air leak manifold?

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Aug 14, 2010 | 11:00 AM

Z1bEST

Thread Starter

Heel & Toe

Joined: Nov 2009

Posts: 23

Likes: 0

From: Canton GA

air leak manifold?

Earlier year I removed and replaced the Oil Pressure Sending Unit and ever since then I hear a faint whistling sound when I start the engine in my 2001 Corvette. The sound goes away when the engine warms up or at least it goes away enough for me not to hear the sound.

Any suggestions beyond another remove and re-torque of the intake manifold? What are the torque specifications?

Aug 14, 2010 | 11:09 AM

87SAM

Safety Car

Joined: Jan 2001

Posts: 4,387

Likes: 691

From: Boise ID

44 lb in first pass, 89 lb in final pass in the following order:

Front
10 4 1 5 8
7 6 2 3 9

Aug 14, 2010 | 11:56 AM

Bill Curlee

Tech Contributor

Joined: Dec 1999

Posts: 32,910

Likes: 2,402

From: Anthony TX

CI 6,7,8,9,11 Vet

St. Jude Donor '08

Did you completly remove the manifold and clean the sand and dirt off the heads and manifold gaskets or just slide it back far enough to gain access to the sending unit???

Torquing the manifold properly is also important!

Aug 14, 2010 | 12:14 PM

byronhunter

Melting Slicks

Joined: Oct 2007

Posts: 2,383

Likes: 13

From: Kinston North Carolina

Quote:

Originally Posted by 87SAM

44 lb in first pass, 89 lb in final pass in the following order:

Front
10 4 1 5 8
7 6 2 3 9

Don't read that!
--------------------------------------------
Read this, ok?
Tighten the intake manifold bolts. Tighten
Tighten the intake manifold bolts a first pass in sequence to 5 N·m (44 lb in).
Tighten the intake manifold bolts a final pass in sequence to 10 N·m (89 lb in).
----------------------------------------
although it's correct, the way it's phrased, it would be easy for someone to mistake it for FT/LBS.

Last edited by byronhunter; Aug 14, 2010 at 12:19 PM.

Aug 14, 2010 | 12:30 PM

87SAM

Safety Car

Joined: Jan 2001

Posts: 4,387

Likes: 691

From: Boise ID

Quote:

Originally Posted by byronhunter

I see what you mean!

Aug 14, 2010 | 05:39 PM

Z1bEST

Thread Starter

Heel & Toe

Joined: Nov 2009

Posts: 23

Likes: 0

From: Canton GA

Thanks, I removed the manifold and tied to clean the sand off the heads. I will take it back off, reclean, and torque correctly. Appreciate the for the information.

Aug 15, 2010 | 04:24 PM

Z1bEST

Thread Starter

Heel & Toe

Joined: Nov 2009

Posts: 23

Likes: 0

From: Canton GA

Took my time and cleaned everything very well and used the right torque sequence, but the vet is still whistling when I start the engine. I am considering buying a set of intake gaskets and replace all of the gaskets. The Vet runs great and looks fantastic, but she does have 140,000 miles on the engine and the individual gaskets looked very flattened when I pulled the intake manifold off.

Any other suggestions before I try this again next weekend?

Thanks for the advice.

Aug 15, 2010 | 10:46 PM

Toxiclemonade

Racer

Joined: Sep 2009

Posts: 257

Likes: 0

From: Charleston SC

I had the same exact problem. The whistle is coming off a vacuum line coming off the back of the manifold. The only way to get to it is to take off the intake manifold. I suggest adding some vacuum line to the stock line so you can give it a little play as the stock line is pretty tight and can rip out easy. Good luck.