the local muffle shop wanted a bundle of money to replace the stock headers with aftermarket ones.. does anyone have link to more in-depth information on how to install new headers? the manual I have states:
disconnect battery raise & support vehicle spray retaining bolts with penetrating oil. remove the exhaust manifold heat shields disconnect the exhaust pipes from the exhaust manifolds remover the exhaust manifold to engine bolts in the opposite order of the tightening sequence. front engine> firewall side 3 2 5
4 1 6
discard gaskets
to install: clean gasket area install gaskets install manifold & torque to 13-16 ft. lbs install exhaust manifold heat shields connect negative battery cable start engine & check for exhaust leaks...
sounds easy yet I while changing the oil last night I didn't see much room in there.
please share stories about this adventure into exhaust mods
Because the shop knows that a couple of those studs are going to break and cause hours of work trying to drill them out. Why are you replacing them? If their not leaking, you'd be wise to leave them alone.
having got 1/2 through the header replacement project I now see what the muffler shop was talking about. the rear header (close to the firewall) was hidden well. the heat shield could be unbolted but not removed unless you unbolted the manifold header first. the heat shield kept you from getting at the bolts easily. a normal 14mm socket didn't fit because the stud protruded just far enough to block it from seating properly. the option was a deep socket which was hampered by limited clearance. I first tried
1/2 inch drive deep, then 3/8.... even with my articulated head ratchet I couldn't get at several of the nuts on the header. I bought those ratcheting open end one side wrenches at sears a while back and they helped... what I ended up doing to get to the top side of the header was remove the air intake box, mass airflow upper intake plenum (which incidentally had a hose on the bottom with about
2" of flex so you had to lift twist then blindly remove the clamp then the hose to swing the intake out of the way. I ended up using vise grips to take the side pipe that takes exhaust gasses to an erg valve or some other thing under the mass air flow area... the nuts were difficult to get loose and I used wrenches at dog leg style extra force levers. I even used my rake handle to act as a pile driver to hit a wrench where I didn't want to stick my hands & force (no room and sharp parts next to it).... PB blaster was instrumental in nor shearing anything, this weekend I hope to start putting stuff back on..... john 6 pack job so far, but I see this stretching into a case or two easy....
Wait till reassembly - getting that hose back on is a royal PITA. While you have the plenum off, make sure you clean out the EGR port and that guide tube you disconnected from the back of the plenum. Getting some of those bolts is much easier if you pull the IACV off the plenum first...
OH GREAT fine just scare me a wee bit more the stiff hose that goes into the side of the plenum is nearly clogged solid with carbon... I'm reluctant to ream the sucker out and ingest bits & pieces, so I will take it further apart so that I can properly clean it. this hose I suppose a feature of trying to re- ingest unburnt waste oil from the valve area back into the intake so that the gunky stuff gets burnt up in the engine instead of tossed out into the atmosphere.... I'll know more when I look more closely tonight. John
OH GREAT fine just scare me a wee bit more the stiff hose that goes into the side of the plenum is nearly clogged solid with carbon... I'm reluctant to ream the sucker out and ingest bits & pieces, so I will take it further apart so that I can properly clean it. this hose I suppose a feature of trying to re- ingest unburnt waste oil from the valve area back into the intake so that the gunky stuff gets burnt up in the engine instead of tossed out into the atmosphere.... I'll know more when I look more closely tonight. John
OH GREAT fine just scare me a wee bit more the stiff hose that goes into the side of the plenum is nearly clogged solid with carbon... I'm reluctant to ream the sucker out and ingest bits & pieces, so I will take it further apart so that I can properly clean it. this hose I suppose a feature of trying to re- ingest unburnt waste oil from the valve area back into the intake so that the gunky stuff gets burnt up in the engine instead of tossed out into the atmosphere.... I'll know more when I look more closely tonight. John
John - thats the EGR guide tube. Exhaust gases are recirculated back into the combustion chamber via that tube. You should just pull the tube off (there are two 12mm nuts at the other end near the EGR valve) that hold the tube on. Those nuts are best attacked with a 12mm box-end wrench. Even after getting the nuts undone, there wasn't enough clearance between the larger EGR pipe that runs near the EGR valve and the flange of the smaller tube to get that hose out... Mine was 1/8" or so too tight... in fact on mine, the thicker washer at the lower end of the tube wouldn't even clear that tight gap... hopefully yours will line up differently. Make sure you clean out the EGR port on the plenum itself too and the IACV and throttle body.
I really don't know how the Nissan techs. attack reassembly of those coolant hoses... I tried every angle but eventually got it by luck rather than some calculated approach. But then again, I'm not one to set a benchmark :), so hopefully you'll be better at it than I was.
I would recommend replacing the plenum gasket and the EGR guide tube gaskets.
yes, sigh the cat back exhaust is still "in the mail" anyhow i was thinking of running it with the headers y & cat around the block just for fun butttt I have other things to go break in the garage john hammer mechanic.
update: finished the install last night.... of course UPS did their best to bruise the muffler and I decided to spray the scraped parts with some high temp paint.
the remaining install went fine other than the folks I ordered the cat back exhaust from didn't include 2 gaskets like I though they would? (description said two gaskets) so I had to run up to the local autoparts store for a 2 buck gasket. the pipe lined up pretty close to original exhaust, with the only issue being I have a trailer hitch on my maxima and the muffler is about 1" too far back for proper clearance. I will take the pipe off and re shape it where it goes over the rear axel to make the needed room at lunch time.
the sound is noisier than stock, sort of grumbles at 800 RPM to about 2,000, once above that rpm it sounds like stock exhaust except a slight bit louder. the 1,000-1,500 rpm constant throttle has a bit of a drone and if you slightly poke the throttle in this range it growls. stead throttle from 1500 on up is nice & quiet compared to other road noises. the car definitely breaths better. as I have noticed the rpm gauge swings past 2,500 - red line much quicker. seat of the pants tests on the way to work would say I knocked about 1/2 - 1 second off the 0-55 mph. the car seems to take a lighter foot to reach highway speed and maintain it so I will see what the MPG stuff will be later.
all in all I would not start this project if you do not have a back up vehicle to drive while the maxima is down. I spent every other evening working from 10pm-12 for about a week. the project consumed
1-1/2 slots in my 3 car garage and about case of beer. I only had 2 bolts left over from the project, which frustrated me until I wiggled the wiring harness and found the bolts belonged in the side of the bracket closest to the passenger side. (what's a project with out having bolts left over) the bypass exhaust tube that feeds the EGR valve didn't align up quite right and required some smacks in the vise. the Nissan engineers did not leave enough room in-between the firewall and the exhaust manifold to get the heat shield off without using a little bend & tuck of the shield to remove it. o2 sensors matched up perfect. and the end result is a quicker car that is not too noisy like those cars with the fart cans for a tail pipe. John Project was pain in the tailpipe, but worth it.
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