So those HondAnonymous posts...

"area man" (hurrburgring) 01/27/2016 at 15:10 • Filed to: None

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I’ll admit it, I have no idea what !!!error: Indecipherable SUB-paragraph formatting!!! means. Can someone explain it to a stupid? EDIT: All the informative answers are further proof this place rocks.

Daily Drives a Dragon - One Last Lap > area man 01/27/2016 at 15:15

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Honestly got no clue.

BrianGriffin thinks “reliable” is just a state of mind > area man 01/27/2016 at 15:15

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I’d imagine it means that the bolts/welds that hold the catalytic converter onto the exhaust pipe are known failure points. The bolts either snap under load (remember, exhaust systems have fairly high pressure during heavy engine load) or part of the bolt gets loose.

Why they can’t just start to use better bolts or whatever, I don't know.

area man > BrianGriffin thinks “reliable” is just a state of mind 01/27/2016 at 15:19

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Makes sense, but what does “backing out of the head" mean?

area man > Daily Drives a Dragon - One Last Lap 01/27/2016 at 15:20

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Glad I'm not the only one

Jake Huitt - Two Alfas And A Nissan, Not A Single Running Car > area man 01/27/2016 at 15:20

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On most FWD hondas, the “headers” are just pipes that go in to the cat that runs vertically along the block. The studs thread in to the head and then bolts go on the studs that hold the header/cat to the head.

Saracen > area man 01/27/2016 at 15:20

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the bolts that hold the catalytic converter in place are backing themselves out or snapping off due to a combination of heat(thermal cycling)/pressure/vibration.

crowmolly > area man 01/27/2016 at 15:20

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I am guessing that the cat/exhaust manifold is a single piece, and it is fasted to the cylinder head with studs. Those studs either back out or break.

DasWauto > area man 01/27/2016 at 15:23

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I’m guessing the cat(alytic) converter is integrated into the exhaust manifold and the studs attaching said assembly to the (cylinder)head are not up to the task.

JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t > area man 01/27/2016 at 15:24

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To save space, reduce lag and reduce catlyst heating times (and thus emissions) the engines have the turbo and the 1st catalytic converter assembled as a unit, which is directly bolted to the exhaust ports of the head. the head is aluminum, the bolts are steel, there is a huge heat and mechanical stress at that joint, even more so with the unitized turbo/cat bolted directly to the head. I assume he/she means that the studs come loose from the aluminum head.

BrianGriffin thinks “reliable” is just a state of mind > area man 01/27/2016 at 15:29

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Cylinder head.

RallyWrench > area man 01/27/2016 at 15:32

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It means either the studs are unthreading themselves, breaking off, or pulling the threads out of the head. Expansion/contraction can do that, as can poorly spec’d studs or a design that places the studs in a weird shear.

Future next gen S2000 owner > RallyWrench 01/27/2016 at 15:54

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How do you put a weird shear on a cylindrical piece? The area and moment is the same regardless of the direction of the shear. Unless you sheared along the axis of the bolt which would be really weird.

ttyymmnn > area man 01/27/2016 at 15:57

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You are not the only one.

RallyWrench > Future next gen S2000 owner 01/27/2016 at 16:02

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I don’t know, I probably shouldn’t have called it shear. I’m thinking if the exhaust is hung on the heads without enough support. I’d imagine it’s got close-coupled Cats with the turbos, if not Cats ahead of the turbos, which can place a huge load on studs if the exhaust is poorly supported or doesn’t have well-located flex joints, for example.

wiffleballtony > area man 01/27/2016 at 16:15

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I assume the cat is an actual cat, and the studs are on its collar. When they malfunction it takes the cats head off.

Future next gen S2000 owner > RallyWrench 01/27/2016 at 16:15

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I guess so. Having the exhaust hanging off could induce a moment, coupled with multiple loads in multiple directions. Someone probably missed a load when doing the calcs.

What I don’t get how do studs on the cat back out of the head. If your studs are on the cat how do you thread the studs into the head?

RallyWrench > Future next gen S2000 owner 01/27/2016 at 16:20

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I’m assuming that’s being described wrong, and that it has studs in the head, as commonly practiced. But I’ve never seen any of the new Honda turbo stuff, so I don’t know if that’s true.

area man > RallyWrench 01/27/2016 at 16:23

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The forces inside an engine sometimes boggle my mind.

area man > JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t 01/27/2016 at 16:24

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Thanks for the intelligent reply!

BrianGriffin thinks “reliable” is just a state of mind > wiffleballtony 01/27/2016 at 16:25

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Me-ow, amiright??

area man > DasWauto 01/27/2016 at 16:25

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“backing out of the head” is what really got me, but someone upthread confirmed that studs can actually do that under high stress,

Future next gen S2000 owner > RallyWrench 01/27/2016 at 16:26

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That would make sense to me as well.

area man > wiffleballtony 01/27/2016 at 16:26

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makes sense to me

RallyWrench > area man 01/27/2016 at 16:27

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Inside and outside, as the case may be.

iSureWilll > area man 01/27/2016 at 16:28

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Everyone else has this covered so...

This stud is about to break.

Nobi > area man 01/27/2016 at 16:29

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There is no exhaust manifold on Honda engines. The catalytic converter bolts right to the head. There are four studs that run into the head that the converter then slides on to and is held on with a nut. These studs are made of a metal with a consistency similar to wet cheese. They’ll seize to the nut, causing either the entire stud to back out or snap in half during removal. Should have just used a long bolt for them which is a repair I see often. I’ve worked at an Acura dealership for a bit over a year, and used to work at a Honda dealership for 6 years, BTW.

area man > Nobi 01/27/2016 at 21:08

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So YOURE HondAnonymous

Nobi > area man 01/27/2016 at 23:47

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Hahahaha, I wish. S/he definitely has a fan.