1990lumina Posted April 21, 2005 Report Share Posted April 21, 2005 Like the title says....my car has been suffering from it forever now...I really don't care since GM says it won't hurt anything, but I'm interested to know what it is. What causes it? Was it a defect in the 3.1 that causes it?? I know the pistons have to be replaced to fix the problem, but if I did replace the pistons would the problem return?? Anyway, an easy explanation for me would be good since I'm more familiar with the inner workings of a rotary engine :? In which stroke (intake, compression, combustion, exhaust) does it happen? Thanks!! - Jeff L. Quote Link to comment Share on other sites More sharing options...
maybe2fast Posted April 21, 2005 Report Share Posted April 21, 2005 I think it is play in the rings, the piston has movement and causes the noise...I think Quote Link to comment Share on other sites More sharing options...
Brian P Posted April 21, 2005 Report Share Posted April 21, 2005 I thought it was noise with the wrist pin being a little "loose" at the piston but I'm not positive. A GM warranty mechanic should be able to tell you for sure. Quote Link to comment Share on other sites More sharing options...
glock19 Posted April 21, 2005 Report Share Posted April 21, 2005 http://www.pistonslap.com/ Glock Quote Link to comment Share on other sites More sharing options...
1990lumina Posted April 21, 2005 Author Report Share Posted April 21, 2005 Thanks for that link man! Quote Link to comment Share on other sites More sharing options...
5speedz34 Posted April 21, 2005 Report Share Posted April 21, 2005 Piston Slap is were simply the pistons slap the sides of the cylinder wall. I have heard it on a 6.0. I'm really suprised that GM has this big of a problem with it. Quote Link to comment Share on other sites More sharing options...
Guest Gp crazy Posted April 21, 2005 Report Share Posted April 21, 2005 The biggest problem is the engine never gets an oil change at the normal times or milage! Quote Link to comment Share on other sites More sharing options...
RacerX Posted April 22, 2005 Report Share Posted April 22, 2005 Piston slap is lame. I prefer rod knock. :alcoholic: Quote Link to comment Share on other sites More sharing options...
1990lumina Posted April 22, 2005 Author Report Share Posted April 22, 2005 I like Shawn's signature...something like "I like knockers, firm, soft knockers" - Jeff L. Quote Link to comment Share on other sites More sharing options...
terryk2003 Posted April 22, 2005 Report Share Posted April 22, 2005 my car has this piston slap shit really bad...its freakin annoying...makes me want a L67 even more... Quote Link to comment Share on other sites More sharing options...
1990lumina Posted April 22, 2005 Author Report Share Posted April 22, 2005 Mine has it pretty bad as well...sounds like a damn diesel engine when you start it in the morning lol...but goes away after warmed up. Sounds kinda cool while driving on a calm night with the windows down lol...accelerating nice and smooth..."tick, tick, tick, tick, tick, tick, tick, tick, tick, tick...continue with higher RPM lol..." - Jeff L. Quote Link to comment Share on other sites More sharing options...
terryk2003 Posted April 22, 2005 Report Share Posted April 22, 2005 Mine has it pretty bad as well...sounds like a damn diesel engine when you start it in the morning lol...but goes away after warmed up.Sounds kinda cool while driving on a calm night with the windows down lol...accelerating nice and smooth..."tick, tick, tick, tick, tick, tick, tick, tick, tick, tick...continue with higher RPM lol..." - Jeff L. i know the feeling...mine isnt so bad when its really warm out...thats prolly why i never heard it when i bought the car (in june)...BUT, it started getting cooler i was like WTF!?...oh well...i guess if it blows up, i'll get another engine... Quote Link to comment Share on other sites More sharing options...
GP1138 Posted April 22, 2005 Report Share Posted April 22, 2005 Ok. My auto teacher explained this to my class. I can't remember exactly how, but on the older engines, the piston's wrist pin was placed a little off center so to alleviate piston slap. Piston slap is normal. It's when the engine is cold and the metal hasn't expanded yet, as metal tends to do when warmed, and the piston moves around in the cylinder as the crank rotates. Anyway, setting the wrist pins a little off center has the effect of forcing the piston to rub against the cylinder wall just a little, which makes it so the piston does not rattle back and forth. This has a small hit on gas mileage, because it does create friction and reduces efficiency. For the Gen III revision, they decided to center the wrist pins so that the piston would not rub, for the extra smidge of gas mileage possible. This, unfortunately, creates the piston slap you hear when your engines are cold. Studies were done with these engines, and no adverse effects have been noted. I, having a Gen III engine torn down (and Chris (white93z34) and Matt (InanimateDecay) can vouch for this) have very clean cylinder walls, which indicates to me that this slap is not a big problem. I think that if it was a problem, we would have seen a large-scale recall, as there was with the engine cradle bolts on the First Gen W's. Quote Link to comment Share on other sites More sharing options...
White93z34 Posted April 22, 2005 Report Share Posted April 22, 2005 well put john, if piston slap was much more then noise your cyl walls would have been much more worn and inperfect then they were Quote Link to comment Share on other sites More sharing options...
