80 series exhaust options

[SlowNSteady]

I just swapped out the exhaust earlier this year (old cats were bad and exhaust was all rusted) and then last weekend pinched it at the mini-moab rocks. The pinch is right where the exhaust goes under the frame. Has anyone found a good option for fixing this? It needs to pass emissions, so I prefer to keep the cats. That makes it a bit difficult to go over the frame. And I can't find any skid plates that cover this section of the exhaust, plus it would stick down quite a bit.

I'm leaning towards just repairing it and leaving it in that compromised position.

The only other solution I've seen is to re-route it inside the frame from the headers, but not sure that works with cats.

Pictures of the dented piece and the offending obstacle for reference.

 

[RayRay27]

Is this the section immediately after or behind the cats or further back? If its the section behind the cats there is an expensive solution, whiteknuckleoffroad makes sliders with the CAT protector around it which may help.

 

[Hulk]

I've smashed that exact section of exhaust pipe. It's hard to do much rerouting because of the two catalytic converters. Here is an option I've been considering for years:

Slice the exhaust pipe on the rear side of the frame and weld in a flange so it can be disconnected and reconnected. Then you create two sections:
1. The regular version that starts with cat #2, routes under the frame rail, and then connects to the new flange. This is for street use and for emissions testing.
2. A section of new exhaust pipe that attaches to the rear of the first cat. It routes over or inside the frame rail and connects with the exhaust on the other side. This removes the second cat and keeps the exhaust pipe out of harms way when wheeling. This is for off-road use.

No matter what, you still have at least one catalytic converter in your exhaust system, so you're still controlling emissions in a responsible manner. Option 2 just keeps your exhaust from getting smashed on the hard trails.

 

[SlowNSteady]

Yes, the section right behind the cats. It looks like the white knuckle sliders only cover the cats, so it wouldn't help with the exhaust pipe. My cats are already partially protected by the mounting arm for my Slee sliders (unless I hit a pointy rock right on a cat).

I like Matt's idea even though it makes emissions testing even more annoying since I have to do the swap every time. But that may be worth it. But I imagine I'd have to do that myself since it wouldn't be CARB compliant. So I guess it'll go on my to-do list.

 

[SlowNSteady]

I guess the other thing to consider is whether or not the 420 code will get thrown with one cat. I don't want a check engine light hiding other codes.

 

[Lastresort576]

I guess the other thing to consider is whether or not the 420 code will get thrown with one cat. I don't want a check engine light hiding other codes.

spark plug defouler for the second o2 sensor will get rid of any potential codes

 

[60wag]

The simplest solution is just replace the dented pipe. It might get dented again but it might not. I've had the under the frame pipe for 20 years now and somehow managed to just put some minor scratches on it. Lots of people still run the stock configuration with good luck.

 

[Corbet]

I’ve still got the EMS system on my truck granted it’s been kind of patched up over the years between rust, a cat replacement, and turbo. You can get up and over the frame rail even with cats. But you’ll need to find an exhaust artist to do it. The local bugger welder at Midas won’t. The OEM diesel exhaust went up and over. Maybe ordering that section if available then handing it to a race shop is the answer?

 

[subzali]

AA performance can make the over the frame work. Even with 3” tubing. Have it on both mine. It is very tight with the two cats - I like Matt’s idea

 

[coloryan]

AA performance can make the over the frame work. Even with 3” tubing. Have it on both mine. It is very tight with the two cats - I like Matt’s idea

Was that awhile ago? I asked AA performance to do the over the frame routing a few years back and he said he doesn't do that anymore. Something about the interior getting too hot.

Pursuing another solution, I went as far as buying the inside the frame downpipe from partsouq but I haven't installed it yet. If anyone is interested in it I might be willing to part ways. Seems like the wheeling I do these days is less intense, making its installation arguably less necessary.

 

[justcruisin]

What is this inside the frame downpipe you speak of? Do you have a picture or diagram? I might be interested.

 

[Inukshuk]

Is this the section immediately after or behind the cats or further back? If its the section behind the cats there is an expensive solution, whiteknuckleoffroad makes sliders with the CAT protector around it which may help.

I installed White Knuckle sliders on my 93 in February. I picked them up while in CA with LongCruiser and drove them home to my other 80. Great people, great product, Cruise Moab sponsors.
My prior Slee Sliders did not have this cat protection. In 25 years wheeling never hit the cats. Now I hit the White Knuckle cat protection regularly - its about 2 inches lower. They are SOLID so the hit is hard. I just have to live with and learn this new low spot, and its not a huge big deal, but I'd rather have the clearance.

 

[Stuckinthe80s]

If I'm reading it right, Matt's idea is basically how I built my exhaust on the passenger side when I did my 2uz swap: v-band just downstream from the manifold and a standard flange where it goes over the frame.





You'll note that I also positioned the cat horizontally for more clearance. The bottom of the cat is just above the bottom of the frame rail.

 

[coloryan]

What is this inside the frame downpipe you speak of? Do you have a picture or diagram? I might be interested.

See this ih8mud thread: https://forum.ih8mud.com/threads/97...il-exhaust-using-105-series-downpipe.1352109/

I also posted a link to partsouq in my original post.

 

[Inukshuk]

If I'm reading it right, Matt's idea is basically how I built my exhaust on the passenger side when I did my 2uz swap: v-band just downstream from the manifold and a standard flange where it goes over the frame.

v-bands are AMAZING! I used several on the LongCruiser. I have had top R&R the exhaust a few times and they make it so easy. The only connection that has given me leaks is the standard two-bolt flange to header.

 

[Lastresort576]

Keep in mind...if aircare knows how the routing is supposed to be, they could fail you. the routing isnt supposed to be modified.

 

[subzali]

Was that awhile ago? I asked AA performance to do the over the frame routing a few years back and he said he doesn't do that anymore. Something about the interior getting too hot.

Pursuing another solution, I went as far as buying the inside the frame downpipe from partsouq but I haven't installed it yet. If anyone is interested in it I might be willing to part ways. Seems like the wheeling I do these days is less intense, making its installation arguably less necessary.

Yes it’s been a while. There is a heat shield used on 93-94 cruisers that bolts right into place that helps. I’ve never had a problem with interior temps there. The passenger floorboard gets hot though.

I had Al’s exhaust shop in Cheyenne do my most recent one. They did over the frame and did a good job.

Oh joy, P0401 is back... (and how 80's fail emissions)

Yeah, probably. The good news is (after looking through this thread and seeing everyone's numbers) that, for the people that passed, there is still at least a 20-30% margin to work with on HC and NOx, and even more of a margin on CO. As much as I hate to admit it, keeping our trucks tuned and...

risingsun4x4club.org

 

[Hulk]

Keep in mind...if aircare knows how the routing is supposed to be, they could fail you. the routing isnt supposed to be modified.

In theory this is correct, but in practice, all the guys do is look to make sure your cats are installed. "It says here there are supposed to by 2 catalytic converters, and I see both of them. Pass."