Topic: Exhaust leak 75 L48
in Forum: C3 Engines
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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...
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
C3VR Lifetime Member #56
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
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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
Larry
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
Scott

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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
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"
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
ranger3 2008-11-14 17:31:55
Scott
Scott, that's great, I'm sure it'll work out for you

corvette440hp
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
Scott
in Forum: C3 Engines
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