Also if the loss of pressure on an incline is both hot and cold.

 

Its nose up, and seems to be when hot. First time it happened was when I was coasti g backwards down the drive towards the garage. I shut it off, got out and checked the oil level, which appeared to be ok. Started it again and still showed no pressure. Later, after it cooled a bit, I started it again and it showed I had pressure.

 

I'd still bet on it being the gauge. My OP gauge reads 20 psi low. So at cruise speeds hot, it reads 30, at idle it reads near zero.

Since you don't mention it, I assume you don't hear rods knocking when it shows no pressure?

 

Is this a Flatty or a Y Block?

 

I think we're discussing a flathead. I just threw the Y block thing out there, hopefully not as a confusion factor.

 

I would do an oil change and put five quarts and check the reading on the dipstick. Check you year, make, and engine specs to see if it actually needs five or six quarts. Park it back on the driveway after the oil change and see what happens. Would not hurt to check the oil pressure with a manual gauge. If this continues you may have a dirty oil pump screen or a broken tube. Lots of luck!!

 

No noise that I've noticed.

Besides my driveway, the only time I've noticed it hit near zero was as I neared the top of the hill my father lives on. It's a fairly steep grade that requires that I downshift to second gear to climb it. I was keeping an eye on my temperature, and noticed my oil pressure gradually decreasing as I drove.

I'll pick up a mechanical gauge this week and see what it reads. I'm also going to go ahead and change the oil. While I'm at it, I may order the gaskets and drop the oil pan and make sure it's clean on the inside.

 

I agree with Ray on the sludge. When I pulled the pan on my flathead last week the screen on the pickup tube was heavily coated with sludge/coke particularly on the bottom. Three days in the cleaner tank and lots of scrubbing with a brass brush got it clean. If you found sludge when you drained the oil your screen is probably blocked too. It would be worth dropping the pan and checking if for no other reason than to clean out the remaining sludge which could be significant as it didn't drain out of my pan when I drained the oil. You also might want to check the bottom of the oil filter as it never drains and mine had about an 1 ½" of sludge in it. The out outlet holes are small and on either side of the center post about even with the inlet orifice. Hence it never drains unless you take the canister off and empty/clean it. I had a '49 Jeepster that has a plug near the bottom of the canister for cleaning . . . a messy job.