Diplomat

Yeah I was just reading on it too and its happening more and more often than, more than I though...however its only happening on stock motors I think GM is starting to cut corners and use low quality materials.

But back on the subject I would have though of maybe a loose valve/rocker arm, which may very well be but I like to start with easy sets first before going into the engine.

Taking the belt off takes 5min, take it off run the car and see if the sound stops. If it does not take those couple of bolts off on the valve cover and check the valve lash on all valves. Now that I think I had to replace one of my rockers a long time ago. I can't remember why though..???

Diplomat

It all depends on the manufacturers...I've yet have to personally experience a "piston slap" on one of my engines. It happens for often with low profile pistons which stock V8's almost all have. Most aftermarket manufacturers have virtually eliminated this with their new tech and more advance materials used for piston rings. Also their pistons are the same with at the top as they are at the bottom which prevents the piston from moving too much with the assistance of rings it eliminates it.


Check this picture out, you can how bottom piston it thicker and all around better built and designed that a stock-er.

To answer your question: (Why it occurs?) It's hard to say, mainly heat would be one reason, constant over heating could cause it, blown ring or spun barring...

Diplomat

These pistons will not stand a chance inside of a cylinder if there is free room to move around...this is what happens, this is what the inevitable outcome of "piston slap" which I don't think this guy has. Like always I'm not saying it isn't its just my opinion and I would hate to see him take his engine down to find out he had a exhaust leak, you know what I mean?

neil350

One from the top:

http://www.youtube.com/watch?v=7RLZGUTcGHI

One from the bottom:

http://www.youtube.com/watch?v=4hWry7ptUiw

Diplomat

That a boy, in the bottom video you can see where the sound is coming from, its your idler pulley. The spring on it is shot...watch the video a few time and you will see it jump up as the tone "tick" goes...

Easy fix, but to be sure, put a wrench on it, let it lose, take the belt off and see if you can hear the sound, motor will run fine with the belt off.

Good looking engine too!

neil350

Took the belt off and started it, the car didn't make the noise at all. I had the battery charging on a battery charger so I let it run a good minute or two and it never made that noise. This means that the new NAPA belt tensioner was bad out the box, since I changed it during the heads and cam swap, and it's made the noise since. The starter is acting up as well (auto zone) brand, so looks like I'll be warrantying that. Thanks for the help. Putting a genuine ac delco back in this time, I have had nothing but bad luck with these parts store parts.

Diplomat

Yeah I knew it could not but anything serious, but serious enough to make you think twice about driving the car. Those little parts your better of with AC Delco since when they go its easy to replace and you don't have to wait for mail. Today's technology help you resolve your problem. Glad I could be of assistance.

Injuneer

You might want to think about HOW this thread got off subject. There was nothing wrong with someone suggesting "piston slap", because it is a common issue on the LT1. Where things went wrong was the overblown debate that you seemed to want to start with some fairly inaccurate statements. That's not the way we do things here.

Diplomat

Yes, point taken, my fault!

marshall93z

My Mahles make a bit of noise on COLD mornings, but goes away within 10-30 seconds. Depending on HOW cold it is! lol

Injuneer

You ought to hear a set of BME 2618-T61 aluminum nitrous pistons when they are cold.... fortunately, the rattle of the solid roller cam covers it up pretty well.....

Venomous360

By the way glad you figured it out. My motor on a freshen up with just a tank job, bearings all the way around, and new rings has started a slight cold knock on the cold cold mornings. Cant wait to get the Other LT1 block I got going.

Oh and sorry if I steered the thread in the wrong direction. Its been real hard to get anyone to listen to me on this piston slap causing many more problems down the road. Most say " change your oil every three thousand miles and you wont have that problem"

neil350

So far I have a had a bunch of dumb problems with this heads and cam set up, three so far have been brand new parts that were bad right out of the box. But I will say it's been a good learning experience if any thing.

marshall93z

I bet!