New engine, now odd oil pressure anomoly...

Backround info:
Newly built (by me) 306
Only pressure gauge is stock gauge.
Before rebuild, the gauge read between the "R" and "M" in "NORMAL" when cold,
and between the "O" and "R" when hot.
The engine had 250k + miles, and we live in a warm climate, so I used 20/50 oil.

Now, with the new engine, we are using 5/30 for break in, since the engine was built 'tight'.
Yesterday it was driven for the first time. It was 60* out.
Today it is 40* outside, and the engine ran for the first time dead cold at low outside temp.
We noticed during trial runs yesterday that the new engine was reading at the "L", which is much higher than before.
Today, it was running between "L" and the red zone at startup...
After driving 2 miles, the gauge creeped up into the red zone and pretty much pegged.

The sending unit is the same exact one as before. No changes there.

I know that generally speaking, the stock gauge is basically a 'yes' or 'no' gauge.
If it reads, you have oil pressure, if not, you don't have oil pressure.
So I am not really worried... just curious if anyone has had something like this happen.

I used a stock replacement pump, and a hardened pump drive.

So, is this just an anomoly of a poor gauge?
I know the pressure has to be high, but I can't imagine it overpressurizing.
Is the sender not used to such thin oil, and therefore acting differently?
Thoughts?

As a side note, may or may not be related...
The stock volt gauge is reading lower than before now, but NOTHING was changed there.
Same alternator, same wiring, same battery.
It used to read in the middle, now it reads about 1/4, or between the middle and the "8" on the low side.
I was worried, and checked it with a volt meter while running, and it is charging, and it is showing no real signs of being low.
It turns slower when starting, but the engine is still very tight, so that doesn't bother me as long as it is charging.

It's just curious that the gauges are reading different than before, but with no reason to read differently, at least in the case of the volt gauge.

gearheadboy said:

The only thing I can say is you need to find a standard mechanical oil pressure gauge and check it. The electrical gauge, sending unit, could be an issue and being new you could have a pump issue.

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I wouldn't guess that a stock pump could overpressure...

I won't have access to the car again until Monday.
So now this is all just for the sake of discussion until I put a gauge on it.

I primed the engine on the stand with a drill, a very old single speed that I don't consider very strong. It did fine. I can see that particular drill burning up if there were any overpressure situation. I was thinking it might burn out just priming the engine without any issues. So I figure it is just an anomoly with the sending unit and difference in oil weight or something.

gearheadboy said:

If the pressure regulation valve in the pump were to stick in the closed position.......

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Didn't think of that.
Thanks!


No, really, thanks for more to WORRY about!
J/K!

UGH!

Bad head gasket on a new engine...
What I thought was a thermostat issue turns out to be water getting into cylinder #6.

84Ttop said:

i see the word anomaly and I'm instantly drawn to this post, probably cause i was just watching big bang theory, anyway. you need a mechanical gauge to be sure what is going on. i would only be worried if you had 100psi of oil pressure or more. mine idles with 60psi and is right at 100psi cruising.

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That's great oil pressure.
Seeing as how the stock gauge is a yes or no affair, I don't even understand how ours can read high.

Gotta stupid head gasket to deal with first now.