CARspec had the unique opportunity to repair a 2005 Lexus LS430 recently – this particular vehicle suffering from a loud ticking noise and a rough running engine. After some diagnostics and a compression test of the suspect #1 cylinder, the technician used a digital boroscope to inspect the cylinder while the head was still on the car. The camera show 3 out of the 4 valves were open. This is not normal – only 2 intake or 2 exhaust valves should be open at any time on this engine. Suspect was a failed valve, guide, or seat that was holding the valve open. The owner ok’d the technician to remove and tear down the cylinder head as well as inspect the block and piston for damage. The process is major surgery:
LS430 cylinder head removal
It didn’t take long to find the culprit:
LS430 Damaged Valve Seat
The first intake valve’s seat on cylinder #1 had partially fallen out of the head and cracked, a rare occurrence on any Lexus (especially on the normally bulletproof 4.3L V8). The technician inspected the valve, lifter bucket, and shim, all of which were also damaged:
Damaged Valve Set
The inside of the head was also gouged from the shim and lifter bucket being forced into the valve spring’s bore. The head was declared a total loss due to the damage. The technician inspected the rest of the head and block, finding no further damage, and recommended a new cylinder head (reusing all the old valvetrain parts save those pictured above). With the new cylinder head now installed the vehicle ran perfectly and was returned to service.
As Minneapolis, Minnesota independent Toyota, Lexus and Scion specialists we pride ourselves on the highest quality Lexus and Toyota repairs, even if it is major engine repair and cylinder head rebuilding. If you have a Toyota or Lexus with issues major or minor, don’t hesitate to call us at (952)426-4798 to schedule an appointment today!
