Tough Smog Pump Question

Evil Joe · 03-25-2003, 12:33 AM

I've installed an off-road H-pipe which has no port for the air tube originating from the smog/air pump. I've also removed that metal pipe that leads from the rubber "Y-split" down to the H-pipe. So, basically I'm left with is an open rubber tube which creates an annoying loud puffing sound (obviously from the air pump). (The other part of the rubber "Y-split" leads up to the heads). I've noticed that the sound from the open rubber hose happens only when the engine starts to warm up. So, there must be a switch somewhere that turns this pumping on and off. WHERE IS IT?

I don't want to fully remove the pump, nor do I want to bypass it...but I really want that sound to just go away.

Anyone have any ideas?

Mountain Main · 03-25-2003, 11:24 AM

I am trying to fing the diagram that allows you to bypass the smog pump. I don't know about any switch that allows you to turn it off. It is a mechanical driven pump that does the work. I believe that as the RPM increases the pump increases output to burn unused gas at the Cats.

Evil Joe · 03-25-2003, 02:19 PM

Yeah, now that I think about it...you are probably right.

I tried disconnecting the little hose that connects into the diaphram located at the top of that rubber "Y-split" connector I was talking about, but that didn't seem to do anything.

Please let me know if you figure this out.

crazypete · 03-25-2003, 02:25 PM

What are you doing, dude?

Remove the crossover tube behind the heads, stick 2 bolts in the back of the heads with rtv silicone, remove the smog pump and tubing and get a shorter belt (just go down to napa, they'll let you experiment with different belts). Put rubber caps on the top of the tab and tad solenoids to keep the computer happy. Looks a lot cleaner. Without cats, you wont need a smog pump because the unburned gas just goes right through.

Have fun

Evil Joe · 03-25-2003, 04:12 PM

Crazypete,

Thanks for the suggestion...but, I was trying not to go that route because of the periodic smog checks we have out here in CA. But, I suppose, it wouldnt take too much additional work to put the smog pump back on when testing comes up.

Anyways, got a question...

How in the hell do you get to the bolts at the back of the heads? Do I need to remove the upper intake manifold?

What size belt do I need? I read somewhere that 84.5 inches is the correct size...?

crazypete · 03-25-2003, 04:52 PM

When you unbolt the crossover, you'll see the two holes where the air was pumped in. Well, you can feel the holes with your hand..... I stuck two bolts that just barely fit into these holes, just pushed them in and shlacked them with rtv silicone and they stayed put for months

HiFlow5 0 · 03-25-2003, 07:39 PM

Quote:

Originally posted by Evil Joe
What size belt do I need? I read somewhere that 84.5 inches is the correct size...?

84.5" belt is the correct size when bypassing the smog pump. When you remove the thermactor pipe from the back of the heads you will need bolts that are 5/8" thread about 1" long. No need to RTV them. Just use a Teflon tape and tighten them in. This will hold them tight with no leaks. Plus if you ever need to take them out you don't have RTV caking the threads.

03-25-2003, 12:33 AM	#1
Evil Joe Registered Member Join Date: Nov 2002 Posts: 23	Tough Smog Pump Question I've installed an off-road H-pipe which has no port for the air tube originating from the smog/air pump. I've also removed that metal pipe that leads from the rubber "Y-split" down to the H-pipe. So, basically I'm left with is an open rubber tube which creates an annoying loud puffing sound (obviously from the air pump). (The other part of the rubber "Y-split" leads up to the heads). I've noticed that the sound from the open rubber hose happens only when the engine starts to warm up. So, there must be a switch somewhere that turns this pumping on and off. WHERE IS IT? I don't want to fully remove the pump, nor do I want to bypass it...but I really want that sound to just go away. Anyone have any ideas?

03-25-2003, 11:24 AM	#2
Mountain Main Registered Member Join Date: Feb 2003 Location: Minturn, CO 81645 Posts: 109	Smog pump I am trying to fing the diagram that allows you to bypass the smog pump. I don't know about any switch that allows you to turn it off. It is a mechanical driven pump that does the work. I believe that as the RPM increases the pump increases output to burn unused gas at the Cats.

03-25-2003, 02:25 PM	#4
crazypete Registered Member Join Date: Sep 2002 Location: Boston Posts: 592	What are you doing, dude? Remove the crossover tube behind the heads, stick 2 bolts in the back of the heads with rtv silicone, remove the smog pump and tubing and get a shorter belt (just go down to napa, they'll let you experiment with different belts). Put rubber caps on the top of the tab and tad solenoids to keep the computer happy. Looks a lot cleaner. Without cats, you wont need a smog pump because the unburned gas just goes right through. Have fun __________________ 91 GT Carb conversion, holley 600 double pumper, edelbrock performer intake, FMS "C" drop springs, march 1000 underdrive pullies, crane 1.7 roller rockers, GT-40P headers, bassani x pipe, american thunder catback, FMS 4.56's, msd aL6, trunkmount battery, A/C eliminator kit, 3000 stall tci streetfighter, AOD with transgo kit, A+ servo, 300M hardened lockup shaft, kevlar bands and 28,000 gvw trans cooler, 3 core radiator, 300 lbs stripped with a full interior

03-25-2003, 04:52 PM	#6
crazypete Registered Member Join Date: Sep 2002 Location: Boston Posts: 592	When you unbolt the crossover, you'll see the two holes where the air was pumped in. Well, you can feel the holes with your hand..... I stuck two bolts that just barely fit into these holes, just pushed them in and shlacked them with rtv silicone and they stayed put for months __________________ 91 GT Carb conversion, holley 600 double pumper, edelbrock performer intake, FMS "C" drop springs, march 1000 underdrive pullies, crane 1.7 roller rockers, GT-40P headers, bassani x pipe, american thunder catback, FMS 4.56's, msd aL6, trunkmount battery, A/C eliminator kit, 3000 stall tci streetfighter, AOD with transgo kit, A+ servo, 300M hardened lockup shaft, kevlar bands and 28,000 gvw trans cooler, 3 core radiator, 300 lbs stripped with a full interior

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03-25-2003, 02:19 PM	#3
Evil Joe Registered Member Join Date: Nov 2002 Posts: 23	Yeah, now that I think about it...you are probably right. I tried disconnecting the little hose that connects into the diaphram located at the top of that rubber "Y-split" connector I was talking about, but that didn't seem to do anything. Please let me know if you figure this out.

03-25-2003, 04:12 PM	#5
Evil Joe Registered Member Join Date: Nov 2002 Posts: 23	Crazypete, Thanks for the suggestion...but, I was trying not to go that route because of the periodic smog checks we have out here in CA. But, I suppose, it wouldnt take too much additional work to put the smog pump back on when testing comes up. Anyways, got a question... How in the hell do you get to the bolts at the back of the heads? Do I need to remove the upper intake manifold? What size belt do I need? I read somewhere that 84.5 inches is the correct size...?