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Topic: Doughnut?

in Forum: C3 Fuel, Emission Control, and Exhaust Systems

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Doughnut? (1/8)
6/19/10 5:21pm

KDADDY79
Former Member
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Dutchess County, NY - USA

Vette(s):
White '79 Corvette. It's a driver.

Joined: 8/27/2007
Posts: 2484

Earlier this spring I had a 700R4 installed in my '79.

Then I had to replace the true dual exhaust. The new exhaust had to be bent and dimpled in order to fit around the new trans.

Last Tuesday my son and I really drove the Vette for the first time this year. We put around 80 miles on it. It ran, shifted and sounded good.

After we got home, I let the Vette sit in the driveway for a few hours. When I started it up to put it away I thought I heard an exhaust leak up near the driver's side exhaust manifold. As the car warmed up the noise from the leak got less and less pronounced.

Today I drove it again. During warmup the exhaust leak was noticeable only for a few minutes.

After it cooled down I poked around and found that the 3 bolts that hold the driver's side exhaust to the manifold were a very little bit loose. I tightened one of them easily. The other two were difficult to get a wrench on good, but I turned them a bit.

I started it up again and it was louder than ever. Wits End

Could it be the "doughnut" gasket between the (driver's side) exhaust manifold now has uneven pressure on it? Could I have made it worse by really only tightening one of the 3 bolts?

Hopefully I'll be taking it back to the exhaust shop this week.

Any opinions or suggestions would be helpful.

Kevin

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Doughnut? (2/8)
6/19/10 6:21pm

rraider1
Former Member
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Woodland, WA - USA

Vette(s):
1977 T-Top,350,Auto Black Ruby Pearl,Steeroids R&P conversion

Joined: 10/14/2003
Posts: 1165

It sounds like the gasket, I beleive the best way to tighten those bolts is from under the car with two long extensions and a swivel at the socket.

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Doughnut? (3/8)
6/19/10 8:09pm

indy99
Former Member
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Newport, MI - USA

Vette(s):
1980 L-48 still in the middle of a frame-off.

Joined: 6/9/2005
Posts: 932

Sounds like a gasket/donut to me.

I coated the threads on mine with high temp anti-seize just in case I have to take them off again.

______________

Corvettes and women are the same...You want to make love to them but they keep breaking down.

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Doughnut? (4/8)
6/20/10 12:08am

ranger3

Lifetime Member
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North Charleston, SC - USA

Vette(s):
1975 L48 AT AC T-top

Joined: 3/20/2004
Posts: 4176

Yep, need to get under there with a socket that fits properly.

Scott

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Doughnut? (5/8)
6/20/10 10:25am

DaveM

Lifetime Member
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Flanders, NJ - USA

Vette(s):
1982 Black, ZZ4, Hooker Side Pipes, 3.55 Rear, Rebuilt & upgraded 700R4, All new suspension, brakes, & new Charcoal interior.

Joined: 1/27/2004
Posts: 2552

You scared me for second, I thought you were out doing doughnuts in the parking lot Wink

Dave

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Lifetime Member #116
Dave's '82

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Doughnut? (6/8)
6/20/10 11:45am

lukesvette

Lifetime Member
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HOWELL, NJ - USA

Vette(s):
1979, Targa Blue (72 Color), Pace Car rear spoiler, L88 hood, Dark blue factory interior, 525HP 406, HD 700R4, 370 gears,Steeroids, composite rear spring, TT IIs wrapped in T/A Radials.

Joined: 5/18/2004
Posts: 6812

Soak the threads with PB blaster, see if you can spin them off, then use a thread chaser to clean up the studs, apply anti seize and het some new nuts and washers.

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Doughnut? (7/8)
6/20/10 1:38pm

KDADDY79
Former Member
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Dutchess County, NY - USA

Vette(s):
White '79 Corvette. It's a driver.

Joined: 8/27/2007
Posts: 2484

I'll definitely have it up in the air when it goes in for the fix. I'll make sure to clean up the threads while we're at it. Let's hope it goes quick and easy. I just want to drive it!!!

Thanks,

Kevin

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Doughnut? (8/8)
7/5/10 6:06pm

KDADDY79
Former Member
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Dutchess County, NY - USA

Vette(s):
White '79 Corvette. It's a driver.

Joined: 8/27/2007
Posts: 2484

The verdict is in;

T'was the 3 studs (driver's side) that hold the exhaust on to the exh. manifold. They were replaced along with new nuts, washers and another "doughnut" gasket.

The exhaust guy was decent. "No charge" is what he had to say when I picked it up early this morning. He said he should have at least checked the studs earlier on when I kept coming back in with leaks. Nice guy! Mistakes & brainfarts happen. The good ones own up to their side of these things.

I may just take it for a ride if the temp. goes below 100!!!

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