Oil pressure drops after 10 minutes
 

I have an 87 5.0 w/ AOD. It blew a radator hose and my son tried to make it home. It ran very hot. It shutdown. He started right back up and ran it again until it shutdown again. NOW, it runs fine for 10-15 minutes then the oil pressure drops and I hear a tapping (valves, maybe lifters). I have deslugged the engine, changed the oil and tried to thicken it up with some 20W-50 weight. No difference. No oil in the water, no water in the oil. Any thoughts on why the pressure drop? Crank bearings? PS. My son now drives a WV, he is not allowed in the Mustang.

Thanks.

I would recommend adding a manual oil pres guage. Those fact gauges aren't very good. This will give you a good idea of what the pres is really at and if it's a problem. You could also try some 40wt oil. my 2 cents..

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85GT 5.0 was CFI converted to Holley 650. Hooker full length headers. Weiand Stealth manifold. 86 roller motor, crane 1:7:1 alum rocker arms(roller). SSI 220@.050/498 Roller cam. Summit double roller timing chain. HD oil pump, stock bottom end. Mallory Hi-Fire ignition. Under drive pulleys. Accell coil and Ford Motorsport 9mm wires. 93'8.8 posi. Working on getting 4:10s. AOD w/B&M shift kit. No figures yet, still working on it.

I would splice or tee in a manual gauge, right at the sender,and check the pressure, but with the other symtoms it doesn't sound good.
You probably have a lower end to rebiuld, maybe a head gasket and who knows what else, but hay, good reason to tell spouse you need a new Gt-40 crate motor right!
Good luck...Mac