1990lumina Posted April 23, 2005 Author Report Share Posted April 23, 2005 So why is it this problem is more noticeable with Ws (not all of them, but I know a few). My dad's Taurus is very smooth when it is started cold on the coldest of mornings. Same with my mom's Acura CL...very smooth. Just wondering..... Thanks for that explanation John!! Very informative. So, would my 1990 3.1V6 have the pistons slightly off center then?? - Jeff L. Quote Link to comment Share on other sites More sharing options...
terryk2003 Posted April 23, 2005 Report Share Posted April 23, 2005 i don't think its necissarily(sp) w's...i think its more GM's problem...the 3400 in my mom's alero does it...but its nothing compared to my 3100... Quote Link to comment Share on other sites More sharing options...
Brian P Posted April 23, 2005 Report Share Posted April 23, 2005 some of you may not know the difference between "piston slap" and lifter noise. My friend had a 3100 which made all the typical "old 3100" noise when it was cold. Replacing the lifters w/new eliminated it. Quote Link to comment Share on other sites More sharing options...
1990lumina Posted April 23, 2005 Author Report Share Posted April 23, 2005 No your right, I don't know the difference lol...although my sound goes away after the car has warmed up for the most part - maybe I have a combination of both problems lol.... Quote Link to comment Share on other sites More sharing options...
terryk2003 Posted April 23, 2005 Report Share Posted April 23, 2005 No your right, I don't know the difference lol...although my sound goes away after the car has warmed up for the most part - maybe I have a combination of both problems lol.... i'm beginning to think the same thing about mine...would the car run shitty if it had a lifter problem!? :? Quote Link to comment Share on other sites More sharing options...
Brian P Posted April 23, 2005 Report Share Posted April 23, 2005 not unless they're severly fucked. As in collapsed. But that would be a sound you'd hear more than just when cold. Quote Link to comment Share on other sites More sharing options...
terryk2003 Posted April 23, 2005 Report Share Posted April 23, 2005 not unless they're severly fucked. As in collapsed. But that would be a sound you'd hear more than just when cold. well, my car is severely fucked...its pissing me off...i wanna shoot the POS 3100 & the guy who invented it...it keeps warming up on me...like past 210* (have to turn the AC on to kick the cooling fans in to keep it down)...fuckin surges on takeoff...ahhh...then that loud, annoying noise when i start it up...and mine lasts like 5 minutes before it calms down just a bit... Quote Link to comment Share on other sites More sharing options...
1990lumina Posted April 23, 2005 Author Report Share Posted April 23, 2005 I think your car is a little more fucked then mine then...I don't have any surging (yet), and it defiantely doesn't get hot...not even warm (less then a quarter on the guage). That L67 swap must be looking pretty good for you terryk2003 - Jeff L. Quote Link to comment Share on other sites More sharing options...
Brian P Posted April 23, 2005 Report Share Posted April 23, 2005 210* as per your gauge? The gage is never accurate. Let me tell you I went thru 3 temperature sensors until I found one that read correctly. Then I switched to the "2 in 1" sensor in the LIM (OBD2) as opposed to having 1 sensor in the rear head and one in the LIM, now I finally have an accurate reading vs what the ECM sees. IIRC the cooling fans won't come on until 223*F w/o the AC on (well my '90 3.1 was programmed for that, and my '95 seems about the same) , so you're not having a problem there. What kind of surging on takeoff? As for the sound I hate it too, but it's not so bad when the weather is above 50F. My dad says it sounds like a coffee grinder....LOL Meantime his Envoy sounds like a Diesel when cold Quote Link to comment Share on other sites More sharing options...
terryk2003 Posted April 23, 2005 Report Share Posted April 23, 2005 210* as per your gauge? The gage is never accurate. Let me tell you I went thru 3 temperature sensors until I found one that read correctly. Then I switched to the "2 in 1" sensor in the LIM (OBD2) as opposed to having 1 sensor in the rear head and one in the LIM, now I finally have an accurate reading vs what the ECM sees. IIRC the cooling fans won't come on until 223*F w/o the AC on (well my '90 3.1 was programmed for that, and my '95 seems about the same) , so you're not having a problem there. What kind of surging on takeoff? As for the sound I hate it too, but it's not so bad when the weather is above 50F. My dad says it sounds like a coffee grinder....LOL Meantime his Envoy sounds like a Diesel when cold well, my coolant temp. sensor is new...it usually doenst get that warm though...maybe i should get a new thermostat!?.. :? ...the surging is just fucked up...does it when i take off easy...it seems like it doesnt wanna go...it also does it when i'm cruising @ a speed and start going up a hill...i have some really rough idle too... Quote Link to comment Share on other sites More sharing options...
terryk2003 Posted April 23, 2005 Report Share Posted April 23, 2005 That L67 swap must be looking pretty good for you terryk2003 - Jeff L. yeah..BUT, i don't have the $$ to be doing it yet though...i was hoping this 3100 with only 72k miles would last a little longer...@ least to 100k... Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.