hey, i have a 86 mustang with a 5.0 that i rebuilt and the oil pressure is dropping. Here is the situation, when i start the car up the oil pressure is sitting in the middle of the gauge and over a twinty min. period it lowers down to low. Iam trying to figure out wether or not if i should get a new oil pump or if it is a bearing.Is there any tests i could do to narrow down things.
oil pressure
- Thread starter Rushman04
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cenok is family
15 Year Member
are you sure your gauge is accurate? stock fox gauges are almost worthless. regardless, it sounds like the pump is going out. how many miles are on the motor?
Jaswir
Member
wow that is one of the most import things to replace on a rebuild... get a aftermarket gauge and hook it up and see what kinda of pressure you really have!
cenok is family
15 Year Member
are you wondering why it's going from middle to low after 20 minutes? Because the oil warms up, gets thinner, and you get less pressure.
If you're just wondering why your oil pressure is low, it's because your bearings are worn, but I second the idea of getting an aftermarket gauge on it because the stock gauges are junk on your 86. So are the ones on my 85.
If you're just wondering why your oil pressure is low, it's because your bearings are worn, but I second the idea of getting an aftermarket gauge on it because the stock gauges are junk on your 86. So are the ones on my 85.
bloopbloob
Member
yup! i'm with the pump or bearings crowd. since it's rebuilt, that puts me on the pump crowd's side. only time i ever had oil pressure drop was when my bearings went. and i replaced them, and the oil pump (cheap insurance when doing a rebuild!!!) when it was rebuilt. no problems ever since.
mustangfan1990
New Member
I think bearings. Pumps dont go out often they are simple piece of metal that is turned by the oil pump driveshaft that connects to the bottom of your distributor. I wouldnt think that it is the oil pump even though when you pull the motor you change it good or bad cause you dont want to have to pull the oil pan off with the engine in the car ( BIG BIG BIG BIG BIG PITA) and you dont want to pull the engine just to change the oil pump. I would say the engine need a rebuild OR you could be low in oil lol
ninety15.0
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- Mar 10, 2004
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i would get a real gauge on there. Mine was doing something similar after my rebuild. It wasn't responding to revving the motor. The pressure seemed to just always been just below half. I put a mechanical autometer on there. And viola 25psi hot idle and 50psi cruising.
The stock gauge is inaccurate and the stock sending unit can be a problem as well. If the oil pressure is low when the motor is at a hot idle thats ok. Then it should rise when you rev it. I would get a real gauge on there.
The stock gauge is inaccurate and the stock sending unit can be a problem as well. If the oil pressure is low when the motor is at a hot idle thats ok. Then it should rise when you rev it. I would get a real gauge on there.
