9T3VETTE

Ok so feels like I've been chasing this for years, basically ever since I installed long tubes. If you saw my last thread recently I installed a hotcam kit and the "ticking" has gotten louder since. I'd think the valvetrain would be noisier but not this loud?? Since it showed up after installing LT's years ago it seems the exhaust would be the obvious place to look.

However, I've probed EVERYTHING I can think of with a mechanics stethascope and hose end listening for leaks at the manifold or collector. Can't find anything.

lifters and pushrods were reused during install as they all check out fine, but clearly that doesn't rule these components out.

So I need a trained ear....exhaust leak? Valvetrain issue? Normal LT noise amplifying the valvetrain?

I should also note that it is more pronounced when fully warmed up. The video was taken after about 45 minutes of driving.

Tom400CFI

Sounds like an exhaust leak over the 'puter....does it go away when decelerating, like while engine braking? Does it get more pronounced under load?

Get a piece of small hose or vacuum line, put one end in your ear...move the other around the engine, exhaust flanges, etc. When you get to the source of the noise, it will be very obvious.






.

C4Coupe

Sounds like mine did on a Camaro I had with a small hole in the header with a defective weld on a tube at the header flange. Drove me nuts trying to find it. Good luck!

9T3VETTE

Well sounds like I'm on the right track looking for an exhaust leak.


It seems more pronounced at idle just because I can hear it over the exhaust, but does increase increase linearly with engine speeed. I've probed the flanges and collectors with hose but have not found an obvious leak.





Thanks, This is driving me nuts too!! How did you end up fixing the leak? I bought a rubber plumbing adapter, drain pipe end cap and air fitting that I'm going to use to pressurize the exhaust. Kind of like a boost leak tester...it's the only way I can thinknto find the leak or rule it out.

C4Coupe

I was winter and I was able to see it early in the AM using a flash light in the dark on first start up. I had been looking for it since the end of the summer that year. I bitched to Hedman and they sent a new set since they were less than 6 months old.

81c3

The fact that you are moving from one side to the other leads me believe you think its on both sides.... Also, you say its worse when warmed up... Generally, I have found that exhaust leaks will actually get more quiet with the expansion of the metal.....

I know I have had some engines with headers and more aggressive cam profiles magnify the valve train sounds through the thinner walls of the primaries... Its something you dont notice with cast iron manifolds...

Another possibility is proper gasket sealing on both sides at the header flange and maybe loose fasteners.... Header bolts can become loose after some time. After initial install, did you re-torque after driving a few hundred miles or check them?

desertmike1

Pressurizing the exhaust is a pretty good idea!

Years ago I had Valve trane noise as well, and it turned out to be worn Intake Guides. For some odd reason the Exhaust guides where still well within Spec..

my noise subsided when the engine heated up to operating temperature.

cardo0

Well you need to locate the source. HF has automotive stethoscopes for nearly pocket change. That gives you metal to metal sound tracing/tracking to the source.

Next method would be to get a junkyard center bolt valve cover and cut open the top. You need to file the cut edges smooth for safety. You can now access each valve and rocker arm to trace the sound location. Use rubberized/silicone reusable gasket to stop oil running down. The last test I can suggest is to pull the rocker arms and p-rods one cylinder at a time and see if that kills the tick. If this doesn't identify the"tick" it is either the exhaust or something internal. You would be surprised to find something like the crankshaft flange hitting the flywheel inspection cover tin - happened to me but sounded more like a rod.

BTW that open top valve cover is very handy, mostly for adjusting the valves while running.

Hope this helps and good luck.

9T3VETTE

Thanks guys appreciate all the advice. I used my HF stethoscope to probe the rockers and dodint find anything unusually loud. Honestly I need to just pull the drivers valve cover and adjust each rocker while it is running.

This weekend is Woodward dream cruise so nothing is happening lol. Really just looking to see what others thought, if it's an exhaust leak or valvetrain issue

drcook

Mine was ticking last night after we came home from a cruise-in about 30 miles away. A bunch of cut finger tips, 2 new pulleys (tensioner and idler, they are both the same on a 96 LT1) a new serpentine belt cause the old one was 20 yrs old and NO tick.

Not saying that this is your problem, but it was mine.

9T3VETTE

Stumbled across this video over lunch today. The "ticking" sounds exactly like mine which I found interesting...It's also a 93

Going to get the exhaust adapter hooked up tonight and pressurize the system. Hopefully between pressure and soapy water I can either find or rule out exhaust leaks...

1993C4LT1

Wish I could help! Hope you find what is causing the tick

Can wait to hear some WOT pulls

hockeyhead019

check the fuel regulator. It sounds vaguely like mine does although mine is a little deeper in tone. I too thought it was an exhaust leak but put the stethascope on that regulator and boom matched perfectly. It's the little pancake guy inline with the fuel run.

Best of luck!

9T3VETTE

Think exhaust leaks may be the culprit after all. Got the exhaust rigged up and fed some pressure into it. Worked like a charm..

Found quite large leaks at the x pipe -> intermediate pipe connection and smaller leaks at the header > collector connection. ALSO....found leaks leaks at the passenger header flange. So basically the whole damn thing is leaking lol

Need to assess how to get it all sealed up. Short term is probably use lap joint clamps for the slip fits. Long term I may have some flanges welded on the header collectors to ditch the slip fit.

For the header flanges, not sure. The bolts are tight and I'm using Percy's seal for good aluminum gaskets which are supposedly the best. Maybe a coat of copper rtv on for it to seal? Someone also suggested cutting the flanges in between primary tubes sets to allow each to seal individually. Pretty apprehensive about doing that on a pair of 1k headers. Anyway onto the pics

1993C4LT1

Wow that's amazing. Thanks for sharing

Tom400CFI

Any bubbles up by the head/flanges? A ticking is usually a leak from a primary pipe. Down stream, it's typically more of a "fffa-fffa-fffa-fffa-fffa-"....rather than a "tick-tick-tick" sound.


NICE WORK though. I'm impressed with your test.

bjankuski

Guys in my opinion it sounds like the valve train and not an exhaust leak. Maybe the rockers are set incorrectly or some mechanical issue, or it could just be the normal sound of a hot cam kit.

9T3VETTE

Thanks, something I picked up working in engine dynos years ago but never tried it at home.

There were some leaks at the primary tube, specifically from the #2 cylinder (on top), one of the bolts (even though it's tight). I noticed when I pulled spark plugs that the housing of #2 and #4 plugs had heat stress/carbon marks on the exposed steel. This is what originally got me thinking it's a manifold leak. Unfortunately the adapter blew off before I could probe the drives side well. Need to let the epoxy cure a little longer!

I triple checked lifter preload before firing it and also adjusted with the motor running, so I'm pretty sure they are set correctly. Still could be valvetrain related though. It also made the noise before the valvetrain was touched....

Think i'll try and get the exhaust sealed up and if it's still making noise, valvetrain will be next.

hockeyhead019

great trick, may be worth a write up and a sticky for all the people who are trying to diagnose exhaust leaks on these 25+ year old cars lol

Tom400CFI

Good finds. I would focus my efforts there and not worry too much about the down stream, band clamp leaks. IDK if you can ever get them totally leak free.