PISTON SLAP

WEEKEND WARRIOR · January 3, 2004

I have a 2001 HD 6.0 with 24000 miles and piston slap.

I like this engine except for the piston slap. My question is,

there must be some kind of fix. How about changing the pistons?

Are the ones in the 345HP 6.0 better? Are there better after-

market pistons? Has any one tried STP Complete Fuel System Cleaner?

The directions said it cleans the injectors, cylinder heads,

combustion chambers, valves, pistons, ect. Good or bad?

It states to use no more than every 4000 miles.

I do have the 6 yr/ 100000 mile warranty from GM on this problem,

but I just can not stand the noise!!!

I know this is an old topic but I want to fix this problem

even if it cost me money. Any help please.

BrokenBoots · January 3, 2004

Just drive it.... IF it takes a chit, rebuild.

Butch 02 Denali · January 4, 2004

I have a 2001 HD 6.0 with 24000 miles and piston slap.
I like this engine except for the piston slap. My question is,

there must be some kind of fix. How about changing the pistons?

Are the ones in the 345HP 6.0 better? Are there better after-

market pistons? Has any one tried STP Complete Fuel System Cleaner?

The directions said it cleans the injectors, cylinder heads,

combustion chambers, valves, pistons, ect. Good or bad?

It states to use no more than every 4000 miles.

I do have the 6 yr/ 100000 mile warranty from GM on this problem,

but I just can not stand the noise!!!

I know this is an old topic but I want to fix this problem

even if it cost me money. Any help please.

The F-body guys cure or at least lessen their LS1 CSK with heavier oil. They use a 50/50 mixture of 10w-30 and 15w-40 synthetic and they swear by it. If your winter temp goes close to 0 just run the 10w-30 in those months, if it goes below 0 run 5-30. Won't hurt to try it, you got nothing to lose. Even if it only cuts the noise in half isn't it worth it?

Butch 02 Sierra Denali

JayMan · January 4, 2004

I have a 2001 HD 6.0 with 24000 miles and piston slap.
I like this engine except for the piston slap. My question is,

there must be some kind of fix. How about changing the pistons?

Are the ones in the 345HP 6.0 better? Are there better after-

market pistons? Has any one tried STP Complete Fuel System Cleaner?

The directions said it cleans the injectors, cylinder heads,

combustion chambers, valves, pistons, ect. Good or bad?

It states to use no more than every 4000 miles.

I do have the 6 yr/ 100000 mile warranty from GM on this problem,

but I just can not stand the noise!!!

I know this is an old topic but I want to fix this problem

even if it cost me money. Any help please.

The F-body guys cure or at least lessen their LS1 CSK with heavier oil. They use a 50/50 mixture of 10w-30 and 15w-40 synthetic and they swear by it. If your winter temp goes close to 0 just run the 10w-30 in those months, if it goes below 0 run 5-30. Won't hurt to try it, you got nothing to lose. Even if it only cuts the noise in half isn't it worth it?

Butch 02 Sierra Denali

Mobil1 cured the "CSK" on mine, but I'm wondering if it has more to do with oiling than CSK. True CSK or Piston Slap doesn't go away until the motor is warm. Mine would clatter for 20-60 secs, less if I stepped on the pedal to raise the RPM to 1500-2000.

So I switched to Mobil 1 0W-30 for winter and Mobil 1 10W-30 for summer. No more clatter at all.

If it does it when hot, perhaps a thicker oil may help. I wouldn't try a 20W-50 as that is too thick. If you're near a commercial Mobil distributer, try Mobil Delvac 1, which is a 5W-40. This stuff is a HD diesel engine oil with excellent shear characteristics.

Or maybe try Mobil 1 15W-50 just for a few miles. If it doesn't help, you shouldn't hurt anything running an oil that thick just for a few miles. If it DOES help, carry on.

WEEKEND WARRIOR · January 4, 2004

JayMan, I run mobil 1 5W-30 all the time. The knock is mostly when cold out,

And engine is cold. What weight were you useing befor you changed to 0W-30

Thanks again

miket · January 4, 2004

If you feel fine with the oil change then that might be the route. If you feel like you purchased something inferior then contact Ann mandt who is an attorney at :

Ann Mandt

Charfoos& Christensen, P.C.

