Cold Weather, Oil Pressure

[theleisure]

My car is doing something a bit odd in this cold weather. I park it on a hill (facing downhill) and lately when I start it it's reading about 25 on the oil pressure gauge until I roll down the hill and turn onto a flat street. Once i get around the corner and let it idle on level ground it's back up to 60+ after a second or two. I don't recall it doing this before the recent cold spell. Oil level is fine. How much damage is this going to do to the car if I have to let it warm up for a minute before I can head to level ground? I could park it on the other side of the street facing uphill bu I like having it in front of my house.

 

[Morris]

My oil pressure gauge has been acting weird in the cold weather, too. It behaves correctly once things warm up. Don't really have any insight... just throwing that out there.

 

[tdskip]

So I think the key question here is if it is the gauge or your actual oil pressure.

Is the gauge otherwise behaving correctly? Have you ever had reason to test it?

 

[DrEntropy]

This is a car with a "hard" gauge, yes? It usually means the pickup is not sucking oil on initial start-up. I'd look for an alternate position to park it overnight.

Yinz livin' on Mt. Washington an'at?!?

How 'bout parking perpendicular to the slope with the butt-end to the street... or a couple pieces of 2x4 under the rear wheels to try "leveling" it a bit?

 

[Tullamore]

I thought the same thing as DrEntropy, it is creating a bubble at the pickup because of the cold weather making the oil more viscous.

 

[mightymidget]

Put a shop light (75watt)under hood near OP line overnite and see it you have the same readings when you crank and start engine the next morning

 

[DrEntropy]

If you're able to string a light, it'd be put to better use by bein' under the oil pan... but that invites some ~other~ concerns...

 

[twas_brillig]

What temperatures are you seeing at night, and what are you using for oil - a multi-grade such as 5-30? or something thicker? I tried adding a quart of 10-30 once at about -20F, and the oil had to be squeezed out of the jug - it would not flow.

What might be happening is that the oil pressure relief valve (down on the passenger side of the block; a big spring that is held in place with a bolt into the block and that forces a 'bullet' shaped piece up against a machined facing within the block: if the oil pressure is too high (eg cold, thick, oil), it pushes the 'bullet' away from the seat and lets the excess pressure bleed back into the sump, all before hitting the oil pressure gauge.

We have an AH 3000 that had low oil pressure; turns out that the spring had gotten weak over the years and was letting the oil drain back into the sump; the pressure came back to nice and healthy with a new spring, so that's why I'm thinking it might be thick oil being bypassed back into the sump

My perception is that 25 psi is fine, and Bad Things are not happening, but I wouldn't claim to be an expert.

Doug

 

[Hairyone]

I would think it's the pipe to the gauge, with a little water or "mayonnaise" in it which is freezing.

 

[jlaird]

But then 25 lbs is enough that it won't hurt anything. Enjoy your ride.

 

[Guest]

Doug, it has to get to the gauge (whole system) before the relief opens. You have to buld complete system pressure for it to work.

I think it might be sucking air too.

How much "erl" you got in it?

Don't fire her off till you coast down the hill onto the flat street.