normal for these engines, but..piston slap?

[gmchevroletruck]

2002 Chevrolet 1500 5.3 v8 engine, ...

The Gen III v8s have characteristically had a "noise", which, after much internet research, I have yet to find one that failed because of it, but it doesn't stop me from wanting to quiet it. It's not super loud, but it's noticeable for sure, and seems to be more prominent lately. Supposedly, the reason for a cold-startup noise is that these engines have hypereutectic pistons which have a tendency to expand and contract for better sealing at different temperatures, but they also are prone to the noise. I must also add that at least sometimes, and possibly consistently (at least lately) it makes the noise I'm experiencing, even when fully warm.

I'm not even completely certain that "piston slap" is the exact noise that I have, but would like to know...any help in diagnosing would be much appreciated.

I use M1 (regular formula) 5w30, and have since 88k when I bought it. The noise was probably less then than it has been lately, but especially the last week or so, I'm noticing it more. I really should be more attentive and make a point to note if it's constant, etc, but honestly it's a work truck and so I'm on the phone when driving it, thinking about the next job, etc.

I tow a 3000lb trailer with it daily, about 60 mi / day, few cold starts, and run the m1 about 8k between changes, have gone to 10 (this last time). Looking in the valve cover, engine appears extremely clean, almost freakishly so, for 139k.

Just wanted to provide as many details as I could...now...how to tell where the noise is coming from and what it is...and, how to get rid of it?

Additional note: driving style: until fully warm, I drive it like a grandma (with or without trailer), and even when fully warm, I mostly still drive it like a grandma)

 

[pickled]

Try Amsoil XL 5W30 it worked for my buddy in Chicago. Otherwise try a Redline 5W30 product because several folks have reported that it has quieted their Chevy's piston slap too.

 

[gmchevroletruck]

should also add that it needs plugs...I think they may be the original plugs at 138k (hey...money has been tight, what can I say) lol

And I've cleaned the throttle body (although certainly that woud have no bearing...old plugs just conjure up images of carbon buildup, so it was pertinent to that...)

 

[FusilliJerry82]

Originally Posted By: gmchevroletruck
(hey...money has been tight, what can I say) lol


You could at least clean and regap them.

 

[gmchevroletruck]

can you do that on platinums? I probably need to just buy new plugs soon, they may be worn thin on the ends anyway, with that many miles. Then again, they may not even be original, I'm just assuming that, since the service schedule is 100k on the factory platinums, and I bought it with 88k, and haven't done it.

 

[gmchevroletruck]

wait, i'm hijacking my own thread lol...

ok, about the piston slap, lifter noise, whatever it is...

How can I tell the difference, tell what this is specifically, and get rid of it. Suggestions?

 

[wirelessF]

Cracked exhaust manifolds?

 

[defektes]

I replaced my AcDelco factory plugs at 110k and they were in very good condition.

 

[gmchevroletruck]

ahhhhhhhhhhhhhh.....

hadn't thought of that.

And...the procedure for differentiating between piston slap, lifter noise, exhaust leak, would be....

(other than tons of experience)

I've never had luck with the long screwdriver test or "mechanics stethoscope" but the latter is fun to yell into, if you're not the one wearing it...

 

[gmchevroletruck]

that's comforting...I'm hoping for the same at 138

 

[Turk]

I had 2 slappers.

- PP or Amsoil ASL.

- Top quality filter.

- Decarbonization at regular intervals.

- MMO doesn't hurt.

 

[tig1]

Originally Posted By: pickled
Try Amsoil XL 5W30 it worked for my buddy in Chicago. Otherwise try a Redline 5W30 product because several folks have reported that it has quieted their Chevy's piston slap too.


Nothing will quite the Chevy piston slap except the newly designed pistons some have come out with .

 

[tig1]

I guy I used to work with had an 02 Silverado with the slap and he sued GM and lost. However the attorney in his case had documintation of failed 5.3 engines caused by the slap. They had handled many of these cases and claimed they never lost one till my friends. Go figure. My brother in laws 02 also has the slap and just lives with it.

Call Jasper engines and talk to them about it. My friend did.

 

[NHHEMI]

In addition to the piston slap issue for that time frame and engine there was also an issue with carbon build up on the piston domes leading to noise issues. Stop by the local GM dealer and get a can of GM's Top End cleaner and follow the directions for an overnight soak. Might help.

 

[SteveSRT8]

We have a fleet of GM products. Several "slap" motors in our stable, one of them has 400k miles on it.

It is a problem only till around 04 somewhere. Updated piston design cured it.

But it is really only an annoyance, the engines run forever with it.

 

[Mr_Incredible]

I've got a '98 LS1 in my Z28. It has the piston knock for all about 50 yards of driving, then it goes away. It does it on thin 5w-30 and also with 5w-40 TrSUV M1.

I'm not concerned. 104k miles and still ticking (if you'll pardon the expression).

 

[Jakegday]

from what ive read piston slap is "normal" on the 3.8L in my Grand Prix, for like the first 30 seconds-1 minute of running. i found that valvoline maxlife quieted it down quite a bit

 

[fsskier]

Nobody yet has replied to your first question, how do I tell if its piston slap?

OK, here goes. It is a light clicking noise, it sounds a lot like lifter noise. Now most cars have hydraulic lifters and this noise has become uncommon. And those of us that spent hours adjusting mechanical lifters and setting them on the "edge of clicking" are rare also!

Piston slap: Idling upon cold startup it will sound like lifter noise. Put it in gear and proceed immediately up the street with light throttle application the clicking will be much louder. let off, hear it get quiet. Step on it again, clicks louder. in about 2 blocks the clicking will become much quieter, as the aluminum piston quickly warms and reduces its side clearance. It may totally disappear within a mile.

Causation: at TDC (top dead center) the rod angle changes from one side to the other, and when the throttle is open
the force is much greater, resulting in a louder noise.

lifter noise tends to be "unaware" of the throttle setting, of course the frequency of both increases with increased throttle but only the piston slap gets louder.

In the old days, pistons were longer (and heavier) and did not cock in their bores and make noise until old age. Sadly, those motors life could be tracked, quiet for 50 k miles, then piston slap cold, then at 100K miles the piston slap continued all the way to hot, finally at 150 k it never went away, it was just plain loud. At about that time you were putting in a qt of oil with every fillup and it was time for a rebuild.

Nowadays the GM motors seem to have a cold click , but so little bore wear that they never wear out for most of us anyway. My severe use 3.1 litre V6 GM tow vehicle sounds the same after 265 K miles, still clicks cold, and quiet when warm.

My experience: Something in your head makes it much louder some quiet mornings, and other days you do not notice it - even with the same oil -I have always used M1 0W20. I suspect that changing to a different brand of oil might change your perception but not reality!

 

[mrsilv04]

Dad's 2000 Sierra has the 5.3. Using Pennzoil Platinum 10w-30 vs. 5w-30 seemed to cut the slapping by about half. 10w-30 in this engine is acceptable (per the owner's manual) down to 0 degrees, but since I'm using a synthetic in it, I'm, not worried about the 0 degree issue.

 

[FusilliJerry82]

Originally Posted By: gmchevroletruck
can you do that on platinums? I probably need to just buy new plugs soon, they may be worn thin on the ends anyway, with that many miles.


Sure you can clean and regap platinum plugs, and in your case it sounds like it would be worth doing. Theoretically, you should be able to clean and regap a plug over and over until/if it becomes quite obvious it would be a futile effort or is impossible (broken porcelain, extremely worn electrode).