I took a video of it on my phone, but my phone won't let me upload it to youtube. Says the file size is too large. But basically the oil pressure fluctuates dramatically on a cold start up. When I start the car, cold, the oil pressure is about 80 psi. Within a few seconds, the oil pressure slowly drops a few psi, to around 65, then decreases fairly rapidly to 18-20, and then skyrockets back to 80-ish psi. It then repeats the process several times. Once the engine starts to rise in temperature, the fluctuations become less frequent and less dramatic, until the engine reaches operating temp, and the pressure stops fluctuating altogether.
My engine was a problem free, previously rebuilt, 65k stock spec engine. I had the cylinder head rebuilt, performed a BSE, polished the crank, replaced all of the bearings and re-ringed the pistons. I did not replace the oil pump, as I probably should have, because there wasn't anything wrong with the engine prior to disassembly. The engine is equipped with a 1990 OFH, which has a ported relief hole to remedy the excessive oil pressure caused by the BSE. The sender for my oil pressure guage is remotely mounted, on the end of a 4' long, 5000 max psi hydraulic hose.
So here's my thoughts. First, I need to install a second temporary gauge to act as a tattle-tell to comfirm if my current sender is playing nice or not. If the second gauge shows all is well, boom, problem solved, just get a new sender/gauge and be done with it.
But I don't think that is really the problem. Another option is that I shot myself in the foot by reusing the oil pump. Still not likely in my eyes because a pump has so few moving parts that I can't imagine it would almost fail, fix itself, almost fail again, fix itself again, etc, etc.
So we come to the pressure relief valve. I think it is probably sticking in its bore, bleeding off pressure until the spring pressure overcomes the combined forces off the sticky valve and the oil pressure, at which point the piston pops back to the top of the bore and the process repeats itself.
Obviously this is incredibly concerning, and I would greatly appreciate any and all input from anyone.
The engine has roughly 1700 miles on it since my refreshing. I use 10w-30 royal purple oil. The oil pressure never drops below 16 psi @ normal operating temp, and I have not seen less than 10 psi per 1000 rpm (i.e.; at least 30 psi @ 3000 rpm, 50@ 5k), and usually the pressure is 20 psi per 1000 rpm.
My engine was a problem free, previously rebuilt, 65k stock spec engine. I had the cylinder head rebuilt, performed a BSE, polished the crank, replaced all of the bearings and re-ringed the pistons. I did not replace the oil pump, as I probably should have, because there wasn't anything wrong with the engine prior to disassembly. The engine is equipped with a 1990 OFH, which has a ported relief hole to remedy the excessive oil pressure caused by the BSE. The sender for my oil pressure guage is remotely mounted, on the end of a 4' long, 5000 max psi hydraulic hose.
So here's my thoughts. First, I need to install a second temporary gauge to act as a tattle-tell to comfirm if my current sender is playing nice or not. If the second gauge shows all is well, boom, problem solved, just get a new sender/gauge and be done with it.
But I don't think that is really the problem. Another option is that I shot myself in the foot by reusing the oil pump. Still not likely in my eyes because a pump has so few moving parts that I can't imagine it would almost fail, fix itself, almost fail again, fix itself again, etc, etc.
So we come to the pressure relief valve. I think it is probably sticking in its bore, bleeding off pressure until the spring pressure overcomes the combined forces off the sticky valve and the oil pressure, at which point the piston pops back to the top of the bore and the process repeats itself.
Obviously this is incredibly concerning, and I would greatly appreciate any and all input from anyone.
The engine has roughly 1700 miles on it since my refreshing. I use 10w-30 royal purple oil. The oil pressure never drops below 16 psi @ normal operating temp, and I have not seen less than 10 psi per 1000 rpm (i.e.; at least 30 psi @ 3000 rpm, 50@ 5k), and usually the pressure is 20 psi per 1000 rpm.
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