when I start my 98 Z28 A4 recently ( colder weather ) I have noticed this dull ticking and after awhile it seems to go away. Is this the beginning of - OR - Piston slap I hear about in here? It bothers me a bit but from all I've read in here it is normal and nothing can be done. I guess why it bothers me most is this car with now 41,000 miles has absolutely been perfect, best car I have ever owned. Furthermore, I just traded the opposite of my Z28 in on a Silverado with a 5.3 V8 Vortec engine and while test driving these I heard a couple of them make this same ticking noise, HOW similar are these two engines? Thanks...

 

Sorry to say, but yes, your car is suffering the infamous "LS1 piston slap". Many people (myself included) have questioned the service department at the dealership, and their response is "it's normal".................. while it is common, that's . You're lucky if your's only does it when it's cold. My '02 has made the noise since it was brand new in the summer.

As far as the 5.3L Vortec's, they are very similar to the LS1's.......only difference being the displacement, and they use cast iron blocks instead of aluminum. My dad's work has a couple trucks with the 5.3L, and he says they make the same noise my car does, although he feels like the trucks are a little quieter, but that's probably because the iron block dulls down the noise a little more than the aluminum.

Well, hope that helps...................IMO, you can rest easy knowing your LS1 is "normal" .

 

try some engine cleaners to help remove deposits if you don't use them regularly already. I wouldn't say this is normal i've never heard anything from my engine. and i run fuel system cleaner reguraly,the stuff actuallt pays for itself with the octane boost it gives saving gas. and on top of that i run synthetic, that keeps the engine much cleaner. also better quality gas will help. you would be surprised how many stations water down gas and sell 89 or 91 octane though a 93 pump, on the other hand the engine is designed for 91, maybe 93 is causing it, maybe you should try mixing some 89 with your 93.

 

pardon my ignorance, but what exactly is this "piston slap", is it like the piston hitting carbon deposits in the chamber?

 

The piston slap heard in LS1's is usually worse when the engine is cold, and this is because the pistons haven't warmed up to operating temperature, and until they do, they haven't expanded enough to "fill" the cylinders, so when they're cold, they're actually loose inside the cylinders, and therefore they can rock back and forth slightly on the wrist pin and cause the "knocking" noise. I've heard that a carbon build-up on the top of the pistons contributes to the noise somehow, but I'm not sure I buy that explanation 100%, since my engine has had the "piston slap" since day 1 (and I'd like to think a brand new engine doesn't have a carbon build-up yet?! ).