Packard Forum Index » Pre-War (1899-1942)

When I first start my 443, the oil pressure at idle is around 22 lbs and it quickly goes all the way to 50 lbs (highest indicated level on the guage) if I apply the throttle. Even after getting warm it seems high-ish, with the pressure at idle between 15 and 20 lbs, regularly getting to 40 lbs or above at speed.

However if I pull the choke out (say between 1/3 and 1/2) it instantly drops to much lower levels. However when I do so it feels like I’m running excessively rich, even though I probably do need a slightly richer mix because I live at altitude (in Denver).

I wonder if people think this seems like a problem and if so if there are any suggestions on how to address it?

Also, just for fun, I’m including a pic of my car with the post. :)

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The oil pressure is not a problem. Assuming you are using an appropriate oil for the conditions, higher oil pressure usually indicates the engine is in good condition.

Normally, carbureted cars will run richer at higher altitudes, not leaner. There is no need to use the choke once the car has been started (cold) and run a few minutes. There is rarely any need for the choke in warm weather or if the car has been run in the last hour or so.

I have no idea why using the choke would affect the oil pressure, as long as the engine speed was held steady.
The choke is used for cold starting, and it is good practice to open the choke as soon as the engine will allow it, and open it fully as soon as possible and leave it open.

That is a beautiful car.

Operating instructions and service information can probably be found for your car in the Literature Archive section of this website, and original advertising material is likely available there, too.

Hey thanks TxGoat, I appreciate all the advice you give here. And yeah, the oil pressure drops when I pull out the choke, even while the engine is running the exact same speed. Once warm, it does seem to run a little better with the choke pushed all the way in but seeing it nearing the top of the gauge on oil pressure always has made me nervous - it sounds like you’re telling me I don’t need to be.

And yes, I have been reading the materials - they don’t have the owner’s manual for the 443, but they do for the ‘28 6 cylinder models, and the commonalities are enough that it’s pretty useful (the instruction manual partly what inspired the question). But still on climbing the learning curve…slowly. :)

Spencer,
The engine in the 643 has a system in the oil system that feeds oil to the sides of the cylinder walls to lubricate the piston skirts on start up,
it is controlled by a valve on the right side of the engine where the oil pressure gauge feed line is located.

It is controlled by the choke cable and is only active when the choke is on, if you follow the choke cable from the fire wall toward the carb. you will see it goes to the oil valve then the linkage goes up to the choke on the carb.

Being that it draws oil from the same place as the oil gauge would explain the drop in pressure when the choke is on.

Sincerely, John

Thanks John, my 443 has the same system so that makes sense. I probably should’ve thought of that.

Pre-oiler. That's the explanation, for certain. A good idea.

A follow-on question to this topic: reading my materials indicates that if I did need to adjust oil pressure, I could do so adjusting the relief valve located within the fuel pump. My question is how to access the adjusting screw. Below are the instructions from the service manual (instructions for this operation are the same for the 6 and 8), and a sectional cross drawing from the same.

I do not read this to indicate that you need to drop the whole oil pan to access this piece. However when I remove the cover below the oil pump at the bottom of the crankcase, there remains a casing covering fuel pump mechanisms which can be seen in the illustration. None of the materials I’ve consulted suggest to me how to remove this casing, and examining it myself I cannot see any obvious way to do this. Is this a job that would require me to drop the oil pan to access the full fuel pump (not a job I want to do if it can be avoided) or is there something I’m missing here in how to remove this casing? Thanks.

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It looks as if your indicated oil pressure is very close to spot-on, with around 20 PSI at idle and around 50 PSI at higher speeds when first started, and dropping by 10 to 15% with the engine warm. I wouldn't touch it.
It looks as if what you are seeing with the oil pump outer cover off is the oil screen assembly. It should be removable for cleaning. I don't have any direct experience with that type pump. I suspect the screen assembly is held by friction and secured by the pump cover, but I don't know for sure.
I doubt if it needs attention based on your oil pressure readings. A clean engine using modern oil is not likely to need regular attention to the oil screen, as was the case in earlier times.

"medium cylinder oil" corresponds roughly to SAE 20 oil of high quality.
A quality multi-grade detergent oil will give excellent service in a old engines that are in good condition. A 10W30 oil, either "conventional" or synthetic, should give good results at temperatures from around 10F to around 90F. In very hot weather, or with a worn engine, 20W50 usually gives good results.
Modern motor oil offers superior lubrication under a wide range of ambient conditions and is far superior to the best oil available prior to WWII.

Our 526 SIX had the same problem....pegging at 50. We solved it by removing the plate under the oil pump, the screen pops out with a little coaxing.
We removed the spring and ball, cleaned the ball, cleaned the seat and reassembled.
Be careful to note the depth of the adjustment screw when you take it apart.


Bob

Sorry to be late to the dance on this, but every 1920s Packard I've seen runs fairly high oil pressure, seems to be normal on these cars. My '29 runs straight Lucas 30 weight zinc-infused oil (I'm in Louisiana, it's always warm here), and the engine idles at 35-40 psi, at speed it usually stays at 40, at higher speeds it will go to 45 or 50. Been driving it like that for four years, it's never caused a problem. Friend in Texas has a '30 coupe, it does pretty much the exact same thing. I don't think you've got anything to worry about. Fantastic car and love those headlights!