? bout what Oil Pressure should be on '91 350 - Off-Road Forums & Discussion Groups
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post #1 of (permalink) Old 02-07-2002, 01:23 AM
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? bout what Oil Pressure should be on \'91 350

Ive got a couple questions.

First is what should my guage look like in a 91 Truck. I was under the impression that the guages should be the style like is in the 88's with the "slides" style guages or whatever they are called. Instead I have analog style guages like what would be in say a 1994. Also I was wanting to know why my oil pressure readings on my guage are calibrated from 0 to 30 to 60psi. I have a buddy with a 1994 350 Blazer and his guage reads 0 to 40 to 80psi. Why the difference???? BTW i dont know whether my manufacture date would have anything to do with my guages but my truck was made late in 1991, Cant remember exactly but Im thinking it was made in July of 1991.

Second is what should my normal oil pressure be per factory specs. I recently replaced the sensor so Im 90% sure theres nothing wrong with it. Anyway my oil pressure when cold starts out at 30, and doesnt change hardly at all with rpm, pretty much stays on 30 to 31, then when it is warmed up the oil pressure at idle is typically around 25 to 26 psi, and under load and throttle doesnt really go above 28 psi. Is this normal or is it just because my engine is old (160K miles on it).


Sorry for all the questions.

Thanks in advance for the replies


1991 K1500 350 TBI and Reg Cab Long Bed. 5spd w/152K mi presently about ready to blow up. 700R4 soon!

1996 Pontiac TA WS6, Ram Air LT1, Black, Loaded, A4, No T-Tops
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post #2 of (permalink) Old 02-07-2002, 11:42 PM
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Re: ? bout what Oil Pressure should be on \'91 350

If your oil pressure is stable, then it is fine. When the needle starts to fluctuate a bit, then watch out. If you have changed oil and filter regularly, and kept your truck in a good state of tune, then it should last you well beyond its current life span. I like to use synthetic oil, costs more, but is real slick stuff. Worth the cost if you want your engine to last longer. As for oil pressure, note that the cam manufacturers don't like high oil pressure, high volume pumps, or any kind of splash control such as windage trays. They say it can lead to pre-mature cam wear. Stock pressure has a lot going for it, including distributor/cam gear longevity.

post #3 of (permalink) Old 02-08-2002, 12:36 AM
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Re: ? bout what Oil Pressure should be on \'91 350

Ive been wondering about oil pressure on too on my 90. Starts out at about 50psi when it's cold, but goes down to 25-35 when warm. At idle in D it's only like 15psi though. My truck has 200k on it but the engine was rebuilt before I got it so I'm not sure how many miles are on the rebuild. I guess higher milage engines have lower oil pressure though.

Gallup, how much fluctuation are you talking about? My oil pressure fluctuates with engine rpm's, but stays pretty stable when cruising. Is this normal?

90 Z71
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