Oil Pressure at start up

[dwp]

doing some quick searches and it doesn't seem to be an issue.

2021 with the pentastar, bought in july used.

On occasion, and i can't seem to find a rhyme or reason, on cold mornings it will start up at 80+ psi on the oil pressure, and will stay there 3-4 minutes, even after the revs kick down. (and it never comes close to 3,000 rpm on start up at idle).

Kinda curious if this is normal, it doesn't seem to be temperature or rpm related.

I've had colder days were it started up and would idle just over 30 psi even before the rpms dropped after warming up.

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[Old Dogger]

Yes, it is a two-stage oil pump. The high stage is used for startup, and when the engine RPM reached 3500, which also activated the piston oil squirters.

 

[Pape]

Yes, it is a two-stage oil pump. The high stage is used for startup, and when the engine RPM reached 3500, which also activated the piston oil squirters.

Was not aware for the piston oil squirter being turn off in normal operation.
Also is it not 3000 rpm the threshold before switching to high flow in normal operation ?

 

[Old Dogger]

Also is it not 3000 rpm the threshold before switching to high flow in normal operation ?

It appears that the factory has changed the piston oil injector supply, to where they are now on all of the time!

Oil system and engine lubrication
The advanced oil filter system eliminates oil spills, thanks to an incinerable filter element instead of the typical spin-on filters; the filter is conveniently located on top of the engine.

A chain-driven, vane-type variable displacement oil pump adjusts the flow rate and pressure as commanded by the engine management system, which uses a solenoid to drive the pump into low or high pressure mode. For example, below 3,500 rpm, the pump conserves energy by using low pressure; at speeds over 3,500 rpm, the pump switches to high pressure.

A force balance mechanism inside the oil pump adjusts the size of the pumping chambers to alter oil flow. If the oil is cold, the pump reduces the size of the internal chambers. When the oil is hot and thinner, more oil is needed, and a spring increases the size of the pump chambers. This also saves energy.

The pump is driven at a 1:1 drive ratio; its location under the block is more efficient than an on-crankshaft location. An internal, mechanical ball-and-spring relief valve dumps oil into the sump when needed, for conditions such as a cold start with high engine speed. Both pump and pressure regulation solenoid are non-serviceable.
the oil pick-up tube is supported at the windage tray. Three oil gallery plugs are in the engine block; oil pressure an be monitored with a scan tool. Oil pressure and temperature sensors are on the oil filter housing assembly, which is mounted on top, between the heads; the oil cooler (a plate-style coolant to oil heat exchanger) is mounted to the oil filter housing as well. With Wrangler, specific upper and lower oil pan requirements have been engineered into the engine to provide increased grade requirements, keeping the oil within reach of the pump when the vehicle operates at steep angles (Wrangler also has a higher-mounted alternator to allow for water crossing, and a unique intake system with induction handled by a revised throttle body on the left side, where other Pentastars keep the intake on the right).

 

[dwp]

Yes, it is a two-stage oil pump. The high stage is used for startup, and when the engine RPM reached 3500, which also activated the piston oil squirters.

I'm aware of that as mentioned in my post.

My question is the lack of consistency with why sometimes it starts high and other times it doesn't.

What triggers it on a day when its 30 degrees but not on a day when its 20 degrees out.

anyone know what the temp parameters are for it?

 

[Zon]

Sometimes you think engine is cold but it doesn’t shoot up.

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