LS-1st-Gen

In case you guys dont remember, I pulled missed shift over-rev on sunday, and now I have a distinct tapping that is either valve train noise or an exhaust leak. I pulled all 16 pushrods today, and none were noticebly bent. I rolled them all on a sheet of glass, and while they ALL had an "uneven" noise while rolling, none of them rolled to the side or wobbled noticebly. In all of the searches Ive done, everyone has said that thier pushrods come out looking like spagetti, but mine arent even close. So what now??? Do I assume the worst, IE bent or broken valve??? Where do I go form here?

Has anyone ever blown out a collector gasket before??
-Gordon

sleepersilverado

iTrader: (1)

do a leak down test or get someone to a-tap the car would think if if you had a bent valve you would be getting misfires. not sure though. o and the collector gasket i have blown one before and it sounded just like i had a horrible exhaust leak did not tick but not saying it couldn't. to check them start the car and get a little piece of hose and hold it up with the hole to the hole in your ear and run the other end around the collector. you will prob hear a little leaking but if it is blown it will be alot more noticeable and you could also see mine.

hope this helps and hopefully some one else will chime in. i know that you can check the valve with a leak down test but not 100% sure if the a-tap thing would work.

Smoke_Ford

Or just to be safe, get comp hardend one piece pushrods. They are not that much money, and are well worth the price, even more so on a 6-speed.

LS-1st-Gen

ttt, any other info???

soundengineer

iTrader: (16)

even a slight bend can cause valvetrain noise....
My hardened pushrods made no wabble noise at all...bent even 1% is still bent....
I would replace the pushrods....stock ones are cheap thru gm parts...hardened ones are not too much more....good cheap insurance with a cam and high revs.

LS-1st-Gen

OK, thanks guys, I guess what I will doing is heading into Houston tommorrow and picking up a set of hardenend pushrods from MTI on my way around the beltway...They are far cheaper than stock I believe. I'll drop them in and hope that solfes the problem. Has anyone ever bent valves without bending a pushrod??

BergerMan

Just check the compression on each cylinder and see what you get. They should all be 200psi+. If one is noticeably less, its a bent valve.

Mid-Life Speed

You might also have collapsed a lifter ...

I am fighting the same issue. About two weeks ago, my ride developed a tapping noise on the passenger side bank. The noise was timed with the valve train, not the crank, so I pulled the cover and inspected the pushrods. Same as you mine had a little "wobble", but no bends. Went to MMT and had Sean take a look/listen. Also looked at some of his stock take out rods, and they rolled the same way mine did. I looked at rockers and springs and didn't notice anything unusual, so I'm down to suspecting a "lazy" lifter.

LS-1st-Gen

Mid-life, have you driven the car with the problem? Also is there a way for me to test for a bad lifter without pulling the heads? Will a compression test do the trick?

-Gordon

Mid-Life Speed

I've been driving it OK, and last week had it on the Dyno at MMT up to 6200 rpm trying to see if I had valve float or other valve related pbs. It ran without any issues (other than the annoying tapping), and actually after the dyno runs the tapping was very minimal for a while (again leading me to suspect a lifter that might not be pumping up fully at lower rpm's). I think the only way to check the lifter is to inspect it, and unfortunately that means pulling the heads on the LS1 ... I don't think a static compression test will tell you anything about the lifters, but a running compression test might.

Steve