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My Successful APN header install

mhopton

NAXJA Forum User
Location
Marietta, GA
Now, this might not be a big deal to a lot of you guys that either turn wrenches professionally, or have a lot of experience doing your own work. Me, well, I'm no wrench, I'm a banker. I sit in an office all day and tell business owner's NO, you can't borrow money - despite what Nobama is telling you on the tube. Sure, I have always changed my own oil and I understand the basic concepts of how an engine and related components work but never really got into it for fear of f'in something up.

So, after picking up my new to me, 4x4, daily driver XJ w/90k on the clock, I made the decision to do my own work this time around. I bought it knowing it needed a PS Pump, an exhaust manifold, a fog light switch and a few other assorted common issues.

With help from this site and others, I replaced the PS Pump, put it all back together and found that the gear also needed replacing. So the next day, I took out the pump, gear and replaced it putting it all back together - oh yeah, I did that all w/out jack stands or even a floor jack:D...

Meanwhile, I had ordered the APN header from ineedparts, so I knew it would be here last week. I went about reading everything I could find on replacing this thing and by far the best writeup I found was dailydriventj.com. But first, I knew I needed more working space under the vehicle, so I went to Northern Tool and bought a really nice, long body 3-1/2 ton floor jack and a couple of 3 ton jack stands to get it up off the ground - man, wish I had done that sooner. My wife has an Excursion, so this thing will get her truck off the ground too. Someone here also highly recommended swivel head gear-wrenches - I bought a set of metric Gear Wrenches, too from Sears hoping they'd make the job easier.

Anyway, to the install. I had read that some folks had to modify their intake to fit the APN header - I hoped mine wouldn't be the case, so I set off with the best intentions.

After removing the airbox and PS pump, I started taking pics of the intake plumbing and labeling the FIs to make sure not to get them mixed up.
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Then I started removing the intake plumbing and found that I could unclip all of the sensors on the TB, unscrew the holder for the throttle/cc cables and lift it straight up w/out disconnecting anything - I hung it from the open hood by a couple of coat hangers.

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From here, I went under the car and loosened the header/exhaust connection. I had sprayed w/PB blaster for a few days, so it came loose like butta'..

Next came the FI rail. After unclipping the injectors and unbolting, I wiggled them free from the intake.

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From here, I used the gear wrenches to get under the intake and loosen the bolts. They all came off with no problem and off came the intake and header.

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I pulled off the old gasket, which came off very clean and then used TB cleaner and a scotch brite pad to clean the head. I did the same thing with the intake manifold.

A close-up shot of the intake/exhaust ports - gaskets still on in this pic.
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I used a fel-pro gasket and coated it really well on both sides with Copper gasket spray. New APN header installed loosely.

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Took a close look at the old manifold and found that it was cracked all the way around at the collector on one tube and the #4 pipe was cracked up at the head.

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From here, I buttoned everything back up using the 14 & 15mm gear wrenches and putting dilectric grease on all electric fittings and thinking that I didn't have a clearance problem between the intake and exhaust manifold. To this point it had only taken me ~3 hours, not bad at all. When I cranked up the Jeep it immediately revv'd to 3k RPM and didn't drop, so I knew I had a big vacuum leak - time to tear it back apart. Funny thing is, it only took 25 minutes to break it back down to the intake manifold now that I knew exactly what to do. I broke out an old tappet gauge and tried to slide a .15 feeler between the #6 runner and exhaust pipe and found the problem. I pulled the intake back off and proceeded to use a bastard file to file down the edge of the intake to fit the APN header. I also found that I had to file down the rib-casting on the #1 side of the intake where that supports one of the PS pump bolts - that too was rubbing.

Several test fits later, I could finally get the intake to sit flush on the block w/out resting on the exhaust pipe. I bolted it all back up, cranked it up and it was quiet as can be - purred like a kitten. Success...:roll:

New header installed
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Couple of points...
The swivel-head gearwrenches were invaluable. I can't imagine doing this job w/out them. I was able to get to all of the bolts on the intake and exhaust manifold from the top by reaching under the intake and snaking my arms through.

Next up for this non-mechanic, Rear Main Seal replacement. Time to start reading...:)
 
Good job. I leave the tb on the manifold and unplug sensors and cables, or else totally remove it and clean it out(IAC port, plate, etc). I also remove the stock airbox and use 1.5-2 extensions to get at 3 or 4 of the underside 14mms. I want to get some of those big beefy Jackstands.
 
