Low oil pressure. Bearings going bad?
01-03-2015, 01:15 PM
#1
Low oil pressure. Bearings going bad?
Hello everyone, I could use some words of wisdom from you guys.
I'm having a problem that's really worrying me.
The car has a lingenfelter crate motor in it that only has 4k miles on it. About 500 miles ago, the previous owner had to go through the motor and replace all of the bearings/etc because one of the arp bolts went into the motor and caused some problems. Everything was fixed at "wall2wall" and the car was back to normal.
Now here's my problem.. yesterday I noticed the oil pressure was reading 10 psi at idle at a red light. I gave the car some throttle on my way home while keeping an eye on the gauge, and it only got up to about 35psi at full throttle.
I parked the car overnight, and I went outside this morning and started it up. Oil pressure was normal (35 psi at idle and gets up to 60-80 when i give it gas).. so I decide to go drive it around for a bit. As the car continues to get warmer and warmer, the oil psi continues to get lower and lower. Once car was at full temp, the oil psi was back to 10psi at idle. There is no weird noises or knocking.
So car was towed to a shop this morning. First thing being checked is the sending unit (which i dont think it is because it usually gets pegged out at 0 or 100 when that goes bad).
My question is... if sending unit is working properly, where do i go next? Do i just change the oil pump and hope that fixes the problem? Or should I check the clearance of the new bearings? Just trying to go the route that will cost me the least amount of money obviously..
Any advice is appreciated..thanks
I'm having a problem that's really worrying me.
The car has a lingenfelter crate motor in it that only has 4k miles on it. About 500 miles ago, the previous owner had to go through the motor and replace all of the bearings/etc because one of the arp bolts went into the motor and caused some problems. Everything was fixed at "wall2wall" and the car was back to normal.
Now here's my problem.. yesterday I noticed the oil pressure was reading 10 psi at idle at a red light. I gave the car some throttle on my way home while keeping an eye on the gauge, and it only got up to about 35psi at full throttle.
I parked the car overnight, and I went outside this morning and started it up. Oil pressure was normal (35 psi at idle and gets up to 60-80 when i give it gas).. so I decide to go drive it around for a bit. As the car continues to get warmer and warmer, the oil psi continues to get lower and lower. Once car was at full temp, the oil psi was back to 10psi at idle. There is no weird noises or knocking.
So car was towed to a shop this morning. First thing being checked is the sending unit (which i dont think it is because it usually gets pegged out at 0 or 100 when that goes bad).
My question is... if sending unit is working properly, where do i go next? Do i just change the oil pump and hope that fixes the problem? Or should I check the clearance of the new bearings? Just trying to go the route that will cost me the least amount of money obviously..
Any advice is appreciated..thanks
01-03-2015, 01:52 PM
#2
Le Mans Master
What weight oil is in the engine? Do you know if there is any "break-in" oil from the partial rebuild still in there?
I'd do an oil and filter change first and see if that makes any difference in your pressures. Cheap and should be done 500 miles after any kind of rebuild using break in oils anyway.
I'd do an oil and filter change first and see if that makes any difference in your pressures. Cheap and should be done 500 miles after any kind of rebuild using break in oils anyway.
Last edited by Biggus Blockus; 01-03-2015 at 01:58 PM.
01-03-2015, 02:58 PM
#4
Ditto, check actual oil pressure with a hand held gauge!!!!
As for the pressure drop if a hand gauge is showing low pressure, could be as simple as small derbies from the engine build finding it way into the oil pump relief valve channel, and not allowing the valve to close all the way (read oil pump does not need to be replaced, but instead pulled apart and cleaned instead).
Hence all it takes is a piece of RTV the size of a pin head to find it way into the relief valve to not allow it to close all the way, and the pump will not build up full pressure.
Black strings of RTV next to the quarter is all it took for one op's oil pumt to stop from building up any pressure at all. And yes, they are small enough to be sucked up past the oil pump pick up tube screen.
As for the pressure drop if a hand gauge is showing low pressure, could be as simple as small derbies from the engine build finding it way into the oil pump relief valve channel, and not allowing the valve to close all the way (read oil pump does not need to be replaced, but instead pulled apart and cleaned instead).
Hence all it takes is a piece of RTV the size of a pin head to find it way into the relief valve to not allow it to close all the way, and the pump will not build up full pressure.
Black strings of RTV next to the quarter is all it took for one op's oil pumt to stop from building up any pressure at all. And yes, they are small enough to be sucked up past the oil pump pick up tube screen.
01-03-2015, 03:43 PM
#5
What weight oil is in the engine? Do you know if there is any "break-in" oil from the partial rebuild still in there?
I'd do an oil and filter change first and see if that makes any difference in your pressures. Cheap and should be done 500 miles after any kind of rebuild using break in oils anyway.
I'd do an oil and filter change first and see if that makes any difference in your pressures. Cheap and should be done 500 miles after any kind of rebuild using break in oils anyway.
01-03-2015, 04:09 PM
#6
Safety Car
FWIW and IMO 35psi at start up on a cold engine is not normal, 50-60 is.
01-03-2015, 05:47 PM
#8
Melting Slicks
i had the exact same thing happen to my engine, I changed the oil put in a external gauge everything an the oil pressure issue didn't change. my brother kept telling me my engine was shot but I refused to believe it mainly because it was making no noise no knocking or taping or anything. finally I decided it was time so I agreed to pull the motor an take it to get repaired. the guy at the machine shop showed me the internal damage done to the motor every internal part had to be replaced the only thing that wasn't damaged was the block an he told me had I driven it much longer I would have cracked the block an all would have been lost. cause of the blown motor, the previous owner put a supercharger headers cam in it but did not get it tuned. he didn't even change the map sensor
01-04-2015, 12:33 PM
#10
Don't Wait.
The hot oil pressure at idle is very low, and very indicative of excessive bearing clearances. 35psi with throttle isn't great, but acceptable. If it were me, I wouldn't run that engine again until I could drop the pan and have a look see of all rod and main bearings and journals.
It is possible to salvage the engine with custom bearing if the journals are still round. The fix could be cheap if you are lucky.
It is possible to salvage the engine with custom bearing if the journals are still round. The fix could be cheap if you are lucky.