2004 Maxima, 3.5L SE. I have my collector off to replace my rocker covers. I noticed peering into the EGR tube in the collector that I have some restriction due to buildup. I was wondering if it would be ok to remove the plug on the opposite end of the collector (i'll post pics) and run a bottle brush or maybe even a brass bore brush through the tube to clean out the gunk.

My main concern would be possibly clogging one of the small EG ports running from this "tube" to the larger individual collector tubes of course. Is it OK to remove that plug and replace it after cleaning? Would I need to coat the threads with something before re-installing it? It shows nothing about it at all on the FSM schematic of the collector. I was thinking of spraying carb/choke cleaner down it and brushing it out but I don't want to risk stopping up one of those ports. Does any one know or have any experience with this? Thanks for any help or suggestions.

 

 

I'm thinking if I do this I should probably remove the upper intake collector from it, as well as the power valve, then I can probably get to the individual ports on the upper collector side with some pipe cleaners or wire to make sure the ports are clear.

 

Got it done and it's pretty clean. I'll post what I did on this thread with photo's of my experience. Here's the first photo of the final job.

 

First step was removing the collector. I had read that it was a pain, and there are a lot of good video's out there with a lot of write ups on the process so I'm going to skip the details of that part. Other than to say that it wasn't really bad if you remove the MAFS and tube, then the Electronic Throttle actuator, you can approach the two rear collector bracket bolts from the drivers side without removing the wipers, wiper motor and windshield cowl as suggested in the FSM. I have fat, stubby arms and fingers and it wasn't really that bad. Also, as I had read on another thread here somewhere, on the passenger side, the two green electrical connectors that are side by side. You do not have to even unplug them, if you use a small screwdriver to push in the tab on the bottom of them and remove the complete plug assemblies from the metal bracket you see pictured on the rear left of the lower collector above.
There is no need to even remove this bracket unless for some reason you want to get to the rear passenger side, lower bolt of the upper collector. Which you really do not need to do at this point. You can remove the whole assembled collector en mass as a unit. This really wasn't any problem for me. Of course you have all the hoses, vac lines, sensor brackets, and EGR tube to remove as well, but they were a breeze if you have these tools pictured next. Go to retailmenot . com Search Harbor Freight. Get the 20% off coupon and print off 4 or 5. If you have one close as I do, you can buy one tool a day at 20% off, and get these $50 worth of tools for $40. They are invaluable! Especially the long bent needle nose, for removing hose clamps; and the double break 3/8" ratchet. Without this ratchet I could not have removed the two upper collector bracket bolts, approaching from the drivers side. With it, handle up and bent around the top of the upper collector to loosen, it was A BREEZE!. The stubbys came as a set and were handy as well. Also, you will see the brushes for cleaning the EGR collector tube, and an 18" breaker bar I used (with a 10mm hex bit socket) to remove the tube plug from the passenger end of lower collector. TOOL's needed:

 

My first step was to disassemble the collectors, and remove the power valve. Follow the correct order of bolt removal as advised in the FSMs. When replacing them there is a specific order as well, all located in the FSM's under EM- Intake Collector Removal and Installation. It is also recommended that the two gaskets for the Power Valve, and the upper to lower collector gaskets be replaced when disassembled. I bought all three at Landers Nissan for a whopping $38. I couldn't find them online anywhere, but you might.
Here's the disassembled parts:

 

Next was to remove the Collector EGR tube (my terminology) plug on the lower collector. I figured it would be seized from the inside with carbon, so I soaked the whole tube the night before with both PB blaster, and brake cleaner and carb cleaner to also help loosen up the crud in the tube. I tried to break it loose the next morning with the 10mm hex socket on adapted to a 1/2" drive ratchet but couldn't break it. I considered using my smaller 3/8 impact turned low, but was afraid I might crack this cast aluminum, so I put it on my 18" breaker bar and with a little effort broke it loose and it came out fine. You can see how clogged the tube was with a flashlight on the opposite end.

 

Next I soaked the tube from both ends with a combination of the cleaners listed above and let it soak for about 30 minutes. Most of the heaviest occlusion seemed to be near the ends of the tube so I took a 1/2" drill bit that's about 7" long, and GENTLY twisted it back and forth by hand on each end of the tube to clear this main build up. Spraying cleaner generously, cleaning off the bit after each cleaning untill I was satisfied I had gotten what I could. Next, I took the 3/4" stainless steel long handled brush from the pack from Harbor Freight and proceeded to push it into the plug end and luckily I stopped about an inch and tried to pull it back. DO NOT, I REPEAT DO NOT USE THE 3/4" brush in this manner. It's like a pelican swallowing a fish head first! It will go in fine, but the bristles bend back and catch on the carbon and will not allow it to be removed backwards. I switched to the 3/8" inch brush which allowed me to scrub in and out, reaching well past the center from each end. Scrub, spray the tube, spray the brush off with brakekleen, scrub, spray, etc. etc. etc. Like this:



3/8" brush

 

I wanted to really "fill the bore" up with a brush to get a good cleaning, so I used some tin snips to trim some areas of the 3/4" brush down to give the thing room to move around in the tube a little, and to allow me to move it in ONE DIRECTION from end to end, I took a piece of coathanger wire and made a long handle so I could then pull the brush all the way through from one end to other. This worked great as long as I didn't try and reverse inside the tube. I swabbed, sprayed, swabbed, sprayed many times from each direction until I was satisfied. Here's my contraption:

 

Next I bent the coat hanger wire at about a 90 two inches from the end. I used this to probe the port tubes clean through those six holes in the bottom of the lower collector. It takes a little probing to hit the holes, but then you can observe down through the EGR tube to see your coat hanger wire exiting the port inside, give it a little back and forth and a giggle to make sure no sludge or plug is blocking the port. Check all 6 for obstructions.
Next, I soaked the whole inside of the thing down one more time with brakekleen and PB Blaster. I also soaked down the inside of the upper collector. THEN.. I soaked them both inside and out with some Engine Degreaser. Put em in a box and took them down to the car wash, where I pressure washed them inside and out and rinsed them well. I got home, set em in the sun to dry, then probed each port hole one final time with a pipe cleaner to make sure they were clear. Voila! Just awaiting my gaskets to come in tomorrow to put it all back together. Hope this helps someone else.