oil pressure at idle

In my 91 TT I have the stock oil pressure gauge. it has 108k miles but the thing is i feel like my pressure is really low considering my 93 NA sits at about 1/3 the way on the gauge (maybe the 4th hash mark). sometimes the gauge on my 91 TT will read even lower (only 1 hash mark from the bottom) after driving it and letting it idle once i park. most of the time it will sit no higher than the 2nd hash mark while idle.

i attached a picture. my question is where should my idle pressure be at? it has no problem while driving and the pressure rises normally as it should while driving.

The stock gauges are CRAP. What the hell is a TICK anyway?

If you're concerned about your pressure, get an aftermarket gauge and find out what your REAL pressure is....

Just my .02.

Bob.

Nothing says "knowing" like a quality mechanical oil pressure gauge. If the car has as little as 8-9psi hot at idle it can still be good. Look for 20-25psi at 1750rpm, 25-30psi at 2000rpm, 35-40 at 2500rpm. All of these numbers are "about". And the pressure should continue to climb as rpm increases until it reaches the relief valve set point, around 85psi.

In general, 10psi per 1000rpm is considered to be acceptable. Based on that, 7psi at 700rpm hot idle is sufficient.

While the stock gauge is total crap, even the best gauges will have some range of accuracy. The range of accuracy is usually expressed as a per-cent of "full scale deflection. If that is even 1%, then the accuracy of a 100psi gauge is 1psi. That 1psi is minimal compared to 35psi, but is very large at 7psi.

My engine is an original unopened 98 turbo with 155k miles. It has 23 psi at hot idle (670 rpm) and 58 psi at 2000 and 90-95 at 3500 and up.

It is possible your pressure is in the low teens at that reading on the stock gauge but you wont ever know for sure until you install a decent aftermarket one. I've seen a car race on a track with about half my oil pressure at any given RPM up to 3500 or so (then it ramped up to about 70 psi max) and it handled it fine throughout the hot summer day on the road course so don't take my numbers as prophecy.

OEM oil gauge is about as useful as the OEM boost gauge. I put a $25 manual OP gauge from advanced auto into my car and am much happier.

i will update when i do that. I have never done it before, though, so ill look around and see how its done right so i can get the right reading. thanks

a little update...

got the oil change done yesterday. sure enough i only drained 3 quarts. big reason why my oil pressure was low. didnt know that the dipstick reads incorrectly until i read it on 3sx . as for now the engine seems quieter and the oil pressure is reading a little higher at idle. still kinda ticked off that i kept reading my oil as full when it wasnt....will see what happens when i get a better oil pressure gauge

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Originally Posted by b_rad

a little update...

got the oil change done yesterday. sure enough i only drained 3 quarts. big reason why my oil pressure was low. didnt know that the dipstick reads incorrectly until i read it on 3sx . as for now the engine seems quieter and the oil pressure is reading a little higher at idle. still kinda ticked off that i kept reading my oil as full when it wasnt....will see what happens when i get a better oil pressure gauge

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Do you have a link to this information? News to me...

He might be referring to this http://www.3si.org/forum/f36/after-m...7/#post6542281

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3SX used to carry one years ago that was the right length, but it is long since discontinued. But something to watch out for that was a "sometimes an issue" with that one was the shaft itself that went down into the pan. The stock one is a flat piece of metal and bends relatively easily. That aftermarket one was a round wire probably 60 to 80-thou thick (about 2mm) and was almost too stiff for the double-bend that our dip stick tubes make.

Just something to consider in your aftermarket pursuits...

EricB

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the link i was referring to is this

http://www.3sx.com/faq/oilpancapacity/

its under the tech/faq page on 3sx. i frequent the site so when i saw it recently then they must have just added it.