I have a 99 GP SE with the 3100 engine. When I start it up in the morning, or when it sits for about a day without use, I hear a knocking sound. It is not too loud, but loud enough to hear outside the car. I thought it was the power steering pump, but no sure. Steering seem to be fine, but I do see PS fluid on top of the PS pump after a few days of driving. I wipe it off, and it's there again in a day or so. But off that, it seems to be coming from the block???? I use Pennz. 10-30.....Should I switch to synthetic first to see if that would help the knocking sound. After about 15 minutes of warming up, it does go away. No clue why it does it.

Just thought I'd post it and see what flys back my way.
Thanks

Oh.....and the car has 70k on it......

It goes away when warm you say. I think that you might be experiencing piston slap. GM is currently fighting a class action law suit with their V6 engines (not the 3.8L by the way) for false advertising on reliability since most of the other V6 engines were built with sloppy piston cylinder clearances and so the engines produce "piston slap" The class action lawsuit is trying to get GM to either fix the engines, give you the money to have it fixed or to replace it all together. I'll have to do some digging around I think I still have that article somewhere.

You should also be running 5w-30 oil. Not that it'll fix the problem, but may cut down slightly on engine noise upon startup. It's also what almost all manufacturers recommend these days, and GM specifies it for 2.8's/3.1's/3.4's.

I dont know if 3.8L are known for that, but intermittenly i hear a knocking type on start up.
it only last a few seconds, what do you guys think?

change oil viscosity that usually does the trick

Ummmm my series 3 3800 does this just like my old cutlass 3100 did. Also this affects ls1 and the 6.0l. I know because i drive all these vehicles. In fact the 6.0l is in the show as of this coming monday i will let you know what happens. I may have mine looked at but it does go away after 10 minutes or so. Didnt do it brand new tho?????

Bought it with 30k on it and it just started...I'd say......around 65k.....give or take. Guess I will change oil weight next oil change and see what happens. If that doesn't work, I'll take it in and have it looked at...still under warranty.

Oil change wont fix it take it in make sure they know your having the problem before your warranty poops...

hey zachd so all the cars you mentioned knock at start up? ... for how long?..

Most engines do, since it takes the oil a couple seconds to make it up to the top of the engine. The advantage of running 5w30 instead of 10w is that the oil is a bit thinner when cold, therefore able to get up to the top of the engine quicker. It's the engine running "dry" that partially causes the noise.

Here in Texas, it's HOT all the time, Like fry an egg on an ice cube hot, so I don't want to really go thinner......Won't it break down alot faster? I change my oil every 2,000 miles.....(just a habit....dont ask)(Did that with my old 84 corolla and it made it to 380k)

Umm the ls1 is in a vette and always ran mobil 1 oil whatever is recommended and it does it for about 5 minutes just like all of them . my GP stopps after it warms up and only does it cold. The 6l is in the shop right now for the problem no new but will find out tommorow it is my cousins.....

Woops only diff is the 6l does it all the time......someone has told me that when they made the 6l they used the 5.7l pistons....doubt that can be tru but adam you the man fill us in......

please correct me if I`m wrong, there are two numbers in oil viscosity, ex. 10w30 I thought the "w" standed for winter, the 10 is therefore the viscosity of oil during winter months(more or less) and the 30 is the viscosity of oil during the summer (or above a certain temperature of engine start), higher viscosity is needed for an engine to pick up the oil from the pan when the weather is warm or hot, that is why these oils are called multiviscosity so when I hear someone saying that they are going to change from 10w30 to 5w30 on July makes me think that it won`t make a difference unless they live in Alaska as far as engine start up, again if I am wrong in any of this please correct me, but this information is what I remember form a seminar I attended taught by Mobil, Chevron, and Shell personel.

The W is for the "weight" of the oil, not standing for "winter"