Can you gut 5.5 Gen Pre-cats while on the Car?
05-19-2011, 08:13 AM
#1
Can you gut 5.5 Gen Pre-cats while on the Car?
I’ve had “bees in a can” for well over a year. It’s that gentle rattle that occurs when lightly accelerating from idle to under 2000 RPM’s. Now I know noises like that can be just about anything… pinging, heat-shield rattle, or just plain old exhaust rasp. Whatever the actual cause, I’m strongly suspecting one or more of the pre-cats has loose material banging around.
My mechanic is on-board, and has done countless cars for similar situations… although never a 2002-2003 Maxima. So he’s concerned about stripping the studs, and has recommended doing this thing with the pre-cats still on the car. Of course, we’re going to get the car up on the lift and assess things before whipping out the impact gun. But until then, it’s a reasonable question to ask the Org: can you gut the 5.5 Pre-cats while they’re still bolted to the exhaust manifold?
My mechanic is on-board, and has done countless cars for similar situations… although never a 2002-2003 Maxima. So he’s concerned about stripping the studs, and has recommended doing this thing with the pre-cats still on the car. Of course, we’re going to get the car up on the lift and assess things before whipping out the impact gun. But until then, it’s a reasonable question to ask the Org: can you gut the 5.5 Pre-cats while they’re still bolted to the exhaust manifold?
Last edited by Rochester; 05-19-2011 at 09:56 AM.
05-19-2011, 08:33 AM
#3
You can gut the rear while still on the car, but the front pre-cat has an obstructive bend in it. If you strip the studs on the front, it takes no time at all to pull the manifold with it still attached and drill out the studs. (Ask me how I know.) I would be inclined to not gut the rear on the car because it's a very hard material and I'm super paranoid about kicking debris up into the manifold. I have seen numerous threads where people have used this method, though. Start using the PB now, Yankee. 
Your mechanic will thank you.
Your mechanic will thank you.
05-19-2011, 08:46 AM
#5
Senior Member
Join Date: Dec 2005
Location: Leicester, Ma
Posts: 1,124
Rochester, i have experience with both. The front maybe. It is made of a ceramic type filter that basically breaks like glass. Like nelledge said it has a bend at the bottom which will make the job very hard to do as getting to it is tough. The front one is not hard at all to take out. Maybe a half hour total and that is getting all the stuff out of the way to get at the bolts. If your mechanic is doing it he should know all he has to do is PB or WD 40 them, let sit, and then use a torch to heat the bolts to make the rust break loose. Once out just get a big screwdriver or whatver is handy and break it out. Just watch out for all the dust and junk
No you can not gut the rear one while on the car. It is a metal honey comb with a metal cylinder around the outer edge. For the rear you can get at the top bolts with out removing the UIM. YOu just need a breaker bar as the bolts are super tough, meaning very tight. The rear cat like i said has the metal honeycomb and cylinder holding it all in place. YOu will need things like a drill, hacksaw, 5lb hammer, chisel ect as that **** is a pain in the b@lls to get out. It took me about 3-4 hours wrestling with it to finally remove (the honeycomb) and you can do it. Just takes time. I say take the cats off and do it, dont leave them on, you dont want to risk getting junk in the cylinders. I can get the rear off now in about 10 minutes flat. Had to remove mine like 3 times.
Edit:
forgot to mention. If you do gut them you will get codes. To fix this the lower o2 sensors in each cat need to be manipulated. Meaning go to auto zone or whoever and get yourself some spark plug anti foulers. I dont remember the length but there is limited space in the front between the o2 and the exhaust. Get an antifouler that still gives you room. U will need to drill thru the antifouler as the nose of the o2 wont fit unless you drill out the fouler. Do this for both front and rear and clear your codes and you should be good to go. The only time i get codes now is if the car sits for a few days and it has been raining. So over the 9 months ive had this done for maybe 2 times ive gotten codes so not often at all.
No you can not gut the rear one while on the car. It is a metal honey comb with a metal cylinder around the outer edge. For the rear you can get at the top bolts with out removing the UIM. YOu just need a breaker bar as the bolts are super tough, meaning very tight. The rear cat like i said has the metal honeycomb and cylinder holding it all in place. YOu will need things like a drill, hacksaw, 5lb hammer, chisel ect as that **** is a pain in the b@lls to get out. It took me about 3-4 hours wrestling with it to finally remove (the honeycomb) and you can do it. Just takes time. I say take the cats off and do it, dont leave them on, you dont want to risk getting junk in the cylinders. I can get the rear off now in about 10 minutes flat. Had to remove mine like 3 times.
