What does this tube do?
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Junior User
Joined: Feb 2007
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From: Eastern Washington
What does this tube do?
I have a 1995 F150 w/5.8l. At the rear of the heads, there is a pipe/tube that bolts to the heads themselves, and runs to a series of tubes that lead to the catalytic converter. Do they recirc gasses from the heads to the cat? If so, is it okay to not have them connected?
I replaced my heads, and one of my new ones doesn't have the bolt holes in the back to connect it properly. Right now I have the tube connected to one head, and not the other, and it seems to run fine. Just wanted to make sure I'm not damaging anything with it setup this way.
I replaced my heads, and one of my new ones doesn't have the bolt holes in the back to connect it properly. Right now I have the tube connected to one head, and not the other, and it seems to run fine. Just wanted to make sure I'm not damaging anything with it setup this way.
FTE Legend
Joined: Jun 2006
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From: Ottawa, Ontario
That's air injection system, it pumps air into the exhaust ports on the heads on cold starts to help the cats burn off excess gas fumes. If you can't completely connect it, remove all of it and plug the head with the port in it. You don't want any leaks in the exhaust system upstream of the O2 sensor, it'll throw the calibration out of whack.
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Junior User
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From: Eastern Washington
When you say "remove all of it" do you mean to pull out all of that tubing in the rear of the engine compartment? That stuff connects to canisters and vents and all kinds of stuff on the passenger side of the engine compt. If I did that, do I leave the air pump connected? Does that hurt anything, will the cat still function without the extra air?
I know thats a lot of questions, and I thank you in advance for anyone who posts back!
-Steve
I know thats a lot of questions, and I thank you in advance for anyone who posts back!
-Steve
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Joined: Mar 2007
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From: Florida
I know a few people that get the pump delete kits and everything functions just fine...It's smog injection is all and I won't get too in depth on it because I've been in arguments about whether to keep it or not....for me....not and no it shouldn't hurt anything....it's just pumping air.....Just plug off the head port and yank all the tubing associated with the pump......
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Junior User
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From: Eastern Washington
I think I'll try removing that stuff. I'm going to keep it all, of course, in case it needs to go back on later. I am lead to believe that the smog system is for older exhaust systems anyway, and I just replaced my cats with new ones. My friend has a '96 and his truck has a totally different setup than mine, but it doesn't pump air into his cats. So, as long as mine are new, I'll give it a shot!
FTE Legend
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From: Ottawa, Ontario
Originally Posted by S_Bruce
When you say "remove all of it" do you mean to pull out all of that tubing in the rear of the engine compartment? That stuff connects to canisters and vents and all kinds of stuff on the passenger side of the engine compt. If I did that, do I leave the air pump connected?
So yeah.. remove all the rubber hoses and valves. You can leave a piece of hose connecting the air pump to the muffler on the passenger side inner fender.. to cut down on noise from the pump, and it'll keep splash water out of the pump as well. Cap the vacuum lines that drive the diverter valves, but leave the solenoids in place(they are near the coil). Also cap the steel line that goes to the cat if it's still connected, otherwise remove this a swell. This won't affect performance.
BTW... are you absolutely sure there isn't a plug in the hole where the air injection tube would bolt to the head at the back? I believe it came up in another thread about an exhaust leak on the front of a head. These heads should be bored right through front to back, and one end is tapped and plugged depending upon which side of the motor the head is on.
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Junior User
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From: Eastern Washington
Yeah, thats wierd. I got two reconditioned heads. The one thats on my passenger side had threaded ports in the front and rear. The drivers side head has no ports at all. Originally, there was a long slender tube that connected to the back of both heads. Now, when bolted to the passenger side head, it does not line up with the drivers side head, and vice versa.
On my factory heads, the forward port was plugged by an alternator bracket bolt. The original bolts weren't big enough to thread into the new heads hole, so I left it unplugged and this caused a seriously loud exhaust leak. I have since plugged that port, and the exhaust leak has gone - from there. I plan on also plugging the port in the rear of the passengers side head, because I think that it is leaking a bit as well, seems how its only about half connected (doesn't line up with both heads anymore...)
I really think I'm just going to plug the heads, pull the smog tubes, leave the air pump connected (for now), and leave all of those vacuum lines and plugs connected until I can figure out what they all go to.
On my factory heads, the forward port was plugged by an alternator bracket bolt. The original bolts weren't big enough to thread into the new heads hole, so I left it unplugged and this caused a seriously loud exhaust leak. I have since plugged that port, and the exhaust leak has gone - from there. I plan on also plugging the port in the rear of the passengers side head, because I think that it is leaking a bit as well, seems how its only about half connected (doesn't line up with both heads anymore...)
I really think I'm just going to plug the heads, pull the smog tubes, leave the air pump connected (for now), and leave all of those vacuum lines and plugs connected until I can figure out what they all go to.
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Junior User
Joined: Feb 2007
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From: Eastern Washington
I wonder if one of those holes was supposed to be plugged, and someone forgot to install them? I guess thats the risk you run when you are crunched for time and buy remanufactured parts instead of doing it yourself with your local machine shop!
-Steve
-Steve
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Joined: May 2003
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From: south louisiana
Originally Posted by flareside_thunder
I wonder how much hooking that outlet tube to the intake would improve anything....only reason being is mine is doing nothing but pumping into the atomosphere.......hmmmm future project?
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Originally Posted by baddad457
On a smaller engine it DOES improve things. I had a 79 Jeep with a 250 six and I did just this, it never pinged before the mod, but did slightly afterward. No sense in wasting the pump output if you're going to leave it in place.
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Joined: May 2003
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From: south louisiana
Originally Posted by D.A.V.E.
As long as you recognize that you are injecting un-filtered and un-metered air into the engine...I guess the risk is up to you.