This can be a tough repair/mod to do but the end results will be pretty good if you pay attention and of course read as much as you can. I set this up as a dedicated write-up and perhaps it will get sticky status. The cracked manifolds aren't going anywhere on the v8 engines plus headers are just cool.

Needed tools and supplies:

-Swivel socket and two 12" extensions at least. I wish I would have had more in 1/2" but 3/8" works fairly well. Clearances are at a premium.
-Box wrenches
-Long shaft wrenches (ratcheting or standard end)
-Impac with swivel, extensions, deep and shallow sockets
-Swivel head ratchets with deep and standard sockets, shallow might make some things easier but not necessary.
-Breaker bar, not too long but be careful pulling the studs, I estimate its about 75lbs on them but I will look it up for installation. Warning not to bust the stud off in the head again
-Torque wrench, for installation....this is a must to seat the gasket properly. Two torturing sessions are necessary. One week apart.
-2 bottles of your favorite penetrating oil (snapped off bolts in the head is absolutely a terrible idea, you would have to pull the head if you mess it up)
-Rags, many or all of them
-jack - not the stocker.
-2 jack stands of non harbor freight brand
-good shop light
02 sensor sockets or 7/8" wrench
-Torx sockets(I had to order these)
-2x4 wood(16" but that may differ with your jack, explained later)
-safety glasses, lots of rust flakes will come out or dirt while you're down there. Don't get that crap in your eyes.
-deep socket bolt extractors

For the welding:
-tig or mig welder, I'm fluxing it personally (this method worked very well actually. I use a Hobart 140 but I am not sure that a flux only machine would have the ooomph to get the job done. There's only one way to find out but please get a test pipe and play with the welding wire before going at it on expensive headers)
-stainless 304 wire or rods
-triangle magnets (at least 4)
-stainless wire brush
-paint marker


New hardware:
-Exhaust manifold botl/stud set (I went with level 8, there is also titanium and also arp studs you can get)
-Exhaust collector donut gasket
-A couple of donut gaskets for the cat to ypipe
-New exhaust studs if you snap one
-nickel anti-seize

You need to remove the airbox completely to give you access the needed space.

Completely remove the ypipe first as you will need all the space you can get. Impac comes in handy busting this. Just get the studs out and toss it. I highly recommend the urd ypipe. Its well made and the elimination of flow impediment will assist with the hp/tq gains.

Take the tires off and get the runner up on stands. You will be spending a lot of time on your back, knees, crouching, etc. The higher the better but I only lifted mine high enough to get the tires off the ground since I have a lift and larger tires. I use a set of 12t jack stands because of the height. Take down the floppy engine splash guards as this is how you will be accessing a lot of the bolts.

Organize your parts! I have a makeshift table that I fill with bolts sitting in or on the parts I have to remove.

Now spray down all of the bolts with ludicrous amounts of penetrating oil. The more time you can get them to soak the better. You can work on the heat guards but you won't be able to remove them till the next step. You also need to spray the engine mounts on the frame side! Those can be a real bear and since they are specialty bolts I'm sure Toyota charges a mint for them.

Close down the garage and let them soak overnight. There are some bolts you won't be able to spray easily without getting the heat guards out of the way so do what you can and then shut er down.

Remove the oil dipstick and tube. It bolts to the manifold.

Loosen the engine mount bolts on the driver side or passenger side and remove them on the other. This will give you the flexibility of allowing the opposite side to tilt while the other side lifts.
You will need a piece of 2x4 about 12 to 16 inches long to get the engine lifted enough to make access easier for the studs.

Now its just down to getting everything off. You can only do one side at a time unless you have 2 jacks and two pieces of wood. Don't twist too hard. If it isn't giving put about 65lbs of pressure on and then spray with more penetrating lube. Patience is your friend. NE types might need 3 or 4 bottles of penetrating lube. Just keep working it with head, oil, until it pops loose without excessive pressure. Not gonna warn you again. You've heard the safety brief 3 times now.

To be continued......


Got started on the headers. Whew its tight spaces in there so hardly any pictures. All I gotta say is pb blaster or deep creep those bolts multiple times. I don't have a huge rust issue but man some of those bolts are tough. The motor mounts and studs need soaking overnight because I ain't busting a stud.