5510 Woodward Ave.

Detroit, MI 48202

Ann Mandt [[email protected]]

I have the piston slap and oil consumption over 3 qts between 3k oil changes. It is carbon build up it is a piston design issue that GM admits they "corrected" for the 03's.

JayMan · January 4, 2004

JayMan, I run mobil 1 5W-30 all the time. The knock is mostly when cold out,
And engine is cold. What weight were you useing befor you changed to 0W-30

Thanks again

I ordered the truck in June 2000 and took delivery in August 2000. So whatever they fill at the engine plant, probably the cheapest 5W-30 oil. I imagine they run the motors on the engine dyno for 30 minutes or so to break it in and do QC checks, then they change the oil to some nasty cheap 5W-30 "low bidder" oil

I never noticed the "CSK" or cold start clatter until November, when I had to park outside my shop and it dipped to 10 F. It knocked like an old diesel but when I stepped on the pedal, at 1500 RPM the clatter went away after about 30 secs.

At that time I had on about 800 miles, so I changed the oil and filter, using Mobil 1 0W-30 oil and the dealer filter. The clatter disappeared.

Next spring around May, I changed to Mobil 1 10W-30 oil and a cheap Purolator filter. The clatter came back worse than ever. I put a dealer AC Delco filter back on and the clatter went away. Has never returned, though at -40 F it will make a "ticking" noise for about 50 secs.

Note: I wouldn't use the Mobil 1 0W-30 oil in summer as the HTHS is a little on the thin side. I need the cold temp performance, or "borderline pumping temperature," so I use it from November to April.

The newer Vortec family V8's have the oil pump at the very front of the crank. With that rear sump oil pan, there is a very long oil pickup tube, so the oil pump has to suck oil a very long distance. In my case, with very cold winter temps, it was an oiling issue and the lifters were taking too long to pump up. Make sure your oil filter has a good anti-drainback valve on it, such as the AC Delco, the Mobil 1 filter, K&N, Amsoil, etc.

Some folks have mentioned a carbon buildup in the crown land and/or ring land area of the pistons. Seems to me, it would take a long time to get carbon deposits that build up to a point where they cause noise. It certainly wouldn't happen from new. I suppose a very poor quality 5W-30 would leave crown land and ring deposits, but I'd expect at least 20,000 miles before that happened.

If your motor makes the noise in summer, or all the time, and does it from new, there is something wrong. I doubt changing to a heavier oil woild help, though it's a relatively cheap experiment.

FWIW: with Mobil 1 0W-30 in winter I average 4,400 miles per quart of oil. With Mobil 1 10W-30 in summer, I average 6,800 miles per quart oil consumption. That's about what I'd expect with a modern tight gasoline motor running a good synthetic motor oil. Mobil Delvac 1 5W-40 should do even better.

WEEKEND WARRIOR · January 5, 2004

A little of topic, but I thought the AC PF59 was the only filter

with the anti-drainback valve. I use only mobil 1 synthetic filters

on all my other vehicles. However while at the parts store I notice

the AC filter looks like the STP filter! Is this AC filter a cheap copy

of the real AC filter? I am going to the dealership tomorrow to check

theirs. I also have heard that thay make a AC Delco Gold filter which

is supposed too be better.

If it is a carbon build up issue woulden't useing a cleaning agent like

STP Complete Fuel System Cleaner ever 4000 miles help?

I wonder if the flat top pistons used in the 03 345HP engines have

this problem? If I do change out to a new piston I might as well

bump up the compression.

JayMan · January 5, 2004

A little of topic, but I thought the AC PF59 was the only filter
with the anti-drainback valve. I use only mobil 1 synthetic filters

on all my other vehicles. However while at the parts store I notice

the AC filter looks like the STP filter! Is this AC filter a cheap copy

of the real AC filter? I am going to the dealership tomorrow to check

theirs. I also have heard that thay make a AC Delco Gold filter which

is supposed too be better.

If it is a carbon build up issue woulden't useing a cleaning agent like

STP Complete Fuel System Cleaner ever 4000 miles help?

