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"

It's easy;

The first number shows cold temp flowability, the second shows warm or hot.

5w30 flows easier at a lower temp than 10w30 does, but when warmed up both are the same. Almost all the manufacturers are recommending at least 5w30 these days in nearly any gasoline engine, almost regardless of climate. It's also slightly better for fuel economy and emissions, which is why Honda and Ford have actually gone to 0w-20 and 5w-20.

I knew I wasn`t crazy, the W DOES mean winter
http://www.river2u.com/autoparts/oil.htm

Did I mention I'm new?

Yes, the W does stand for winter

no big deal Austin, , it was like one of those things that you can`t remember and by the end of the day it starts to make you feel like you are crazy

I jusy bought a 03 GP SE for my wife and I experience a knocking sound from its 3100. Its sounds more like a valve tap to me. I havent had any experience w/ these engines b4. It seemed alittle low on oil so I added some to get it to the right level on the dipstick. Seem to lighten up the sound a bit but it still can be heard from in the car slightly. If its true what is said about the piston slap w/ the 3100's thats what it could be. Ive been wondering what the hell it is since we've had the car about 2 weeks now. Its got 32K miles on it. The noise does seem to go away after it it driven for a few minutes so I thought an oil change would do it some good but the oil still has some good life to it. HercMan if you could come up w/ that article that would be great. Im going to have a Pontiac dealer look at it. Im not about to have an engine blow at 32K miles. If anyone has anymore info it be appreciated.

I experience the same with my '01 GP SE 3.1 engine. Was told by a GM mechanic that indeed, it's a "dry" start-up issue (engine sitting for hours). Goes away after a minute or two when the oil reaches all parts of the engine. I was told it's nothing to be concerned about, I do use 5W-30 Pennzoil.

So is there anything GM can do about it? That seems to me to be a design flaw. If those parts are knocking they are wearing faster since no oil is there at startup.

That's the reason for a class action lawsuit against gm for the engines built between iirc 96-02 not all engines 3.8Ls are exempt and 5.7Ls are exempt.

So since the suit is for 96-02 model engines, us w/ 03's are SOL, or was the problem somewhat corrected post 02? The knocking sound I get in my 3100 does go away after about 5-10 mins of driving. But its still not good for it to be knocking at all. HercMan anyway you could get that article on the lawsuit?

I'll see what I can find.

Cool...Id like to have some bullets for when I go and talk to GM about it.

http://www.bigclassaction.com/class_action/gm.html
http://www.prnewswire.com/cgi-bin/stories.pl?ACCT=sent_auto.story&STORY=/www/story/11-14-2003/0002058678&EDATE=FRI+Nov+14+2003%2C+03%3A04+PM

I couldn't find my original but did a search and found these. They all address the truck motors but iirc my original newstory said that it pertained to all vehicles with the said motors.

Thanks for that info, regardless of it pertaining to truck engines there is no difference between a 3.1 for a car or a truck. Im going to start watching the oil comsumption. If she starts using oil Ill know that I do have a problem. Like Ive said b4 the noise does go away after a few minutes of driving. I am concerned since I just bought the car and have no experince w/ 3.1s b4. I noticed in your profile you were in the USN. I take it your an airman judging by the pic of the C130 in your signature. Im also in the USN, a Seabee. Thanks again for the info.

Yep I am in the Navy. I'm an AM1 stationed at NAS Brunswick and that's one of the 5 C-130s we operate.

Thanks for the links Herc Man! Your second link about the liability against GM interested me. My '01 3100 GP "ticks" on every start-up after sitting an hour or more. I don't like that. Like I posted earlier, I had a GM mechanic tell me that's no problem and not to worry, but after reading your links you posted, I'm wondering if the GM mechanic was "told" to say that. My GP is past warranty now, and this news concerns me as I only have 49,000 miles on the car. Thanks again for the news Herc Man. Keep us posted.

Dave

I've done some more searching to see if I could find an outcome but I have been unsuccessful.