My 84 GL hatchback has some slug butt issues. I am wondering if my catalytic is clogged, but I am not sure I even have one! How can I tell if my Y-pipe is a catalytic or not? There are no electrical / O2 sensors connected to it. Any help on this is greatly appreciated!

Edited May 13, 20187 yr by Claus

Easiest test to check for blocked exhaust, is loosen the 4 y pipe to head nuts. Make sure the studs are not backed out. Get about a 1/2" gap between the head and the flanges. Take a drive. It will be loud. But if the exhaust is blocked, it will now have normal power.

my 86 EA-82 GL wagon has the CAT just behind The Y pipe. its short and fat.  if you have one that is most likely where it will be.  No sensors or wires.  if you have it do the check Dave T suggested and if  you drive it  the CAT will be really hot, so be careful not have a fire.

Thanks Mack, and Dave for the responses. I am getting rid of the exhaust and muffler past the Y anyway, which does include what looks more like a resonator than a cat to me. The problem is that when I drove it with just the Headers and Y, it was still moving sluggish. I am putting 2"pipe from Y back, with a new resonator and a turbo muffler. Just trying to figure out if my Y pipe is actually a cat, or just a Y. Anyone know offhand? I could cut into and find out, but I don't want to have to do the extra welding for nothing.

If it is just a Y, it won't have a big bulge like there is for a cat or a resonator.

 

I can't be specific about 84, as I skipped from a 78 to an 86 back in 1988.  Never touched anything in between those years.  Just the way it happened.

 

Changing the exhaust will  make it sound different, not much else.

It doesn't seem to have much of a bulge, but again it is hard for me to be certain. Anyway hopefully I get a few more HP's out of it. I already installed a Weber...we'll see!

If it is 84 and stock, the CAT is part of the Y pipe. Two pipes coming in the front in a V configuration and one pipe coming out the rear of the 'bulge' (CAT). A replacement Y pipe only is just that. Three pipes in a  Y configuration, no bulge.

Hp is mostly limited by the heads. Also the original carb. Exhaust is minor.

Thanks Skishop69, this info helps a lot. Given that my Y-pipe is a cat, any suggestions on how best (and cheapest) to get ride of it if it is clogged? I am excempt from emissions, should I buy a new y pipe and and cut and weld the headers to it? How hard would it be to cut a window in the cat, scoop out the interior and weld it back up? I am wondering what others have done or recommend. Thanks!

I broke one up through the o2 sensor hole and the output pipe once. If you are good at welding thin metal, cutting an access hole would be easier.

 

If you buy a new y pipe, no need to remove the catalytic. It won't make a difference in power.