Packard Forum Index » Post-War (1946-54)

I was driving the 51 200 with the rebuilt 327 around town today - warm about 80 degrees. Temp gauge got to the "M" in temp, so it wasn't too hot. The oil pressure light started flickering, first around an idle - no concern there. But then it starting staying on bright at 30 in 3rd. I have a gauge on it as well, and it looked ok around 35 psi. I did replace the sender after I rebuilt the engine with one I got at O'Riley's. Basically found one that would fit. The engine was originally a 288, but swapped cam/crank/rods etc from a 327 into it. The oil pump was working fine before the rebuild (last winter), so I just cleaned it and primed it with grease when the engine was fired up. I do have the oil pump from the 327 donor engine. The engine now has about 300 miles on it - this symptom started showing up about a week ago - it does seem to be related to engine temp. The oil is Rotella 10-30 with ZDDP added. Any suggestions? (short of more snake oil....)

Specs say the pressure should be 40# at normal driving so yours doesn't seem too far off. Perhaps the sender has become a bit sensitive or was the wrong range as they do come with various pressure on/off points. Here is one from the x-ref Kev found that might be worth trying or perhaps you can verify yours operates around that 20# range.

Attach file:

---

  (13.21 KB)


  (20.46 KB)

No snake oil necessary, but you might want to bump up to Rotella 20-50.

The 288 and 327 pumps are the same, no need to change. Check the thickness of the gasket under the pump cover. Sometimes they are supplied really thick, should be .005 or less.

But I agree, 35psi at 40 mph is not bad. There are many running around happily with a lot less.

If you have an accurate gauge i would trust that over a sender from a non-packard vendor. However i found my packard dash gauge doesn't read as accurate as the little one i mounted down by the oil sender on the block.

I heard a rule of thumb was 10psi for every 1000 rpm. 35 psi would be fine cruising.

I also thought that the manual said somewhere, when hot, 10ish psi idle and 35 (or maybe 40?)psi cruising down the road. It would sound like you're right on, but i'd check the manual rather than my memory.

I'm running straight 30 weight (rotella) at the moment with good luck. I was running 10-30 as my first flush after the motor swap for the first few tanks, and noticed after it was dirty that it was a good 3-5psi difference at idle, and about 5-7psi lower than the clean straight 30.

thanks - I'll order a new sender and switch to straight 30 weight oil. The oil pump has the super thin gasket - looks like about the thickness of office paper.

Ok - problem solved. First I put a good mechanical oil gauge on the car to test the pressure. I removed the old sender - I had put teflon tape on the threads to help seal it. Bad idea. A bit of teflon was just slightly over the hole in the sender. Stripped the tape off and reinstalled the sender. No more false alarms. Oil pressure at 40 mph is 48 psi, and about 8-10 at an idle. Life is good again.

Good to hear it wasn't anything major

I'm running Valvoline 50 wt racing oil (excellent quality) because of the problem you are having and have had good success.

Denny, the heavier oil like the SAE 50 you're using does give higher pressure because of it's greater resistance to flow. And a bit more "cushioning" effect.

But like so many things, there is a trade-off and in this case it's lower flow volumes and hence poorer heat transfer from bearings, etc. Which way is the better compromise I have no idea.