Piston slap and oil consumption

[addyguy]

I have a 2002 Chev Cavalier with 100k km's (60k miles) that has the typical GM OHV piston slap when the engine is cold. The engine runs great, and is smooth and quiet when warmed up, and also doesn't use a drop of oil between changes.

If piston slap is caused basically by the piston being loose in the bore and rattling around, how is it that a motor that has this condition doesn't use any oil at all? Wouldn't oil get past the piston and into the CC while the piston was loose, before it expanded and fit properly?

Obviously, I'm not complaining about my car not using oil - it just seems that if a pston is loose, the engine would use oil. Anyone with piston slap also have bad oil consumption?

 

[Rickey]

Don't worry about it, my '93 cavalier 2.2 has made noises on cylinder #2 when cold since new. I disabled the # 2 spark plug when cold to prove this for myself. The original engine now has over 240K miles on it. Many imports have been retired with fewer miles due to engine or other failure. Drive on! Oh by the way mine still doesn't use any measureable amount of oil. Caution sarcastic "merican biased comment ahead. My worn out Chevy will still outlast any two asian imports. Rickey

 

[Lumberg]

COuld be the oil flow upwards from under the piston on that particular design isn't that great, the amount that does make it into the CC while the mixture is ultra-rich.

I could see that not being an issue.

 

[Cardsfan4life]

The piston rings are still making contact with the cylinder wall that is why you are not losing any oil. The skirt of the piston could be slapping away but the rings still have good contact with the cylinder wall

 

[Lumberg]

That's a great point CF4L

 

[2KBMW]

Addyguy. I don't think that noise is piston
slap. I have not heard of the dohc 2.2 engine
having the piston slap problem. The engines
with the problem are the 3.4 and some of the
4.8/5.3 V8 engines. I have a 05 Pontiac Pursuit
with this engine and I've been hearing a faint
tap noise which lasts about 45 seconds. I did
not hear this noise all spring and summer . If
it were piston slap, wouldn't you hear it all
the time

 

[TonyC230]

GM uses Forged pistons and they heat up slower causing them to flop around. If the noise goes away in two minutes or less then the tolerences are ok but if it takes more the three minutes then you have a problem. Newer engines have the pistons teflon coated to extend their life span. An engine rebuilder told me that bit of info.

 

[burnout]

The old 2.2 engine and the new *ECOTEC* 2.2 are completely different.

 

[addyguy]

2KBMW - my car has the base 2.2 litre OHV engine...not the optional EchoTech 2.2 DOHC engine, so like other GM OHV engines of this period, it is prone to piston slap.....the EchoTech 2.2's don't have this problem at all, as far as I know.....

 

[cousincletus]

My 2002 Cavalier has the slap too but only on cold mornings. It goes away after a minute or two. No oil consumption either. I wouldn't worry about it either. I had a 1984 and 1993 Cavalier OHV before this one and they were very good cars. I have seen Cavaliers with over 300,000 miles and still running well. Just do the maintenance.

 

[caprice_2nv]

My Caprice doesn't even knock with no oil in it, just kept stalling the day that that happened almost 100k ago!

 

[LarryL]

Turn up the radio.

 

[vairox]

another 500,000 miles to go rickey.... git-r-done

 

[Al]

Quote by Larryl: Turn up the radio ..Best suggestion. As mentioned it is the design of the piston. I believe it is bc of the short skirt (did I say that) allows piston movement and then carbon gets in there. This causes more noise and possibly it leads to this:

"Hello gang, I'm a 23 year service Director at a G/M dealer. Here is my take. G/m is not happy with thier little problem. They have thier heads buried in the sand hoping it will go away. But try as they might the beat (knock) goes on. I also have 02 Denali with a 6.0 that has 15k and the cold morning knock just started in mine. Yes, doing a top eng clean works as a temp solution. The squid technique works the best. This drops the top engine cleaner into each spark plug hole and then cycles the pistons up and down with the chemical in the bores. After this method you clean out the engine oil with an engine flush. Here is what G/M will not tell you. I have replaced now 6 engines in the last 5 months that have blown up with low mileage, less than 20k miles. Two as low as 5k. All were maintained (oil changed) normally. All let loose with broken piston skirts. Knock, knock who's home, get it. Short piston skirts, out of round holes and carbon build up. Pistons rocking and the engines knocking. Ouch ,we have a problen Houston! All complained of cold morning knock. Yes, all were taken apart by my techs and we found that the cyld walls were crosshatched nicely, but the cyld walls were out of round by as much as .50 thousands of an inch. Now having done about 20 engines for excessive oil consumption and cold morning knock I can tell you that all the engines have out of round cyld walls. It is my opinon based on my evidence that G/M has several problems that they do not want to take care of. Even though I work for the General, my District Service Manager would not auth a replacement engine in my own vehicle. Let's just say that I'm more than unhappy. Just wanted to let other people know that the Denali is a great machine, G/M is going to have pull thier head out of the sand and take care of us. Thier future sales are hinged on thier current customers. I do know that they coated the pistons mid year in 03. Your dealer can run the vin on your machine and let you know if your's in an effected engine. The 03's so far do not have this problem at lower mileage. So time will tell as the coating wears if the noise will be previlant on the newer engines. Got to love em. Peace."

I know..different engine. But I found it humerous.
http://www.automotiveforums.com/vbulletin/t150872.html

You LSI guys probably are aware of this:
LS1

Also there has been mush discussion onthis forum, but I'm to lazyto search.

 

[LarryL]

If you expect a straight answer from a new car service department on a problem like piston slap when the right answer might cost them a lot of money, you might be disappointed. I have heard the GM piston slap from one of their V8 engines. I'm sorry, but any noise like that can't be normal. Noise like that has to come from something that should not be there. These vehicles cost a lot of money and I'll bet their value is reduced if they have this noise. That means you can't trade your vehicle into any GM dealer after the problem has been noted in your vehicle's service records, without taking a hit on its value. I'm sure a GM dealer does not want a vehicle with a noisy engine that they won't be able to fix on GM's warranty. The answer is clear. If you have one of these problems, GM's answer is, go away. Maybe you should take their advise. You're not the kind of customer they want.

All that aside, the Yukon owner's piston slap has been stopped for a while, now, with Auto-RX. So those that say it's carbon build up above the rings and/or around the cumbustion chamber might be right, that and pistons that don't fit too well. He expects the noise to come back and has put his Yukon up for sale. He has been looking at Sequoia's becase they appear to not have any such problems. It's too bad. He spent a lot of money on the Yukon and really liked it. It drives well and has a ton of room for the family. His problem is that he is afraid of what will happen in the future. There is a problem in the engine and he does not feel that such things cure themselves. He has zero confidense that GM will standup to any future warranty problem.

 

[LarryL]

That may be a good way to get some warranty help. A knock can be explained away as normal for that vehicle. A blown up engine is a little more difficult to ignore. I don't think the Yukon problem is acute, but noise like that is not good, no matter who explains why it's happening. And this explination is coming from a service department that says Mobil 1 oil causes leaks, and that you should change your oil every 3k miles and at 30k miles you need a fuel injector service that costs a couple of hundred bucks. I appears the the problem with buying a new vehicle is often time the dealer. And I guess we are lucky that the service department is there to help us. This all brings us back to my original solution, turn up the radio.

 

[dave1251]

Larry please PM what service department this is.

 

[Lumberg]

What would happen if you had a vehicle that started to knock, and it was still under warranty, and you just started to drive the heck out of it, and blew the engine up?