Right after it overheated most recently, oil pressure was up. Now, it's back down where it originally was, if not a little lower. I think either the oil pump is wiped out or the front cam bearing is toast. This engine spends its life at 3-4000 rpm daily on the highway. Perhaps 40,000 miles of that is too much for a sbb.
I must have the only adjustable oil pressure regulator, when I found my hot oil pressure below 20 psi last year, I swapped out my spring and adjusted it from 40 cold and 15 hot, to 50 cold and 25 hot. How can that be explained? 3-4 guys here say it does nothing, so why then is it called adjustable?
It adjusts the max pressure. It is the relief valve. When pressure reaches that level it releases it. Below that it is just flowing at whatever pressure it generates.
That rpm is fine, won’t hurt anything. So the pressure increased when it overheated, then retuned to normal?
Yes, pressure increased after the overheat. My guess was maybe it tweaked the timing cover, and after awhile the gears re-wore in the pump cavity. Then after driving it a few thousand miles later, it went back down, lower than it was before the overheat. Driving around town it's perfectly fine, its the highway when the oil gets as ho as possible it's illumining the light and not going past 35/40psi at all, no matter what spring i use or how many turns on the adjuster.
Didn't lock up, didnt rattle, heater hose blew and it was 5 miles to the next exit, so probably drove about 3-4 miles with little to no coolant at all in the engine at 3-4000rpm.
because you can? that overheat put the toast in that motor, you should have not drove it once water came out 1200 rpm is one thing but 3-4 k? no, can't handle that. now if you had synthetic in it that may have taken that heat a few more miles but overheat will eventually kill any oil. BTW the adjuster works, well at least mine does.
I was on the highway, 50 miles from home, did not have the money nor time to have it towed, just needed to pull off to a place with water. Did such, cleaned up the mess, looped the hoses, filled the system with gas station sink water (warm, not cold), and drove home.
I can't tell for certain, and won't know for some time, but I do believe either the pump is worn out, or the cam bearing is toasted. It doesn't make any noise except for that cold start piston rattle (lifter?) if it hasn't been started in a few days, but again it doesn't do it all the time.
I wouldn’t worry as long as the noise goes away when pressure comes up. As I said before, critique everything at that time. Same as above. Did you forget you put the factory spring back in there? It maxes out at 38/40 lbs. What gear you have in your rear? How fast you drive? What your describing sounds normal.
The pressure regulator controls the MAXIMUM pressure the pump can produce. If your oil is to thin when hot, OR if your bearing clearances are too big, the pump MAY NOT be able to achieve and overcome those conditions, and tightening the adjuster to increase spring pressure won’t do ANYTHING, Why??? Because the pump hasn’t reached the pressure to overcome that spring and open the valve. On a cold start when the oil is thicker, it’s VERY easy to achieve the regulator setting.
If it doesn't produce more pressure with the adjustable regulator, you have too much clearance or too thin of an oil. In either case, try adding something like STP to the crankcase to see if that helps. It will thicken the oil and possibly limp you along for another year or more before you have to get inside of it. Also, make sure your oil filter has an anti-drain back valve. That cold rattle you describe could be mains knocking.
I suppose it stands to reason, the maximum pressure my pump produces is at cold idle. 70-80psi, once it's hot it never gets above 40. Bearing clearance was .002 on the dot when assembled once back from the machine shop.
