Bacon

I actually have a 2000 GMC Sierra, but with little help coming from other sites, I thought Id try you guys since I have heard good things.

My problem lies within my 5.3 V8 with 107K miles. At idle, it runs and sounds like a champ. At cruising speeds, same story. However, under acceleration where the exhaust doesnt overpower, such as lugging in overdrive on a highway withought shifting down, there is a noticeable ticking sound coming from the engine. Ive gone back and forth as to what it may be, but I dont want to throw parts or time tearing it down without a good idea. Could it be a collapsed lifter? Maybe a sticky valve? Something else? I have good oil pressure, I change the oil religiously, I have recently seafoamed the engine, gas, and oil, and the overall performance is perfect. Oh yea, its not knocking or detonating either since I run 92 octane all the time on a custom tune which was designed for 90.

Any help would be GREATLY appreciated. If it matters, I have toyed with the idea of swapping in a 2001 LS6 cam and new lifters and retuning, but it gets pricey real quick.

Thanks everyone,

Matt

chaman

iTrader: (5)

Could be an exhaust leak at the manifold?? Those sometimes tick like that. You could just check those bolts to be sure....just a thought!

01redws6ta

I thought maybe exhaust leak too. Those engines are known for exhaust manifold (usually end ones) bolts breaking and creating a leak. Another possibility is "spark knock". Determine if it's either of these. I doubt it's a collapsed lifter by your description. Have it scanned for knock sensor codes and knock retard while driving as you decribed if you suspect that.

Bacon

Well, Ive looked and looked under the hood before...reving and listening in the past, even using the old long screw driver to the ear trick trying to find the tick. Problem is, like I said, its only under load. I cant replicate the sound at idle or even revved in park. I thought I had ruled out an exhaust leak today, but, as fate would have it, I found a broken manifold bolt on the drivers side today. It was hidden by the coolant temp sensor wire so I never saw it before. So...here the real question. How can I get that out without breaking off the 1/4" of it I have to grab? I know how heat likes to seize things up...dont wanna make it worse. Thanks for any help!

01redws6ta

It may turn out easier than you think...sometimes the head breaks off, but the threads are OK. I assume you'll have to remove the manifold to get it out. I'd spray it with some penetrating oil and work it back and forth once it breaks loose (stud remover or locking pliers) until it comes out.