Edit:
forgot to mention. If you do gut them you will get codes. To fix this the lower o2 sensors in each cat need to be manipulated. Meaning go to auto zone or whoever and get yourself some spark plug anti foulers. I dont remember the length but there is limited space in the front between the o2 and the exhaust. Get an antifouler that still gives you room. U will need to drill thru the antifouler as the nose of the o2 wont fit unless you drill out the fouler. Do this for both front and rear and clear your codes and you should be good to go. The only time i get codes now is if the car sits for a few days and it has been raining. So over the 9 months ive had this done for maybe 2 times ive gotten codes so not often at all.
Last edited by jeff5347; 05-19-2011 at 08:54 AM.
05-19-2011, 09:09 AM
#6
Good advice, guys. Thank you. Repeated applications of PB Blaster before the process... yep, will do. Bend in the front pre-cat... 
Damn it.
From what I can tell here, gutting the precats (or installing headers) is a strong likelihood for throwing a code, although not a guarantee. But it's doesn't matter because I'm planning on introducing an O2 sim to head that off.
Nope. Just bees-in-a-can turning my brain into mush.
Damn it.From what I can tell here, gutting the precats (or installing headers) is a strong likelihood for throwing a code, although not a guarantee. But it's doesn't matter because I'm planning on introducing an O2 sim to head that off.
Nope. Just bees-in-a-can turning my brain into mush.
05-19-2011, 09:19 AM
#7
Good advice, guys. Thank you. Repeated applications of PB Blaster before the process... yep, will do. Bend in the front pre-cat... Damn it.
From what I can tell here, gutting the precats (or installing headers) is a strong likelihood for throwing a code, although not a guarantee. But it's doesn't matter because I'm planning on introducing an O2 sim to head that off.
Damn it.From what I can tell here, gutting the precats (or installing headers) is a strong likelihood for throwing a code, although not a guarantee. But it's doesn't matter because I'm planning on introducing an O2 sim to head that off.
Hopefully, your mechanic finds it's just the rear heat shielding broken loose of a fastener and you can save yourself some labor time.
05-19-2011, 09:53 AM
#8
When I did my header install, it was much more difficult to pull the precat off the y-pipe (never actually could get it off with my hand tools) than to get the manifold off the engine. The studs were fine, and I probably have more rust on my car than you do.
Just my experience...
Just my experience...
05-19-2011, 09:54 AM
#9
It's very possible he'll see what you're saying about the front pre-cat design, and agree that the cats need to be removed in order to address their innards. We'll see.
05-19-2011, 10:06 AM
#11
the words bees in a can do not help me imagine the noise....
i had some nice rattles, and it was sheilds that needed 2$ clips, and like someone said pin my case im thinking more is invovled in the flex pipe.
simply put what does the 02 sim exactly do? trick the computer to think its ok?
i had some nice rattles, and it was sheilds that needed 2$ clips, and like someone said pin my case im thinking more is invovled in the flex pipe.
simply put what does the 02 sim exactly do? trick the computer to think its ok?
05-19-2011, 10:13 AM
#12
Really? Because that's the very phrase that led me down this path.
Yep. Here:
http://forums.maxima.org/5th-generat...tallation.html
http://forums.maxima.org/5th-generat...tallation.html
05-19-2011, 10:57 AM
#14
05-19-2011, 11:00 AM
#15
I gutted my front one just cause it was super done for and had to take the y pipe and the front pre cat for the job to be real quick, could of done the rear without taking it off but got smog coming up soon and in Cali it is a B1tch so better for me to buy one pre cat instead of two while the rear only has like 25k on it.....Good Luck though.....
Last edited by Rods03Max619; 05-19-2011 at 11:10 AM.
05-19-2011, 11:10 AM
#17
Been thinking about this also i rip my flex section in my custom maxima headers and install stockers on tomorow til i get new headers. So in short what would need to be done just spilt the precats open gut and install
05-19-2011, 02:18 PM
#20
05-19-2011, 02:30 PM
#21
Senior Member
Join Date: Dec 2008
Location: South Jersey (Near Philly)
Posts: 511
I started having "Bees in a Can" the other day and I'm pretty sure it's my flex section. It is completely loose around the entire front flange.
Going to try and see if I can get a local muffler shop to give it a shot an weld it.
Not sure they can weld the mesh, but it's worth a look.
I'd love a Cattman Y-pipe, but I don't have the $350 much less the $550 for the OEM.
Worse case I may have to go with the $150 Walker which will really suck.
Going to try and see if I can get a local muffler shop to give it a shot an weld it.
Not sure they can weld the mesh, but it's worth a look.
I'd love a Cattman Y-pipe, but I don't have the $350 much less the $550 for the OEM.
Worse case I may have to go with the $150 Walker which will really suck.
