I just went out and did some tests. First before starting it, I checked the oil level. Dead on the full mark, stone cold engine after sitting in the garage all night.

It is 74 degrees and beautiful weather. I started the car, and the first start in the morning always takes a few extra spins to build the fuel pressure for the fuel injection system. Maybe three seconds of the starter running and the pressure was up to 60, just from the starter spinning. I ran the RPM up to 2,000 and it went to about 70. I shut it off, and turned the ignition on to power the gauges, and it slowly dropped to zero. Start it up, and up to about 65 psi and not much higher at 2,000 RPM. Shut it off, and watch the pressure drop to zero, and start it again. It fires off almost instantly on the second and third start. This time it stays at 65 again.

The oil sure did not heat up much in 30 seconds of running.

It really looks like the gauge is showing what the sender is sending. The oil pressure sender is right next to, almost under the distributor, and really hard to get to and it is next to the firewall. I would hook up a mechanical gauge to get a real reading, but I have no idea where I would connect it to. I don't know of any oil passage ports with a plug that would come off to install the connector to the gauge.

I will do an oil change as soon as I get the 911 off of the lift in the work bay. I hope that is tomorrow. I am working on the electrical seats and the recline motor for the seat back is not working.

Check above the oil filter- there is a pressurized opening there, should be 1/4" NPT IIRC. Easy to get to. My 89 silverado OE pressure sender is there.

Personally, I think somehow you got a cracked exhaust manifold- goes away when slightly warm. Are you using gaskets with the OE manifolds? If so, ditch them.

GM did not use exhaust manifold gaskets iron to iron. the ones that come in various gasket sets are useless.

PS as long as the engine doesn't start getting hot and ticking and getting lethargic at idle, you should be OK for oil pressure.

A SBC with a failing pump does all those things :)

Its super easy to put on a direct read bourdon type gauge on a 350, i run that on mine. Then at least you know.

The ticking really does sound aligned with a manifold leak.

OK, more data. The car sat for two hours after the 30 seconds of running from earlier in the day. I had a 40 mile round trip errand to run. On initial startup the pressure got to 60 or maybe 62 PSI and never went higher. No ticking sound at all.

As the water temp got to 180 and the thermostat opened the oil pressure was already in the totally normal range. I drove 20 miles, had to merge onto a 70 MPH interstate, and the RPMs got to 3,000 or so before a shift and oil pressure was all normal.

On the return trip the engine was at full temp and all was normal.

Tomorrow morning I will do a cold start and drive the same errand. It will be interesting to listen for a taping and to watch the oil pressure.

Replacing the oil pump is not a task I want to do unless I am convinced it is trashed. I presume that means removing the oil pan, and that means lifting the engine a few inches and lots of work. If the pressure was low, it would make more sense that the pump was bad. I will investigate the oil pressure relieve valve. I am sure it is a pain to get to as well.

<strike>The relief valve is built into the oil filter male fitting the filter attaches to. Held in by two little bolts. It's looking right at you after you remove the filter. Drop the filter, two (5/16"??) bolts. </strike>

EDIT: that's the oil filter bypass. Sorry

Pulling the pump will be an almighty pain in the ass. You'll have to raise it enough to drop the pan DOWN to clear the pickup, deal with the timing chain cover, etc. Might as well pull the engine, then at least you can work in comfort.

Might also just be clatter from lifter bleeddown. My Pontiac does that crap now and then. It's totally fresh.

Another idea: there's a crack somewhere in the manifold which closes when the block gets warm enough. OP and ticking are unrelated. OP is just the cold oil, and the reading on the gauge was faulty as in out of range.

Mentioned a couple of times. One comment mentions exhaust gaskets failing. I think that's really plausible. Problem is so new maybe the telltale exhaust carbon is not even showing yet.

My reading on the web found guys saying you swear it's a lifter, you know it's a lifter but it's the exhaust.

I don't like 70-80 psi though if his gauge is close on a 60F day.

Those manifolds are a pain in the butt to keep the nuts tight. Part of my routine oil change and lube is to check and on occasionally tighten the nuts on the back of the manifold, closest to the firewall. The other nuts are always tight. The manifolds were truck manifolds I got from a junkyard that had the proper larger size ports to replace the 305 manifolds I had from the old engine. They were in very good shape and have been flawless for 71,000 miles with the occasional tug of the back bolts.

I will double check all of the manifold bolts. Some are behind the AC compressor and other brackets so a real pain to get to, but they never get loose.

