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Intake or Gasket leak? Or????

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Old Aug 18, 2011 | 07:31 AM
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Default Intake or Gasket leak? Or????

My 2000 T/A isn't running great and has had this problem since I got it.

My trusted mechanic and I checked fuel pressure, fuel injectors, compression, coils, plug wires and plugs. Everything checked out great. I have a lean code on Bank 1, and cylinder number 1 has a random, not constant, misfire when on the scanner. The old school starting fluid check didn't change the idle either.

We hooked the smoke machine up and the intake is leaking somewhere.

He suggests changing the intake and the gaskets at the same time, because for the prices he is going to charge to do it, it probably makes sense. I figured I'd do it myself. Is it worth it to try just the intake gaskets? They're $20 instead of $600+ for a new intake?

Do these intake gasket O-rings ever go bad? Is there any way to test and see which one it is while it's on the car?

What should I do? I need my baby to get better. Thanks.
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Old Aug 18, 2011 | 07:54 AM
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Why would you replace the intake? They dont wear out

Intake gaskets do go flat overtime but if you've never had the intake off, its probably not your problem

Not a surefire test, but if its sucking air, you should see a change in vacuum from the MAP sensor
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Old Aug 18, 2011 | 12:28 PM
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yes...the gaskets go flat......ask me how i know.....do you still have the crappy stock PCV hose setup? that would be my 1st suspect....ask me how i know
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Old Aug 18, 2011 | 02:00 PM
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Originally Posted by sjsingle1
yes...the gaskets go flat......ask me how i know.....do you still have the crappy stock PCV hose setup? that would be my 1st suspect....ask me how i know
Exactly.


The gaskets do flatten and leak, typically a vacuum leak will be worse when the engine is cold since things expand once they are warm. That is unless it is a hose like sj said. My PCV hose also had a hole in it. Check that real close, its the hose that has a big bulge in it that connects to the intake right behind the throttle body.
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Old Aug 18, 2011 | 08:36 PM
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You can swap to a better PCV system for about $10 using off the shelf SBC parts that works better than stock. Sure beats paying +$100 for the FBody PCV crap
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Old Aug 21, 2011 | 09:57 PM
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Originally Posted by sjsingle1
yes...the gaskets go flat......ask me how i know.....do you still have the crappy stock PCV hose setup? that would be my 1st suspect....ask me how i know
Did your gaskets go flat while you were still using your stock, never removed the engine, intake?

How did you figure out it was your PCV hose setup?

Did your PCV hose problem cause your car to run like mine is now?



I tried to old school trick of spraying carb cleaner and starting fluid to check for leaks. There was no change in idle so I couldn't find a leak that way.
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Old Aug 22, 2011 | 07:33 AM
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Originally Posted by brewersprts
We hooked the smoke machine up and the intake is leaking somewhere.
I'm curious as to what this "smoke test" is. Please elaborate.

A vacuum leak will raise you idle speed.

Have you swapped the ignition coil from the offending cylinder with a good one from another cylinder? If the PCM still reports misfires from number one, this will confirm the coils is not intermittent.

(While these coils do not "wear out" or go down in power, they can go out completely and then "come back")

If it is your intake manifold gasket, you can get a set of gaskets. Like Pocket said, the intake manifold itself doesn't go bad.

If you're taking off the intake, I would suggest you do the change to the LS6 PVC system. It'll make your half day project a full day project. Full details and instructions are here:
http://ls1howto.com/index.php?article=18
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Old Aug 22, 2011 | 10:39 AM
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Originally Posted by brewersprts
Did your gaskets go flat while you were still using your stock, never removed the engine, intake?

How did you figure out it was your PCV hose setup?

Did your PCV hose problem cause your car to run like mine is now?



I tried to old school trick of spraying carb cleaner and starting fluid to check for leaks. There was no change in idle so I couldn't find a leak that way.
my intake had never been removed..........the gaskets were HALF the size of the new 1s i had bought for my LS6 VC install.........my idle had really gone wonky......i had a LS6 VC that was sitting around to be put in......finally put it in and found how common it is that the PCV hose takes a crap from being so old
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Old Aug 22, 2011 | 10:41 AM
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Old Sep 4, 2011 | 09:14 AM
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it could be a number of things, had the same problem.
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