The air pump will help,even without the Cat,it keeps the exhaust very hot,especially before the muffler,as you know,more heat=cleaner exhaust.Then ther's the dilution factor-remeber they arent measuring the quantity of exhaust,just the quality,so an air pump can be used at idle only in most cases,until the engine is totally up to temp to dilute the exhaust with Oxygen.That little bit of oxygen is enough to get some trucks that are borderline to pass an emission test.If the air pump valve sticks on or rusts up and check valve leak,which is common when they get old,air will be allowed to flow ,even at high engine speeds and after warmup,I have seen the entire exhaust manifolds glowing red,the Y-pipe and front pipe totally red from the heat that adding oxygen for to long or at high speeds.You failed the visual inspection,before you even got to the sniffer right?.Do your exhaust maniflods have the bosses for AIR tubes in them,with brass plugs in them?If so thats a give away someone removing the AIR equipment-the tubes rot out or a backkyard mechanic breaks them doing valve cover gasket job,and plugs them instaed of replacing them.If i do a VC gasket job on one of them trucks-the customer drops to the ground when i give em a price-i always put new air tubes on,figure it into the price,because they always break off when you bend them down or try to remove them.As for the Air pump brackets,some engines have them even thoiugh they dont use a pump-its just cheaper to puit the same bracket on all trucks.The emissions sticker under the hood or on the radiator shroud should read like this. Non Catalyst,AIR. if you need an air pump,if it says just NonCatalyst and nothing about an AIR puimp,them you dont need it and never did-never will.Why these idiot environmentalists bother these old trucks is beyond me-there aret many on the road,and they account for hardly any of the miles run every day.I thinlk in NY if your car/truck needs more than 200 worth of work and it is more than 12 yrs old,they will give you a waiver so you can get inspected if you cant afford the fix-Im not sure if there's truth to that or not.
[Edited by John DiMartino on 12-26-2000 at 03:48 PM]