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Unread 10-19-2011, 09:05 AM   #1
alisa65
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79 Jeep CJ7 258 what to use to cap off metal pipe

My CJ has 2 small metal pipes (pic) that I need to cap off. The caps need to withstand heat from the exhaust. Any ideas what I can use? I can't find anything at a supply store to use for this. I am not even sure where this links to. Thanks

img_0416.jpg  
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Unread 10-19-2011, 10:21 AM   #2
Balvar24
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Those don't looke like metal pipes to me. Look like part of the valve in the exhasut manifold.
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Unread 10-19-2011, 11:02 AM   #3
jeepmaniac
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Agree with Balvar24 - the upper shaft is the exhaust flap in the manifold. There should be a coil spring (looks like a choke pull-off spring on a carb) attached to the upper shaft (see the slot in the shaft?) The lower shaft is just a pin that the spring rests against. The spring closes the flap at idle, allowing the intake plenum to warm up faster when the engine is cold, then opens when the rpm's come up. The upper shaft should rotate when working properly.
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Unread 10-19-2011, 11:22 AM   #4
alisa65
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Ok. I had a mechanic looked at it and he told me to bypass it. I don't have the coil spring. Can I do without that? Would this be a problem? The vehicle starts and runs ok. (just needs a little tuneup). If someone has a pic of what it should look like, I would appreciate it.
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Unread 10-19-2011, 02:59 PM   #5
stodg73
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Here is a pic of the spring.
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Unread 10-19-2011, 03:37 PM   #6
alisa65
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Can I purchase this spring and where? Or can I do without it?
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Unread 10-19-2011, 04:53 PM   #7
hp_lovecraft
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Quote:
Originally Posted by alisa65 View Post
Can I purchase this spring and where? Or can I do without it?
Mine broke off years ago, so I've left it bypassed.

It helps to warm up the intake air during a cold startup. The temp-sensitive spring controls a baffle that pushes the exhaust upward onto the intake. When it warms up, it closes the baffle, and the exhaust flows normally.

I have no cold-start issues, so I've never cared enough to find another spring. Maybe those rebuild kits for the climatics would work? Never cared enough since it probobly is mostly an emmisions thing.

Anyway, without the spring, yours would be always bypassed. There is a weight on the otherside of the exhaust that pulls down as the spring weakens (warms up).

So just leave it.
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Unread 10-20-2011, 06:57 AM   #8
CSP
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Exhaust doens't actually get pushed upward into the intake. Exhaust gases are in direct contact with the bottom of the intake when the baffle is open. Exhaust doesn't ever to into the intake manifold. It flows normally, out of the manifold and into the exhaust pipe whether the baffle is open or not.
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Unread 10-20-2011, 07:16 AM   #9
John Strenk
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That was 'old school' manifold heater called a heat riser.



There was a spring that would control the position of the flapper. Usually rusted away as in these photos.

When cold it would divert exhaust gases onto the floor of the intake manifold to keep it warm so gas would not condense out onto the surface of the cold manifold and pool on the floor.


These manifolds are usually bolted together and made of cast iron. They didn't realy flow very well.

Even my old '63 Chebbie had one of these. This knowledge has been around a long time.

Those jeeps with water heated manifolds used an electric manifold heater.


These would turn on when you had enough oil pressure and turned off when the intake was warm enough to keep the mixture from condensing out.
These manifolds are usually made of aluminimum.
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Unread 10-20-2011, 07:47 AM   #10
Balvar24
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I assume it helps, or AMC wouldn't have added it?
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Unread 10-20-2011, 10:52 AM   #11
John Strenk
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Quote:
Originally Posted by Balvar24 View Post
I assume it helps, or AMC wouldn't have added it?
They never add anything that would cut profits....
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