Magnaflow Catalytic Converters - Gen II V8

R

rallyusa

Active LVC Member
Joined
Jul 21, 2012
Messages
118
Reaction score
2
Location
Lilburn
Look what the FedEx man just dropped off :) I'm going to install them tomorrow and take pictures, I'm not sure a write-up is needed since it's so simple, but I'll put one up if you all think it's a good idea.

Box

All

3rd Cat
^^There looks to be some packing debris that is in the last pic, I'm going to thoroughly clean everything out tomorrow before I install them. And also, some people have said the crossover portion or "H-pipe" part of the system is not a CAT, well in this case it is a CAT, not sure if they were all built with 3 cats or not....
 
Write ups are never a bad idea. Some people (like me :rolleyes:) are pretty novice under the hood. I would surely be interested in reading it. Installing my CA intake was about the extent of my knowledge lol. Ill be replacing my serpentine belt on sunday
 
Interesting.. my car has that "3rd cat." Are they supposed to be direct fit?
 
Stopsign002 said:
Write ups are never a bad idea. Some people (like me :rolleyes:) are pretty novice under the hood. I would surely be interested in reading it. Installing my CA intake was about the extent of my knowledge lol. Ill be replacing my serpentine belt on sunday
Click to expand...

OK, for you I will do a write-up, I personally think this is a great bang for your buck, do it yourself project. I live in Georgia, so I don't have to deal with rusted out exhaust systems like a lot of people in the north, so what might take me an hour or so to do, may take much longer for someone who needs to wrestle with rusted nuts and bolts (especially the ones going into the manifold).

M4rk, these are advertised on Magnaflow's website as direct fit, I'm going to compare the bends and the pipe size when I get the old one off, supposedly this one flows more freely. Plus it's going to be a good match when I get cat-back Magnaflow in the not so distant future...

All in all, I paid $452 with shipping and handling, and this carries a 5-year warranty from Magnaflow. I think that's a pretty decent deal for direct-fits. I'm planning on saving my old ones and having the cats replaced so I have a spare set...

If the write-up isn't posted tomorrow, it will be by Sunday...
 
I can't see the pics. I get this error:

Error
Something went wrong. Don't worry, your files are still safe and the Dropboxers have been notified. Check out our Help Center and forums for help, or head back to home.
Click to expand...
 
I've got a Magnaflow universal 2-way high performance cat on my Silverado, seems to work well enough. It doesn't feel like it's being held back by the exhaust or anything. Been on a year or so now.
 
here is your write up,

unplug all four O2 sensors,
remove two nuts on left exhaust header/cat,
remove two nuts on right exhaust header/cat
remove two nuts (one from each pipe) after the third cat (or that weird stamped section for some of you guys)
then pull all pieces apart.

to put it back together, just reverse the steps if it is a one piece part, if it is a three piece part, you have to clamp the three pieces together as well.


the front bolts are just ridiculous to get to, i think i had to use two or three extensions and a pair of wobble bits.

the tricky part is what you have to do if nuts round, snap, or the front cat section is rusted to the rear section.
 
Just got the old one off, after about 45 minutes. Here is my write-up, using 1LoudLS's as a base:

Extras needed:
4 new bolts for the exhaust flanges (10MM 1,5 by 30MM length, anodized or exhaust specific) they are not included in the Magnaflow kit.

Tools:
3/8 or 1/2 15MM deep well socket, 10" extension and Universal adapter (swivel, if you don't have one, you'll need it).
PB Blaster or equivalent
Elbow grease

1. Coat all nuts/bolts with PB Blaster and let soak for 20 minutes.
2. Unplug all four O2 sensors (I unplugged them, then removed them after the cat was dropped)
3. Remove two nuts on left exhaust header/cat
4. Remove two nuts on right exhaust header/cat
5. Remove two nuts (one from each pipe) after the third cat (or that weird stamped section for some of you guys)
6. Drop the front of the Y piece to the ground, then using force (if necessary) pull it apart from the rest of the exhaust.

Notes, when going back in with the new cats, do it in three steps, first the H-pipe section, use some brake cleaner to lubricate the ends before sliding it in. Then do each cat one at a time, you have to position it just right and then slide it in place, but it makes it a lot easier than putting the whole assembly in at once.

