, you might want to leave the plugs out until you crank the engine to prime the fuel system.

Check the fuel tank for contamination/rust/holes. If the tank is a mess, (and it is usually worse than you think it is), connect a temporary gas line to the inlet of the fuel pump, and run a fuel line into an external fuel source. Make sure the external fuel source is secure. Once the engine starts and everyone gets excited, spilling a gallon of gas under the vehicle is a good way to spoil the whole day. Crank the engine (easier to do with the plugs out) and observe the carburetor for fuel leaks. When the fuel bowl has adequate fuel in it, install plugs and try and start the engine.

Resist the urge to use a starting aid such as ether or another starting fluid. This could cause harm to the pistons or a fragile head gasket. Have a clean rag or a glove close to the carburetor to snuff out any carb fire that may happen if an intake valve doesn't fully seat. Also, if there is a back fire through the intake, check to make sure that there is no obstruction in the exhaust pipe. Mice will store a ton of acorns and bedding within the muffler. (They can also pack the bell housing with straw as tightly as a hay bale!)

Listen to the engine to determine if it is receiving enough or too much fuel. If the choke butterfly isn't closing enough to pull enough fuel into the carburetor, cover the carb inlet with your hand to limit the amount of air going into the carb. Shutting off the air supply allows the carburetor to draw more fuel into the intake. This may have to be done until the engine is running, and the air fuel mixture is adjusted.

If you are not receiving fuel into the carburetor, and you have fuel at the carburetor inlet, then the needle and seat are stuck closed within the fuel bowl. If you are receiving too much fuel, then the float may also be stuck in the down position, allowing fuel to drain constantly into the carb throat. A minor carb kit may be needed for the gaskets, if the float and needle need attention. Eventually you will want to rebuild the carburetor – nothing except whiskey and wine improve by sitting twenty or so years.

Since old gauges and sensors are always suspect, it is a good idea to put a mechanical oil gauge on the oil sensor port of the block. When the engine starts, pay attention to the oil pressure, to ensure that it comes up quickly after start. Listen for any odd noises, and make note of anything out of the norm. If it doesn’t sound right – it probably isn’t! Try not to race the engine until you have a good sense that everything is normal. There is a lot of crud and dirty oil in the galleries and passages in the engine at this point. Leave the radiator cap off to observe that there are no combustion gases escaping through the coolant. Let the engine reach operating temperature, and then shut it off. Change the engine oil, the oil filter if the vehicle has one and change the coolant. You will be surprised at how nasty the oil and coolant are. Change them again after you’ve driven a couple of hundred miles. It takes time for all the crud to work its way out.

If all is normal, then you have yourself a good engine. Now, the real work begins. Good Luck!