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Topic: Exhust Leak or////

in Forum: C3 General Discussion


Exhust Leak or////

Posted: 3/26/12 2:52pm Message 1 of 18
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Joined: 2/20/2012
Posts: 21
Vette(s): 76 Vette, 383
So.. new noise today and cant figure out if its an exhaust leak, a lifter or a some valve slapping or just time for an oil change..
 
The noise should be easy to pick out... has gotten worse over the last few days...
 
And if anyone can tell me what that valve is on the heater hose off the intake on the passenger side that would be great.. I assume it has something to do with the climate control.. just never saw one before...
 
Any help would be great!!!
 


|UPDATED|3/26/2012 2:52:16 PM (AZT)|/UPDATED|



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Re: Exhust Leak or////

Posted: 3/26/12 7:43pm Message 2 of 18
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Duncanville, TX - USA
Joined: 11/8/2003
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Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas
Exhaust leaks can certainly mimic a loose rocker arm(valve adjustment). If it has gotten worse over the past few days, I'd suspect an exhaust leak. First place to check would be the spot where the manifold meets up with the head pipe. On the drivers side, there is a doughnut gasket there, that has a lead covered wire mesh. The lead deteriorates over time, and the pipe can start with a small leak that gets louder. Once the lead is gone, or the doughnut is crushed, the joint there will be loose. Sometimes, you can get by with just tightening up the 3 nuts, but...that's a band-aid at best. On the passenger side is the heat riser valve. It sit flat against the manifold with an asbestos-type gasket that can burn out, and cause the same problem.

I can't see the video here(dial-up SUX!Censored), but someone else may be able to give a better idea of the noise.
From the description of the valve in the heater hose, it is prolly the heater control valve....it opens/shuts to control the amount of hot coolant entering the heater core. It prolly has a vacuum hose on it?



Joel Adams
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Re: Exhust Leak or////

Posted: 3/27/12 4:40am Message 3 of 18
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Vette(s): 76 Vette, 383
Thanks...i should have mentioned the car has headers,, so not sure that applies. Already checked the bolts on the headers but have not done the collectors yet. Will check the exhaust gadgets too. Bodes not seem to get better when the engine gets warm. As for the heater control. I would assume its safe to move to a spot that will hide it better


Re: Exhust Leak or////

Posted: 3/27/12 5:10am Message 4 of 18
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Greer, SC - USA
Joined: 3/13/2012
Posts: 264
Vette(s): 1978 Black with Viking mural painted under hood AM/FM/CB radio, T-top and a 2013 Cyber Gray Grand Sport Coupe, 2LT for my daily driver
I have hooker headers on my '78 and the bolts do work loose occasionally.  When that happens I hear a ticking sound (no, not a bomb either).  But you have indicated that you have tightened those bolts.  Did you use a torque wrench?  My '78 had a loose intake manifold which caused the engine to suck up some oil and deposit it in the left rear cylinder.  I was always adding oil and it would tick when the oil level dropped BUT when the engine warmed up, that sound would go away.
David



Warning: The surgeon general has declared that it is NOT unhealthy to smoke your competition AND I just discovered that my corvette is a hybred.  It burns gas and rubber! 

Re: Exhust Leak or////

Posted: 3/27/12 5:28am Message 5 of 18
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Flanders, NJ - USA
Joined: 1/27/2004
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Vette(s): 1982 Black, ZZ4, Hooker Side Pipes, 3.55 Rear, Rebuilt & upgraded 700R4, All new suspension, brakes, & new Charcoal interior.
I have Hooker headers also, and they do lossen up at times at the head. Just had a loose bolt that I tightened up on Sat. Good luck with it.
Dave



 

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Re: Exhust Leak or////

Posted: 3/27/12 5:30am Message 6 of 18
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Vette(s): 76 Vette, 383

Thanks.. mine does not seem to get any better as the engine gets warm...

 
I did use a t-wrench but they where all pretty good.. just needed to tighten one down.
 
I have not checked the collectors yet, will do that later today.



Re: Exhust Leak or////

Posted: 3/27/12 7:58am Message 7 of 18
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Germansville, PA - USA
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Vette(s): 1974 Coupe 358ci 4 speed Black w/Medium Saddle interior w/79 custom leather seats. . 1999 C5 Convertible, 6 speed, Atomic orange, Oak interior.
Might want to check gaskets between heads and headers, could be blowing out even if bolts are tight.


   

DanT

Re: Exhust Leak or////

Posted: 3/27/12 9:25am Message 8 of 18
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Duncanville, TX - USA
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Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas
Yeah...headers will eliminate my post above...except if they are loose at the head.
I watched/lissened to the vid just now. Hard for me to tell exactly what the noise is, I think I hear what may be a valve adjustment that is too tight. I dunno....
A tip that I have posted here many times before on header gaskets....if you're using the paper/asbestos type gaskets, soak them in water for about 4-5 minutes before installing them. That softens them a little, so when you tighten the bolts, the gaskets will deform a little, and the header flange will sink into the gasket, making a really nice seal. Once finished, run the engine to get the gaskets hot, and then retighten. Then let the engine sit until it is completely cooled down. This has worked for me on many header equipped engines...it's one of the kewl things I learned back in my younger days of drag racing.Thumbs Up



Joel Adams
C3VR Lifetime Member #56    

My Link


(click for Texas-sized view!)
             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

Re: Exhust Leak or////

Posted: 3/27/12 9:39am Message 9 of 18
Former Member
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Greer, SC - USA
Joined: 3/13/2012
Posts: 264
Vette(s): 1978 Black with Viking mural painted under hood AM/FM/CB radio, T-top and a 2013 Cyber Gray Grand Sport Coupe, 2LT for my daily driver
Joel,
That was excellant advice about the header gasket.  Even though my header bolts have been torqued, I can still hear a ticking sound and it is coming from that area.  next year I am going to have a Griffan radiator installed and I just might have him pull the headers and do that with the gaskets.  While the water is out of the system, I am going to have the straight cut timing gears installed (can't afford a supercharger but people will think that I have one with those gears).
 
Again, Excellant advice,
David 



Warning: The surgeon general has declared that it is NOT unhealthy to smoke your competition AND I just discovered that my corvette is a hybred.  It burns gas and rubber! 

Re: Exhust Leak or////

Posted: 3/27/12 9:40am Message 10 of 18
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Joined: 2/20/2012
Posts: 21
Vette(s): 76 Vette, 383
Thanks.. will check the exhaust gaskets..
 
I got the car about 3 months ago and have not adjusted anything under the valve covers at this point...
 
It was mild a few days ago and has gotten worse...  its been hard to pinpoint and its been a lot of years since I had a car that any type of adjustment like that was needed so out of practice.
 
 



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