I had to stop today on the second day as the studs underneath needed the heat shields out so I could spray them liberally with deep creep. I took some pictures to illustrate exactly what I'm talking about. Not an easy project to undertake but this is why the shops are charging so much to install.

I'm happy so far with the progress.

Coming soon is the pics and welding of the shorties to the stock cats and reinstallation of everything. Ill break everything down in the coming posts. Ask any questions and I will do my best to answer. I'm working my way through it but I am a guy in the garage.

Stock Y-pipe versus URD Y-pipe


Airbox and other items removed. Tape your removed connections so you don't forget one.


Just a picture of clearance in there


Jack with piece of wood. 16" worked well for me. 2x4 probably works best but on the driver side you'll have to play with it for it to work.


More of the clearance nightmare


Engine Bolts! Do NOT LOSE THESE. Just sayin


Heat Shields finally came off. If you twist off the bolts holding them....never fear. You'll not be using them again and the bolts go into the manifold so crank away.


After the heat shield is gone on the Passenger side.

Added a few tools to the list above and just a single tip right now during day 2.

There is a stud right behind the shock tower. Feel free to discuss this with many expletives. Best way to get to this is to come in from the top with a deep socket and your swivel head ratchet. It isn't accessible through the side or from underneath. Now I won't put an armored bumper on the required list but it sure came in handy. On the passenger side I am waiting on a t6 socket to assist getting that one off. I thought it had seated fully and rounded part of the 14mm nut off. I'm still working on that but the driver side is completely off at this point.

With your sockets you need to have 6 point sockets. 12pt sockets do not have the safe surface area or grab that a 6pt does. Also the deep sockets seat fully and the normal depth sockets do not. It looks like they do but they are about a 1/4" from seating. To get these studs out fully seating the socket is vital. Even with 2 days of pb blaster a couple of the studs took well over 100lbs of pressure to bust loose. I punched myself in the jaw when one let go and it did not feel good.




Ok a few notes about this for the shorties people. Don't drop the damn manifold. Driver side practically fell off except for the studs on the air tube. Those blessed with no air tube need to be careful. Those with air tubes will need to gently pry the air tube back so the studs come completely out.

The issue with clearance has to do with the 02 sensor. Since the manifold would have to come forward the 02 sensor contacts a heat guard attached to the block. Its not razor sharp but 02 wires are sensitive and I would hate for anyone to mess up a sensor because they gave a good yank forward to free everything up.



Just a picture of the backside. There might be a chance you could remove the 02 sensor before but its a lot easier when the manifold is out. 02 sockets are big and take space and even a wrench in there feels like you have a sledgehammer.




Just a picture of the table I put up when I do major projects so I can spread out a little and organize things where they won't be kicked accidentally with bolts going everywhere.

Just got some very bad news. The friend who was going to help me weld up the headers had to leave town so in order to get the 4runner out of the garage in less than 2 weeks I have to do the welding myself. Now usually that wouldn't be an issue but since it is stainless I had to get a special spool of wire. Now I need to get some practice pieces of stainless so I can be confident in welding this up without making a mess of a pair of beautiful headers. The more I research though stainless is easier to flux or mig than it is to tig so I have fortune running with me. From what I've seen slow wire and cranking the heat will make sure everything is solid but I want to practice on some similar pieces before I take a crack at the real thing. Stay tuned......

Not advertising for these guys but they do make pretty good wire so I'm willing to give it a go to get this thing on the road again.

Blue Demon 308LFC-O X .035 X 1# Spool stainless steel flux cored gasless welding wire - Brazing Rods - Amazon.com

Back in the garage for day 3. The extractors came in so naturally I dropped everything on a Saturday morning for some wrench therapy. Stud came out easily and its all about having the right tool for the right job. Deep well extractors added to the tools list. It isn't necessary but if you fudge yourself then it comes in handy. Pics are below and link to the product is as well. Pretty cheap and honestly for us yota people this set should help with multiple projects as well.

