Hey gang, Im searching online in various places and Im getting mixed information on this topic. Im looking to delete the smog system on my 1991 3.9 Dakota. I noticed the other day that the bolts that hold the tubes down on the exhaust manifolds on each side are broke off and the tubes are not making a good seal(if any at all). I can grab the tubes and wiggle them side to side freely about an 8th of inch each way or a little more. Its not making a tick sound or anything like a normal exhaust leak would do but it is leaking cause I can smell the fumes when working under the hood. id like to eliminate the system from the engine all together.

Id like to add that I live in a state that does not have emissions tests(yet) and I do not care if its "against the law" or a "federal offense" to tamper with emissions on a vehicle nor do I care if it effects gas mileage. I just want to know what I need to do to delete this crap off my truck. Is it as simple as just removing the belt that drives the smog pump?? On these 3.9l LA engine the belt that turns the smog pump ONLY turns the smog pump. Thanks!

 

Well, your out would be that emissions parts for your truck have been discontinued anyway. Even IF you had emission inspections where you live, I don't think 1991 would even be included.

 

Thanks TNtech. Good point! I still wanna remove the garbage off the engine tho.

 

If you just take the belt off the pump, the exhaust will eventually burn through the check valves, make its way to the pump, and destroy it. So, if you're going to disable it, take it off and save it in case you ever need it.

BTW, here in California, vehicles need to be smog checked all the way back to 1976. So don't assume that 1991 would be excluded if they ever started where you are.

 

Are you getting exhaust fumes under the hood? I've de-smogged cars in the past--old smog pump systems and the holes in the exhaust manifolds need to be plugged, all ports that run off the intake involved with the system need to be plugged. And you may end up with deceleration backfires.

I can't say whether to pull the junk off or not. If it's leaking exhaust, you need to take care of that one way or another. And if you ever get emissions testing in your area or you move to an area where it's required, you're screwed. But it it ain't functional when you go in for smog check, you're screwed either way.

I can tell you this, from experience, it won't run any better or give more power by pulling the smog pump off--and if your smog pump is doing any good at all, people in your vicinity will notice the different--de-smogged vehicles smell awful!

 

leave the tubes on, just braze the opening closed. the inspector cant see that.