Oil Cooler Line Crimped?

pbyoung · December 13, 2013

I have 2003 Denali XL (6.0l) with 160,000 miles on it. Recently had my oil cooler lines replaced by a local mechanic that I have used without issue in the past for several cars.

However, after the lines were replaced my engine gave out two days later. It just died without warning while driving. After being towed
to another mechanic in another town I was told that one of the oil cooler lines was crimped and caused the failure. There was no oil leakage.

The mechanic that replaced the lines says that even if the line was crimped the truck still would have run because there is a some sort of bypass. He also stated that if the engine wasn't getting any oil after I picked it up i wouldn't have even been able to go several miles much less 50 that i drove.

Is the mechanic correct that a crimped oil cooler line would not likely cause the failure?

gmtech4 · December 14, 2013

Engine lubrication is supplied by a gerotor type oil pump
assembly. The pump is mounted on the front of the engine block and
driven directly by the crankshaft sprocket. The pump gears rotate
and draw oil from the oil pan sump through a pick-up
screen and pipe. The oil is pressurized as it passes through the
pump and is sent through the engine block oil galleries. Contained
within the oil pump assembly is a pressure relief valve that
maintains oil pressure within a specified range. Pressurized oil is
directed through the lower gallery to the full flow oil filter
where harmful contaminants are removed. A bypass valve is
incorporated into the oil pan, at the oil filter boss, which will
permit oil flow in the event the filter becomes restricted. At the
rear of the block, oil is then directed to the upper main oil
galleries which are drilled just above the camshaft assembly. From
there oil is then directed to the crankshaft and camshaft bearings.
Oil that has entered the upper main oil galleries also pressurizes
the valve lifter assemblies and is then pumped through the pushrods
to lubricate the valve rocker arms and valve stems. Oil returning
to the pan is directed by the crankshaft oil deflector. Oil
pressure and crankcase level are each monitored by individual
sensors.

An external oil cooler is available on certain applications,
all 6.0L. Oil is directed from the oil pump, through the lower main
oil gallery to the full flow oil filter. Oil is then directed
through the oil pan outlet oil gallery, located in the left rear of
the oil pan, and to the external oil cooler via a hose assembly.
Oil flows through the oil cooler and returns to the engine at the
oil pan inlet oil gallery, located in the left rear of the oil pan.
Oil is then directed to the upper main oil galleries and the
remainder of the engine assembly.