99 Deville engine squeal when cold.

reek1reek1 Member Posts: 4
Every morning when I start it the engine squeals (hi pitched noise) for the first 5 to 10 miles. Other than this the car runs perfectly. The noise is not a belt squeal, it sounds more like a vacuum whistle. By using a stethoscope I think the noise is coming from the left end of the intake manifold, but I can’t find a hole.

I had the same problem about a year ago, the noise was there every morning for at least a month so I took it to the Cadillac dealer, they kept it for three days so they could start it cold. They claimed that it never made the noise. When I picked it up it didn’t squeal again until a week ago, now it does it every morning.

Any help would be greatly appreciated.


  • bolivarbolivar Member Posts: 2,316
    By the 'left end' I assume it's the driver's side of the motor.

    You have another belt there. The water pump is driven off the cam at the front of the motor, on the driver's 'end'. There is a small belt under a cover there. It also has a tension idler on it. The belt might be squeeling, or the idler bearing is going out. If the belt breaks, the engine will overheat very quickly. If an idler seizes, it may break the belt.
  • reek1reek1 Member Posts: 4
    Thanks for the reply. When I said left side of the intake I was wrong. The noise seems to be coming from the passenger side of the intake manifold. Behind the power steering pump.

    The first time this noise happened I replaced both belts, idlers, tensioners. Had no effect on the noise.

    Another test I have tried is to spray starter fluid in the area of the noise however engine idle never changed.

    Still looking for a fix.
  • reek1reek1 Member Posts: 4
    I Found it !!!!

    The squeal was driving me nuts so I kept looking and testing. With the help of a very small inspection mirror I was able to see into the area the noise was coming from. I found there is a spring loaded flapper valve in the intake manifold. (I assume this is a relief port so you don't blow the intake manifold apart in the event of a backfire.) I made a tool out of a cheep screw driver and was able to move the flapper around enough to clear any debris. Even if the noise comes back I know what it is and how to stop it.
  • bolivarbolivar Member Posts: 2,316
    I've never heard of this 'valve'.

    Glad you found the problem, and came back here and posted about it.

    Most people ask questions on forums and get several replies with information, and you never hear from them again.
  • bolivarbolivar Member Posts: 2,316
    http://www.cadillacforums.com/forums/northstar-engines-system-technical-discussi- on/60406-northstar-intake-manifold.html

    This is a link to a discussion of the valve on a Cadillac forum. And you are right about the purpose of the valve.

    This Cadillac forum has good discussions about Cadillacs
  • reek1reek1 Member Posts: 4
    Thanks for the link. I read all the postings and fine it interesting that no one else talked about the valve squealing. Mine must be unique.

    My problem started after a minor backfire because I didn't hold the key long enough for the engine to start. All makes sense now.

    The link will be helpful in the future.
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