Also, make sure you check the position of the cats before tightening up, make sure you have clearance between the cats and the bellhousing of the transmission and that you have space between the floorboard and the top of the cat.

I had a friend of mine at the Ford dealership diagnose mine with a PO420 (bank 1 below efficiency threshold) code, and he said my O2 sensors were fine, that my cat was the culprit. However, now that it's off, I'm looking inside and it seems to be OK, it's a little brownish looking, but it's not melted or anything. I'm going to go ahead and go back on with the Magnaflows, but if it does turn out to be just an O2 sensor, I'll have an OEM cat for sale (the one that came off didn't have a third cat, it was hollow) for a very reasonable price :). I'm going to swap the 2 rear O2 sensors while I'm at it just to see if the code comes back for the other bank.
 
Last edited:
So an update, good news and bad news:

Good news, after about an hour of wrestling this thing back in, I got everything lined up and ready to be tightened down. Be warned that the Magnaflow cats are much wider than the stock ones, and they have this lip that extends out quite a bit, if I had more time, I would trim this down but I don't, so I'm just dealing with it.

Bad news, I bought new LS specific exhaust manifold studs and nuts to go back on with, there's a major problem though, the flange goes down about 10mm further with the new cats, and these studs have a stop on them that doesn't let the flange go down past a certain point. So for now, I am leaving it sitting in the garage and I'm going to get some new studs tomorrow from Advance that don't have a stop on them, then I should be able to get 'er done.

Oh also, when I went in with the new studs, I felt a lot of resistance, so I used a 10MM by 1.5 TAP to clean out the threads before I went back in. I also used just a little bit of anti-sieze compound, should help keep them from rusting together in the future.
 
Update, all done, finished up this morning. Looking at my old cats, they don't look to be in too bad of shape, however they are very dirty looking. I was a little worried that the diagnosis of bad cats was wrong after seeing them. However after I bolted up the Magnaflows and took it for a spin my fears were gone. I can say without a doubt that the car is much more responsive off the line and during throttle tip-in, plus it has a throatier sound to it (don't ask me how, I didn't replace the mufflers...). Also, the rough idle I was getting until the car warmed up has vanished.

All in all, I'm happy with the product, I would only add to the instructions that you need to get 4 new bolts for the exhaust flanges (10MM 1,5 by 30MM length, anodized or exhaust specific). I've cleared the PO420 code and should know in a few days of driving if it is gone for good.
 
Excellent.

rallyusa said:
plus it has a throatier sound to it (don't ask me how, I didn't replace the mufflers...).
Click to expand...

Any time you make a change to the exhaust system you change how it sounds. Plus, your system is more open since you no longer have clogged cats.
 
rally,
So you've had it installed for about four months now, how is it holding up. Any problems, exhaust leaks developing or any general concerns or comments regarding the Magnaflow system? Would you install it again?

I am also getting the PO420 code, and like you I also had a friend who is a Ford Tech check it out. He confirmed that it is in fact the CAT. In my case it appears that a small piece of the CAT has broken off, as you can occasionally hear it rattling around inside the CAT housing, usually at idle.

Anyway, I am just looking for feedback on the system because this is the route that I am likely going to take as well. Possibly with the catback system to come later... have you done that yet?

I've read posts from others who have used it, but current feedback from anyone else who has this system is welcomed as well.


BTW, obviously I'm new to LVC. Although I posted in the new members section when I joined back in September, this is only my second post overall and first in the LS Forum (which is the whole reason I am here) Been busy reading ;)


Thanks,
 
I plan on taking on the installation, got p0420 and p0430 codes even after replacing all four o2 sensors. Any other do's and don't do's during the install?
 
Do make sure the car is secure in the air, you don't want it falling on you.

Do soak all bolts you will be removing the night before with break-free. It'll make it easier the next day.

