Oil pressure sending unit

Jason Morgan · February 22, 2020

Hello, I'm new to this forum. I have a 2012 GMC Sierra with 150,000 miles. The 5.3 litre engine has had the oil changed every time the oil life has hit 30% , around 5 to 6 thousand miles. The oil pressure dropped and I replaced the oil pressure sending unit (opsu) and the problem was fixed for about a month. The old screen filter under the opsu was dirty but not severely clogged. After about a month the oil pressure dropped to 20 lbs and the check engine light came back on. I am considering pulling the opsu back out , @ operating temperature, and squirting brake cleaner or something down the oil passage followed by 2 hot oil changes. My question is , 1: is this a good idea?, 2: where does that oil passage directly lead to?

swathdiver · February 22, 2020

42 minutes ago, Jason Morgan said:

Hello, I'm new to this forum. I have a 2012 GMC Sierra with 150,000 miles. The 5.3 litre engine has had the oil changed every time the oil life has hit 30% , around 5 to 6 thousand miles. The oil pressure dropped and I replaced the oil pressure sending unit (opsu) and the problem was fixed for about a month. The old screen filter under the opsu was dirty but not severely clogged. After about a month the oil pressure dropped to 20 lbs and the check engine light came back on. I am considering pulling the opsu back out , @ operating temperature, and squirting brake cleaner or something down the oil passage followed by 2 hot oil changes. My question is , 1: is this a good idea?, 2: where does that oil passage directly lead to?

AFM engines do not like incorrect oil, dirty oil, or additives in the oil. I would not add anything to the crankcase but oil that is Dexos1 or Dexos1 Gen 2 approved. I've seen several guys on these forums using top quality oils from Mobil One that were not Dexos rated and they had engine problems.

Jason Morgan · February 22, 2020

Thanks that is the diagram I was looking for.

newdude · February 22, 2020

57 minutes ago, Jason Morgan said:

Hello, I'm new to this forum. I have a 2012 GMC Sierra with 150,000 miles. The 5.3 litre engine has had the oil changed every time the oil life has hit 30% , around 5 to 6 thousand miles. The oil pressure dropped and I replaced the oil pressure sending unit (opsu) and the problem was fixed for about a month. The old screen filter under the opsu was dirty but not severely clogged. After about a month the oil pressure dropped to 20 lbs and the check engine light came back on. I am considering pulling the opsu back out , @ operating temperature, and squirting brake cleaner or something down the oil passage followed by 2 hot oil changes. My question is , 1: is this a good idea?, 2: where does that oil passage directly lead to?

Hard pass on shooting brake clean down the oil galley.

What brand oil filters are you using?

Jason Morgan · February 22, 2020

I usually get it changed at a jiffy lube. But when I change it it is ac delco

nqabigt · February 23, 2020

see carnau video 2 post down

worked for me

silveradosid · February 23, 2020

remove the oil filter and the screen, then blast it with brake clean and blast it out with air

nqabigt · February 23, 2020

17 minutes ago, silveradosid said:

remove the oil filter and the screen, then blast it with brake clean and blast it out with air

+1

Jason Morgan · February 23, 2020

That's what I'm thinking. The oil passage has got sludge in it. And from the diagram above it look to lead straight to the filter.

Thanks

Jason Morgan · February 24, 2020

I found this video on youtube . I hope this will fix the problem.

Jason Morgan · February 24, 2020

Thanks everyone for your help. When I get time to try this I will post my results

mookdoc6 · February 24, 2020

1 hour ago, Jason Morgan said:

Thanks everyone for your help. When I get time to try this I will post my results

You need to get on a BG diet and stay on it!

diyer2 · February 24, 2020

IMO

Shorten your oil change intrevals or use a better quality oil.

Use some Sea Foam in the crankcase before an oil change.

See instructions here

https://seafoamsales.com/knowledge-base/how-to-add-sea-foam-motor-treatment-to-crankcase-oil/

It will clean it out. Might take a few times.

mookdoc6 · February 24, 2020

On ‎2‎/‎22‎/‎2020 at 12:24 PM, Jason Morgan said:

Hello, I'm new to this forum. I have a 2012 GMC Sierra with 150,000 miles. The 5.3 litre engine has had the oil changed every time the oil life has hit 30% , around 5 to 6 thousand miles. The oil pressure dropped and I replaced the oil pressure sending unit (opsu) and the problem was fixed for about a month. The old screen filter under the opsu was dirty but not severely clogged. After about a month the oil pressure dropped to 20 lbs and the check engine light came back on. I am considering pulling the opsu back out , @ operating temperature, and squirting brake cleaner or something down the oil passage followed by 2 hot oil changes. My question is , 1: is this a good idea?, 2: where does that oil passage directly lead to?

You have one of the earlier AFM engines with different piston Ring pack,Valve covers, PCV system. My recommendation is to utilize BG products and you will be good to go. BG clean the engine thourghly and change your screen for the last time. USE BG EPR product every time you get ready to dump oil @5K miles. Don't get confused with a darn good engine and crappy one when all you need to do is be a little proactive. They are good engines..good luck!