98 LS1 - Ticking on cold start, goes away when warm

[meissen]

As most of you know, dad is selling his 98 Trans Am convertible. He hasn't run it that much through the winter, but I guess when he went to start it with a prospective buyer there it had a ticking noise on cold start. As the engine warmed up it went away. I've heard of LS1 piston slap but I'm not sure if that would sound like a tick? Dad thinks he needs to adjust his valve lash since it has over 100k miles on the clock, but it's bone stock and it seems weird to me to adjust valve lash on a bone stock engine.

What are your guys' thoughts? Could it just be piston slap?

[PewterPan]

If the tick is more like a sewing machine noise, im pretty sure its typical. My '02 does the same.

[farmington]

only way to adjust is different length pushrods. Get it warm and drain the oil. maybe just some crap from sitting all winter

[GlennT]

Piston slap sounds more ominous, almost like a rod knock, but distinct enough to identify. Even at it's mildest, I don't think I'd ever describe it as a tick, but it can be a light tapping sound.

It's likely lifter noise from at least one lifter not pumping up right away. I wouldn't attempt to adjust hydraulic lifters, *especially* when the noise goes away when warmed up. At best, a valve will get hung open. At worst, something breaks.

I've had reasonably good luck freeing up lifters by running full synthetic oil, and Seafoam engine cleaner or Marvel Mystery Oil, but it can takes months to free up a particularly stubborn lifter. There are more aggressive methods, but they require at least pulling the valve covers and rockers, to attempt to spray cleaner down the push rods and into the lifters, then letting it soak, spraying more, letting soak longer, etc.... Beyond that is pulling the intake to actually remove the lifters, to either soak them in cleaner or replace them.

[pferris]

The lifters have a fair amount of travel, adjusting valve lash really isnt really a thing. Different pushrods would just adjust lifter preload. But my ls1 did have a bit of a sewing machine sound too it, and there were no problems with the motor.

[zeeman]

There really isn't any adjustment to be made. It probably has some gunk in it, it happens. change the oil, maybe try a synthetic for a bit to try and flush out the lifter. There are a few videos on you tube of guys removing the valve covers and spraying a good carb cleaner down the push rods to try and dissolve the deposit plugging the lifters.


I just saw Glen beat me to this.

[meissen]

Thanks guys -- our experience is more with the LT1 and we adjusted valve lash on my cammed LT1 and on his stock LT1. I didn't realize it's not really a "thing" on the LS1.
@98blackbeauty

[Lucky SOB]

Lifters are taking some time to pump up. As the others have said, there is no adjustment for the rocker arms. There's really no way to fix it without pulling the heads and replacing the lifters. I wouldn't be too concerned, just don't rip on it until it's at operating temp.

[1BADAIR]

exhaust leak

[BlackJesus]

More than likely piston slap IMO. 100% normal.

[meissen]

Well I went over to his house today to listen to it -- no noise what so ever. I agree with Fred - I think a lifter likely needed to cycle for a bit to get pumped up with oil and that's all that was going on. After a few runs today it was fine.

Should make it easier for him to sell.