• Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang Tech

Few questions on Emmisions and smog pump hosing

  • Thread starter Thread starter JenkinsBS
  • Start date Start date Sep 2, 2010
  • 1
  • 2
Next
1 of 2 Next Last

JenkinsBS

Founding Member
Apr 16, 2002
1,001
1
39
Washington
Sep 2, 2010
#1
  • Sep 2, 2010
  • #1
Alright, so as i was talking about in a previous post, i dont have my smog pump hooked up to my current stock H pipe with cats, which is causing some problems, possibly fire inside the pipes! lol, i dont know... but i have a MAC OR H Pipe as of right now, just waiting to install it.

But i have a few questions regarding my current exhaust.. firstly, what is this...



its attached to the pipe as it comes off my shorty headers, which i do no think is a cat.

Secondly, i see 2 spigots coming from the smog pump, i know one runs to the air pipe on the stock H pipe, but where does the other go?



And after i install the OR H pipe, can i just leave the pump hooked up as is? or do i need to plug the spigots, also do i need to plug the air hole (if there is one) in the MAC OR H Pipe?
 

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,260
17,945
224
Massachusetts
Sep 2, 2010
#2
  • Sep 2, 2010
  • #2
First one is the pre-cat. They are close to the headers so they warm up fast when the car is cold and help with emmissions then. So technically you have 4 cats...dont just scrap the pipe...the cats have value these days

When you put the o/r h pipe on, you can remove the smog pump. You can use a short belt and simply reroute the way the belt runs. My smog pump doesnt look like yours, i don;t have the spigots on mine...my outlet is on the bottom and there is only 1...about 3/4" in diameter.
 

JenkinsBS

Founding Member
Apr 16, 2002
1,001
1
39
Washington
Sep 2, 2010
#3
  • Sep 2, 2010
  • #3
So the pre cat was what was smoking all sorts of bad stuff after i got done driving it around the block a few times, almost like it was on fire, or blocked.

I really want to run cat-less, as in my county, they dont do emmissions testing, and i dont want to spend the extra money

And again, i want to do the least ammount of work as possible, im not looking to race this thing out yet, just want a reliable daily car that is fun to drive.

If i dont eliminate the smog pump, and run catless, does anyone forsee this causing problems?
 

JenkinsBS

Founding Member
Apr 16, 2002
1,001
1
39
Washington
Sep 2, 2010
#4
  • Sep 2, 2010
  • #4
essentially, can i leave my smog pump as is, and just install the catless O/R H pipe without any problems?
 

HISSIN50

"How long does it take to get help in here?
15 Year Member
Nov 29, 1999
31,179
34
129
Sep 2, 2010
#5
  • Sep 2, 2010
  • #5
Running the AIR pump with an O/R pipe is fine.
 

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,260
17,945
224
Massachusetts
Sep 2, 2010
#6
  • Sep 2, 2010
  • #6
Why is the cat smoking? Make sure tranny fluid or engine oil isn't leaking on it from somewhere first.
 

madspeed

Colonel Mustard
Founding Member
Nov 29, 1999
8,914
1,332
204
a van down by the river
Sep 3, 2010
#7
  • Sep 3, 2010
  • #7
def looks like fluid stains running down that pre cat! Check for leaks! Valve cover gasket at the rear of the pass head, rear main seal shot and slinging oil all over...
 

JenkinsBS

Founding Member
Apr 16, 2002
1,001
1
39
Washington
Sep 3, 2010
#8
  • Sep 3, 2010
  • #8
I really hope its not engine oil, it did not smell like oil burning when i got under the car... i do not know what transmission fluid smells like when it burns, but i know on these t-5's, the caps can come off pretty easily....

Also its JY exhaust, so the fluid stains may have been there from the previous vehichle it was on.

But threre is also some material in there, you kind kind of see it in the picture, i pulled some out, and it looked like cotton with aluminum attached to it, i dont know what it is or what it does, but only the passenger side pre cat has it, the drivers side does not.

So as far as the air pump goes... i can leave it as is when i get my O/R H pipe installed safely?
 

madspeed

Colonel Mustard
Founding Member
Nov 29, 1999
8,914
1,332
204
a van down by the river
Sep 3, 2010
#9
  • Sep 3, 2010
  • #9
If you don't have to pass emissions, just put that off road h pipe on and throw the cap pipe in the attic, shed, basement whatever. Dont scrap it, you'll regret it one day. Then see if there's any oil leaks etc
 

madspeed

Colonel Mustard
Founding Member
Nov 29, 1999
8,914
1,332
204
a van down by the river
Sep 3, 2010
#10
  • Sep 3, 2010
  • #10
and yank that smog pump and do the same thing with it
 

JenkinsBS

Founding Member
Apr 16, 2002
1,001
1
39
Washington
Sep 3, 2010
#11
  • Sep 3, 2010
  • #11
if i yank the air pump, then ill have to get shorter belt and possibly elimitate the tensioner, im not sure... i just want to leave it on there, i really dont care about the HP it robs, unless keeping it on there without being hooked up will cause problems...
 

madspeed

Colonel Mustard
Founding Member
Nov 29, 1999
8,914
1,332
204
a van down by the river
Sep 3, 2010
#12
  • Sep 3, 2010
  • #12
shorter belt is all you'll need. Like $25
 

JenkinsBS

Founding Member
Apr 16, 2002
1,001
1
39
Washington
Sep 3, 2010
#13
  • Sep 3, 2010
  • #13
is there a specific length? or do i need to take a string and measure? But again, is there anything detremental to leaving the belt on there with nothing hooked up to it?.. as long as i have the O/R H pipe on there w no cats?
 

madspeed

Colonel Mustard
Founding Member
Nov 29, 1999
8,914
1,332
204
a van down by the river
Sep 3, 2010
#14
  • Sep 3, 2010
  • #14
 

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,260
17,945
224
Massachusetts
Sep 3, 2010
#15
  • Sep 3, 2010
  • #15
JenkinsBS said:
is there a specific length? or do i need to take a string and measure? But again, is there anything detremental to leaving the belt on there with nothing hooked up to it?.. as long as i have the O/R H pipe on there w no cats?
Click to expand...



