WTF? No oil pressure and the engine still runs?

Discussion in 'Classic Mustang Specific Tech' started by bull999999, Aug 28, 2004.

  1. Just when I thought the end was near...

    Last night, the Haneline oil pressure gauge that normally reads 20psi of oil stopped registering any pressure. I figured since I installed the sender a couple of days ago maybe it was the sender that was bad, esp since I didn't hear anything funny from the engine, so I did about an hour worth of test drive last night.

    Today, I was going to do the oil cooler + remote filter location kit install. However, when I took the oil filter off, it was nearly empty. Alarmed, I took off one of the valve covers and started the engine to find that there's no oil going to that area, so I guess the guage was right after all.

    First, if engine runs without oil, shoudn't it be seized up? It's a tired old motor so I wouldn't be very heartbroken if it did but it seems to be running OK.

    Second, where should I start looking to find the oil pressure problem?
  2. Odd, I figured it would seize up quicker than hell driving around with no oil pressure. First off, check your oil. Is it low?
    If it's ok, check or replace your oil pump. It may have quit working.

    Seems odd that the engine didn't make any strange noises or seize up with no oil pressure. Are you sure the gauge is working?
  3. Oil pump shaft.....

    along with new oil pump.

    Probably just took some serious life off the bearings but since it's still spinning it should be ok. :) At least for a few more miles.
  4. Change your oil recently? First time I ever changed mine years ago I accidentally left the old filter gasket on the block which created a pressure leak. Made it home right before all pressure was gone...phew! Learned that lesson the hard way lol.

    EDIT: oh yea....I bet that convertible behind me will never follow an old car again lol. Man I felt bad...

  5. Unfortunatly, Fostang's right here. I pull the distributor off and the bottom of the oil pump shaft was twisted up.

    I still find it odd that the engine didn't seize up. It had some valve train noise before (as I said, it was a tired old motor), but I really didn't hear anything different after the pump went out.
  6. I took the oil pump apart, and it looks like some junk got into it, causeing the rotor to lock up. Interestingly enough, I found another oil pump shaft (in good shape) at the bottom on the oil pan.

    I found some small pieces of metal on the bottom of the pan, but I think that those came from the broken pump shaft. I'll put on a new pump and see how it runs.
  7. I have a '92 F-150 that my wife ran out of oil TWICE! The first time, she picked me up for lunch. We were sitting in a drive through and suddenly I realize over the sound of the radio I can hear the engine knocking. The oil pressure was zero, and it was off the bottom of the dip stick. I have no idea how long she drove it that way.

    The second time I was riding with her and I happened to be watching the oil pressure gage (I wonder why...) :rolleyes: And I saw it jumping, dropping to zero, jumping back up..

    Both of those incidents happened over 4 years ago. It has 175,000 miles on it. It's tired but still runs fine.

    I was and am amazed that a motor could continue running under those conditions, but it can happen. I think an older, looser motor is more likely to make it through without seizing. A new rebuild would seize pretty quickly, I'd think.
  8. The Checker Auto parts nearby didn't have a pump in stock so I just took the old one apart, clean, lubed, and installed it along with the oil pump shaft I found in the pan. When I restarted the car, I got a brief rise in the oil pressure before going to zero agian. I shut the engine off, took the pan off, and hand cranked the engine to confirm that the shaft is indeed turning the pump.

    When I took the pump of, it was full of oil, so does that mean that the pump is taking up oil but too worn to build pressure, or is there a blockage somewhere?
  9. bull999999

    You will find the oil pumps are sensitive to debris. Will twist that shaft right off. Try priming the pump with an electric drill. You'll know when you get pressure the drill will almost come to a halt.

    Use to race an SCCA American Sedan Mustang. 302 about 400hp. Using Mobil 1 15-50, I lost pressure on the pace lap, decided to continue & did 20 laps at NHIS. Oil temp at 300 by end of race. Pulled the motor down & found that the pickup tube had snapped off. Motor was still in good shape, could not believe the condition of the crank bearings & cyl all good.
  10. Technology has improved alot in just the past 10 years for oil. If you have fresh oil in, and it's a good weight for your engine, then the engine shouldn't sieze right away, it should actually go quite'll hear those rocker arms knocking away. Engine will also get hotter than hell.
  11. PONY XPRESS: Shouldn't idling the engine prime the pump as well?

  12. You really want to prime a new pump before you use it because you wouldn't want to run with no oil while it primes now would you?. :rlaugh:
  13. Also I'd get a new pump just to be safe maybe even a high pressure one just to build some extra psi with the large bearing clearances you probably have now.

    Adding a hardened oil pump shaft also helps.
  14. Where do you live ? Siberia ? They didn't have an oilpump in stock ? Unbelieveable, what motor do you have in there ? :rlaugh:
  15. bull999999

    Its always a good idea to prime your oil system whenever it is taken apart. I have seen pumps that are air bound & drive people crazy.

    You say you had pressure & lost it. Check the bottom of your distributor were the oil shaft connects & make sure it is not damaged. I think you said that you broke a shaft. You can reuse the pump if you know the specs for the gear clearance & they are within spec, but a new pump is fairly cheap it may be the way to go. Definitely get the hardened shaft & make a priming tool out of the old shaft. The oil pan & block area has to be spotless form any kind of debris, these pumps are very susceptible to the gears locking up & your done. Hope this helps.

    PS You should also use a little Vaseline around the gears to help it prime if you have it apart.
  16. Are you sure these smallpieces are metal? A friend of my had a broken oil pump once that was caused by hardened valve stem seal pieces. The rubber was as hard as metal! After replacing the pump, installing 16 new valve stem seals and cleaning the pan, the engine ran like new!

    Erwin, The Netherlands
  17. Also check the dist gear to see if it sheared the roll pin. If it did that will keep the gear from turning the pump too, also play hell with the timing.
  18. I got a new oil pump and pick up and installed them. The oil pump shaft is sitted well and I hand cranked the engine to make sure it was spinning.

    Fostang: While it's still not registering any pressure at the gauge, there is flow of oil as the oil gushes out then I lossen the oil filter and about half of the lifters feel pumped up with some oil circulation going on under the valve covers. As you stated, it probably has some mega sized clearnances by now but I'm not going to bother with getting a high volume pump as I'm planning on doing an engine swap soon anyways.

    PONY XPRESS: I just poured some oil in to the pump and hand spun it before installing. I hope I didn't screw it up by doing that...

    66candy: You're probably right. The peice I found in the oil pump felt like a very hard rubber.

    D.Hearne: The dist gear seems fine and the timing is stable.

    Thanks for all your inputs folks!