Jeep question
 

Looked at a jeep tonight and its has piston slap at idle, goes away at around 1300 rpm. I know this is a common issue with the 4.0, its a 1990 cherokee. Anyone know how long these motors last with this problem?? Thicker oil help??

you sure it is piston slap and not lifter tap? lifters are a normal issue. i had a 89 cherokee with over 250k miles on it and it was still running. the oil pressure was starting to get low but it still ran.

louder than a lifter, went away off idle. could it be torque converter bolts also a common isue.

Was this more of a problem for the Renix era 4.0s? I rarely hear piston slap mentioned in connection with a 4.0 HO.

- Justin

Lifter noise is pretty common and can be cured...well, covered up, anyhow...with slightly heavier oil. It would seem that the only way to cure the piston slap is to rebuild the motor, so you would either have to do so or live with it until the engine warms up. How many miles on this Cherokee? Might be worth it to keep shopping.

If it is piston slap it generally should go away when warmed up. Does it?