APN Header Cracked????

[Blaine B.]

Well just because it vibrates does not mean it's cheap. To win some, you must lose some. For added durability, you get more vibes.

I haven't really ran into any OEM crap. Excluding the high prices, that is.

 

[joshv98xj]

Well, here's the carnage. The first pick doesn't look all that bad, which is why I hadn't suspected the header in the first place- it's hard to get a good look at it with all the other stuff in the way. But the second pic shows the real issue- the entire center weld was blown out! Also, the header was so whacked, that when I held it up against a 4 foot level, there was 1/4" deflection from one end of the mounting surface to the other!

I did get a good look at my motor mount with the manifolds out, and it doesn't look all that horrible, but it is slightly torn, so I'm going to go ahead and replace it while I can get at it; it's not going to get any easier than it is right now.

 

[Ben824]

OEM crap example # 1 stock header (not the newer one with the little expanding sections) # 2 rear main seal # 3 factory sound systems in general haha there are many other things that if jeep had put a little more design time in that would go bad as often but then jeep wouldnt make any money off of jeeps comin back in for repairs

 

[Blaine B.]

At 196,000 miles, I can't complain if all that's "majorly" wrong is a cracked header and a leaky rear main that only really drips. Yes the sound system sucks. I need new speakers. Did any vehicle made back then have a good sound system?

But wow, how loud was your rig with that center weld "not there"?

 

[joshv98xj]

Loud enough that when I picked up my brother from the airport at Thanksgiving, he, who doesn't know anything about cars, says - "Wow. What's wrong with your Jeep? It sounds like crap."

 

[Blaine B.]

Did your gas mileage go down at all?

Since it has been concluded that gas mileage will go down with a cracked header due the oxygen sensor richening the mixture up from seeing more oxygen....I suppose yours would be a worst case scenario!

 

[cds36]

now you guys got me thinking I got a new apn header along with daystar poly motor mounts and poly trans mount. My rig vibrates like a Mofo at idle can that be doing more damage to the header then I want ? I have no problems now and I love the apn, wondering if I should go back to rubbermounts

 

[beakie]

as said above, I too added one of those woven exhuast pipes that allow movement without transferring vibes.

can't find a pic, but my exhuast goes; header, downpipe, flex pipe, cat and bak.
figured if I put the money into a Banks, new cat, FM and all why not. Not sure if those flex pipes give up anything in the power dept. but I can deal with that if it means less breakage.

 

[hot_rod_hooligans]

Here:
http://dailydriventj.com/mfr.shtml

"There is an inherent problem with the one piece design. The root of the problem is the big long pieces of metal pipes that extended to different directions which are ultimately welded to a single point. When these pieces get hot, they start expanding, pushing, pulling, and ultimately twisting each other. However, they are all welded tight. Something has to give to relieve the stress of the expansion. It is usually the welding that gives."

 

[Blaine B.]

now you guys got me thinking I got a new apn header along with daystar poly motor mounts and poly trans mount. My rig vibrates like a Mofo at idle can that be doing more damage to the header then I want ? I have no problems now and I love the apn, wondering if I should go back to rubbermounts

I wouldn't think so. Considering some of the desert racers out there without cracked manifolds....can't think of anything more stressful on a header than desert racing with that sort of terrain!

 

[joshv98xj]

Yeah, my mileage has been in the toilet for a while, I think I'm getting around 10 or so. I stopped figuring it on every tank because it was depressing; I was near 15 beforehand.

I'd like to have a new downpipe bent up with one of those flex fittings in it, that sounds like it couldn't hurt anything to have it done, it's just that all of this has taken a lot longer than I expected and cost me more too. Although, I am working on a Jeep, so that is all to be assumed from the beginning.

It kind reminds me of a few years back when a buddy of mine and I were doing some carpentry work on the side. After a few weekend jobs, we realized that the most accurate way to judge how long our work would take was to figure it out step by step, double check it, and then double whatever number of hours we came up with. By doing that, we were nearly right on every time. Kinda pathetic though.

