Strange Exhaust Pipe connection

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Nov 30, 2004 | 04:56 PM

muckypaws

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From: Derbyshire, UK.

Strange Exhaust Pipe connection

My Bronco was suffering from a leaking exhaust so I had a look. The main problem was a 3/4" hole just after the first Cat which looks like it was connected to a pipe hanging down next to it. When the motor is running air is blown from the pipe.

1) What is the air pipe for? EGR/ emmissions? Dilute the exhaust with fresh air?
2) I have bunged up the hole in the exhaust.
3) Will having the air pipe vent to atmosphere cause a problem?

Am in the UK so our emmissions rules are slightly different.

Nov 30, 2004 | 06:27 PM

BOJOFASO

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From: NJ

i have the same problem that you have. it is a connection for the air system to pump fresh air int the exhaust to help the catalitic converters burn the unburned fuel left in the exhaust.
what did you use to plug the hole? you really need to fix it the way it was desighned or you will eventually ruin the catalitic converter,

Nov 30, 2004 | 11:37 PM

greystreak92

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From: Gateway to the West

Actually, the CAT just won't heat up and burn off the additional unburned crud without the air injection. Not sure what your emmissions laws are across the pond so it may not make any difference. The air coming from the pipe is straight out of the smog pump which is just fresh air that has been filtered before its drawn into the pump then pushed out the pipe and (as originally equipped) into the CAT. In short, if not having a functioning catalytic converter on the truck is ok, what you have done so far is enough of a correction to the problem. If you need the CAT to be functioning, then you will need to have the pipe welded back onto the exhaust pipe in the place where it had separated or replace the Y-pipe all together.

Dec 1, 2004 | 03:00 AM

muckypaws

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From: Derbyshire, UK.

I "fixed" the hole by inserting a M16 short bolt coated in exhaust paste and then held it in with a large 4" pipe clamp (Juibile Clamp) and then filled any further leaks with paste. A total bodge but its only temp.

As for the air pipe it looks like I have two cats and a muffler, the air pipe/hole was between the 1st and 2nd cats....

Dec 1, 2004 | 03:04 AM

muckypaws

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From: Derbyshire, UK.

Just an idea... if I choose to leave the air pipe diconected - can I use the compressor for somthing else? What sort of cfm and pressure will it produce?

Dec 1, 2004 | 07:07 PM

BOJOFASO

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From: NJ

it will not give enough of anything to help your performance. at least i think you are talking about pumping it into the throttle body.
hey grey the pipe from the air pump is held to a nipple that is between the two cats with a small clamp. the pipe is made of thin wall tube and tends to rust out. it is almost impossible to get the other end off of the anti backfire valve because you jus cant reach up to get the clamp loose.i actually fixed mine with a small piece of copper pipe. it was 3/4 inch . then i held it together with 2 hose clamps.

Dec 2, 2004 | 09:01 PM

Cheggie

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From: South Carolina

Muckypaws,
Unfortunately, the "smog" pump isn't powerful enough to do anything but push some air into the cylinder heads and catalytic converter. Some people have converted the A/C compressor for airing up tires, running small air tools, etc. If I was here in the US (which I am) I'd take it to a muffler shop to weld in a new bung for the air tube, then use a high temp rubber hose to connect the two lines. I KNOW there are some experienced welders over there, what with the tinworm and all.