Oil pressure oddity

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Tahoehybrid18

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08 Tahoe Hybrid. Was drinking last weekend when oil pressure slowly went down to zero while driving. Read the forums, seen the sensors are suspect, so I replaced it and the screen. Drive good for about a week, now tonight it did the same thing. Pressure started out good, then slowly crept down to zero over 2 to 3 mins. I got home, turned it off for 15 seconds, started backup and pressure was steady around 40 at idle. What gives, seems pretty odd. Oils full, was changed about 1500 miles ago.
 

Derick

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Well you fixed 1 of the 3 issues...

1) sensor
2) oil pickup tube o ring
3) oil pump check valve

I'd go for marvel mystery oil ASAP to see if you can perhaps free up that check valve in the pump. Either way, depending on mileage, plan to replace the pump. The high pressure/high flow aftermarket pumps are 150+30 for a new pickup tube.
 
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Tahoehybrid18

Tahoehybrid18

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Yes screen replaced, now the first time I had to drive 10 blocks home, with the gauge at zero. When I got home, engine was quiet, no lifter tick or anything. Is it possible that this is a electrical issue? I find it hard to believe the pump is bad or this valve just randomly messes up after the engine gets warm. I'm fairly knowledgeable as I have built SBC engines for circle track racing.
 

swathdiver

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Yes screen replaced, now the first time I had to drive 10 blocks home, with the gauge at zero. When I got home, engine was quiet, no lifter tick or anything. Is it possible that this is a electrical issue? I find it hard to believe the pump is bad or this valve just randomly messes up after the engine gets warm. I'm fairly knowledgeable as I have built SBC engines for circle track racing.

Did you plug it back in? LOL Did you replace with GM OE or ACDelco Professional?
 

SnowDrifter

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At this point, I'd say hook up a mechanical gauge. Separate mechanical from electrical and proceed with diagnostics from there

It doesn't escape me that it's an annoying thing to hook up given where the pressure sensor is. But it's gotta be done. If your oil pressure is truly low, it'll stop you from blowing up a couple thousand dollar engine. And if it's not, you can avoid chasing your tail and throwing un-needed parts at the thing
 
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Tahoehybrid18

Tahoehybrid18

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I'm going to have a dealership diagnose it for me, it's hard with Wisconsin winter right now to do much on my own lol
 

dnt1010

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Hopefully something simple. Not that many Hybrid 6.0s around so it catches my attention when I see someone post a problem with one.
On your 2008
1. How many miles on it and is this the original factory engine?
2. Have you added anything to the latest oil change that might have loosened internal oil sludge deposits? (Kreen etc)
3. In the past say 1 year what pressures were you normally seeing on the dash guage. Usually pretty high on cold startup? and then a lower number at idle after completely warmed up?
4. Any other dash gauges or center screen controls acting different lately?
 

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