I have a rebuilt engine in my 1989 Suburban. For the last 15K mile the
oil has always indicated around 50PSI at speed and 28-30PSI at idle. I
didn't catch the exact moment that it did it but it was within a day of
driving. Now the gauge indicates 30PSI at speed and sputters between
0-and 20PSI at idle. Finally settling in at 0. I know there are 3
possibilities: The pump is damaged, The relief valve is stuck or the
sending unit is bad. Is there an easy, no cost way to determine which
it might be or do the symptoms tell you which it is most likely to be.
I was going to spend the money on a new sending unit since it is an
original part, but was hoping not to waste $40 if it wasn't bad.
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Re: Low oil pressure indication in suburban
Dan, If your oil pressure actually dropped below 10 psi at idle, your hydraulic lifters would start to collapse. This would cause them to "tick" or "click" at idle. If you are not getting this clicking, change the sending unit. Charlie
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Have you checked the oil pressure with a mechanical gauge or are you going by the gauge in the suburban. If you're going by the electric gauge in the suburban I would suggest checking it with a mechanical gauge. If the mechanical gauge confirms the oil pressure is low then you probably have a serious engine problem. If the mechanical gauge indicates normal pressure the O/P sender is probably the culprit.
Hard acceleration will burn more oil, also the 5.3l V8s are well known burning oil. so just check the oil every time you fiil up with fuel. Seriously, your already waiting for the tank to fill so grab a towel and check the oil level- if its low put a bit in. Trust me, you dont want to have to replace that engine just because you didnt want to pop the hood!
Oil pressure should be around 30 at idle and then sit at 60 when engine is above 2,000 RPM. If pressure varies at all engine speeds it indicates a sticking pressure relief valve which is located within the oil pump. You could try using some oil flushing product in the engine oil before the next oil change to see if it removes the gunk that is causing the valve to stick. If that does not improve it you should see a mechanic about replacing the relief valve.
You'll lneed to test for 3 things:
Spark at the plug
Fuel, making it to the cyliinder
Compression, above the minimum spec.
Sometimes when engines have been rebuilt, they have really poor compression as they try to start for a few minutes of cranking. If you have good oil pressure, check compression, if low add a tablespoon of oil to each cylinder to build compression, as soon as it starts it will begin to seat and seal itself, as well as provide ample lubrication.
For Fuel and Spark, just normal diagnostics, based upon your description, I won't mention doublechecking now that it has been cranked a bit.
WD40 can be sprayed into the intake while cranking to get one lubed a bit and to start to idle, it will stall when you stop spraying, indicating a shortage of fuel.
sometimes you can get a little water trapped. you can try removing the sending unit and cleaning it. you will probably have to replace the unit. the pressure is acceptable though as long as youre not pourong oil out through the seals.
Try checking the fuel filter and then the pressure regulator on the rail. If the pressure regulator is bad it will not let the pump push enough pressure. And if the filter is clogged then it will also not let the engine get enought pressure. I have seen pumps starter going out by losing pressure. I have also seen aftermarket pumps quit after about a week unles you did not change the whole assembly.
your oil sensor comes on at less than ten psi, you may have internal engine damage how many miles on engine, any gum up inside engine, you can try to put on a high pressure high volume melling oil pump to try to help for the time being, but you may need to have it torn and repaired.
Brakes and Traction Control
Evaporative Emissions System (E)Inspect all the fuel and vapor lines and the hoses for proper hook-up, routing and condition. Ensure that the purge valve works properly, if equipped. Replace the components as needed.
Exhaust Gas Recirculation (E)
Fluid - Differential
Inspect front/rear axle fluid level and add fluid as needed. Check constant velocity joints and axle seals for leaking. Lubricate
Steering and Suspension
Lubricate the front suspension, ball joints, steering linkage, transmission shift linkage, transfer case shift linkage, parking brake cable guides, and brake front axle. Ball joints should not be lubricated unless their temperature is -12 degrees C (10 degrees F) or higher or they could be damaged.Replace
Air Filter Element (E)
Engine Oil (E)Change engine oil and filter as indicated by the GM Oil Life System (or every 12 months, whatever occurs first). Reset the indicator. Never drive the vehicle more than 16 000 km (10,000 miles) without and oil and filter change. The system will not detect dust in the oil. If the vehicle is driven in a dusty area, be sure to change the oil every 5 000 km (3,000 miles) or sooner.
Fuel Filter (E)
Oil Filter, Engine