By Roy Berndt

Figure 1: KA24 Nissan SOHC block may have timing chain wear that looks like a machined surface. The black square area is a hole into the coolant passage.

Many of you may have not seen this issue, but once it bites you, you will always remember the Nissan KA24 engine series in the SOHC configuration. 


When the timing chain, guides and tensioner get high miles and wear the chain can actually start rubbing against the front of the block (Figure 1). 



The wear actually looks as though it is a machined area and you may over look the big grooved area. But when the chain cut/rubs into block long enough it may actually break into the water passage (Figure 1).

More often than not when this situation occurs the chain has trashed the front cover as well and if there was coolant in the oil the cover gets the blame. 


So take heed when you encounter the KA24, 2.4L SOHC Nissan engine for remanufacturing: there may be a hidden problem that can easily get over looked. Make certain that you inspect the front of the block and if there is any chain rub groove you better make certain that enough casting thickness remains not to end up with a coolant breach.

Roy Berndt has decades of machine shop experience. He is the Program Manager for PROFormance Powertrain Products, a PER in Springfield, MO. You can reach Roy at [email protected].