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Old May 15, 2018 | 01:10 PM
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Hi, i got a high oil pressure reading on my 04 GTO LS1 . Does anybody know where the oil pressure relief valve is
on these engines and how hard it might be to change? Thanks, Johnny
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Old May 15, 2018 | 05:31 PM
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It's inside the oil pump, which is on the front of the motor, around the crank, just inside the timing cover, right behind the crank damper.

Can't speak to "how hard". How hard is brain surgery? Depends on lots of things, eh? as well as whether it's your own brain? or whether you expect the patient to ever walk and talk again? Are you a brain surgeon? That said, it would take several hours to fix; the most commonsensical fix would be to not bother with the bypass valve and instead just replace the pump.

Why do you think the oil pressure reading is "high"? A little history perhaps? Have you checked the sending unit to make sure the wire isn't disconnected?
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Old May 15, 2018 | 05:52 PM
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Thanks for your insight and quick response. Pep Boys was checking the engine light, and, along with the knock sensor, he said the
oil pressure was high. My attention is on the sending unit now, and I'm thinking it would be easier to replace that first, and at the same
time check the pressure from there with a gauge. I'm happy to hear from you, that the location of the relief valve is not part of the oil pan,
which on the GTO, I'd have to lift the engine or drop the cage. Thanks again, Johnny
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Old May 15, 2018 | 05:58 PM
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Well, the pan has to come down a bit to allow the pump to come out (which it would have to do to mess with the bypass anyway); I haven't worked on a GTO so I can't say how much clearance you would/wouldn't get. But yeah, I'd surely start with the sending unit, long before jumping to the other conclusion. However if all it was is some code on the code reader, I'd clear it and keep on driving... especially if the gauge reads the same thing it always has. The gauge is operated by the ECM, so what you see on it, is the same as the ECM is seeing; and if it looks normal on the gauge, then there's probably nothing wrong with it.
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Old May 22, 2018 | 04:41 PM
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RBO4Av, Thank you. I did buy a new oil sending unit, or sensor, along with the correct socket ( not too deep or short) to get the thing out. With the right tool the job was easy. Location for mine was on the drivers side of the engine in the far back. The GTO doesn't have a gauge, so I got the information from Pep Boys computer check. Anyway, the message is off the dash and the LS1 is alive and well. Thanks, Johnny
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Old May 27, 2018 | 09:31 AM
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First of all, the problem isn’t with your oil pressure - the problem is you taking your car to Pep Boys for work. Seriously. Stop.
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Old May 27, 2018 | 08:36 PM
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Originally Posted by 8.Lug
First of all, the problem isn’t with your oil pressure - the problem is you taking your car to Pep Boys for work. Seriously. Stop.
You Sir win the internet today.
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Old May 27, 2018 | 08:40 PM
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Put a mechanical gauge on it for verify actual oil pressure. Yes it can be a sending unit, depending on what vehicle and OS. "Most of the time" when the sending unit fails it will show stupid high oil pressure. If you have a scanner, check oil pressure KOEO, if it's showing 80+ psi...it's probably bad.

I know on the trucks, which has a gauge, will max out the oil pressure gauge, and after the 2nd or 3rd time it will fall back to 0 and kick a DTC. On the cars I can't say 100% on that.
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Old May 31, 2018 | 01:08 PM
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The GTO doesn't have a oil pressure gauge (just idiot light) so he would need to put a mechanical one on to verify.
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