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Discussion Starter #1
Good news my boat is running fine, but I am having an issue with my truck. 1997 GMC 2500 with 5.7 150,000 miles. After motor is warm my oil pressure is dropping to 10 psi or less at idle with truck in gear and my Check Engine Light comes on. If I shift to neutral the RPM goes up about 150 more RPM’s and the oil pressure goes to about 10 psi and the light goes out. When running the oil pressure is pretty solid at 40 to 45 psi.

I have put a mechanical oil pressure gauge on to verify the accuracy of the electronic gauge and it validated that the low pressure is real. The mechanical gauge would sweep up and down as expected and showed 40 to 45 psi as well.

Any thoughts to what it may be? Oil pump screen clogged? Needs new pump? Engine is tired? Can I remove the oil pan and change the pump without lifting the engine or removing steering components?
 

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I'm famous !
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150,00 miles - have you been changing the oil regularly ? not alot of miles on the new engines . another deal your going to start seeing is lifter noise ( rollers ) Then one will fail ...

Cost factor vs truck condition ! Do you really want to band aid a 97 truck ! Run it till it dies then put in a New engine - 1900. bucks for a long block and a weekend of beer - :D


Good news my boat is running fine, but I am having an issue with my truck. 1997 GMC 2500 with 5.7 150,000 miles. After motor is warm my oil pressure is dropping to 10 psi or less at idle with truck in gear and my Check Engine Light comes on. If I shift to neutral the RPM goes up about 150 more RPM’s and the oil pressure goes to about 10 psi and the light goes out. When running the oil pressure is pretty solid at 40 to 45 psi.

I have put a mechanical oil pressure gauge on to verify the accuracy of the electronic gauge and it validated that the low pressure is real. The mechanical gauge would sweep up and down as expected and showed 40 to 45 psi as well.

Any thoughts to what it may be? Oil pump screen clogged? Needs new pump? Engine is tired? Can I remove the oil pan and change the pump without lifting the engine or removing steering components?
 

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mo balls than $cents$
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oil pump pick up is prob getting clogged with oil parafin. if your's is a 4wd, just drop the frt diff out and drop the pan, throw in a new high volume oil pump and new pick up. while you're there, lose the factory oil cooler on that thing, all you have to do is take off that adapter at the oil filter, get the screw on adapter. the oil coolers on those trucks had a huge internal volume and really hurt the motor imo. the lil thermostat in the oil filter adapter will stick open and allow oil to reach the cooler before it ever should, this in turn starves the bearings during the warm up cycle, not a good dealio.
 

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Discussion Starter #6
oil pump pick up is prob getting clogged with oil parafin. if your's is a 4wd, just drop the frt diff out and drop the pan, throw in a new high volume oil pump and new pick up. while you're there, lose the factory oil cooler on that thing, all you have to do is take off that adapter at the oil filter, get the screw on adapter. the oil coolers on those trucks had a huge internal volume and really hurt the motor imo. the lil thermostat in the oil filter adapter will stick open and allow oil to reach the cooler before it ever should, this in turn starves the bearings during the warm up cycle, not a good dealio.
IM1,

Interesting post. I cannot remember what the exact oil pressure was prior to having work done on the truck. I started seeing this issue after I had the radiator replaced. You mentioned above the oil cooler and I know that the oil and trans coolers are built into the radiator. I am sure they only disconnected and reconnected the hard lines, but you have me thinking now.
 
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