Just a heads up, my truck kicks the TC out when i let off lightly as in going down an overpass. And when i run over 73mph. The DTC codes says cylinder missfires and cylinder#7 missfires. I have chased everything electronic finally put a stethoscope to it at #7, oh my heavens!!! Ive never heard such a noise from a "good" running motor. Gotta get in there asap. Check your misfires??
1998 GMC Sierra K1500 5.7/4L80E, longtubes, 411 w/COS 5, marine cam/intake, Whipple. 91 octane at 6000'.
1997 GMC Sierra K3500 7.4/4L80E, 411 w/COS 3, Whipple, small cam.
2004 Corvette Z06 with longtubes.
Steth is fine... I'm wondering if it's just valvetrain, or if it's more severe.
sorry i wasn't notified of the responses, yes, I used a Stethoscope, I have had the valve cover off, couldn't see anything obvious. I hope to get the G6 out of the shop tomorrow. (bad fuel tank vent valve, leaking oil sender took out the starter, starter took out the battery "weak anyway") lol Are we having fun yet??? anyway?? The truck is going in for exploratory surgery Monday or Tuesday, worst case - broken piston, not burning oil?? best case - collapsed lifter, probable issue - pitted camshaft. my machinist thinks this is the problem claims to have seen a lot of them lately??, it does sound like a stinking diesel at idle!!! gurrrr I've got $13000 invested, not quitting now.
look at this https://www.youtube.com/watch?v=ux84a6SJAc0
Last edited by Tinbender59; March 9th, 2019 at 01:56 PM.
My 454 did that. Got the truck like that and didn't even know it, the belt sqeaks were louder than the ticking. When I was addressing the belt squeak I heard the tick so I just ordered a cam and lifters without opening anything. I was right. I'm not sure that the 8.1 was prone to this as well? If so, you can run a GenVI cam if you get the plate so you're not subject to the terrible aftermarket of 8.1 cams.
1998 GMC Sierra K1500 5.7/4L80E, longtubes, 411 w/COS 5, marine cam/intake, Whipple. 91 octane at 6000'.
1997 GMC Sierra K3500 7.4/4L80E, 411 w/COS 3, Whipple, small cam.
2004 Corvette Z06 with longtubes.
Long story short found the rocker arms wore out where the ball sets, making a popping sound when you move the ball. Second Long story short expert wasn't going to tell me that unless I bought his rockers. But he did mention if I put a larger than stock cam in I would wear them out , so I went looking. Also found camshaft had gald marks on it, check the rollers in the lifters, all three that I checked, the roller bearings had rough spots in them. I guess it isa blessing in disguise that I caught it before it destroyed the motor. I'll be Going back stock with everything. my research shows if I put a bigger cam in, I'll have to put in roller rockers, next will be springs, then headers, then??? where does it end. Ill just stay stock, it's a farm truck. Besides $600 repair bill beats $1600+++++??