Nice write up and pics, this has been on my list of things to do for a long time now. I just can never seem to decide on a new manifold. I go back and forth with apn and other brands. Going chinese knock off scares me but everyone swears by them in this case.
 
I just did this install Saturday. It went pretty smooth. I didn't have to file anything down to get it to fit on my '91. It did smoke some and smell bad after I fired it up the first time. I think that was just burning the grease I got on the header during the install though because now it seems fine. My exhaust manifold was cracked as well. The XJ seems to idle lower now for some reason. I hope the gasket that came with the APN header will last because its the one I used. It seemed to fit fine when I installed it.
 
Nothing like jumping into the deep end of the pool! Nicely done. We look forward to your RMS adventure.
 
great write up!

I am doing an APN soon on my 97 but did a banks on my 99 and swivel wrenches and or swivel sockets are life saving! I too had lower rpm's after the install but nothing drastic... i too used the banks gasket which i believe was a fel pro... anyways nice work!! I feel like the header is a great mod for the xj - pair it up with a good set of motor mounts though now you got a good jack and jack stands!
 
Just one more thing to do on that exhaust header--protect it.

Add a section of stainless steel flex tube between the downpipe and the CAT: http://www.cxracing.com/mm5/merchant.mvc?Screen=PROD&Store_Code=CXR&Product_Code=FLEXPIPE-250x8-E

This will eliminate (at least reduce) the torque on the exhaust header to prevent cracking.

Cutting and welding this you would need to take to a muffler shop based on your auto skill level. Do an internet search and find the best price on the 2.5" in 6" or 8" length and then just take it with you to the shop.
 
I for one have to say I'm proud of your accomplishment, most of the guys here (myself included) are very mechanically inclined. It's extremely rewarding to do your own work and it makes you feel less helpless when it comes to controlling the things around you, I find working on my XJ very theraputic and relaxing even when the job is fiting me all the way.


You happen to pick one of the most pain in the ass jobs to start on, trial by fire to say the least. I waited until I pulled the engine out so I could do this job the easy way.

Keep up the good work and enjoy the fruits of your labor.


By the way, take Joe peters advise about the flex pipe because your new header will crack again it will just take longer this time. Releive the pressure from it and its life will be greatly increased.


Kelvin
 
Nice write-up and good pics to boot. I am planning this exact upgrade in the near future.

Good luck with your RMS project. I'll PM you with what I found when doing mine over the weekend.
 
Great job, you owe urself a beer or seven sir...

Now if someone would just make an affordable header for my damn Y2K with the stupid seperate pipes and 4 O2 sensor hookup:rattle:
 
Nice write up! Interesting you had clearing issues on the #6...from what i've read it seems to be hit and miss. Others have had the same problem, however I just did this on my 99 a little over a month ago and did not have any issues.

It's really not that hard of a job at all...just seems like it. I'll be doing 2 more on 4.0's here in about 2 weeks if all goes as planned.
 
Successful header install yesterday (I'm assuming it's an APN). Thanks to mhopton for the timely response on the GearWrench info. Underside bolts came off easily enough with ratchet and several extensions; flex-head GearWrenches were invaluable in reassembly. Clean, trouble-free install start to finish. I can finally scratch "header" off my to-do list. :smoker:
  • No clearance issues with 97 intake.
  • Used Fel-Pro gasket and a generous coating of copper spray.
  • Very low idle for first few seconds of startup; seems to be improving.
  • Heavy buildup of sticky oily gunk in all 6 intake manifold runners and cylinderhead intake ports (yet the intake valve stems were clean). Spent all day removing sludge with Dremel wire-wheel, carb cleaner, and foaming engine degreaser. What's the story with this?
 
  • Very low idle for first few seconds of startup; seems to be improving.
  • Heavy buildup of sticky oily gunk in all 6 intake manifold runners and cylinderhead intake ports (yet the intake valve stems were clean). Spent all day removing sludge with Dremel wire-wheel, carb cleaner, and foaming engine degreaser. What's the story with this?

Low idle might be in response to you breaking up some of the crap that was in the intake. I broke some of mine up simply by removing and installing the intake, and it ran kinda funky for a couple of minutes after start up.

Normal crud from every day driving is all that is. Seen it on every one i've torn apart now.
 
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