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Second Chance Garage

For the Classic Car Restoration Enthusiast

Second Chance Garage


Second Chance Garage

For the Classic Car Restoration Enthusiast

Second Chance Garage

Second Chance Garage

For the Classic Car Restoration Enthusiast

Second Chance Garage

DR. CRANKSHAFT

After a complete rebuild, it was perplexing when Dabney didn't get any oil pressure...

It was a pleasant Fall day when Dabney and the Doctor were finishing the reassembly of a 283 cubic-inch V8 engine that was to be installed in Dabney's newest acquision, a 1959 Chevy Impala convertible. The engine ran very poorly when Dabney bought the car back in the Spring, and the two had diagnosed its problems early on: worn rings and burned valves. Since that time the engine sat around until an opportunity presented itself. In the late summer months Dabney and the Doctor got around to the rebuild and were putting the finishing touches on the engine.

"Well, we've got it all together, so there's nothing to do now but start it up and see how it runs," said the Doctor. "We'll test it here on the stand to make sure it's okay before putting it back into that cavernous engine bay."

"You're right there, Doc," said Dabney. "That's one large area to lean over in the old '59, so it would be nice not to have to fiddle around with things in there."

They created a "dashboard" for the engine test. It contained a start switch, ignition switch and one for the electric fuel pump they would use for the occasion. It also held oil pressure and temperature gauges, but the first "run up" would be done without a cooling system. After hooking up a battery they checked the starter (it worked) and then the fuel pump. Once the carburetor's float chamber was filled they hit the accelerator pump twice to prime the engine and then engaged the start switch.

To no one's surprise (the Doctor and Dabney have built several hundred engines, after all) the engine fired right up and ran smoothly. After about 20 seconds the Doctor yelled "shut it off!"

Dabney did so, asking "what's wrong, Doc? It's running great."

"There's no visible oil pressure showing in the meter," said the Doctor. "It's probably air in the gauge's line or some blockage, but let's assume there isn't any internal pressure until proven otherwise."

They removed the pressure gauge's line and fittings and verified that they were free and clear. They then rigged up an air line to the gauge itself and verified that it read pressure. Not finding anything wrong, the Doctor said "Hmmmm, let's unhook the pressure gauge's line and crank the engine. Oil should flow out of it."

They did so and, disconnecting the coil, cranked the starter. No oil came from the open line.

"This isn't good," said Dabney. "Maybe the distributor isn't driving the oil pump."

"Yeah, let's pull it out and hand-turn the pump shaft," said the Doctor.

They did so and verified that the mechanical components were engaging properly, but there was still no oil flow.

"Okay, we need to pull the oil pan and see if we have a loose bearing cap or some other major problem," said the Doctor.

"I was afraid you'd say that," said Dabney.

They drained the oil, rotated the engine and pulled the pan off, being careful not to harm the gasket. Once the bottom end of the engine was opened up they inspected all the main and rod bearing caps for looseness and then re-torqued all bolts and nuts. They remeasured the crankshaft end thrust as well, finding nothing wrong.

"Let's remove the oil pump and test it," said the Doctor. "We put this new one in as part of the engine rebuild kit, so maybe it isn't any good."

They removed the pump and drive shaft and placed it in some oil. They hooked up a drill to the drive shaft and turned it, noticing right away that the pump shot out a steady stream of oil.

"I wasn't expecting that," said Dabney. "We haven't found a thing wrong yet and we're running out of potential causes."

"I agree, old boy," said the Doctor. "Let's put the pan back on and spin the pump with the drill to see what happens.

They did so and, unfortunately, no oil was circulated by the pump.

"Off with the pan," said the now-impatient Doctor. "We missed something in there and we've got to find it."

They removed the pan again and made another thorough inspection, finding nothing wrong. The Doctor started staring at the components...

"There's nothing wrong with the pickup tube and screen filter — I check them before reassembly," he said. "But just for fun, let's measure the depth of this thing."

They did so and found the depth of the pickup tube matched almost precisely the depth of the oil pan.

"According to our measurements, the bottom of the tube sits flat against the oil pan. If that's true, it won't suck oil," said the Doctor.

They removed the tube and inspected it, finding that it had a slight kink in its 90-degree bend. They gently bent it back a little and reinstalled it, taking new measurements.

"Okay, if I'm right about this there should be enough clearance for the tube to suck oil now," said the Doctor.

He was right, of course...