Classic Restorations

Well, I brought my 03 Z06 to a well recommended Corvette specific shop located in Westchester County, NY and was told that the SLP tuning that had been in my PCM for 3 years was sloppy even though I had never had any issues. After this tune that took much too much time and many different excuses since the shop was not equipped with a dyno, I take my Vette back and the engine blows up at Lime Rock on the 2nd lap. Teardown of the motor reveals #7 piston leaned out and detonated sending its shrapnel throughout the motor and taking #2 with it. The #7 cylinder wall has a 2" crack in it. Diagnosis on the PCM reveals bad timing and fuel curves causing the issues. After much thought, I decided to purchase the much vaunted LS7 Corvette Z06 motor.

I purchased the LS7, the oil reservoir and the lines. Upon receipt of the motor, the crankshaft was removed to change the reluctor wheel so my 03 PCM could function. When we disassembled the motor, we found the main bearings to be full of dirt and badly scored along with 2 rods. After many phone calls to GM Performance, an offer was made to rebuild this "new" crate engine. I declined the offer and requested a replacement motor. After 2 weeks, I received the replacement LS7 and upon removal of the crankshaft, we found the same problems, except worse. I have pictures placed on my website under Current Projects and 2003 Z06 LS7 conversion.

I am at the point where I do not want to put any LS7 in my car as this seems to be a major problem. There has been a lot of hype with these motors about the expensive facilities, hand assembly and hand signed along with individual 20 minute dyno runs to ensure the utmost in quality.

Anyone else had these issues with LS7's or GM Performance crates? It has been suggested to me that GM may be pulling these engines off the Wixom plant line that do not meet production car oil pressure specs and selling them as crate "performance" motors.
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98 SNAKE EATER

Yikes!!


Maybe they were handbuilt on a Friday?



BTW, check your PM's





Rick

Aztek T/A WS7 & 70 RAM AIR IV T/A
Moderator @ LS2, FAST LS1, FUELSLUT,
The F-Body Hideout, LS1Turd & ChopperForums

Bink

Damn! Ouch.

GMW-CSL

Your story is really sickening. As silly as I have sometimes felt doing it, I have always completely disassembled any engine, new or otherwise, that was destined for one of my projects, checked, cleaned and measured everything before reassembling it and installing it. In 40 years of fooling around with this stuff I've had only one incident where it turned out to have been the smart thing to do, i.e. I bought a Porsche 904 engine from a guy supposedly with all new parts and professionally rebuilt, and forund that the crank journals had been poorly welded up and re-turned, and the valves contacted the pistions. That would have been very expensive scrap-metal if I had started it up. So, after reading your story I now am compelled to, for the second time, disassemble the LS7 I am currently building, and re-clean everything again before the "final", "final" assembly. Thanks for your story!

c5racr1

iTrader: (1)

I got a Crate LS7 in my Cts v. I had to pull the crank to change the reluctor ring, and my bearings were fing. I have great Oil pressure 34 lbs at 235 degre. I guess it is an isolated case and your bad luck. BTW who was the builder?

Classic Restorations

I thought 1 was just a bad luck deal. 2 in a row? Both built by Knapp.

trumperZ06

Wonder where the dirt & grit is coming from ???

The engine assembly area should be almost a... "clean-room" !

Classic Restorations

I have been told it was a combination of debris during assembly and no oil upon startup. Maybe these motors did not get primed prior to start up?

JASON11WS6

iTrader: (7)

Why don't you just build a resleeved LS1 motor with your old block! You can make way more power that way.

Classic Restorations

I did consider rebuilding my LS6. However, seeing how I almost lost my numbers matching engine (which is critical to the values on Corvettes and other cars), I decided to go with a crate engine so if some other catastrophe occurred it would not be an additional worry. I will rebuild my LS6 to stock specs at a later date and put it back into storage.

Turbostive

iTrader: (3)

That is horrible. Thanks for the heads up.

98blackSS

It is.. I was really impressed with how clean the assembly area was when I got a tour of the LS7 plant this past summer. I'm keeping in touch with one of the engine builders on this particular case for Mel through email. The builder is going to meet with engineering and do some investigating... we'll see.

phoenix

iTrader: (6)

shouldnt the oil pressure on a LS7 be around 50 psi?

V6 Bird

iTrader: (15)

num ber 7 pistons lean out in stock form anyway..I cant really say it was the tuning as much as it was just ready to go...reasearch lean #7 and you'll see its pretty common.

Bink

please post findings.

firefighter

You said both motors were built by the same guy Knapp? To me that seems like the answer to the mystery either the guy is incompetent or a mole for FORD. Seriousley maybe there was just a problem this guy had and either it's been resolved and/or the guy has been dismissed either way it's unexcusible and GM should and prolly will resolve your issue hopefully with a motor built by a different guy.

98blackSS

Will do Bink.. Just sent him another email.

The builder's name is actually James Knipp.

GMPP

What Gm dealer did you by these motor from? I personally look at all warranty return reports. I have not seen this issue that you described before. GM might be a big company, but the people who work in GMPP take a great deal of pride in our product. If you want to send me a private message I will personaly look into this problem you have had.

Robin L

Mel


I read and re read your post several times. Other than asking the question "has anyone else had problems" I wonder what the purpose of your post is.
The part about the tune merrits some warning to others. I have seen many tunes that are great numbers on the dyno, but given some heat soak they would not last more than several laps on a road course. So many people are wanting to see the big numbers they stray from making sure the tune is safe. We see a huge cross sections of uses and then same applies to the members of this board. What works on a drag only car may not work on a road course.

I find it very unusual that you would find the 2 engines with the same problem. Not saying that it could not happen but wow!.

You say now that you don't want to use the LS7. Maybe you have changed your mind for a different combination. I will say that like the post above GMPP takes these situations seriously. They are car people with performance cars just like you and me.

If you would please PM me with the details I will forward them to my contacts at GMPP. I would like the dealer that you purchased the engine from and the names of those who you have dealt with regarding the problems.
As I said I will forward the information to people who can work to resolve your problem.

Robin

WS6FTW

The one good thing I see out of this situation, is that in reading this fourm it shows that GMPP actually cares about it's customer. There are many companies that would simply say "tough, it's your problem not ours". I really have a great deal of respect for GMPP and the willingness to rectify the situation.