05-19-2011, 02:38 PM
#22
Cut out flex section have them weld in a peace of pipe... .. til u can save up for header or catt-man y-pipe or even a warpspeed y-pipe 200 last time i seen
I started having "Bees in a Can" the other day and I'm pretty sure it's my flex section. It is completely loose around the entire front flange.
Going to try and see if I can get a local muffler shop to give it a shot an weld it.
Not sure they can weld the mesh, but it's worth a look.
I'd love a Cattman Y-pipe, but I don't have the $350 much less the $550 for the OEM.
Worse case I may have to go with the $150 Walker which will really suck.
Going to try and see if I can get a local muffler shop to give it a shot an weld it.
Not sure they can weld the mesh, but it's worth a look.
I'd love a Cattman Y-pipe, but I don't have the $350 much less the $550 for the OEM.
Worse case I may have to go with the $150 Walker which will really suck.
05-19-2011, 02:40 PM
#23
Senior Member
Join Date: Dec 2005
Location: Leicester, Ma
Posts: 1,124
Rochester, do you get that bees in a can sound from a dead stop once you get to about 1500 - 2000. I still have that. I have no heat shields left either. Gets me thinking it is the flex pipe. Well sometime im gonna have a whole custom ex done so maybe i can replace the flex area for something different. The anti fouler thuing is real easy. Dont need ot cut or splice wires. just ge the AF's, drill them and instal
05-19-2011, 03:25 PM
#24
I'll be sure to bump this thread again when it gets resolved. Getting rid of these bees has become a priority. Funny how priorities get shifted about, but one way or another, this is getting addressed.
It's at the top of the list now.
05-19-2011, 03:49 PM
#25
I tried that before and everytime i would smack second gear it would crack the weld on the pipe,you need some kind of flex in there other wise when the engine torques its going to try to move the whole exhaust and eventually break something.
05-20-2011, 11:11 AM
#27
I'll post results if I take this route. I also believe it to be only the front facing cat that is making the noise...
05-20-2011, 01:23 PM
#28
This was PM'd to me yesterday. Seems to be some good on-topic info, so I'm reposting it into this thread.
If you can get the car on a lift and hold it at the rpm where the noise is most noticeable, have your mechanic under the car checking where the noise is coming from and if its up over the tranny against the firewall its probably the rear bank pre cat. He will be able to tell.
If it is i would recommend gutting both because once you drop the y, the front one is pretty easy to get at after that, but the bolts that hold the rear bank pre cat are tough to get at. With the right extension you can get at them from behind the manifold.
All in all if your mechanic is good which im sure he is,from start to finish gutting and reinstalling should take like 2 1/2 to 3 hours. Make sure he heats every bolt with a torch. The rear cat is a total ***** to get that stuff out. Put the cat in a bench vise and use an air chisel with an extremely long bit, maybe 12 inches long to punch all the way through.
The front cat has a screen and then you just smack the crap inside with a pry bar a few times and it falls right out. Your car will be a bit louder
and you will absolutely notice a pretty significant power gain throughout the rev range especially on the top end.
If you can get the car on a lift and hold it at the rpm where the noise is most noticeable, have your mechanic under the car checking where the noise is coming from and if its up over the tranny against the firewall its probably the rear bank pre cat. He will be able to tell.
If it is i would recommend gutting both because once you drop the y, the front one is pretty easy to get at after that, but the bolts that hold the rear bank pre cat are tough to get at. With the right extension you can get at them from behind the manifold.
All in all if your mechanic is good which im sure he is,from start to finish gutting and reinstalling should take like 2 1/2 to 3 hours. Make sure he heats every bolt with a torch. The rear cat is a total ***** to get that stuff out. Put the cat in a bench vise and use an air chisel with an extremely long bit, maybe 12 inches long to punch all the way through.
The front cat has a screen and then you just smack the crap inside with a pry bar a few times and it falls right out. Your car will be a bit louder
and you will absolutely notice a pretty significant power gain throughout the rev range especially on the top end.
05-31-2011, 09:39 AM
#29
Went to the Mechanic today. The problem was *not* the front pre-cat heat shields... because they're gone now. They were horribly rusted out and barely hanging on, but was not what was making the noise.
He used a listening tool from below and from above, for quite a while, as I goosed the throttle from 700 to 2000. (I'm riding up and down the lift like a little kid outside Walmart, LOL!) Pretty sure it's not coming from the timing chain area, or the tensionor, and definitely not the main cat. Unfortunately, he couldn't be sure it was either of the two pre-cats, even with the listening tool.
So next and easiest step... gut the rear pre-cat, which can be done while on the car. The front one (front of the car) is the one that has that 70 degree bend. As for the absent catalyst, I bought a still-in-the-box O2 Sim for a great deal from NmexMAX... lucky me.
