91 Montero with external oil cooler.......Help! Tried both electrical oil pressure sender and mechanical with same results....instant 80 psi oil pressure reading!!!! I know there is no oil flowing as I just froze an engine late last year with this same psi reading and could clearly hear extremely noisy valves/rocker arms......20 seconds later.....SQUEAL!!...FREEZ-UP!! I have checked all oil lines and cooler-no blockage. This is a brand new block and heads(I did prime both the oil pump and block) Is there some kind of pressure valve in the oil filter housing. Any ideas??

By brand new I hope you mean it comes with a warranty. It would be them to call first hand. Sounds to me like a spun bearing. There are no one way valves btw. I'm sure there is a pres. relief valve but it does just that.The best thing would be to not keep trying to run the motor (impatience). Maybe try swapping a new filter in and crank the engine with no spark plugs in.
I'm sure more people will chime in, just hang in there! (I know how you feel!)

I haven't yet ruined this motor (and certainly don't want to!)I forgot to say I also installed a new oil pump too.

Yes, there's a relief valve in the oil pump. It's not unusual for oil pressure to go to 80psi on initial startup of a fresh engine. Rev it to 2000 rpms and hold it there for 15 minutes. You should see the pressure drop after a few seconds or so.

If you didn't prime the lifters, they'll be noisy for a few minutes and may take the entire 15 minutes to completely quiet down.

Once the engine's completely warm, shut it down and change the oil and filter plus coolant. Then take it out for some 2nd gear acceleration/coast runs.... easy at first, then gradually up to 5000 rpms with coast-downs after each run, keeping an eye on the temperature. After a few miles of this and if it appears to be ok, run the p*ss out of it until it gets starts to get warm, slow it down to cool off and go home...... your break-in's done.

Frank

That's gonna be a long ass few seconds!!
Good luck and get to it!!

You got that right! I think I know what I'll do. I'll prime the engine with oil again, remove a valve cover, run it, and see if oil is actually flowing out of the pin holes on the rocker arms above the lash adjusters. I am assuming that I should see oil.

Crank it with the coil wire grounded until you see oil pressure steady up!

MAy also want to try pulling the plugs so it spins over faster. Less work on the starter motor and you get pressure faster and it reduces the laod on the bearings while you wait for the pressure to come up.

Also its always good to prefill the oil filter.

Kevin C

OK. Now I know for sure I have oil pressure. I removed a valve cover and started the motor. Oil shot out the pin holes in the rocker arms (glad I wasn't standing to close!). My worry stemmed from a past experience with oil pressure reading normal but no oil flowing and the motor locked up. I could tell as the valves/rockers never quieted down and I didn't respond quick enough. I'm good now! Thanks for all the replies.