71LS2Camaro

I have a 99 LS1 6 speed in my 95 Chevy Stepside regular cab PU. Bought it about 8 mos ago and had a few issues. Aftermarket Street & Perf pully setup, idler bearings, water pump, Alternator bearings etc. It has been in the truck for 9 years. I have driven about 10k miles and always used Mobile 1 10-40 during the summer and now 10- 30. I hear what sounds like a heavy lifter knock not immediatly when starting cold but within about 15 -30 seconds. Truck stays in heated garage overnight so its not freezing on these cold morning but after a minute or so it gets a little better I drive slow till it warms a bit. At about 2k it is the most pronounced and fades above or below that speed. Noise stays now even when engine warms you can still hear the 2k rattle, not as bad at normal operating range though. Doesn't miss, never runs hot, spits or anything noticeable. It does seem to have a flat spot about 2200-2500 rpm in moderate driving but pressing on the gas picks up well.

Anyone have any experience with these older LS1 motors? The previous owner said he had the motor put in with about 40k on it and he had driven it about another 20k or so in 9 years. He had several cars so I had no reason to doubt him. He was an older guy so he wasn't drag racing it just a nice cruizer. I would guess it to be in the range of 75-80k miles now. I do enjoy a spirited run through the gears every once in a while but, not much over 5800-5900 rpm though. No holeshots or drag radials though. Any help or advice would be appreciated.

versz

Piston Slap is my first thought. a video would be appreciated.

ApacheDrill

iTrader: (21)

Thats my guess also.. verry comment in the LS1..

01 CamaroSS SLP

Sounds like piston slap to me too. Pretty common, I have it on mine. When the weather gets really hot it goes away. When it gets cold its louder. I just ignore it.

71LS2Camaro

Wow, that is a shame. They are really great motors. I get about 22 mpg and not many other truck can keep up with it. I dusted a 2010 Challenger RT a few weeks ago.

Is a rebuild in order? Hate to hear it sound like a clapped out old work truck. I have been babying it since it started a couple of months ago. I don't normally hear it if it's not under load (sitting still with the clutch in and holding RPM at 1500 - 2500). It usually is only when I'm rolling through the gears. Does it go away when you have parts laying on the ground?

Thanks again for the quick responses.

There are a few (low mile) motors around here for 1200 - 1500, is that reasonable? I have been burned every time I don't hear them run though.

ds98formula

iTrader: (3)

No need to rebuild piston slap is just normal in some of the motors. That's of cours if it is piston slap and not a lifter collapsing

versz

Look at the bright side. You just added to your "sleeper" appeal. It might be a clapping old truck to the kid in a challenger. But to us its a raging bull.

In my opinion I wouldn't buy a motor unless I heard it run. In other cases I talk them down as much as possible and prepare myself for a project basically. Just my $0.02