1989 240sx KA24E, ticking sound on rebuilt motor...

[Touchdown038]

So I rebuilt my motor this summer but didn't touch the rocker arms in the head, besides taking them off.. well here's the problem.

When it's cold (don't really notice it when it's warm) the motor will tick under light throttle, but not under any other conditions. When I'm engine braking, it doesn't tick, nor under heavy throttle, but only when I hold the throttle constant or light pressure. It's not a deep thunk either, so I *think* I can rule out rod knock, but more of a mid-level tap... I'd attach a sound clip but I don't have a mic or anything that has a mic on it.

I would think that it has something to do with the rocker arms but I'm not sure.

Sound familiar to anybody?

[yellow_jacket]

All too familiar. The last time I had a noise like that, it turned out to be a bad wrist pin on a Toyota pickup truck. Without being there in person, this is going to be very hard for anyone to diagnose.

This could very easily be a hydraulic lifter problem as well. Without actually being there to hear it, it will be too hard to tell.

What exactly did you do when you rebuilt the motor?

[Touchdown038]

Just a stock rebuild... new pistons (with new pins) and rings, new wrist pin bushings, had the rods checked at the machine shop, engine hot tanked and honed, crank journals polished, head job (new valve guides and lap job), new timing kit, new sensors, etc. Rocker arms were left untouched though.

Could it still be a wrist pin problem if they are new pins? They all slid back and forth freely before I put in the C-rings so I figured they'd be good....

[yellow_jacket]

If you had the bushings in the rods replaced and got new wrist pins then that shouldn't be your problem.

More than likely it is just one of the old lifters starting to collapse a little.

[nelson8708]

Just something i thought i would mention. I have what sounds like the same problem. Turns out it is a injector tick.

Just my 2 cents.