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Topic: Exhaust leak 75 L48

in Forum: C3 Engines

Exhaust leak 75 L48

Posted: 11/11/08 8:56pm Message 11 of 23
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North Charleston, SC - USA
Joined: 3/20/2004
Posts: 4176
Vette(s): 1975 L48 AT AC T-top
Thanks Paul...will do.

Scott



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Exhaust leak 75 L48

Posted: 11/12/08 7:58am Message 12 of 23
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Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20214
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
Also, make sure it's not a cracked manifold...they can be hard to detect at times, depending on the location of the crack.
IMHO, the best exhaust gaskets you can use are header gaskets, believe it or not. Get some name brand header gaskets, and soak them in water for a few minutes(2-3 minutes). Then bolt them on before they dry out. Tighten them down really snug. Being wet will allow them to compress around the exhaust ports. Once you start it up, and the heat from the exhaust dries them out, they'll be there, with no leaks ever, unless the bolts back out for some reason. I'll usually put a wrench back on them after running it for 15-20 minutes, just to be sure they're tight. Werks every time fer me...


Joel Adams
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Exhaust leak 75 L48

Posted: 11/12/08 8:56am Message 13 of 23
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Mounds View, MN - USA
Joined: 5/24/2007
Posts: 1031
Vette(s): 70 LT1 coupe, 69 350 HP coupe, 69 390HP 427 coupe, 71 LS5 convert, 85 coupe, 93 coupe
I agree with Adam.  Wet header gaskets from a brand name source work best.  They don't look exactly stock, in case that is a problem.  I would suggest that before you take anything apart, you stuff a rag in the end of the exhaust so it creates more back pressure.  You might have better luck finding your leak.

Larry



Exhaust leak 75 L48

Posted: 11/12/08 3:25pm Message 14 of 23
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North Charleston, SC - USA
Joined: 3/20/2004
Posts: 4176
Vette(s): 1975 L48 AT AC T-top
Thanks Joel and Larry, Vettespecialties. I have alredy tried the rag trick. It made no difference. I will do a thorough inspection of both manifolds once they are removed. I certainly don't see any obvious cracks. Thanks to all for the excellent suggestions. If the weather is good this weekend, I will get er done.

Scott



Exhaust leak 75 L48

Posted: 11/12/08 7:21pm Message 15 of 23
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Canada
Joined: 6/23/2008
Posts: 558
Vette(s): 1972, 1980
If you take the mirror, and check with the vette running it will sometimes be enough to fog up the mirror, help to find cracks.
John



Exhaust leak 75 L48

Posted: 11/12/08 9:03pm Message 16 of 23
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Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20214
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
Or, do the rag trick, but dump a little tranny fluid thru the carb....and watch where the smoke comes out...


Joel Adams
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Exhaust leak 75 L48

Posted: 11/14/08 5:22pm Message 17 of 23
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North Charleston, SC - USA
Joined: 3/20/2004
Posts: 4176
Vette(s): 1975 L48 AT AC T-top
Well, I got the passenger side exhaust manifold gasket and valve cover gasket done tonight. I used the new Mr. Gasket copper exhaust gasket with the raised sealing area. I used a new style rubber valve cover gasket by Fel-Pro. The passenger side should be the most difficult because the AC compressor had to be moved aside. I'll start the driver's side in the morning. Thank you all for your great suggestions.

Scott
ranger32008-11-14 17:31:55


Exhaust leak 75 L48

Posted: 11/14/08 5:26pm Message 18 of 23
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Scott, that's great, I'm sure it'll work out for youThumbs%20Up


corvette440hp

Exhaust leak 75 L48

Posted: 11/15/08 2:50pm Message 19 of 23
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North Charleston, SC - USA
Joined: 3/20/2004
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Vette(s): 1975 L48 AT AC T-top
I completed the project this morning. New exhaust manifold gaskets and valve cover gaskets. No more leaks. Took her for a ride, then re-torqued everything. Sounds like it should and no more smell of leaking oil on the manifolds. Back like it should be. Thanks to all.

Scott



Exhaust leak 75 L48

Posted: 11/15/08 5:52pm Message 20 of 23
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Canada
Joined: 6/23/2008
Posts: 558
Vette(s): 1972, 1980
It will be nice not having that oil smell, or exhaust leak sound.
 
acplus2008-11-15 17:53:43


in Forum: C3 Engines


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