At a loss with oil pressure loss when hot?

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lbern33

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having some major oil pressure issues when my 360 gets hot. Initially was running 10w-30 on startup was getting about 35psi at idle and pressure would slowly bleed down to nothing. I tried a couple different mechanical gauges to confirm then checked oil plug under distributor hole, changed oil pumps, changed oil and filter(fram and napa). Still had problems. Went to heavier oil but still dropping down to less then 5psi when hot after starting up near 60psi when cold. Funny thing is no valve noise or knocking even when running. Took intake off and looks like oil is getting everywhere it should. Motor was supposedly rebuilt not too long before I bought it. Looking for ideas before I pull the motor and take to machine shop or swap. Any help is appreciated.
 
lbern33 said:
having some major oil pressure issues when my 360 gets hot. Initially was running 10w-30 on startup was getting about 35psi at idle and pressure would slowly bleed down to nothing. I tried a couple different mechanical gauges to confirm then checked oil plug under distributor hole, changed oil pumps, changed oil and filter(fram and napa). Still had problems. Went to heavier oil but still dropping down to less then 5psi when hot after starting up near 60psi when cold. Funny thing is no valve noise or knocking even when running. Took intake off and looks like oil is getting everywhere it should. Motor was supposedly rebuilt not too long before I bought it. Looking for ideas before I pull the motor and take to machine shop or swap. Any help is appreciated.
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are the "Plugs" in the ends of the rocker arm shafts ?
 
remove the oil pressure sending unit when the engine is hot and running
if the stream of oil burns your face, its good
(also the reason the put oil pressure lights instead of gauges in cars)
 
I had an engine that did the same thing a 6 cly ford 300 the engine was rebuilt and the crank was turned 10 thousand and std rod berings were used it ran good but when it got hot it had no oil pressure . not saying this is your problem .
 

You have a internal leak, either the bearing clearences are off, the lifter bores are really worn or the wrong lifters are in it.
 
I'm betting the "rebuild" was BS and the bearings are way to loose.
 
Check all the oil galley plugs. Make sure that the two behind the camshaft thrust plate are in...
 
justinp61 said:
You have a internal leak, either the bearing clearences are off, the lifter bores are really worn or the wrong lifters are in it.
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This is likely the issue... too much outflow somewhere. It is easy to keep the pressure up with hot oil with regular clearances everywhere. My son's 340 is at 40-45 psi 10W30 hot idle pressure. An HV pump isn't enough of a flow boost to get this up much.
 
1....Pull distributor and determine if the rear plug which is installed by "reaching into" the rear of the block is in there

2...Use a stick and determine if the drive in plug in the vertical galley coming up to the oil sender is installed.
 
I have to go along with loose bearings bottom end or cam bearings dumping oil after hot. Easy to prove out. Remove thermostat, add a garden hose at radiator cap, and leter run cold maintaining good oil pressure all day.
 
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