Engine knock on cold startup

Ok so i have a 1994 Grand Prix SE with a 3100 engine with about 118000 miles. When i start it cold the engine has a pretty loud knock for about 1-2 mins or untill i drive it a little. i changed the oil but it is still there. Sounds like it is coming from more towards the bottom of the engine not the top like a valve clatter. I bought Rislone Engine Treatment from walmart (Teal colored cleaner that works slow) And it still is knocking. Any ideas whats wrong / i could try to make it go away would help. Thanks

3100/3400 have a serious problem with piston slap. This goes away after a few minutes of operation when the piston expands.

I agree with Troy. Piston slap is very common on these engines, and your symptoms are textbook.

3100/3400 have a serious problem with piston slap.

What exactly is piston slap?

What exactly is piston slap?

See link below.

http://www.pistonslap.com/

Well, that's very interesting. My wife's 1998 Montana (3400) has piston slap. I always thought it was a noisy valve train. It actually makes me feel better knowing that it is piston slap. When the engine warms up, it does not do it. You would think in this day and age, GM could make a good quality engine.

We get it in our Alero. Only lasts for about 30 sec to worse case 1 minute. Some things you can do just to be safe is make sure the engine oil is 5W-30 and of good quality to include the oil filter. Especially a decent anti-drainback valve so the engine doesn't get any so called dry starts. Needless to say other than that something you have just to live with until you get rid of it.

haha, yup...completely normal. my 2004 Grand Am with the 3400 had 40K on it when i traded it in. the "piston slap" started around 15K. annoying as hell...but nothin you can do about it. only 1 of about 100 reasons i got rid of the car not even a year after owning it

why didnt you like the grand am? I agree grand prixe's are way better, but grand am's are OK cars.