Bad news for my LS1!

[Last_Z]

I took my car in this morning to one of the local Chevy dealers for a tire rotation and front brake rotors resurfacing or replacement. I tell the service person what I need, but while I was at it, I asked him to listen to my engine's knock. He said, "will do", so I go sit inside. About 1 1/2 hours, the guys comes out and asks "How do you want to do this?".....I'm like; do what??.....He says; "You need new pistons"

Needless to say, my jaw dropped. To make a short story even shorter, I left the car at the dealer; they will order the pistons today and the guy told me his "really experienced mechanic" might have it ready by Friday depending on how soon they get the pistons.

I have been saying for a while that the knock on my engine is very low and obvious.....as if the engine is very low on oil......I guess they though it was bad enough that I didn't even have to hassle with them.....they actually offered to fix it.
This is very interesting because the latest UOA on this engine showed excellent wear, except for copper, which doesn't relate to the pistons.
So anyway, pray for me and my engine because as it is at the moment, the car runs like a cheetah and burns no oil. I'm hoping I get it back exactly the way I gave it to them minus the knock.

Rick

PS; Pat, there goes my GC UOA!

Oh well, we'll get 'em next time, tiger!

 

[XS650]

Why do you need new pistons?

If the car is still on factory warranty, you can be reasonably confident that it needs serious work.

If the car is off warranty, then ??????

****

 

[novadude]

You should complain until they give you a new shortblock. I would not trust dealership mechanics to swap pistons. Maybe I just worry too much?

 

[Patman]

I was looking forward to seeing the first LS1/GC UOA too.

I sure hope this dealer knows what they are doing? Ask them how many LS1s they've torn down before you let them touch yours!

 

[Last_Z]

XS650,

I need new pistons because my car is suffering from the infamous "piston slap" associated with MANY GM products. Basically, the cylinder bore is slighty bigger than the piston's diameter so the piston rocks or slaps against the cylinder walls.
Hear piston slap here . That's EXACTLY how my engine sounds like.
The car is a 2002 Z28 and it is under warranty.

novadude,
A new engine would be the next logical step. They won't let me get a new engine right off the bat. They need to prove this engine is beyond what a dealer can fix.

Hopefully it all has a happy ending.

ps; I got a rental.....an Impala....the thing also has the slap

.....just goes to show what kind of quality control GM is running.

 

[Last_Z]

quote:

---

Originally posted by Patman:
I was looking forward to seeing the first LS1/GC UOA too.

I sure hope this dealer knows what they are doing? Ask them how many LS1s they've torn down before you let them touch yours!

---

Pat,
I got the impression they know what's wrong and what to do, from talking to the service rep. You guys know how this works....at the end of the day, I'm at their mercy, so I have no option but to let them tear the thing up and hope for the best. If I don't let them fix it and something happens in the future (which I really doubt), then I'd be on my own. I have no choice.

 

[crainholio]

I'll have an LS1 GC UOA this season. I'm presently swapping one into my '82 Z28 project car...it's in the engine bay with a fresh fill of GC, waiting for me to finish the wiring harness.

My present thinking is GC for street use, and Delvac-1 for the road courses.

 

[Chris B.]

Hi Rick

That is what happened at my dealer! No fighting with them, they just said you need new pistons and rings. Well mine burned oil and knocked and now my oil consumption seems to be gone but I still have "dieseling". Maybe the knock is not related to the pistons in my car? My Boss at work has a 2002 LS1 also and his makes the same diesel sound as mine. He thinks it is the lifters and is not worried about it. One a good note my wear dropped a bit after the rebuild and copper went down to 50ish from 100+! Let me know what your repair order says they replaced and we can compair to see if they did the same rebuild!

 

[TooManyWheels]

I have a couple of thoughts on this procedure.

How are they fitting the piston/bore? Are they doing any fitting, or just slapping pistons in with no honing, checking, etc. ? Is that why it takes a "really experienced mechanic" ? If the bore is the correct diameter but the problem is in the piston, how can you trust them to get it right the second time around if not the first?

