VP Losing all oil pressure

[Endz]

Hey guys my engines got a nasty knock, which im aware of and probably wont last much longer... Im currently rebuilding a fresh motor for it, but i would like my current one to last a few more months.
Basically my problem is im getting 40 PSI on a cold start and its near to nothing of a knock, but after about 10 minutes of driving when the oil gets hot the oil pressure drops to 0! And it starts knocking really bad. but when its sitting on 40psi the knock cant be heard..
What would be causing the oil pressure to drop to 0 when its hot?
Would a spun bearing do this or too thin of an oil?
Thanks

 

[Brisbarnz]

Id say spun bearing, same symptoms as my old vn. I just used diff oil with penrite 25/70 engine oil. Got a few weeks of putting around until I thrashed it and snapped the crank. Could still drive it on 4 cylinders but the engine miss was worse than the original knock.

I miss being young lol

 

[somefool]

best you can hope for is get a thick as #### oil to put in. as mentioned above.

a bearing would have to be spun prettty bad to drop all oil pressure tho. if you watch the gauge closely at idle and it sort of.. dips and raises with crank rpm then yes id say spun bearing. For any vn engine with kilometres in it id be running nothing thinner than 25/40 oil. Try penrite 25/70, and maybe speed up the the rebuild for the fresh motor

 

[Endz]

yeah the RPM goes all funny at idle, doesnt sound healthy at all.. ill try a nice thick oil and see if it helps at all.
thanks heaps for the replys guys, guess ill have to get this motor ready quicker lol!

 

[EYY]

Just use the cheapest oil you can find. IMHO, I wouldn't bother wasting money on hpr50. It won't do you any favours with a rooted engine. (Definitely not dissing penrite, I use hpr30 in my cars)

Just remember that oil pressure is a measure of the resistance of oil to flow, which may not be caused by bearing clearances but rather the size of the oil galleries themselves. So essentially, higher pressure doesn't necessarily mean that the bearings are being force fed oil.

Try replacing the oil pump with another used one. The pressure relief valve might be buggered or the pump housing/gears worn etc. A cracked oil pickup will make the pump suck air, and a blocked pickup will restrict flow.

 

[someguy360]

I had a spun bearing in my statesman a couple of years back, I also had good pressure when cold but 0-1psi when warm.

Sounded terrible.

BUT....I managed to drive that for 2500km and it was still running when removed, I ran Nulon extra thick 40w70 and drove it gently and it was fine.

this was how bad mine got:

 

[shadetreemechanic]

Yep, what EYY said get a new oil pressure spring. Yours only holds 40psi max it should be more, and if its never been changed it'd be weak as piss. They uprated the spring for the VR or VS but its the same part number.