What is This??

[xhogboss]

I've searched the web and looked in every Jeep book I have - I can't identify this tube/valve? thingy.

Background; 1985 CJ7 , AMC 258 i6 / 4.2l , Holley ProJection 1D - other than the catalytic converter, this CJ has relatively little for smog/emissions. No air pump, no air fittings into the exhaust manifold, etc. I'm underneath replacing u-joints and I see this tube, maybe 3/4" diameter, running from my head pipe just below the manifold, down and across the bottom of the bellhousing, and then running up to a valve (I think) on the passenger side of the motor. The tube continues upward and runs through the firewall. I can't see where it comes out in the passenger compartment.

I have no emissions requirement where I live, and I'm for simplifying things. If I don't need this and it doesn't through a wrench into things, I'm for removing it. But I can't seem to find what it is.

 

[Lumpy Grits]

Pic #1
Down pipe to the 'cat'.
Catalytic Converter
Pic #2
Vent drain

LG

 

[RiverandSand]

Well it looks like some kind of fresh air contraption, this arrangement would appear to be quite dangerous, if that reed valve would fail it could pump exhaust fumes into the air system for the heater. The hose coming from the firewall is the drain for the cowl vent, that vent provides fresh air to the heater/cabin.

 

[RiverandSand]

Pic #1
Down pipe to the 'cat'.
Catalytic Converter
Pic #2
Vent drain

LG

This ^ , if connected correctly.
OP - There should not be anything going into the vent drain hose, if the pic 2 is accurate.

 

[xhogboss]

Thanks for the prompt replies.

It's clear that this is not hooked up correctly at all. The cat (may he rest in peace) had no connections whatsoever going to it, and had no provisions for any connections. I'm guessing someone threw one under there to pass visual inspection for smog. I'll remove the pipe and cap the connection in the head pipe.

Drain for the cowl vent makes sense. Right location for that - can't see it for the heater duct between it and the dash. I'll continue that downward to someplace convenient and out of the way.

Thanks again for the info.

 

[RiverandSand]

Drain for the cowl vent makes sense. Right location for that - can't see it for the heater duct between it and the dash. I'll continue that downward to someplace convenient and out of the way.

Thanks again for the info.

You won't be able to see the air intake unless you remove the grill cover on the cowl outside below the windshield, it's built into the body.

 

[xhogboss]

You won't be able to see the air intake unless you remove the grill cover on the cowl outside below the windshield, it's built into the body.

Good to know - I'll pop the cover off to make sure the drain is clear.

 

[Scout1067]

There should be a little cap on that cowl vent drain hose that lets water drip out of the hose but keeps dirt and gunk from going back up the hose into the heater. Also, if you live somewhere with lots of trees like I do it is a good idea to clean out the cowl vent box occasionally to keep the drain port from clogging.

The vent cap looks like the one here at vintage jeep: https://www.vintagejeepparts.com/pr...-1977%2d86-Jeep-CJ-and-1987%2d95-Jeep-YJ.html

 

[xhogboss]

Mystery solved - I think.

The tube running from the head pipe was part of the EGR system. The part I couldn't see was the s-shaped hose that had been stuck up inside the cowl vent drain hose. The hose would have connected to the stock air cleaner to recirculate a portion of the exhaust under certain throttle conditions. Rather than remove it, some PO just hid it.

Thanks for the help solving this.