Engine Mechanical problem
1990 Ford Truck V8 Four Wheel Drive Automatic 169000 miles
Help, Changed oil sending unit, Installed new stock rod bearings, new high volume oil pump, cleaned sump pick up tube and inspect for crack (none found). Main bearings seamed sound. Change oil relegiously. New oil filter 10w40 oil. Still have problem. Engine has excellent oil pressure when first starts (Cold). After engine warms up the pressure starts dropping and somtimes fluctuates from low to normal down to normal at idol. Give it a little rpm goes to normal. Stop at light, in gear at idol dropps to low and pulses slightly and sometimes flat-line. Put it in neutral engine rpms increase normally and pressure goes to normal. Put it in drive goes back to low and sometimes puleses. Logic tells me when oil is cold and thinner reaches all ports and normal pressure. Engine heats up things expand worn bearings get sloppy oil temp increases the gets THICKER should go through the bearrings slower then oil pressure should then increase not decrease and hoover at zero. Any suggestions other than OVERHAUL. Is there a seperate pressure relief valve some where on this engine. Oh yes the engine sounds fine and there is no clatter or lifter problems. Help
have the same problem?
Wednesday, July 15th, 2009 AT 10:57 AM