I wonder if the flat top pistons used in the 03 345HP engines have

this problem? If I do change out to a new piston I might as well

bump up the compression.

Well, this was covered in a thread in the LD Forum. It appears the genuine dealer PF-59 is different from an AC Delco-branded filter you buy from Parts R Us. I've experienced this before with other filters for my commercial equipment, so I buy from the source. It isn't unheard of for cheap parts places to use counterfit clones.

I like to use the STP gas treat every other tank or so, and the Complete Cleaner every 4,000 miles like the bottle suggests. Not only does this minimize combustion chamber deposits, it helps keep your injectors and intake valves clean too.

For those with "CSK" or some carbon-related problem, I wonder if they've tried a Motorvac treatment? I've tried that once and it works well. The motor ran slightly smoother afterwards. There must have been carbon buildup in the combustion chambers as the oil turned BLACK after the treatment! They recommend an oil change within 100 miles of a Motorvac servicing.

Sorry, don't know anything about the new piston design. Some folks claim it does help. The Vortec 6.0 is the same motor used in LD 2500 trucks. The performance 6.0 is used in Denali pickups and Denali SUV's, and the Cadillac SUV's.

superbee · January 6, 2004

This "Piston Slap" thing is new to me. We used to call it WRONG SIZE PARTS, or PI$$ POOR MACHINE WORK in my day. Dig your heels in and force GM to tell you why a piston too small for the bore diameter is "normal" or "not a problem". This is nothing but bad quality control, you paid A LOT of money for these rigs. I'm paying very close attention to my wife's 6L now.

SBEE

clk7711 · January 7, 2004

I was using Valviline 10w30 in my truck and it knocked pretty bad when cold. I've since switch to Delo 15w40 and the CSK is gone.

Redapple · January 7, 2004

This "Piston Slap" thing is new to me. We used to call it WRONG SIZE PARTS, or PI$$ POOR MACHINE WORK in my day.

Superbee has it right. Although the politicly correct way to express it is excessive clearance. I don't belive the piston slap thing has to do with carbon build up, although I have heard that as well.

Bill

JayMan · January 7, 2004

I was using Valviline 10w30 in my truck and it knocked pretty bad when cold. I've since switch to Delo 15w40 and the CSK is gone.

Seems the type and viscosity of oil DOES seem to make a difference. Anybody think the heavier oil doesn't bleed down from the lifters as fast??

Delo 15W-40 is a good HD diesel mineral-based oil. Like any 15W-40, it shouldn't be used in temps colder than -5 F. In my commercial equipment I used to run a 15W-40 in summer and a 5W-30 in winter. In 1984 I switched to Mobil Delvac 1 5W-40, which I use year round.

FWIW a synthetic HD diesel oil, like Mobil Delvac 1 5W-40, exceeds the Delo ratings and can safely be used to -44 F.

Chevyfreek · January 8, 2004

Well my 6.0L does pretty much the same thing as what is being discussed here. I have run Mobil 1 5W-30 in my truck since it had 6000mi on it. I did not start to notice the cold start knock until over 10,000mi. Although my truck will do it for less than a minute than be just fine. I have over 52,000mi on my truck now and I cannot say that is has gotten any worse. I have noticed that in the extreme cold weather we have had here in the Chicago area that it seems to last a little longer in the morning when I first start it up. But the overnight temps have been near 0 degress. I just switched over to Amsoil Series 2000 0W-30 a week ago after much research. With all the driving I do I think Amsoil will work out better for me. My truck still runs like a champ so I don't think I have as serious of an issues as some others might. I think I am going to talk with my dealer and see if I can get the extended 100,000 mi warranty. Just in case it take a turn for the worse. I have the my existing 75,000mi warranty now. Does anyone know how to go about getting this extended warranty based on this CSK issue? I hope GM has in fact fixed this issue with these motors. Considering the 6.0L is now going to be in the 2005 C6 Corvette. "A new all-aluminum 6.0 L V8 delivers 400 hp at 6000 rpm and 400 lb.-ft. of torque at 4400 rpm." Sweet.....