Toyota Vellfire /Alphard Engine Knocking noise in the morning (cold start)

Balance Shaft Problem

Engine model :- 1AZ engine 2.4cc

​

Car Model :- Estima, Alphard, Vellfire, Harrier, Camry all 2.4cc

​

Signal :- early morning engine start got "kolo, kolo" sound, but after few minute then no sound already. Afternoon and evening then ok

​

Checking :- remove fan belt then start engine in the morning, if got sound then confirm is balance shaft problem

​

Solution :- remove the oil pan, change balance shaft, flushing the engine to remove fiber powder.

​

Reason :- this engine balance shaft gear is made by fiber "green colour" to protect crankshaft worn out. And this fiber has it's life spent.

Effect of no change :- if you don't change and let it go. The fiber powder might block the oil pump net, causing the oil cannot pump up to cyclinder head. Then change engine eventually.