I've seen this mentioned a few times through out the forum. When cold the 3100 will make an obnoxious knocking/tapping sound. But it usually goes away when warm. A friend of mine has the explanation for you all in the following video, this is why i dont worry about the noise mine makes.

Attention GM 3.1L 3.4L and 3.5L Engine Owners - YouTube

 

Gotta love piston slap

 

Yep, i see people selling/scraping 3100 cars because they make all the noise when they're cold and people think there is something seriously wrong with the engine.

 

OH man that's all it is? I've always wondered! Thanks for posting the video!!

 

..Knock-Knock

..Whose there ?

..Chevy

..Chevy Who ?

..Chevy 3.1 ~>kNOCk ~>KnOCk ?

....

..~>

..Zorry


^ THAT WAS DUMB `KID...^TAKE THAT

p.s. Our MCF Sponsor's love 2 C Activity
Hi Keane, great infor on the 3.1

 

knock knock
whos there?
just my chevy 3.1

 

Geez - luckily mine's not as loud and obnoxious as it is in the video. But I notice it with mine when it's cold, I knew it was normal for the engine but never knew what the term for it was.

 

I believe there is some incorrect information in this video about the noise explained.

I've worked on many 3100/3400 engines for my family and friends (about 8, maybe more). They all have a light valve tick that does not seem to change regardless of hot or cold (these engines are known for that). Here's the break downs of years and drive trains I've been involved with:
3 - 94 Grand Ams (3100)
1 - 95 Grand Am (3100)
1 - 96 Grand Prix (3100)
2 - 00 Grand Ams (3400)
1 - 05 Impala (3400)

None of these cars (oldest being the 94's), with the exception of one, ever developed the noise heard in this video. None of those cars left the people I knew until at least 150,000 miles or more. I am still driving a '94 Grand Am as a daily driver, with an original, well maintained 3100 with over 210,000 miles and it has never made that noise (even on the coldest days of winter, and we get some cold ones).

The one 3100 that I ever worked on that made that noise was my wife's Grand Am, which we sold this past January with 170,000 miles on it (due to an awesome deal on a 2005 Impala with a 3400 that has 150,000 miles on it). It was the ONLY one of these engines I ever serviced/knew of to make the noise depicted in this video (and follow the symptoms of going away after then engine warms up).
In this case, the noise was clearing in the front head on the left side (a mechanics stethoscope comes in handy for that). It was suspected to be a sticking valve/lifter. Since the performance was not affected, I tried the "miracle in a bottle fix". I dumped a bottle of motor honey or Rislone in after an oil change, this noise problem went away shortly after. Change the oil, don't use the additive and the noise came back in a couple days. It took about 3-4 oil changes using motor honey/Rislone before the noise was eliminated.

If it is a common noise, I have only seen it once in the many 3100/3400's I've known and helped worked on for my friends and family. And the one I knew to have the problem actually seemed to be fine after running an additive through it a few times (at the time of sale, there was nothing wrong with the car, just we had too many cars in the driveway).

No matter what, when a car is cold, especially on the cold days of winter, it is BEST to let them warm up before using.

These are my opinions and observations, but I don't feel that noise is as common as the narrator in the video states and I don't believe it's piston slap. Piston slap means damage to the engine, regardless of when it occurs.

 

granted mine doesn't make as much noise either but when its cold there is noise, once it warms up the noise goes away..... Now i wonder if i have a $1000 knocking piece of junk....

 

The down side with not being there in person is it's tough to "isolate" where on the car the noise is originating from.

As I said, I've wrenched on a bunch of these, they all have a light tick (most people hardly notice it and the tick does not change with engine temp). I only know one that EVER made a noise like what was depicted in the video. It was definitely NOT piston slap. On the one it was isolated to the left side of the front head. We suspect a "sticking" lifter. As you noted, the noise went away when the car warmed up.

As I understand, piston slap is damaging to the engine (the piston and the cylinder walls are knocking, it will dent the walls and get worse until something does finally go "boom").

I'm not a big fan of these "miracle in a bottle" solutions. Given my experience with the one Grand Am that had this ridiculously loud tick, you could try what worked for us. Go to the parts store. Grab a bottle of Motor Honey (it's an additive that will thicken the oil, I believe it's also supposed to have some "detergent" to "fix" issues like sticking lifters). I had nothing to loose AND the Motor Honey wasn't going to damage the engine. Drop a bottle of it in, give it a day or two of driving, see if the problem goes away. If it does, change you oil at the next regular change interval. Do not put an additive in, see if the noise comes back. If the noise returns, repeat the additive.

FYI - These engines are supposed to use 4.5qts of oil, you can SAFELY run on 5qts (so adding a bottle that is less then 1qt of additive to 4.5qts is no problem, if you try the Rislone, it's a 1qt bottle, add half of it to stay at 5qts max).

The noise on my wife's Grand Am went away for what I know to be permanently after a few rounds of this routine. The car never gave us a sign of performance problems OR being at risk of damaging itself.

If you try what worked for my one run in with that noise, let us know the results. I'm a believe the 3100/3400 engine is reliable (outside of the nylon intake gasket headaches). The video you shared, the narrator claims these engines can get 400,000 well maintained. Personally, unless he's seen one that is original (not a rebuilt engine), I admire his optimism, but I personally think that is a pretty large expectation. Right now, I just proved a lot of people wrong about my Grand Am (people felt it would only see 200,000 miles if I dumped lots of money and tolerated a lot of brake downs). I feel the car is serving me great with minimal problems and since I do my own wrench work, it has not inconvenienced me or cost me large amounts of time or money.

Sorry for the long posts. I just have a lot to say on this topic apparently.

I just hope it's of help. I'm not an "expert" on these engines, but I've learned a good amount about them over the years and try to share what I can.