Carbed 88 5.0 Weird Oil Psi???

Discussion in 'Fox 5.0 Mustang Tech' started by jk294, Jun 20, 2013.

  1. when i'm cruising on the freeway the oil pressure gets all cattywampus on me. at throttle the oil psi drops and at off throttle it raises. it's a 10 psi variance between 20 and 30 psi.

    when i got off the freeway sitting at idle oil pressure dropped to 11psi. letting out on the clutch to start moving it drops to 4psi.

    this is all when the oil is warmed up. now when it's cold it's running alot better.

    water temp. while i'm on the freeway is pretty much non existent. if i'm in traffic it gets up to about 150 max. I'm wondering if this is having an effect as well.

    also under full throttle i shift a 5500 to 6000 rpm.

    any help would be great. after seeing that drop to 4psi, i'm starting to worry about the engine.
  2. When this happened to me it was because my block was split. Gave it gas, it loaded the block and opened up the clearances. The oil pressure gauge was acting like a vacuum gauge. And my idle pressure was way down.
  3. how would i test for such a thing? oh and what exact do you mean by "split"? i'm guessing it's non repairable, but where was the damage located?
  4. Do a search for split block and you'll get all kinds of pics. They crack between a main cap bolt hole and the cam bores, then along the lifter valley. Not sure how to check for it without any disassembly.
  5. Remove your intake and see ... are you smoking after the engine warms up?
  6. it doesn't smoke after warm up. but it does tend to mark it's territory. if i park it for a couple hours after warm up ill have a oil spot just a little larger than a half dollar underneath the rear of the engine.
  7. That would either be trans seal or rear main seal