Do make sure all wiring is secure and away from all exhaust parts when the job is done, and make sure that you move the wiring after the fact to make sure that airflow won't push the wiring against the exhaust while on the road. Really this should not be an issue for you unless you don't clip something back that you removed for the install if you are doing a factory direct replacement but forgetting to put a clip back on can cause this. I failed to do this once on another vehicle, and after about 2 months of being pushed against the exhaust I started having problems. After about 4 months the exhaust finally succeeded in melting through the wiring. The intermittent shorts were split second events that only took place at highway speeds, so I couldn't trace the problem down. It wasn't until the wiring melted through that I was able to find it, and since it took a couple of months to show up after the exhaust work and it was an electrical problem and not an exhaust problem the first rule of troubleshooting did not appear to apply. It was on a 1987 Chevy halfton that I installed headers on, and for some stupid reason GM was using the starter terminal as its secondary power system source. I didn't notice that there was enough extra in the wiring harness to be windblown against the headers, and when the wind wasn't blowing the wiring would bounce back to its original position. Had to splice and tie the line back as the wire finally melted through 500 miles from home, and the permanent fix was to reroute the secondary power access directly off the battery. I now consider all work done in the prior year as change because of this.

Do use antisieze on the O2 sensors, even though they were just installed.

Do use silicone grease inside the O2 wiring harness to keep water out.

Don't sniff the converters, platinum/palladium will go into the lungs but they don't come out. There may be metallic dust left over from manufacturing in the new ones, and if the old ones are broken inside...

I'm sure others will have more suggestions. Enjoy.
 
Blk04LS said:
rally,
So you've had it installed for about four months now, how is it holding up. Any problems, exhaust leaks developing or any general concerns or comments regarding the Magnaflow system? Would you install it again?

I am also getting the PO420 code, and like you I also had a friend who is a Ford Tech check it out. He confirmed that it is in fact the CAT. In my case it appears that a small piece of the CAT has broken off, as you can occasionally hear it rattling around inside the CAT housing, usually at idle.

Anyway, I am just looking for feedback on the system because this is the route that I am likely going to take as well. Possibly with the catback system to come later... have you done that yet?

I've read posts from others who have used it, but current feedback from anyone else who has this system is welcomed as well.


BTW, obviously I'm new to LVC. Although I posted in the new members section when I joined back in September, this is only my second post overall and first in the LS Forum (which is the whole reason I am here) Been busy reading ;)


Thanks,
Click to expand...

Man, so sorry about the months long delay in my reply, I've been taking on more and more roles at work and since my LS hasn't had any issues lately I haven't dropped in here for a while (it still doesn't have any issues, was just curious about what's happening now :)). Anyways, to answer your question, I have only had one issue with the Magnaflow's since I put them on, and it was caused by me and easily fixed. The problem was I scrubbed the bottom of my car over a bump because I hit it too fast and it rubbed against the H pipe heat shield cover (the infamous 3rd cat) and it made it start rattling, so I had to get underneath and I just pried the whole thing off. Otherwise, everything's great, no issues, car runs fine, now I just need to get the cat-back Magnaflows to complete the system...
 
if you really want to "complete" the system, you should order some of the SS headers!
 
rallyusa said:
Man, so sorry about the months long delay in my reply, I've been taking on more and more roles at work and since my LS hasn't had any issues lately I haven't dropped in here for a while (it still doesn't have any issues, was just curious about what's happening now :)). Anyways, to answer your question, I have only had one issue with the Magnaflow's since I put them on, and it was caused by me and easily fixed. The problem was I scrubbed the bottom of my car over a bump because I hit it too fast and it rubbed against the H pipe heat shield cover (the infamous 3rd cat) and it made it start rattling, so I had to get underneath and I just pried the whole thing off. Otherwise, everything's great, no issues, car runs fine, now I just need to get the cat-back Magnaflows to complete the system...
Click to expand...

haha, no problem. I just changed the CATS last Friday, using the same Magnaflow system that you have. So far so good, stank for a little over a day but then started to fade and seems to be gone now... or I have not noticed it at least.
Would like to do the MF Catback, but that will have to wait.
 
Blk04LS said:
haha, no problem. I just changed the CATS last Friday, using the same Magnaflow system that you have. So far so good, stank for a little over a day but then started to fade and seems to be gone now... or I have not noticed it at least.
Would like to do the MF Catback, but that will have to wait.
Click to expand...

Cool, good to hear man, hope they work out for ya. I'll update this post whenever I finally get the cat-back's done too.

Also, did you notice a throatier sound after the install?
 
rallyusa said:
Cool, good to hear man, hope they work out for ya. I'll update this post whenever I finally get the cat-back's done too.

Also, did you notice a throatier sound after the install?
Click to expand...

:Beer


A little bit, yes, but nothing major.
 
You must log in or register to reply here.

Members online

No members online now.
Total: 125 (members: 0, guests: 125)
Back
Top