High Oil Pressure

[Canon Lansdell]

Hey I need some help. So I bought my 98 Silverado (5.7 350 EFI) at 146k miles with a rod knock. Fast forward, the engine is rebuilt and back in the truck. Oil pressure runs at 70+ psi almost constantly. Oil pump was reused in the rebuild. Also, Cam to Crank correlation sensor is throwing a CEL. Any solutions without an engine tear down?

 

[evilunclegrimace]

Hey I need some help. So I bought my 98 Silverado (5.7 350 EFI) at 146k miles with a rod knock. Fast forward, the engine is rebuilt and back in the truck. Oil pressure runs at 70+ psi almost constantly. Oil pump was reused in the rebuild. Also, Cam to Crank correlation sensor is throwing a CEL. Any solutions without an engine tear down?

Yes, verify oil pressure with a known good mechanical pressure gauge and set CMP offset.

 

[L31MaxExpress]

Hey I need some help. So I bought my 98 Silverado (5.7 350 EFI) at 146k miles with a rod knock. Fast forward, the engine is rebuilt and back in the truck. Oil pressure runs at 70+ psi almost constantly. Oil pump was reused in the rebuild. Also, Cam to Crank correlation sensor is throwing a CEL. Any solutions without an engine tear down?

Did you rebuild the engine? What viscosity of oil are you running?. In an engine with tight clearances a thick oil like 10w40 or 20w50 will have the oil pressure through the roof if the pumps pressure relief valve was altered or stuck. Even on a stock pump the oil pump relief spring can be changed or shimmed. Not many people including myself would reuse an oil pump from an engine that ate its bearings. Oil pumps get unfiltered oil circulated through them. A new pump is cheap insurance.

My 383 is built on the tight side of spec. I see 50+ at hot idle and 70+ @ 2,000+ RPM. Running a factory big block pump in it though. 5w30 synthetic since startup. I have it out of the Van at the moment because I made some major changes to it. Actually ran it on the engine stand today for a while with an accurate mechanical gauge.

 

[alpinecrick]

As far as oil pressure, you wouldn’t happen to be running one of those synthetic 99.9999999% uber high efficiency filters, would you? They tend to restrict oil flow with anything more than 0-20 oil and will run breathtakingly high oil readings on the gauge.

The crank sensor is located in the timing cover. Sometimes small differences in tolerances in the timing cover hole can result in the sensor being located too close to the reluctor ( most common) or too far away (rare). Or differences in how the crank sits with new oversized bearings. If the sensor is too close to the reluctor EFI Connections offers a spacer kit that worked for me.

 

[Canon Lansdell]

Did you rebuild the engine? What viscosity of oil are you running?. In an engine with tight clearances a thick oil like 10w40 or 20w50 will have the oil pressure through the roof if the pumps pressure relief valve was altered or stuck. Even on a stock pump the oil pump relief spring can be changed or shimmed. Not many people including myself would reuse an oil pump from an engine that ate its bearings. Oil pumps get unfiltered oil circulated through them. A new pump is cheap insurance.

My 383 is built on the tight side of spec. I see 50+ at hot idle and 70+ @ 2,000+ RPM. Running a factory big block pump in it though. 5w30 synthetic since startup. I have it out of the Van at the moment because I made some major changes to it. Actually ran it on the engine stand today for a while with an accurate mechanical gauge.

I had a shop rebuild the engine. I was told they reused the oil pump. I run 5W-30. You're recommending a new oil pump? I need to replace my oil pan gasket due to a small leak so should I replace the pump while I have the pan off?

 

[Erik the Awful]

If you're getting 70psi, the oil pump is not the problem.

 

[L31MaxExpress]

If you're getting 70psi, the oil pump is not the problem.

Unless the relief valve is stuck closed.

 

[L31MaxExpress]

As far as oil pressure, you wouldn’t happen to be running one of those synthetic 99.9999999% uber high efficiency filters, would you? They tend to restrict oil flow with anything more than 0-20 oil and will run breathtakingly high oil readings on the gauge.

The crank sensor is located in the timing cover. Sometimes small differences in tolerances in the timing cover hole can result in the sensor being located too close to the reluctor ( most common) or too far away (rare). Or differences in how the crank sits with new oversized bearings. If the sensor is too close to the reluctor EFI Connections offers a spacer kit that worked for me.

Please explain how they run higher oil pressure readings? The pressure tap is AFTER the filter. The only way the filter could change the pressure is if the bypass valve in the engine was stuck or plugged and the internal bypass of the filter was stuck or non existant.

I have not had an issue with Mobil One filters and use them exclusively.

 

[Erik the Awful]

If the pressure tap is after the filter, and the oil bypass is built into the filter block, how would the relief valve being stuck closed cause the pressure after the filter to be 70 psi? Not being snarky, seriously asking.

 

[L31MaxExpress]

If the pressure tap is after the filter, and the oil bypass is built into the filter block, how would the relief valve being stuck closed cause the pressure after the filter to be 70 psi? Not being snarky, seriously asking.

The bypass valves are not the relief valve. The bypass valves allow oil to bypass the filter element. The relief valve bleeds excess pressure and is part of the pump.

Not being snarky either but the bypass valves would only drop the pressure if they were stuck/plugged and the filter media was restricting flow.