TOPEC 5-Piece Spiral Type Deep Extractor Set, Twist Socket Easy-out Set, for Removing Deeply trapped and Broken Bolts, Studs, Fittings, Threaded Pipes and Pins - - Amazon.com



Remove all the 02 sensors at this point. Don't start cutting and welding with those things in or you might have some deep regrets.

Ok on to the fun stuff!

Follow the instructions and cut off the heat shield. Its 1 5/8" off the end of the cat. The weld is kinda sloppy on mine so its going to be a good guesstimate any way you cut it.

For centering I marked the center of the 02 sensor bung in a straight line past where the weld will be so that I could cut the original manifold and line everything up. At this point it is a good idea to take a look at the rotation of the exhaust seals and where the studs are on the ypipe you are using. If you're going custom all the way back do as you please and just make sure you line everything up right. Each side has a unique angle and rotation. I am not sure why they did this but a bull whipping would be a good idea for that particular engineer.


Cut behind the 02 bung on the factory manifold and then seat the cat into the new shiny things. Center everything up. Make sure you mark everything for which side it is on! Please....

After you've sliced and diced make your marks based on the line through the center of the 02 sensor. It should look even across the cat. The directions say 5/8" off the end of the cat. Again since its welded this is pseudoscience but its enough to check your markings you made with the new header slid on top the old tubing.



Now for fun take it apart and then match up your old header for rotation and see if it looks the same. It should be very very close.





Now I have to stop here because I am waiting on my wire to come from the great Amazon. I am tacking everything on Monday and then will check for fit on the whole assembly. You can also go through at this point and start adding the new hardware so mocking and everything is a slick process.

Day 4:

There are still lessons to be learned and hopefully some tips I can share. So to make sure my marks were correct I put everything together because I want a setup with as little bind as possible. Not only will it look better it will also last longer.

Fitting is pretty easy actually with the parts not welded up so I attached everything including the ypipe to see where I stand. Marks were pretty good but I did realize that I had to pull the cats back out so that I could finish the cutting.

I found that my marks were good and perhaps off by a couple of mm. Not bad for a garage brew header setup. From there I made my cuts and this is mostly about making the costs and devouring them. No sexy pics till I tack weld and then pull everything off for beads though. You'll have to stick to whatever Google spits out for entertainment for now.

I had to make my cuts with a grinder because I have that at my disposal. I would recommend a bandsaw or a chopsaw if I had my choice just because you could set it up a little easier and spend less time with the grinder and ruler.

First off make sure you mark the cats for shich side they are on. It will save you headache and excessive language.




I chose to cut in the neighborhood of my marks and finish with the grinder because too much is too much.



Do make sure you stick a rag or shop towel inside the cat while you are deburring your cuts. First off it will increase flow and 2nd you don't want hot shards or excessive powder sitting in the cat itself. I shook them out and used a little air to clean them out after I was done anyway but it helps keep the bits of metal getting into difficult spaces.




Finished side



Other side finished.


***Please note that this is where I screwed up and ended up redoing it. Aboslutely mark for center on the catalytic converter but the header inserts into the Cat and not the other way around. If I would have had my head on straight this makes sense with exhaust flow. Fitting the Cat inside of the header creates a high pressure zone and impedes flow. Do not go any more than 2.6" or 2 5/8" wide on diameter or you will be filling in gap and the Cat burns through much easier than the stainless on the headers. ***

Now according to the instructions it says that the diameter will be about 2.6" but I found that a no stress connection with everything was around 2.4" ish. Im sticking with the 2.4 ish so that I am not filling in a gap when I do the finished welding. There isn't a way to cut and bend the metal so I guess I might end up with less than optimal flow but I will end up with a solid weld. I don't wanna fudge myself here in other words. If I find that my tack welds end up too far on the tube ill break them and take the rest of the material out.

Ok one sexy pic. This is the driver side of course and you can see how tight everything is even with the engine raised. Its much tougher to get the bolts in with the headers in but I'll have more on that later.



Quick pic of the ypipe in and bolted up. I dont have any seals in currently and don't test fit with them in either. Once they are tightened the seals mold, especially the donut seal at the exhaust connection. The 2 hole seals can generally be pulled apart but I like just tightening up once and being done with it.



