calipatient

iTrader: (1)

its still helping people! I'll be cutting mine up and welding tonight. Thanks for the ideas.

axelkoup

still helping people!!!... haha, I'll be cutting and welding mine tomorrow evening...

perfect time for a 3.0 head gasket to fail, right before x-mas... so much for buying longfields with my x-mas bonus... I'll post pics...

riderofthegnar

Dear Red_Chili (and other contributors to this thread),

Did you end up resolving the buzz that you described in the post above? If so, I was wondering what it turned out to be, and how you fixed it, because I am experiencing what sounds like the same phenomenon.

I just had the 3.4 swap done on my 4Runner. Immediately after the work was completed, I had to leave on a road trip from B.C. to AZ. About one third of my way into my first day of driving, the truck started to develop an increasingly pronounced buzz at about the rpms and amount of throttle that you are describing. In addition to the buzz, there is also a kind of "chuffing" or "sputtering" sound. I am thinking that the sputtering sound is due to the back pressure of the exhaust system above the cat, that it is normal, and that I wouldn't be able to hear it if some part of the exhaust system wasn't touching something or if some part of it didn't have a leak. (Please let me know if what I'm thinking here doesn't sound right.) If I increase the throttle, the chuffing and sputtering goes away, and the buzz turns into a nice but loud "purr" that resonates through the whole truck (I am not sure whether it is supposed to resonate quite that much though).

Half-way through the third day of the of my road-trip, the flange between the collector pipe and the cat came apart. At which point my truck started obviously to sound something like a Harley. Both bolts at the connection where completely gone. I am not sure whether the exhaust in front of the cat is vibrating against something and that this caused the connection to come apart, or whether the connection had started coming apart on day one and that that accounts for the vibration and chuffing/sputtering at partial throttle.

I have looked for signs of rubbing, but haven't spotted any so far.

Here are some questions that I am trying to figure out: Are there common spots where the exhaust above the cat can touch the frame, or body, when people do 5VZ-FE swaps into 2nd generation 4runners? How much clearance is required between the crossover pipe and the collector pipe and everything around them, to avoid vibration? Is it plausible that the touching caused the vibration, which caused the connection to come apart? Or, is it more likely that the connection is the cause of the buzzing and sputtering?

smithoman

Awesome information! I have a swap planned for next month and this crossover information was one of the big question I still have. This may sound stupid, buy why not run dual pipes back and crossover back past the transmission?

Red_Chili

It's been done. The question is, where do you want potential problems? You have a clutch slave and they don't like heat; you also have fuel lines on the right and you do NOT want exhaust near it if at all possible!! DAMHIK, I had a slight fuel leak at a junction and would not have wanted heat near it. Glad it wasn't.

Also, where will you put your cat? Now two cats?

A slight update, apparently that buzz I had above was a tight clearance to the bellhousing that I didn't catch. I figured I would live with it. Well, as luck would have it, it caused a crack in the collector that ended up breaking apart on a trip. Had to get it patched together in Wyoming and then pulled and remade it at home. With... uh... more clearance. LOL

I ended up just spraying the repair with VH1 coating and it has held up great. Since then I put a blower on, and things seem peachy.

ebbarc

I have been thinking about doing this myself.... good to see lots of photos of others work... I'ma save a few bucks on this one .

thanks !

GRN-Yota93

hey guys i understand that building the custom crossover pipe makes for a clean install but after hearing about the problems with heat stress and with the probability of a supercharger in the future i decided to run exhaust under the tranny. does anyone have major issues with doing this?

vital22re

iTrader: (2)

If you build it right you won't have problems. I'm runnin a sc and have no issues with my crossover

GRN-Yota93

Thanks dude I ended up running it under the tranny if heat becomes an issue then the crossover Mod will end up happening. Awesome thread thou thanks for the input vital!

UbendImend

Thanks for the write-up! This was one of my biggest questions. Didn't see the sense in paying for a modified cross-over when all the materials are already there waiting to be cut up.

UbendImend

Please forgive me if this is a dumb question, but can the crossover mod be done with the drivetrain in the vehicle?

ebbarc

I installed mine with the drive train in, but it was a pain in the ass. If I were to do it again I would fab it up and install it before putting the motor in.

UbendImend

I was afraid of that, but figured that would be the response I would get. Thanks!

Sas954unner

Great writeup!
This should be a great help in the next few days!
Is it worth it to header wrap it?

Red_Chili

You are far better off to ceramic coat it... inside and out. Header wrap concentrates the heat in the metal; ceramic coating reflects it away.

vasinvictor

iTrader: (3)

Yeah, negative on the header wrap. It seems like a good idea, but really it's not from the experiences I read here.

Sas954unner

I'm about to start building my crossover but mine looks nothing like these.
Mine comes together off the two manifolds into a collector where each pipe is crushed down to a half moon to squeeze together into a singe pipe collector, no elbows or pre-bent pipe to cut off anywhere, looks like I'm going to have to build this thing from scratch!

dntsdad

I'll trade you one picture for all those words.

Sas954unner

Here's what it looks like after I cut the flanges off

Sas954unner