This continues to be very frustrating.
He used a listening tool from below and from above, for quite a while, as I goosed the throttle from 700 to 2000. (I'm riding up and down the lift like a little kid outside Walmart, LOL!) Pretty sure it's not coming from the timing chain area, or the tensionor, and definitely not the main cat. Unfortunately, he couldn't be sure it was either of the two pre-cats, even with the listening tool.
So next and easiest step... gut the rear pre-cat, which can be done while on the car. The front one (front of the car) is the one that has that 70 degree bend. As for the absent catalyst, I bought a still-in-the-box O2 Sim for a great deal from NmexMAX... lucky me.
This continues to be very frustrating.
05-31-2011, 09:58 AM
#31
But since that's not the case, I'll be applying the SIM after gutting the rear pre-cat, regardless. If that doesn't address the noise... then the front pre-cat is next.
If that doesn't address the noise... my only other options are headers, or the Looney Bin. No, that's not true. If the pre-cats aren't the cause of the rattle, then I'm just going to leave it be until I sell the car next year.
06-01-2011, 08:37 AM
#35
And all of this is before we even consider the fact the engine will be able to do it's job a little better due to the reduced restriction.
06-01-2011, 09:13 AM
#36
Do you think that will create any issues with the rear bank breathing better than the front? Assuming that gutting the rear solves the problem and you leave the front alone.
06-01-2011, 09:28 AM
#37
As to issues with only the rear bank "breathing better"?
I have no idea.Believe me when I say my mechanic was frustrated in not being able to pin down where the noise was coming from. He doesn't like not being able to solve problems.
06-01-2011, 09:46 AM
#38
I'm taking baby steps because gutting the rear is easy to do while still on the car, up on a lift, with power tools. Maybe an hour of my mechanic's time, if that. I suppose we'll know immediately if the noise is coming from elsewhere, at which point options will be reconsidered.
As to issues with only the rear bank "breathing better"? I have no idea.
Believe me when I say my mechanic was frustrated in not being able to pin down where the noise was coming from. He doesn't like not being able to solve problems.
As to issues with only the rear bank "breathing better"?
I have no idea.Believe me when I say my mechanic was frustrated in not being able to pin down where the noise was coming from. He doesn't like not being able to solve problems.
Sounds like he's a good mechanic to have though.
09-28-2011, 12:23 PM
#39
Was talking to my mechanic yesterday, and thought I'd bump this related to that conversation. For back story, yes, I had my pre-cats gutted about a month and a half ago. No, it did not solve my mystery rattle. But now I've got a nice little rumble (on top of what was already there), and a little extra grunt in the high-end. So no regrets.
Anyway... the front had to get removed to be gutted, because of the bend in the pre-cat. Once removed, the substrate inside the housing knocked right out. (Old news, I know.)
The rear was indeed gutted while still mounted to the exhaust manifold. It was done this way because he didn't want to break the bolts mounting it to the manifold, and because the car was up on a lift, so he had good access and leverage. The technique was to use a 1" spade drill bit, about 12" long, to slowly drill a bunch of holes through the material. Once it was drilled through in numerous spots, it was weak enough to rip apart with a pry-bar. Easy? No, not at all. And it destroyed his drill bit, LOL. He said he'd do it this way again, if given the opportunity... but next time he might wear a hat. Very, very messy job.
So that's what I was told... thought I'd share while it was fresh.
Anyway... the front had to get removed to be gutted, because of the bend in the pre-cat. Once removed, the substrate inside the housing knocked right out. (Old news, I know.)
The rear was indeed gutted while still mounted to the exhaust manifold. It was done this way because he didn't want to break the bolts mounting it to the manifold, and because the car was up on a lift, so he had good access and leverage. The technique was to use a 1" spade drill bit, about 12" long, to slowly drill a bunch of holes through the material. Once it was drilled through in numerous spots, it was weak enough to rip apart with a pry-bar. Easy? No, not at all. And it destroyed his drill bit, LOL. He said he'd do it this way again, if given the opportunity... but next time he might wear a hat.
Very, very messy job.So that's what I was told... thought I'd share while it was fresh.
Last edited by Rochester; 09-28-2011 at 12:31 PM.
09-29-2011, 09:55 AM
#40
how many hours of labor did it take him?
and how happy are you with it still that its a few months later ?
what are some of the other reasons to doing this besides your reason with the diagnosis of noise issues?
and how happy are you with it still that its a few months later ?
what are some of the other reasons to doing this besides your reason with the diagnosis of noise issues?
Last edited by Prophecy99; 09-29-2011 at 09:57 AM.