Author Topic: What caused this to happen to my header??? (Read 3902 times)

4xtoy · « **on:** Jul 07, 2006, 08:38:36 PM »

A couple of days ago I took a pretty big hit to the bottom of my Runner on a big rock. Shortly after It developed a nasty exhaust leak. My Cat had cracked prior to the trip and I thought it just opened up the crack more. Well after I got home I was looking around under my truck and saw this huge crack.
There was no apparent rock rash on the header so I don't think it took a direct hit. I'm wondering if something is either too tight and not allowing enough flex or are things too loose and causing too much movement.

I took them both off and rewelded them but I don't want it to happen again. Any suggestions on what might have caused it?

Duffil · « **Reply #1 on:** Jul 07, 2006, 09:22:21 PM »

I had a Downey header on my last rig do the same thing. My Thorley hasn't cracked yet, but it hasn't been hit, either. I don't think it's the fault of the header, just the way things are. You're bolted solid on one side, the other side flexes, any hit and the hangers are gonna try to take up the slack. take a big hit, and the hangers hit the frame and the truck keeps moving; somethings gotta give.

DTB · « **Reply #2 on:** Jul 07, 2006, 09:28:40 PM »

hmmmm...does ur exhaust follow the stock routing exactly?

Duffil · « **Reply #3 on:** Jul 07, 2006, 09:37:26 PM »

His or mine??

DTB · « **Reply #4 on:** Jul 07, 2006, 09:40:30 PM »

Quote from: Duffil on Jul 07, 2006, 09:37:26 PM

His or mine??

ummmmmm......both

Duffil · « **Reply #5 on:** Jul 07, 2006, 09:41:50 PM »

ok: me, not exactly stock, but pretty close. header, hiflow cat and 2 1/4". why?

DTB · « **Reply #6 on:** Jul 07, 2006, 09:46:04 PM »

Quote from: Duffil on Jul 07, 2006, 09:41:50 PM

ok: me, not exactly stock, but pretty close. header, hiflow cat and 2 1/4". why?

well, if it was lower or in a different position it could more easily take a hit on the trail. He did say he took a good hit on a rock

Duffil · « **Reply #7 on:** Jul 07, 2006, 09:56:17 PM »

for me, no, not lower. I made sure of htat( a buddy ran my exhaust)

jimbo74 · « **Reply #8 on:** Jul 07, 2006, 10:42:11 PM »

the exhuast pretty much doenst have much play.... smacking it on imoveable objects usually somehting gives..... the rock is harder than exhuast tubing......

how not to do it again, dont smack it on rocks

i say run a sstraight header out the hood, no more problems

Rocksurfer · « **Reply #9 on:** Jul 07, 2006, 10:44:55 PM »

That can happen from the header having to support any weight. When running the exhaust pipe, cat muffler and tail pipe make sure the header is not having to support any weight or over time it will crack.

Willy Mammoth · « **Reply #10 on:** Jul 07, 2006, 11:20:04 PM »

Quote from: Rocksurfer on Jul 07, 2006, 10:44:55 PM

That can happen from the header having to support any weight. When running the exhaust pipe, cat muffler and tail pipe make sure the header is not having to support any weight or over time it will crack.

That and make sure the hangers can flex with the movement of the engine when it torques up or put a flexable connector in between the header and the rest of the exhaust.

DTB · « **Reply #11 on:** Jul 07, 2006, 11:23:26 PM »

Quote from: Captain4x2 on Jul 07, 2006, 10:42:11 PM

i say run a sstraight header out the hood, no more problems

u mean like this?

Prismo · « **Reply #12 on:** Jul 07, 2006, 11:44:29 PM »

My NW Offroad header cracked also. I fabbed up a hanger to replace the stock one off the bellhousing to the exhaust. I attached it to the header. No more cracks in the header, just in the muffler now. It seems to be from engine movement. I have broken a couple motor mounts through the years also. The engine will really move around when I give it gas when I am in low/low.

4xtoy · « **Reply #13 on:** Jul 08, 2006, 04:42:08 AM »

Here is how it is ran. Nothing on my exahust sits below the frame. There was no signs of rock rash or dents anywhere on the header or pipe. I only have one hanger after the muffler. It seems to be just the right amount of flexability but maybe not. Something else I was thinking about is that I have poly motor mounts which provide all the vibration anyone would ever need. I want to go back to stock mounts but they want a hundred bucks a piece for them.

Oh yeah, anyone recognize the brand of header that is? It came with my truck along with the poly mounts.

The ugly straight pipe is gone and now it just dumps right after the muffler with the hanger in the same place.

CTENG in KS · « **Reply #14 on:** Jul 08, 2006, 06:40:06 AM »

Adding one of these between the cat and header would help the exhaust flex more...

http://store.summitracing.com/partdetail.asp?autofilter=1&part=SUM%2D642210&N=115&autoview=sku

CTENG in KS · « **Reply #15 on:** Jul 08, 2006, 06:42:56 AM »

The plate you have here for protection is really hampering the ability of the system to move when the engine flexes on the mount or the frame flexes during articulation, might wanna try and loosen it up a bit?

edit: The way yours cracked, I would bet that this section failed to let the system move and it was engine movement (torqueing) that actually caused the crack. The flex joint between the cat and header would solve this problem.

79coyotefrg · « **Reply #16 on:** Jul 08, 2006, 06:44:40 AM »

you need to un weld it at the end of the header befor the cat, i use a extended slip joint, plenty tight with minimal leak, but allows the engine flex and keeps the pipe from causing twisting force on the header

Rocksurfer · « **Reply #17 on:** Jul 08, 2006, 10:13:35 AM »

Quote from: 79Coyotefrg on Jul 08, 2006, 06:44:40 AM

you need to un weld it at the end of the header befor the cat, i use a extended slip joint, plenty tight with minimal leak, but allows the engine flex and keeps the pipe from causing twisting force on the header

I had mine just clamped at the header too, then into the exhaust pipe. Had to adjust several times after runs here and there from it sliding a little under torque.

Ferg · « **Reply #18 on:** Jul 08, 2006, 11:17:23 AM »

Factory down tube had a clamp at the bellhousing to stabilize the header. Do you still have this? If not, try it.

4xtoy · « **Reply #19 on:** Jul 08, 2006, 04:53:59 PM »

Quote from: CTENG in KS on Jul 08, 2006, 06:42:56 AM

The plate you have here for protection is really hampering the ability of the system to move when the engine flexes on the mount or the frame flexes during articulation, might wanna try and loosen it up a bit?

edit: The way yours cracked, I would bet that this section failed to let the system move and it was engine movement (torqueing) that actually caused the crack. The flex joint between the cat and header would solve this problem.

Acctually it has 3/4" of clearance on every side of it. The plate is only there for structure rigidity since I cut out a huge chunk of a primary cross member.

Quote

you need to un weld it at the end of the header befor the cat, i use a extended slip joint, plenty tight with minimal leak, but allows the engine flex and keeps the pipe from causing twisting force on the header

The header has a ball flange that I guess I could loosen a bit. I like the idea of the flex joint though.

Quote

Factory down tube had a clamp at the bellhousing to stabilize the header. Do you still have this? If not, try it.

Don't have it. How would it adapt to an aftermarket header.

Prismo · « **Reply #20 on:** Jul 08, 2006, 06:09:43 PM »

A large heavy hose clamp would work. I made a strap to attach it to the mount I made,

4xtoy [OP]

4xtoy [OP]

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