Our Repair of the Month for October features a 2017 Jeep Wrangler 3.6L V6 with 85,000 miles the customer reported the vehicle was smoking and overheating, but there was no sign of coolant leakage, even though the coolant level was low. In light of this information, we conducted a chemical test to determine if there was an internal coolant leakage in the engine. The test confirmed the presence of exhaust
gas in the coolant, which is typically an indication of a bad head gasket or a crack in one or both of the heads (top half of the motor). When the head gasket is damaged, exhaust gas leaks into the coolant system, and the coolant leaks into the motor, where it mixes with engine oil. We confirmed that the head gasket was defective and removed the motor and removed the heads.
We advised the customer to replace the heads with new, fully loaded ones, to avoid future problems as other
components such as camshafts, timing components, and lifters could also fail. After installing the new head gaskets
and loaded heads, we believed all the issues were resolved, but during final testing, we discovered that the vehicle
had no heat. It turned out that someone had poured a "stop leak" into the coolant system to fix the coolant leak.
The stop leak entered the heater core, clogging it and resulting in no heat. (The heater core is similar
to a tiny radiator responsible for heating the interior.) We used our coolant flush machine to flush out the stop leak
that clogged the heater core and then flushed the entire cooling system to remove any remaining stop leak and
prevent future issues. With new head gaskets, loaded heads, and a clean cooling system, we were able to restore
the vehicle to good condition and ensure that it would run for many miles to come.
Photography: Adam Winget - Winget.Photos