Having Weird Oil Pressure Issue

Discussion in 'Fox 5.0 Mustang Tech' started by PWR SHFT, May 22, 2014.

  1. New to the forum! New to 5.0s! Thanks in advance!

    So normal driving, oil pressure is great. It is very steady around 60 psi. But under heavy acceleration, the oil pressure slowly drops. It does not drop to zero but goes pretty low to about I would say 20 psi. As soon as you take your foot out of it, it goes right back to normal. Factory gauge.

    Here are the particulars on the car: 89 LX 5speed. I just bought this car a couple of weeks ago. It looks like an aftermarket block but its hard to tell. Was told it is a 306 with forged pistons at minimum. TFS heads, X303, original cobra intake with 70mm throttle body, Vortech V1, Aftercooler, FMU, T-Rex booster pump, MSD 6AL BTM, BBK Long tubes, off road h-pipe, mac 2.5 cat back. When I bought it, the car was way over the previous guys head. It had a wicked vacuum leak that was the plenum gasket and it ran like total crap so I never pushed it hard. That is till today after I fixed all that.

  2. Split block. You apply load, it opens up the clearances and lowers your pressure. Reduce the load, the clearances go back to normal, your pressure comes back up. Been there, done that.
  3. Wouldn't you see leaking oil? Other than the rear main, everything is dry. Oil looks good too.
  4. what was your fix for this problem a girdle? thats what i went with ... just curious?
  5. It's either a loose wire on the sending unit or as MFE said, a split block. Remove the distributor and with a drill and a long 1/4" socket taped to a long extenstion, spin the pump - drill in reverse. Have someone look at the oil pressure gauge. You may be able to replicate the issue but it probably won't put enough load on the motor. Only way to know is to pull the intake and look in the lifter valley or the timing cover.

    A girdle does nothing more than hold your broken parts in the pan. It's worthless in holding a block together.
  6. guess I'll remove it then since its useless ...
  7. Replaced the block when I had the engine rebuilt. And then had the rotating assembly carefully balanced and professionally built.