This morning temp in the garage was about 65 degrees. Once again, just cranking the engine the oil pressure gauge read just over 60 PSI and I backed out of the garage, and turned off the engine, but put it back in run mode to powere the instruments. The gauge was very slow to start dropping, and never did go below 25 PSI. After 30 seconds, I fired it up and ran my 40 mile trip. All the way there the pressure was at 60 PSI and did not change with temp or RPM. I just turned off the ignition, and just removed the key and got out. When I got back in the gauge had not moved as is normal with no power. I fired it up, and it was still at 60, and did not change but a few PSI at different RPMs.

I got home and turned off the engine, and put the key back in run mode, and it took a full 30 seconds for it to drop to 25 PSI, and another 30 seconds to drop to zero. I fired it up to pulled into the garage, and it went to a normal run pressure.

So at this point I suspect a bad sender. Rats. It is such a pain in the butt to get to. That is WAY way way better than replacing the oil pump. So I guess I will order a pressure sender, and fight with that. Oh joy!

And no ticking today. I really think that is a separate issue, and likely a sneaky exhaust leak.

To rule our future problems just drop in a LS7

I think the two problems are unrelated.

Lifter or exhaust leak on the noise. More likely the exhaust.

Bad gauge or sender, could be either. I'd disconnect the wiring at the sender and play with what the gauge says before I'd yank either part out.

I just ran a short one mile errand. On startup it went just past 60 PSI. When I got back home I once again turned it off, and it took over a minute to drop to near zero. Fire it up, and the readings are normal. Turn it off, and restart and the pressure shot to 60+ again.

It is like the sender is not bleeding the pressure down like it should. A new AC Delco sender is 35 bucks or so. I think I will go to the local FLAPS and get one. It is the sender that was on my 305 and I just swapped it to the 350 when I did the engine swap.

And I looked into a LS swap and I would need a new rear end like a Ford 9 inch to hold up to that power, rear disks and a 4 link, and on and on. My base 350 in the car right now is not a tire burner at all, but it is not a drag car, just a daily driver. Plenty of go pwer for that.

With the present sender being such a PIA to get to, I'd look into locating the new one some place else. There's got to be other oil plug holes that would allow that.

Did you change the oil filter? Seems like an easy cheap way to start? If it’s restricted in some way it will do what you’re experiencing. Second thing I’d do is the sender or at least put an oil pressure tester on it to see what’s really happening. I’d bet money on it not being the gauge.
After 30 years of very busy automotive repair shop ownership, I’m sure we must’ve replaced a gauge for an oil pressure reading error but I honestly can’t remember a single time.
It was always the sender or the reading was accurate and something else was wrong.

Good luck

My experience with pressure sending units is kind of embarrassing, but I learned a lot from it.
'73 Alfa Spider with SPICA injection all of a sudden shows NO pressure at all.
Being new to Alfa's I start investigating and find out they have pressed in plugs in the crankshaft oil passages from the drilling process used to put the oil passages in the cranks.
Son and I pull the engine. Pull the pan....story to be continued...I need to go help a neighbor who is climbing on his roof...

OK, neighbor is taken care of.

So we pull the engine and find all the plugs in place, but we pull them out anyways since we're in there and all already. You know the drill.
Put the engine back in the car hook everything up and go for a drive. All is well, until two weeks later when it shows NO oil pressure again.
No way to tell if a plug fell out or not as you can't see them with the pan on in the car, so, out comes the engine again.

Son comments that 'Gee Dad, we're getting pretty good at this, maybe we should open an Alfa repair shop.'

All the plugs are still glued in place. (Heavy sigh here)
Engine goes back in the car.

What could it be?

We try a different gauge and it shows we have oil pressure. Hmmm.

This is a mechanical gauge so maybe it just might be the gauge is bad.

Replace the old gauge with a new one and what do you know, we have oil pressure. And glued in oil plugs in the crank too.

This all took place before the internet was a thing so my diagnosing skills weren't quite as developed as they are now.

Simple stuff first is now the moto.

YMMV.

When you turn the ignition to off and remove the key you know you fully shut the car down. There should not be any residual 12v anywhere except at the ECM and radio. I don't know what kind of ECM you are using, but if as old as the car, there should be no power to a sending unit.

On the ticking, I have problems with the manifold bolt under the alternator.

I'd check the dash gauge before throwing 35 bucks at the problem. OTOH, it's likely time for a new sending unit even if it doesn't solve the problem of reading pressure when the car is 'off'.

z

Yup. Could also be a wickity-wack ground causing in issue. Maybe lost a ground strap somewhere.

Got 316K on my Silverado moon gauges, all kinds of weird gauge stuff occurs when the grounds go bad.

Gauges are all still fine.

Wear and scoring. It's not like they get a lot of oil flow past them, and they are a dead end for crap and crud to accumulate. Not that that's your problem here, but it is why the pistons in pressure relieve valves can stick.