[ February 02, 2004, 05:04 PM: Message edited by: TooManyWheels ]

 

[Ryan00TJ]

Slapping in new GM pistons is not going to fix anything as what is wrong with the LS1's is the cylinder bores are not perfectly round and in most cases the piston diameter is smaller than the bore resulting in oil consumption and knocking. I've also actually seen a LS1 piston that was oblong and not round!!!!!! It seems LS1's with the LS1 block have the most problems but the 01 @ 02's with the LS6 block are void of these problems to an extent. My 02 SS has a LS6 shortblock and is mouse quiet and burns no oil. A friend has a 02 Z28 with a LS1 block that burns 1 qt in 2500 miles and is noticeably louder than mine. GM's quality control sucks period! This is not a Cavalier motor here.....no offense to Cavalier owners but the LS1 GM's flagship engine in their flagship car the Corvette! I would think QC would be a tad higher. I would demand a new crate engine and not let some dealership mechanic tear into your LS1!!! From what I've been hearing you can get an LS6 crate engine for a few hundred $$ more.

 

[Last_Z]

Chris,
Called the service rep back and asked him what the procedure is and he told me that there won't be any bearing removal, except for the rod bearings since they have to take the piston/rod out. I think that might be better since I don't want them to mess with anything unless it's needed.

TMW,
From the TSB I've seen, they get the new pistons and fit the biggest one in the bigger bore. I would have to talk to the mechanic himself and find out exactly what he's doing.

Ryan,
I also have the LS6 block and my car never burned any oil. As stated above, the only problem it ever had was the knocking noise. We'll see what happens after the rebuild....if problems persist, then I would inquire into getting a new engine.....hopefully an LS6.

I suspect though that as long as everything is done right, the worst that can happen is that I get my car with new pistons in the same working condition I gave it to them.....meaning no oil burning, good power and still a knocking sound.......best case scenario, I get it back as it was before MINUS the knock.
I'm hoping for the latter.

Rick

 

[Chris B.]

Deffinetly keep us posted! When you get it back let me know the exact part numbers on your RO to compair to mine and we will see how the 2 compair.

 

[Last_Z]

Quick update guys.....

Just called the dealer to get an update on my car and talked to the service rep. He told me the engine is already disassembled. The pistons came in, but they are now waiting for new piston rods......so the pistons, rings, rods, and rod bearings will be replaced.
I'm hoping all goes well and I can get my back on or before Friday.

Rick

 

[sprintman]

Lets hope they check piston to bore and 'select fit' each piston. I thought all the dodgy LS1's were shipped to Oz as we have thousands of them using oil or getting rebuilt. Not GM's best engine IMO.

 

[Last_Z]

sprint,
According to the TSB that I've seen, they are supposed to check the bores and select/fit the pistons.
I truly believe the LS1 is a remarkable engine, I think the problem is quality control......think about it, how the h3ll do you send engines out with one cylinder bigger than the rest???

They haven't got the slightest clue as to what "Attention to Detail" means.

 

[sprintman]

Yes I saw the TSB way back with the new design pistons and rings. When GM knew they had a problem most were shipped here. Ford have had a big comeback here lately and this helped a bit (new Falcon eats the latest Commodore too)

 

[Last_Z]

Hey guys,
I picked up my car today. I checked all fluids etc and started it up. No noise on start-up. I let it warm up for a couple of minutes or so then take off. I drive a couple of miles and then got on it HARD. Power is at least the same as before......there was no knocking sound even after I let it idle for a while.
They replaced the pistons and rings, rods, a bunch of bolts (don't know from where), associated gaskets and sealers, oil and filter.
I had no oil consumption before the rebuild and I'm hoping I don't have any after.
I could post the long list of parts if requested.

Rick

EDIT: Does anyone know where I can find out what the part numbers are?

[ February 07, 2004, 03:52 PM: Message edited by: Last_Z ]

 

[Amkeer]

Last Z,

I would have taken pictures of the motor taken apart. It would be interesting to see the sides, tops of the pistons, head and valves too.

Daily Drives:
-2003 Toyota Tacoma PreRunner XtraCab, Impulse Red, Peppy 2.7 Liter 4 Banger, Running Mobil1 Synthetics SS 5W-30.
ODO 6900 Miles.
-1995 Toyota 4-Runner, Evergreen, 3.0 V6, Running Mobil1 Synthetic SS 10W-30.
ODO 82800 Miles. (Switching to GC next)Nope sticking with M1.
http://community.webshots.com/user/amkeer

 

[Patman]

Glad to hear the rebuild worked out so well for you Rick! Get some break in miles on it and then take her to the track and see if she'll run the same or quicker!

 

[Chris B.]

Great news Rick! My part numbers were on my R/O. I just listened to my bosses 2002 Trans Am and his sounds just like mine with out the rebuild. Maybe the "diesel" I'm hearing in these cars are not at all related to a slap or knock noise??? Mine runs great and so far has not burned any oil sense rebuild! Did you get to talk to the tech? Keep us posted.