Maybe I'll pull a pipe from the junkyard and have that matched by a shop so that I can keep driving it while it's being made.

This is the tail end of a winter project to replace my 8.25 with a D44. I'm kinda far away from the rear at this point in the game, but it's still up on jackstands and I'm waiting for parts on every piece of the project. I'm waiting for my shims to come in so that I can bolt the axle all up; I'm waiting for the engine mount to show up at the dealer so that I can put my header back in; I need to replace the clutch master cylinder in my little runaroundHonda, but I don't want to start that until I'm sure that my XJ is road worthy. Yikes.

 

[Blaine B.]

Hm, that gives me hope. I plan to replace my manifold this summer.

I get 12-13 mpg. However mine is only cracked, nothing nearly as serious or big as your "hole".

 

[TazXJ]

I *think* my 8 month old APN header might be cracked too. I noticed it a week or so back when I had it on the lift at the shop, changing oil on it. I fired it up to check for leaks after I spun a new filter on and dumped oil in it. It sounded exactly like the OEM header when it cracked. I even checked the manifold bolts too to make sure they hadn't backed out & burnt up a gasket because I thought there's NO WAY the APN header could've cracked in 8 mos.

 

[joshv98xj]

I'm guessing that this motor mount might have had something to do with my manifold problem. Oddly enough, the passenger's side mount looks really good. I decided to go with the OEM mount, I picked it up from the dealer, so hopefully I won't have the same problem as those with the Autozone mounts.

 

[Ben824]

it is common for the driver side to go bad and the passenger side to be fine because the engine torques to the passenger side so it puts a downward force on the passenger side mount and an upward force on the driver side. As you can see there is more rubber below the mounting hole than above so the upward force on the driver side mount over time tears the rubber bushing.

 

[Euclid]

A really good way to check for cracks is put some Seafoam in your throttle body while it's running. If you get smoke in your engine bay, you've got a crack.

 

[corbinafly]

A really good way to check for cracks is put some Seafoam in your throttle body while it's running. If you get smoke in your engine bay, you've got a crack.

Not always true. Depending on the crack the manifold will pull air into the exhaust and not push out into the engine bay.

 

[Nunyabiz]

One thing I have noticed here that no one seems to mention is that the APN headers are made of 321 Stainless which is much better quality stainless than either the Borla or Banks which is 409 stainless.
That is why (barring any motor mount or other problems) the APN headers last longer and have a much lower failure rate.

Combine that with a $130 Vs $400+ cost difference and its no contest.
The only exhaust manifolds that I have seen that compare to the APNs in reliability are the really cheap $86 Ebay ones with the expansion joints on 1&6.

Just my .02c

 

[Boostwerks.com]

The APN manifold is a POS.

Couple things:

- Theres absolutely no way it's 321 stainless
- Even if it is, it hasn't been welded properlly (back purge, TIG welded)
- The factory exhaust design of the cherokee is what leads to ANY of these manifolds cracking. The quality of the manifold simply allows it to last longer.

Why? Because there is not a single flex section or ball coupler built into the down pipe. Almost every vehicle out there has a flex section that allows the rest of the exhaust past the manifold move slightly with engine torque and vibrations. Without one, every exhaust hanger will put leverage on the manifold and crack it at it's weakest point. Ever wonder why EVERY cracked manifold is cracking in the same spot?

What we need is a company (preferably Jeep but thats not going to happen) to build a replacement DP with a built in flex section. I've actually looked into this, but my local mandrel bender required $5,000 for the proper tooling to replicate it. I've also thought about getting the autozone replacements and welding in a flex.

 

[Nunyabiz]

To each his own.
If the APN is a POS then sadly the Banks & Borla @ 3X the cost is even worse because we know for a fact those are 409 Stainless correct?
IF the APN is lying about using 321 then you should report them.

IF the APN is 409 stainless then its still a better deal than Banks or Borla and somehow or another I see quite a few Banks & Borla cracking while very few APNs doing so.
Better to buy a $130 POS than a $400+ one.

and I fully agree about the Flex joint.