04 Lx470. Drives flawless, serviced exclusively by one Lexus dealer since new, until I Purchased with 168k, has 176k now. Shifts like butter under all conditions until yesterday.
Has developed intermittent Slight THUNK on the 2-3 shift, approx 30mph, light to moderate throttle. Mostly exiting turns, but happened once on a straight stretch of road when I slowed down for construction. (Not the common thunk when starting from a dead stop, but it feels identical, just at-speed instead ) Only intermittent, and only if you've decelerated from speed and then reapplied the throttle. It shifts into 3rd and then a second later I feel a thunk.
If you start from a start it shifts smooth through all gears.
It feels like it's from the rear of the truck but I'm in no way certain of this. I am watching the tach now to see if it jumps when this happens (I'll update). I do NOT think the tach moves when it happens.
Vehicle does have very minor driveline lash, i.e. If you get on or off the throttle rough, the rear end will clunk very slightly.
Trans was replaced by PO at Lexus dealer at 135k because it had harsh engagement of Reverse. Thus, trans and fluid are ~~40k old. <-----highly unusual to see one of these 5speeds replaced in the first place...
Vehicle does fall within the VIN range for the rare shudder issue due to breather tubes that allow water to enter trans. Vehicle does NOT shudder at any speed. I assume that the breathers were changed when they replaced trans but am not sure.
My Indy lubed the slip yoke which was bone dry and the thunk has reoccurred 2x over 500 miles since.
Trans is not in ECT power mode, which I haven't tried yet.
Vehicle thunks maybe once every 100-200 miles. No loose spare tire or hitch.
1) trans mounts?
2) slip yoke still?
3) bad trans or torque converter (please no!)
4) seized U joint?
Any thoughts?
UPDATE: 3,500 miles later, running premium fuel since the original post, and it hasn't clunked a single time......ECU must have adapted to the premium fuel and is shifting perfectly.
Has developed intermittent Slight THUNK on the 2-3 shift, approx 30mph, light to moderate throttle. Mostly exiting turns, but happened once on a straight stretch of road when I slowed down for construction. (Not the common thunk when starting from a dead stop, but it feels identical, just at-speed instead ) Only intermittent, and only if you've decelerated from speed and then reapplied the throttle. It shifts into 3rd and then a second later I feel a thunk.
If you start from a start it shifts smooth through all gears.
It feels like it's from the rear of the truck but I'm in no way certain of this. I am watching the tach now to see if it jumps when this happens (I'll update). I do NOT think the tach moves when it happens.
Vehicle does have very minor driveline lash, i.e. If you get on or off the throttle rough, the rear end will clunk very slightly.
Trans was replaced by PO at Lexus dealer at 135k because it had harsh engagement of Reverse. Thus, trans and fluid are ~~40k old. <-----highly unusual to see one of these 5speeds replaced in the first place...
Vehicle does fall within the VIN range for the rare shudder issue due to breather tubes that allow water to enter trans. Vehicle does NOT shudder at any speed. I assume that the breathers were changed when they replaced trans but am not sure.
My Indy lubed the slip yoke which was bone dry and the thunk has reoccurred 2x over 500 miles since.
Trans is not in ECT power mode, which I haven't tried yet.
Vehicle thunks maybe once every 100-200 miles. No loose spare tire or hitch.
1) trans mounts?
2) slip yoke still?
3) bad trans or torque converter (please no!)
4) seized U joint?
Any thoughts?
UPDATE: 3,500 miles later, running premium fuel since the original post, and it hasn't clunked a single time......ECU must have adapted to the premium fuel and is shifting perfectly.
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