Passenger side pic of down the hole



Ok so other things you will want to do is reuse parts if able. Coincidentally the exhaust studs are the same as the header studs. I was able to pull apart enough of the studs with threads intact that I now have studs for the exhaust. I tossed them in a bottle of pb blaster and left them for 24 hours and bam.....the nuts came off easily and I know have studs that can rust up on the exhaust after they are installed.



Also you will want to get as much if the old gasket material off the block and off of the catalytic converters as possible. Those gaskets cook in so once they are used they are toast. Old gasket material will keep the new gaskets from sealing and seating properly.



That's all I got done today. I'm up to about 12 hours of actual work into this and so I am not of the opinion that this impossible in much less time with people that know how to turn wrenches and have a free weekend. Definitely so with the long tubes. I would have already been done with those but I do want my exhaust smelling normal and the conditions here in michigan are better suited for short tubes as well. The stainless grade of these headers is still 304 which is the lowest grade of stainless. I'm not sure if a higher grade would perform better here but letting the stock cats take the brunt of the weather is an excellent idea. I'll see if I can mount up some splash guards to keep some of the sludge off of them. I use fluid film twice a year and have done extensive work to keep the frame in tact for a while but there isn't much you can do for stuff that gets really hot. I will be painting the welds over with high temp paint just to weather proof them a little more.




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Less work than I would have liked to get done but progress nonetheless.

I got some stainless tubing just to see if it was easy to brun through and play around with the settings a little.

As you can see it has a raised edge to it. I didn't think it was a strong weld so I cut it and then fully welded the tube and tried to break it. No such luck with the hammer so I accepted the fact that it won't look quite like a tig weld lol. The settings on my hobart were on 4 and then wire speed was about 35 to 40. Any slower and you don't maintain the pool and any faster it piles up higher which is wasted wire. I could step up to 5 on the power but since the weld was plenty strong and fat at 4 I stayed there.

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I was going to set it up and tack on the vehicle but with the extra tubing gone from the cutting it didn't center nicely that way so I used my marks and tacked it on the table.

Set up took a little while to be satisfactory.





Tacked and ready for test fitting. I made small tacks so if I had to break it all up and start over I could.



Pretty good fit. I wanted to take a picture of it but there was a little pressure from moving the ypipe to line up but nothing unreasonable. So time to weld this sucker. I went with a stitching pattern to make sure I sealed it up completely and welded in opposite sections to allow everything to cool. Stainless loves to seal the heat in and it doesn't spread out like with carbon steel.



Apparently the thing you want to watch for is sugaring of the weld which signifies that the chromium has been compromised. I didn't get any but I will still be using some hi temp paint tomorrow before I throw it in and loosely install the driver side.

Once I get that in I will turn my attentions to the passenger side and wrap this up. Ran out of time today because I was waiting on the post office to deliver everything from Amazon.

First weld ended up being too far off for my taste. It was a great weld though. Busted it loose and I am adjusting my strategy on install. Im saving the driver side for the last side to do.

I was able to separate without damaging either piece. Ill just have to be careful when welding it up.


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Final post of the write-up right here ladies and gents.

So I will share a revelation that I had which led me to my big setback. It should have thrown more red flags than it did at the time because I was more worried about how to weld stainless than what I was doing in front of me.

The directions say to cut 5/8" back from the weld joint on the stock manifold and that the hole should be about 2.6" wide. Let me convert that for you. What that means is that the header should fit into the catalytic converter. So the ID of the header is 2.5". Now you want to be pretty close on fitting the header into the fat but it is going to insert about 3/4" to 1" into the cat. Still plenty of room before the screen but this allows the custom angle that both headers will have off of the ypipe.

This is the picture before the revelation.


Picture of the measurement I had when it inserted easily onto the header.



Other side


Post revelation:


Other side


And how everything lines up below:






So I tack welded both sides with the ypipe installed. Do not do it one side at a time as the angle is a little funky off the header and you'll never get the otherside right unless you just won the lottery.

