Where is my CAT? With photos...

[treetop_73]

I am trying to get all inorder before I try to get my truck smogged and crawled under and didn't see a CAT. I looked online and found replacement cats that were just like my cat on my old Jeep and then some looked like just the manifold and was considered the cat. So now I am confused on if I have one or not. Is my manifold really a cat? I always wanted a truck but don't know much about these engines and all. Give me a inline 6 and I'll tear it apart. This just stumps me for now.


Thanks in advance

[donut]

?, In your pics I don't see one. What's this on?
If I go by your username, I'd assume '73. My K-20 didn't have one, but I'm also not from CA.

[treetop_73]

Sorry, '85 2500 High Sierra

[N2TRUX]

I found it! It looks like you have more than one...

[STOCKISH]

Your truck would have not come from the factory with dual exhaust and the cat would have been just behind the factory y pipe just under the cab floor.

[N2TRUX]

Seriously you need to determine what was supposed to be there. In 85 on the 2500 it should have had at least one cat.

[treetop_73]

Originally Posted by N2TRUX

Seriously you need to determine what was supposed to be there. In 85 on the 2500 it should have had at least one cat.

Thats what I was afraid of. Thanks.

[southside_jon]

my '87 R2500 has a "y" pipe that goes to a 3" cat. Aleast that's what I found out that it should have. PO (my ol'man) cut the cat off at the "y" pipe and put on a glass pack. I'm in the same boat as you with passing smog.

[turbo350]

For 1980 through 1986, the same models as those for '79 used cats. However, a new C6P heavy duty option was offered for C/K 20/25 models which provided an 8,600 lb suspension package. These new, heavier 3/4 tons cleared the 8,500 lb limit, and so did not use converters during this time period, nor did C/K 30/35's.

[gchemist]

Check the PRO codes. A 3/4 ton would not have any from the factory. Maybe a California model.

[Alias137]

I replied to your other thread as well. I think you should check your G.V.W. I think you might not need one. If the g.v.w. is 8600lbs., I doubt it came with one from the factory. I had an 81 with 8600g.v.w. without a cat-passed smog fine.

[treetop_73]

Thanks. I'll check tomorrow.


Can I figure it out from the VIN? I have that on me in the house but its cold and windy outside. VIN starts as 1GTGC24M8FJ******

[andrewmp6]

Move out of ca never worry about smog testing that truck ever.

[Zoerb]

My old K20 had the 350 "M" vin motor. no emmissions/no cat.


when I got it, it smelled like a cat had lived in there.....

[treetop_73]

Originally Posted by gchemist

Check the PRO codes. A 3/4 ton would not have any from the factory. Maybe a California model.

What code am I looking for? None of them say no cat. I have the heavy duty stuff listed, but can't see the GVW anywhere except the VIN code G says its between 8001-9000.

[treetop_73]

Originally Posted by Zoerb

My old K20 had the 350 "M" vin motor. no emmissions/no cat.


when I got it, it smelled like a cat had lived in there.....

I can't smell anything but my wife followed me the other day and said it smells bad when you drive behind it. I drive with the windows down and smell nothing. I did fart that day so maybe she smell that...

[arkracing]

GVW should be on the door sticker if it hasn't been removed, or faded out. It should also be on your registration/title/the previous owner's registration.

[Longhorn Man]

is the vehicle emissions control information sticker still under the hood? If so, it'll say catalyst if the truck came with a cat.

[treetop_73]

Originally Posted by Longhorn Man

is the vehicle emissions control information sticker still under the hood? If so, it'll say catalyst if the truck came with a cat.

I'll have to check. I think most of the stickers are worn but I will check the door also. Its been cold and with the baby, I can't take him outside to check and don't want to leave him in the house alone even for a few minutes.

[treetop_73]

Ok, it says 8600 lbs. The emissions sticker doesn't say catalyst. So I guess I am good?

Will there be issues with the true dual exhaust or not? Did they come that way? The exhaust looks to be really old so I doubt it was installed after the last smog test 2 years ago. Now I am relieved with 1 less thing to worry about. Took her out for a few miles today just to have her driven. She seemed to run better but I know that was only in my head now that I know I don't need to add cats.

Now I need to fix the PS leak as it was dry and a pain to steer and when I hit the brakes it pulls hard to the left. Brakes or just PS effect of being dry?

[Jonboy]

Brakes. If it pulls to the left likely culprits are the right brake hose or caliper.

[clinebarger]

My 85 suburban didnt have a catalytic converter & had the same exhaust system but it did have dual smog pumps im sure yours does too. DO NOT replace any of the exhaust system its made out of a stainless steel alloy, it will out last your truck, It reads right on the mufflers not to replace with any thing but OEM because of a fire hazard (the smog pumps make the exhaust system very hot)

[treetop_73]

Originally Posted by clinebarger

My 85 suburban didnt have a catalytic converter & had the same exhaust system but it did have dual smog pumps im sure yours does too. DO NOT replace any of the exhaust system its made out of a stainless steel alloy, it will out last your truck, It reads right on the mufflers not to replace with any thing but OEM because of a fire hazard (the smog pumps make the exhaust system very hot)

Noted. Thanks for the heads up.

[treetop_73]

Originally Posted by Jonboy

Brakes. If it pulls to the left likely culprits are the right brake hose or caliper.

Thats what I was thinking. I'll check them out.

[JEM]

The stock layout in my '91 2500 454 Sub was the Y-pipe, muffler, with a bead-type cat behind the muffler. It has no smog pump (I don't think any of the 8600GVW vehicles did in those days.)

The cat behind the muffler is a very, very odd layout - it's hard to imagine how long it would take for the cat to get hot enough to 'light off' properly back there - but I guess the smog reqs for 8600GVW+ were not very stringent back then. These days the cats end up as close to the heads as the manufacturers can get them, because the cold-start smog requirements mean the cats have to heat up very quickly.

1991 was very, very late for anyone to be using a bead-type cat - they're very restrictive - but I was once told that the bead-type cats are less sensitive to variability in the air-fuel ratio - richer mixtures make cats run hotter, and continuous rich running will cause honeycomb cats to melt.

At any rate, when I installed headers I wasn't willing to put up with the bead-type cat corking up the exhaust any longer, so it was replaced with an aftermarket honeycomb cat. I'd very much like to have a real dual exhaust, but this is California...