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Gary, GMC Technician
Category: GM
Satisfied Customers: 17006
Experience:  15 years gm master tech/15 years ASE master tech
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My oil pressure is erratic and goes down...pressure gauge..oil pump

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My oil pressure is erratic and goes down. The mechanic I took it to, already charged me $350 to change the filter, pressure gauge, and oil. But they told me it didn't do much and they want to install a new oil pump and screen. How much would that cost for a 2005 Yukon and do you think it's necessary? The way he described the reasoning for it seamed very vague.
define erratic?needle jumping ?or cold the PSI is high and as it gets warm it slowley drops down?
Customer: replied 6 years ago.
When I start the car the needle is low and my car starts beeping and telling me I have low oil pressure. Whenever I have driven the car for a while, the oil pressure levels out and seems to be at the normal pressure. But if the car is cold, like in the morning when I'm stopped at a red light or stop sign, the pressure goes really low again.

The mechanic said he hooked up a pressure gauge to the oil and he said it did the opposite though. He said it decreased when the car was warmer.
did they test it with a mechanical guage cold to confirm what the actual oil PSI was reading?or did they just test it hot?
Customer: replied 6 years ago.
I think they did both. They tested it hot yesterday and then tested it again this morning cold. Is that what you are asking?
yes it just confused here when they started it cold didnt they see it acting up and the low oil pressure light on?and if they saw that WITH a mechanical oil guaged installed was it in fact low?you following me?
Customer: replied 6 years ago.
They installed a new filter, guage, and changed the oil before they let it cool down (since it really only goes that low in the morning or Tuesday when it rained all day), I believe. That's where I'm confused too and that's why I wanted to ask you. This is what they said...the new filter they put on has a valve (or something) that keeps oil in it, so when it is started up oil pressure already exists; they said I didn't have the "right" oil filter in my car. The place where I get my oil changed installed the oil filter, but I can't remember when; it was within the last year though. I don't know, I'm confused about this...I'm decently mechanically enclined, but I don't know a thing about car parts. They never told me if they saw the light on, but they did say it got low to 4 psi (guage I assume) on their guage, but they didn't tell me when it got that low.
since its doing this with the correct oil filter on it.we need to know if it fact has low oil cold or not.or the guage is lying to you in the truck.i just don't understand why they didn't confirm the problem before they attempted any it comes back to confirming if in fact the oil PSI is reading that low cold or almost tempted to have you run down to Napa or Pep Boys and pick up a mechanical guage and have you put it in where the oil switch is then start it cold and see what it reads threw all the ranges.also remember as things warm up they expand and could be tightening up a possible bearing clearance problem or the oil pump.confirmed low oil pressure hot or cold there is either the wrong oil.bad oil pump.or a be a clearence.problem.oil pressure is just like putting your thumb over a garden hose end with water coming out the more you take your finger off the end the less pressure you have
Customer: replied 6 years ago.
how much should changing an oil pump will cost?
is this engine a 6.0 or a 5.3 or a 4.8 ?
Customer: replied 6 years ago.
I honestly don't know, I think it's a 4.8, but it could be a 6.0.
can you tell me the 8th digit of your vin number that will tell us for sure
Customer: replied 6 years ago.
My car is at the shop, and I can't remember, sorry. I think he said he wants to charge me $1,000 to do it.
yes your looking at anywhere from $ 800 to $1000 depending on the labor rate and parts mark up to change that oil pump
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