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Not getting enough oil pressure?

Tiny
6.0ANG
  • MEMBER
  • 2004 CHEVROLET SILVERADO
  • 6.0L
  • V8
  • 2WD
  • AUTOMATIC
  • 15 MILES
I have a built lq9 and it was not getting enough oil pressure so I bought a Melling 296 high-pressure high-volume oil pump and after installing it the pressure was way too high, it would idle at 80 PSI after cold starting it and after a few minutes it would drop back down to 60 PSI. I was driving on the highway at pretty high speeds and RPMs and my pressure just dropped and read zero and knew I had blown something. I really don’t know why the pressure was so high from the beginning after installing the new oil pump I know it’s a high-pressure pump but I don’t know why it ran so high up.
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Wednesday, March 13th, 2024 AT 7:15 PM

25 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Hi,

Does the engine still turn over (crank no start)? Was there any knocking or noise from the engine prior to this happening?

As far as the oil pressure is concerned, it is higher than expected, but these vehicles do have an oil pressure release valve if it exceeds the manufacturer's pressure specifications.

How low was the pressure prior to the new pump? Did it fall below the specifications listed below? If the starter still turns the engine, record it cranking and upload it for me to hear.

Let me know.

Joe

See pic below.
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Wednesday, March 13th, 2024 AT 8:05 PM
Tiny
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I haven’t even tried to crank it but I'm pretty sure it will start. I had a slight tick before the new oil pump when I would go highway speeds but nothing major. After the new oil pump I noticed there was really no tick. Before the new pump it would idle at 20 on the gauge and when accelerated or revved the pressure would go up to 40 and topping out the truck it would get to 60 but usually the pressure was 40 or lower. I really don’t want to turn the engine over I blew something that made the oil pressure drop insanely and started leaking oil.
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Wednesday, March 13th, 2024 AT 8:14 PM
Tiny
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  • 16 POSTS
I took a video of the pull I did though. I didn't instantly realize the pressure had dropped to 0. After the video I got shocked and shifted it to neutral so I can stop ASAP, but when shifting to neutral it jumped and went into reverse and locked up all the wheels and I lost control and I slid far and almost flipped, thank God I did not. Though I definitely messed something else up too.
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Wednesday, March 13th, 2024 AT 8:19 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Hi,

Can you tell approximately where the oil is leaking from? Also, the prior pressures were well within the specifications. The tick was likely caused by something other than pressure.

Let me know if you can tell where the leak appears to be. Also, try turning the engine by hand to see if it's locked. Keep in mind, if the oil pressure is lost, it will shut down the fuel pump, so hopefully that is why it likely shut off.

Let me know.

Joe
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Wednesday, March 13th, 2024 AT 8:22 PM
Tiny
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  • 16 POSTS
I had noticed the oil leak before taking it out I could not tell if it was coming from the filter or the pan or anywhere else. And no, when I lost control the truck was still on I immediately put it in park and turned off the truck a few minutes later my dad was pulling my truck with a chain and I had put the truck in neutral on the run position and I would hear the fuel pump buzzing.
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Wednesday, March 13th, 2024 AT 8:29 PM
Tiny
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Hi,

Listening from the computer, it doesn't sound bad. Is it still showing oil pressure? Have you checked the oil pressure switch for damage or leaks?

Joe
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Thursday, March 14th, 2024 AT 7:36 PM
Tiny
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I have not checked the pressure switch. Can you please tell me everything to look for? I was under the truck today and could not tell where the leak was coming from.
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Thursday, March 14th, 2024 AT 7:39 PM
Tiny
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Again, I was going around 100 MPH when the whole truck lost oil pressure. How do I fix such high oil pressure?
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Thursday, March 14th, 2024 AT 7:40 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Hi,

The oil pressure switch is at the rear of the engine (top) behind the intake manifold. I attached a pic showing its location. Check that and let me know if it appears to be leaking. Also, the high-pressure oil pump is going to produce more pressure. However, the pressures you mentioned are not crazy high.

There is an oil pressure bypass valve under the oil filter. Check to make sure it is there, and nothing is plugging or restricting it. See pic 2.

Let me know.

Joe

See pics below.
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Thursday, March 14th, 2024 AT 7:58 PM
Tiny
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I will check that tomorrow. So, there’s nothing really wrong with the pressure being so high? What do you recommend me upgrading or checking to make sure the pressure doesn’t zero out again?
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Thursday, March 14th, 2024 AT 9:07 PM
Tiny
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Also, I want to add I was going pretty fast to when the truck accidentally shifted in reverse what could’ve I messed up doing that.
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Thursday, March 14th, 2024 AT 9:08 PM
Tiny
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Hi,

I'm hoping the sensor failed. As far as the pressure is concerned, it is higher than the original, but I don't feel it is high enough to cause problems. If it was over 100 psi, I would feel differently. Chances are at that pressure; you would see the oil filter expand or fail.

As far as the reverse, did the engine shut down?

Joe
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Friday, March 15th, 2024 AT 6:21 PM
Tiny
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I don't know if the pressure was close to 100 though on my gauge it only goes to 80. No, the engine was still running I cranked it a bit yesterday but didn’t turn it on because of the oil pressure problem, although I did see transmission fluid start leaking. What could that indicate?
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Friday, March 15th, 2024 AT 9:12 PM
Tiny
JACOBANDNICKOLAS
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As far as the oil pressure, there is a pressure bypass that should limit the amount of pressure produced. It's the one I indicated is located under the oil filter. The transmission fluid could be a concern, but we need to know where it is coming from.

Joe
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Saturday, March 16th, 2024 AT 1:24 PM
Tiny
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Oil all over the place behind the fire wall.
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Sunday, March 17th, 2024 AT 11:55 AM
Tiny
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Can't tell where the transmission fluid coming out of.
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Sunday, March 17th, 2024 AT 11:56 AM
Tiny
JACOBANDNICKOLAS
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Hi,

As far as the transmission is concerned, I attached a pic below showing areas that could leak. Take a look at the pic and see if anything in those areas appears to be wet.

For the engine oil, without being there all I can recommend is to use an engine oil dye. It is added to the engine oil, the vehicle will need to run, and you check for leaks using a black light to see if you can locate the leak.

Were you able to check the oil pressure sensor for leaks?

Let me know.

Joe
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Sunday, March 17th, 2024 AT 8:02 PM
Tiny
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Yeah, I figured out why the system lost pressure the sensor behind the intake you told me about went bad.
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Sunday, March 17th, 2024 AT 8:05 PM
Tiny
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I ordered a new sensor, but how will I prevent it from any other sensor or anything else from blowing or going bad?
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Sunday, March 17th, 2024 AT 8:06 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Hi,

I'm hoping that won't happen. It shouldn't. The engine produces higher pressure when cold regardless of the pump you used. It should withstand what you have. Also, other sensors won't be affected.

Let me know if that resolves the issue. Also, that would explain the oil on the firewall and throughout that area.

Joe
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Sunday, March 17th, 2024 AT 8:13 PM

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