This weekend I finished my engine rebuild so I tried to run it, after a few tries I was gone check the oil pressure on engine head bolt and not even a drop. I had run the engine sometimes but not longer than 60 seconds and only retry after it cooldown if I need to guess I run it for about 8 minutes in total, is that time enough to damage something on the engine?

The oil pump is new and on the lower part of the oil system has oil on it, this will sound stupid but can be air bubbles?

  • Isn't air bubbles. Yamaha doesn't sell new oil pumps with it's o-ring, so I went to check the older one, lucky enough I didn't throw it on trash earlier, and standing on its place, laughing at me, the o-ring ¬¬. Opened the right side of the engine put it in place and oil pressure is on skies. Dec 19, 2016 at 12:42

1 Answer 1


If you are saying that you have run the engine with no oil for 1 minute at a time, for 8 minutes. I'd have to ask why.

Running an engine with no oil is just asking for trouble and running it 8 times for 1 minute at a time Is easily enough to cause damage or at least wear to any components that are contact with each other.

I'm afraid that if it were my engine I would be pulling it apart again to check for bearing or piston ring to cylinder wall friction damage.

  • I did it to test the engine, as I said I thought that only turn the crank by hand or use starter would not do the job, it was not entirely without oil all parts was lubricated during rebuilt. And I already open the oil lines, filled the radiator and I don't see oil coming out, the pump works but I can't tell if should be stronger or not as the service manual doesn't specify the oil pressure, it does say to when change oil check the pressure and wait for 1 minute to oil begin to exit the check bolt.ore Dec 14, 2016 at 12:34
  • Was there the correct amount of engine oil in the sump or not?
    – Orb
    Dec 15, 2016 at 5:34
  • yes, I had filled in the sump with the specified oil amount. I removed the valve cover and has oil all over the place, I begin to think that the oil pressure check bolt don't work well Dec 15, 2016 at 12:31

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