Just swap the H-pipe and don't worry about it. It's 2 pounds, and maybe 0.25HP. Plus if you ever need to put cats back on...you are good to go.
 

JenkinsBS

Founding Member
Apr 16, 2002
1,001
1
39
Washington
Sep 3, 2010
#16
  • Sep 3, 2010
  • #16
Thanks Mustang5L5

And just to clarify, i do not need to hook up the air hose that normally would goto the H-pipe as that supports that Cats, which i will not have?
 

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,260
17,945
224
Massachusetts
Sep 3, 2010
#17
  • Sep 3, 2010
  • #17
Well, you need to do that...otherwise the air from the pump has nowhere to go. Most h pipes have the provision for it. It's an easy hook up, just cut the pipe, cut it back 2" or so and use 3/4" heater hose and two hose clamps to secure it. But the o2 from the pipe is for the cats to aide in conversion. Without cats, you don't need it...but you technically have no place else to put it

If the h pipe you get does not have the provision, remove the pipe back at the headers where it connects to the rubber hoses, and run a short belt to bypass the pump otherwise you'll hear it pumping away.

Easiest way is to get a pipe with the smog provision and just hook it up.
 

JenkinsBS

Founding Member
Apr 16, 2002
1,001
1
39
Washington
Sep 3, 2010
#18
  • Sep 3, 2010
  • #18
cool, thanks for all the help!

now as far as the air pump goes, there are 2 outlets on that spigot thing, is there a 2 inlets on the h pipe? or is it an unknown as to what that is on my air pump... casue if i cant figure it out, i may just get a short belt...
 

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,260
17,945
224
Massachusetts
Sep 3, 2010
#19
  • Sep 3, 2010
  • #19
I believe that pump has been replaced. That spigot is for cruise control. What happens is that if manifold vacuum drops, the smog pump takes over and provides vacuum temporarily. I only know that the mark 7s use this setup though...not mustangs. My car is non cruise, and I do not have that spigot.

One outlet on the pump...on the bottom. It's ssplit down by the headers, one pipe to the h pipe and one pipe to the back of the heads.



The valve on the right is the diverted valve. It directs air from the pump to the heads or the h pipe. Top line runs to pipe on back of heads. Bottom line runs to pipe to h pipe. You can see where the pipe connects. Undo that hose clamp and disconnect the h pipe and you can pull that pipe out. Then youncan stick a bolt or something in with a clamp
 

JenkinsBS

Founding Member
Apr 16, 2002
1,001
1
39
Washington
Sep 14, 2010
#20
  • Sep 14, 2010
  • #20
So i have my new MAC OR H pipe, and was inspecting my old ones air inlet hose for the cats... and its been welded shut!

Now the smog pump is hooked up the pulley system, but not hooked up to anything else. so i did some looking around on my cars old H pipe, and come to find out that the inlet on the pipe has been welded shut...

Now keep in mind that the picture of the pipe i posted was what was smoking last time i drove the car (pre cat maybe) but there is nothing else farther back on the H pipe... So are the 2 things right below my header collecters cats? or somthing else?

Mainly cause the exhaust shop wants to look at it today, but i dont want to drive it too far if not having my air hose hooked up to my h pipe will cause problems, espcially if its been sealed.
 
  • 1
  • 2
Next
1 of 2 Next Last
You must log in or register to reply here.

Similar threads

9
Engine Donor '00 Mountaineer meet '91 Fox
  • 91firecracker
  • May 11, 2026
  • Fox 5.0 Mustang Tech
  • 2 3
Replies
41
Views
924
Fox 5.0 Mustang Tech May 28, 2026
91firecracker
9
Resolved Three way cat converters..?
  • PonyGTrider
  • Nov 2, 2025
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
7
Views
270
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Nov 2, 2025
PonyGTrider
I
Engine What Aluminum Heads???
  • Iceman1998
  • Sep 8, 2024
  • Fox 5.0 Mustang Tech
Replies
19
Views
2K
Fox 5.0 Mustang Tech Sep 15, 2024
Noobz347
Fox BBK X-pipe replacement Cat?
  • TIGGER
  • Aug 26, 2025
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
7
Views
305
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Aug 26, 2025
AeroCoupe
B
Airaid reduction sleeve?
  • BriansNSane
  • Dec 20, 2025
  • SN95 4.6L Mustang Tech
Replies
0
Views
148
SN95 4.6L Mustang Tech Dec 20, 2025
BriansNSane
B
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang Tech
Menu
Log in

Register

  • Forums
  • What's new
  • Media
  • Resources
  • Contact
  • Sponsor
X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?

X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?