Ok if you didnt know I just replaced my 4.8 with a LS1 about 4 days ago. Everything went smoothly the tune is great it runs great untill last night. My buddy 99SilveradoSS came over and wanted to see the truck so we went for a quick ride on a frontage road at the back entrance to my place. I get on it not as ahrd as I would say at the strip but I smoke the tires and when it goes to shift into 3rd at 6k+ it starts knocking really really bad(really loud)! ****
It didnt lose any power and it drove fine(i was probably going 25mph) just as it did this morning on the way to the shop. It didnt lose any oil pressure(per the gauge) and the oil didnt have any metal shavings(per dipstick). It was gettign late so I didnt check anything else and just wanted it to cool down and sit. My buddy CRAZYCUTER4.8 came over and just a guess he said it was lower end and I think that could be a good guess. Maybe a rod! We call my installer on his cell and he asked if we checked the oil(damn it) and we had. Altough it was over a cell phone he guessed lower end-connecting rod and he also said that this morning when I brought it to him. This is so shitty. I hadnt sprayed the LS1 and didnt plan on it for a while untill I at least recovered from the assload of $ i had spent in the last month-damn near 6k! Im praying it is a loose bolt or something because Im screwed if its major! Hell I know you have to pay to play but damn that **** is to the extreme. I got the n20 done about 5 weeks ago. A week after the n20 I get a smiliar sound and we replaced the cam,pushrods, and springs and it took care of the noise but none of the stock items were damaged at all!??????? 2 weeks after the cam I get my updated tune and that night I destroyed a piston. I replace the 4.8 with a LS1(with 9k miles on it) and now 5 days later this! It ridiculous! I needed to vent! Pray that it is something stupid please!

 

Damn man. I really hope it is nothing serious. That is terrible. Do you have any insight as to why the previous owner bought a new motor and sold this one? Did he spray it? Did you get a look at the pistons prior to install?
Damn man I really hope it isnt anything serious. Good luck and keep us posted.

 

Yeah the guy that had it did a 408 and he hadnt sprayed at all. As far as the pistons all I saw was the tops and all was fine. Im hoping it isnt a rod for the obvious reasons but when I find out everything I will share!

 

I'm gonna say rod bearing and it has stock rod bolts.

 

Thats insane. I cant imagine it being a rod with only 9K on the motor and nice pistons. I'll keep my fingers crossed for you that it isnt anything major. Hopefully some others will chime in with possibilities since Im dumbfounded.

 

Mine only has 9k on the rebuild--it only had 500 miles on it when we tore it down. It was a warranty engine so I wanted to be sure that everything was okay. We did a full rebuild w/ new GM rings, cam/rod/main bearings (Clevite), ARP main studs/rod bolts/head bolts, etc and it's making a similar noise, although I have metal in the oil. Still haven't heard back from RP about the oil analysis. Once I find out what kinda metal is in the oil, I'll let everyone know.

Haven't driven the truck since the 27th. This blows.

 

THE PROBLEM IS RICHARD(99SILVERADOSS) . He was riding with me when I blew up my G80. I had just installed a second cam & told him, want to see a 4.8 spin the 20's. we leave the dealership, get 1/2 mile down the road and BAMN! I blew it up!

I find it odd that richard was with both of us. hmmmmm.....

 

Dood .. this sucks.

Have you thought about trying to work on it yourself? You can get to those rod bolts pretty easy.

 

we could do it micheal!

 

I was thinking the same thing! I'm just gonna stay away from you guys! I think the reason for your G80 going out is because you stopped right in the middle of the on-ramp to I-20, with cars behind you, trying to do a burn-out!

Mike, that sucks man. I know it's been one thing after another for you. We'll just pray that it's something small, easily fixable, and very Inexpensive, if it costs anything.