Oil Pressure FSM Spec Questions

[kastein]

Thank you for your replies. Exactly TWO people attempted to answer me with the data I requested. The others went off into a tangent regarding how accurate I am able to read my gauge. Not helpful!
For the two people that attempted to actually offer me advice based on actual oil pressures and experience...Thank You.

However...my original question was NOT answered by anyone:

ARE THE NUMBERS SPECIFIED (11 AND 13 RESPECTIVELY) THE NORMAL NUMBERS FOR HOT IDLE OR THE MINIMUM NUMBERS?

It is really a simple question. The answer would read something like this: "Those numbers are the recommended numbers, by the factory, for a new, good engine." OR "Those numbers are the MINIMUM safe numbers recommended by the factory and your engine is worn."

Anyone who actually KNOWS??

I am really not interested in a discussion of whether or not my gauge is accurate within 1 or 3 psi. That was NOT the intent of this thread.

It was a simple question. Are these numbers NORMAL or MINIMUM? I am referring the numbers specified by FSM and Chilton.....NOT your opinion on the accuracy of gauges.

Any help is appreciated. Hopefully a person who works on Jeeps for a living or a person who understands the FSM will step up and offer the actual answer to the question.

Thanks in advance to anyone who can offer any more useful answers.

JG

You realize cruiser54 and the other guys you're being a dick to here are either very respected members of this forum, or current/former dealership techs, or both, right?

Verify the gauge readings with a mechanical gauge before you start eyeballing the engine.
Totally possible the gauge sender is damaged / defective. It wouldn't be the first time somebody messed up the sender while changing the oil. Hell, I've done it myself.

Agreed. And I've broken a couple, usually when the damn filter's on there real tight.

I like to see around 15-20 hot idle, but as long as it's over 10 and not making any ugly noises, I'll run it. I like to see over 40 cold and over 40 hot running.

I saw one engine that had over 60 cold and over 50 hot running develop a severe mid throttle rod knock a few hundred miles after it was installed. It's all in how much crap is in the system and what has happened to it in the past, pressure doesn't tell the whole story.

Hell, you could put GL-5 in your engine (I would NOT recommend this) and get 100psi idle, but it'll be because the pump can't force it through the passages well enough and you will starve your bearings. You want the oil viscosity that results in maintaining good oil coverage/oil wedge on the bearing surfaces and also has a high enough flow rate to flush heated oil out and replace it with cooler oil from the sump, not the oil viscosity that gives you the highest pressure. These may or may not be the same thing.

 

[O-Gauge Steamer]

It is both true and slightly disturbing that the Factory says 11PSI oil pressure at idle on an engine at operating temperature is acceptable.

It has always annoyed me but... That is how they run and they can run that way for hundreds of thousands of miles.

The viscosity does play as Kastein points out and thicker is not always better. You can easily reach a point where the gauge (located just at the pump discharge point) is reading high but there is virtually no flow owing the the oil's viscosity.

In your case, IMO, I should not worry about it much at all.

 

[holysirsalad]

It is both true and slightly disturbing that the Factory says 11PSI oil pressure at idle on an engine at operating temperature is acceptable.

Weeell consider the context... the FSM is the repair guide for the dealer techs. Perhaps 13 PSI is just high enough that it won't cause any problems during the warranty period. In other words "not worth fixing, by the time it's totally screwed we won't have to fix it for free"

 

[GregGA]

At one point, I had an Autometer low oil warning light on my 87. It was set for 20 psi and would flicker on and off at hot idle. The factory gauge read about 20 psi when it flickered,so I feel my guage is fairly accurate.

The Autometer light saved me one time when I dumped all my oil. The reason I emptied the sump was becsuse the Autometer's sending unit was attached to the factory sender by a brass T. The Autometer sender was big. So after a few years, the T fatigued and broke, pressure washing the engine in oil:flame:

KISS. I no longer have the warning light I always read about 25psi at hot idle. Wix 50515 filter and Rotella 15-40.

 

[BMXxXJ]

My hot idle has been just over the 10psi make for 111k now and on it's 3rd head. still pulls like a beast

 

[yossarian19]

Mine has been around 15 psi on a hot idle since '07 when I bought it. No noises, no troubles, no complaints here. I'll fix the problem when I have one.