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Old 04-21-2021, 02:54 AM   #1
Rob Doe
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Default How do you all test for an intake manifold air leak?

What are some of the methods you all use? What do you spray around the manifold, starter fluid(some percent ether), brake cleaner, WD40?



I'd like to be as safe as possible.
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Old 04-21-2021, 06:50 AM   #2
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Default Re: How do you all test for an intake manifold air leak?

DO NOT USE BRAKE CLEANER---------------- The gas cloud it produces could kill you!!! I've used carb cleaner in a spray can and the little tube pointing it around the flange
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Old 04-21-2021, 07:20 AM   #3
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Default Re: How do you all test for an intake manifold air leak?

Starter fluid will do the trick to
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Old 04-21-2021, 07:44 AM   #4
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Default Re: How do you all test for an intake manifold air leak?

the wifes hairspray...and as an added benefit it will hold for hours with a pleasant scent
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Old 04-21-2021, 07:46 AM   #5
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Default Re: How do you all test for an intake manifold air leak?

WD 40 worked very well for me . Sprayed it between the block and manifold from the top The engine did an instant speed up ..

John in lovely spring weather Suffolk County England .
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Old 04-21-2021, 07:47 AM   #6
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Default Re: How do you all test for an intake manifold air leak?

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WD 40 worked very well for me . Sprayed it between the block and manifold from the top The engine did an instant speed up ..

John in lovely spring weather Suffolk County England .
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Old 04-21-2021, 07:52 AM   #7
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Default Re: How do you all test for an intake manifold air leak?

you can say that again John
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Old 04-21-2021, 08:52 AM   #8
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Default Re: How do you all test for an intake manifold air leak?

Quote:
Originally Posted by john charlton View Post
WD 40 worked very well for me . Sprayed it between the block and manifold from the top The engine did an instant speed up ..

John in lovely spring weather Suffolk County England .
That is the method I have used over the years. Very effective if you have a
vacuum leak at the intake manifold.
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Old 04-21-2021, 09:20 AM   #9
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Default Re: How do you all test for an intake manifold air leak?

I just assumed I had a leak since it felt under powered and I felt a little light headed after driving a few miles. So I just spent an afternoon replacing the gasket. Really isn't that hard. After it was replaced I notice more power and she can drive a little faster.
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Old 04-21-2021, 09:22 AM   #10
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Default Re: How do you all test for an intake manifold air leak?

An unlit propane torch. Leaves no residue.
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Old 04-21-2021, 09:31 AM   #11
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Default Re: How do you all test for an intake manifold air leak?

I have tried all of the above methods and the best for me is Blockheads way. No residue, drips, fires.

But unlike Jacks method I would not be caught dead with my wifes hairspray in my tool box! My wifes red nail polish in my toolbox is bad enough. (great for marking objects)
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Old 04-21-2021, 01:03 PM   #12
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Default Re: How do you all test for an intake manifold air leak?

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I have tried all of the above methods and the best for me is Blockheads way. No residue, drips, fires.

But unlike Jacks method I would not be caught dead with my wifes hairspray in my tool box! My wifes red nail polish in my toolbox is bad enough. (great for marking objects)
Look,I'll wear the fishnets but I won't belt out show tunes on demand...nope,not anymore
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Old 04-21-2021, 05:21 PM   #13
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Default Re: How do you all test for an intake manifold air leak?

Blockhead, what does the unlit propane do? Does the engine speed up if there is a leak?
It sounds like an easy and clean way to test!!
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Old 04-21-2021, 05:53 PM   #14
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Default Re: How do you all test for an intake manifold air leak?

If you are using a flammable spray of any kind to locate a leak, Rig up a flexible hose for an air intake well away from the carburettor. I use a length of vacuum cleaner hose and duct tape. It doesn't have to be very big diameter - the engine is only idling. You need to draw air from well away from the volatile spray or the carb will suck some in and give a false response. Just my experience.
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Old 04-21-2021, 06:47 PM   #15
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Default Re: How do you all test for an intake manifold air leak?

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Blockhead, what does the unlit propane do? Does the engine speed up if there is a leak?
It sounds like an easy and clean way to test!!
Yes the propane is sucked into the intake thru the leak and the engine speeds up just like any of the other methods using a flammable gas or liquid. Just no mess. I have used those micro-butane torches also.

And as Synchro pointed out, you don't want to point it towards the carb inlet.
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Old 04-21-2021, 06:54 PM   #16
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Default Re: How do you all test for an intake manifold air leak?

I was thinking about fire risk too. I think I'd opt for a can of WD-40 with a nozzele in one hand, and a garden hose in the other hand. I have been in a fire before, and I tend not to take it lightly.
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Old 04-22-2021, 08:32 AM   #17
Bob Bidonde
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Default Re: How do you all test for an intake manifold air leak?

Try this easy test technique:
Attached Images
File Type: jpg Vacuum Leaks The Sneaky Ones.jpg (67.8 KB, 72 views)
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Old 04-22-2021, 09:51 AM   #18
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Default Re: How do you all test for an intake manifold air leak?

A completely different technique is to use a small diameter rubber hose. Hold one end near your ear and the other at the suspected leak location. If you hear a hissing sound, that is where the leak is.
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Old 04-22-2021, 09:51 AM   #19
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Default Re: How do you all test for an intake manifold air leak?

Is there a central internet repository for Bob Bidonde infographics? If not, we really need one.
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Old 04-23-2021, 04:27 PM   #20
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Default Re: How do you all test for an intake manifold air leak?

Quote:
Originally Posted by alexiskai View Post
Is there a central internet repository for Bob Bidonde infographics? If not, we really need one.


Try this:

https://www.modelalongisland.com/technical
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