Then carefully disassemble the ypipe and until the cats from the underside so the ypipe is free to move around. You will need it to wiggle the new assembly onto the weld table for final welding.

No pictures of the final weld on the cat. I was moving too fast but I'll get one for the driver side.

What I do have pictures of is the completed passenger side.





I had a couple of extra little jack stands assisting me in holding the ypipe in place while I bolted in the cats and wiggled them over the header.

On the driver side you can leave the exhaust studs in the cat but on the passenger side the clearance is too tight so make sure the studs are removed when you are sliding it into position over the header end. The other reason to have everything bolted in is so the ypipe is correctly installed. It is free to rotate and if you have it out of rotation it will find quite badly.

I fought with this for a while but once I had a method to the madness it fell into place.

Here is the driver side all welded up. Everything looks good so its going in. To combat some of the difficulties of getting the rear topside bolt in I am using a stock stud in its place. I had a few come out that were very clean and since it is a grade 10 stud there shouldn't be any stretching that might have occurred. I think the bolts are handy if you really need to replace the hardware but the stock studs, new or reused, are just fine as well. The arp bolts are probably the nicest however at the 300 bones they run it is probably overkill unless you are going to be building a boosted application down the road.


The top rear and second from the rear are bar none the toughest to get started from the ground. I know there were some that got the bolts in but studs do have the advantage of being able to be put in first without the fear of cross threading anything. Be very careful running the bolts in.

Well all thats left is putting the remaining bolts in on the block and then reconnecting everything.

It was quite the project and I would not recommend this one without at least a friend to help out. It is tedious and at times difficult. If you go in with everything listed though there should not be an issue.







I'll also post up a video of how it sounds. Stock muffler and urd ypipe only. No other mods to the intake or exhaust system.

No pictures to speak of because there's no room. Tip on getting the rear upper stud tightened. To get the nut started the header has to be away from the block so the nut will fit through the space. I honestly don't see how you can do this without one person on top with a finger on the nut and then someone going through the side putting a finger on it. Teamwork makes the dream work on this one. Very difficult to get started and another tool set is required. 1/4" swivel sockets.

Also don't use the darn bolts on this. Use a stock stud if you want to keep your sanity. I used a couple on the driver side because getting the bolts started was a nightmare. Torque to spec is 32ftlbs.

Thank for working on this writeup, thats great! I haven't seen any writeups on this, and with how common swap it is, surprised there isn't that much material on it. I really enjoy seeing all the pictures!

I'm definitely trying to get some solid info out there on this mod and provide help where I can.

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Good deal! Glad your putting this together. I didn't have time to really do a write up and I'm not that good at those anyway. Cuss words don't translate very well into instructions. I got lucky with rust being that mine spent most of it's time in Florida, so most of my fasteners came loose with the right leverage and angles.
Cool Jack by the way.

That jack was tossed out by the military because it was broken. I had to refill it with oil and replace the fittings but it is handy to have around the garage. Its a 4 ton jack and has incredible reach. My only complaint is that it isn't on wheels. I might heavily modify it in the future to see if I could get some casters on it and then put the pump on the assembly and keep it so its removable with a longer handle. That's for another day though.

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Do you need to use thread locker on the stud nuts? I've lost a few of the stud nuts when I put my Doug Thorley Headers on, quite annoying.

I would not recommend a thread locker for 2 reasons. First you should do a retorque on the bolts a week later or so and second because if you have to remove it you will hate yourself. I personally have never had a problem with a header stud coming out of torque after double checking the studs. They usually don't even back out. What occurs, in my opinion, is that the gasket flattens and seats as it breaks in with the high temps and then cooling.

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That's what I was thinking, thanks for the reply!

Good stuff. I recently did mine and put some info in my build thread:
ZLJUANN'S RallyRunner Build Thread

Feel free to reach out if you need any help. I only used standard tools, namely a Gearwrench ratcheting wrench set, Stanley socket set, and various extensions from Harbor Freight, an engine hoist to lift the engine and had mine out in 1.5 hours. took about 2.5 hours to get the shorties in. Dexterity is key.

I've done a couple of write ups like the steering rack bushings but nobody seems to care. Good job writing this up anyways!!