Unzie22

Hello all,

I recently purchased a new to me 4Runner V6. It's a 97 SR5 with the posi rear end and the 3.4 litre V6, 182 ticks on the dash and the best kept runner I have seen in a while. I purchased the truck down in San Diego and drove it back to Montana (long, long drive) with no problems and averaged around 22 MPG all the way up to MT. The truck was in immaculate condition when I bought it and I have driven it really easy since I have had it.

I just recently diagnosed a clogged cat. and exhaust manifold leak. My diagnosis is due to higher temperatures and higher humidity in it's old home that the manifold may have finally bitten the bullet and developed a crack. It is showing classic signs of cold start clicking and low power in lower revs, diminishing as the motor climbs through the revs. Also as the vehicle warms up the noise fades ever so slightly, which would indicated that the manifold has expanded as the engine has built heat.
I previously had a 96 4Runner with the 2.7 4 cylinder with a similar problem, the manifold was basically cracked in half and I ended up having to buy a header due to problems with stock replacement manifolds (was sent two defective units and did some research only to find they all take a dive early). I recently read a thread, however, where the guy had found a stock header off of another 2.7 4cyl, which peaked my interest as to whether or not anyone recalls if Toyota had ran a stock header on the 3.4 on a TRD supercharger equipped 4Runner.

I would love to avoid spending $600+ on headers and a new cat.

Any input or suggestions (other than welding the manifold) that you might have would be much appreciated.

j-man

so what's your question? You can buy a set of Doug Thorley headers to replace both sides, or try and replace one stock long manifold if you can pin point where the leak is. Just to note tho: removing and replacing manifolds is a royal pain in the a$$ - if your gonna go thru all the hassle, might as well pony up for some DT headers and be done with it. Your also going to need to replace all of the manifold studs/nuts (qty 12), new manifold gaskets - 1 each side. Prepare for bloody nuckles, swearing, and an amazing sense of acomplishment when done - have a beer close by.

j-man

oh also, im not aware of any 4runners from the factory with a posi or limited slip, unless you have the locker - (is there a RR Diff Lock) switch next to the steering column? IF the previous owner said there's a posi/LSD, chances are someone may have installed a true-trac or the japanese LSD after they drove it off the lot.

Unzie22

My mistake on the locker, the truck came stock with that system.
I helped my uncle do headers on his 3.0 V6 Pickup and the motor mounts had to be loosened and pulled on one side. At this point I am preparing for the worst. I have narrowed the ticking to the left bank towards the rear of the motor. As I mentioned my experience with stock manifolds has been negative and the performance advantages of the aftermarket headers are very noticeable.
I asked about the Doug Thorley Headers because of the price difference between those headers and the same set up from Downey and LC Engineering, who also offer a chrome and ceramic model. I am going for the most bang for your buck deal at this point, still trying to pay my way through college.
I was hoping to find someone who knew of a TRD Supercharged 3.4 factory stock with headers instead of the manifold. I fear, though, that I am being too hopeful.

turboale

My TRD headers will be coming off shortly, they are extremely soft and have warped so badly its embarrassing. Has anyone on the forum gotten the DT headers? Whats the price difference from the others?

I have never heard of an S/C coming stock on a 4Runner. It would be a dealer installed option that I'm almost positive was considered "aftermarket" from TRD. Some dealers might have had a bundle deal or something, but unless the previous owner added headers they will be stock. I could be wrong here but that is my understanding.

okie81

Thorleys are great, you may want to consider replacing with an OEM manifold though. The performance gains aren't too exceptional since the true benefit comes in conjunction with a supercharger.

turboale

I'm s/c'd with small pulley and bigger injectors...

Where did you get yours? I just checked the downey site and it says there are clearance issues with trucks that have a body lift...? Can anyone verify this? They say the steering shaft might need to be adjusted...

Also has anyone tried the ebay "obx" headers? They look decent in pictures but don't particularly want to be the ginny pig. They sure are a good steal compared to Thorley and TRD...

hross14

i bought the headers and within the next couiple months will be installing them and my new motor.

As for stock manifolds--i have a set out of a 1997 4runner, 5Spd. Pay shipping and the price of a twelve pack and they are yours.

okie81

I got mine while back on ebay. I believe Thorley designed the TRD headers? definately cheaper though. I'm thinking about a 2.2 pulley as well, did you have to tweak anything for the switch?

The OBX headers I've seen on Ebay are racing headers. They're probably good for performance, but there goes your drivability and smog. I don't wanna be the guinea pig either

mt_goat

My guess is headers will give you more problems than a stock 3.4 manifold ever would. The 2.7L 4 cyls are a different story though, those things are always cracking.

turboale

You don't need bigger injectors since you added the 7th injector. I'm also not familiar with the 7th injector setups but you might have to adjust that system for the extra boost but thats it. Basically what you did is add an extra injector instead of swapping out all 6 for bigger ones.

DT made the headers for TRD and improved on their design to eliminate the issues of leaking and made installation clearances easier. That seems to be the best route at the moment. Anybody know where to look for them? I found them on URD's site for $600, is this the best price for them?

turboale

Bump...?

okie81

All I've seen have been in that price range too. I did come across a set of Edelbrock headers (discontinued) on Ebay a while back. If you're lucky enough to find a set of those for a decent price, I heard they were excellent headers as well.

CLin9383

i see alot of cracked 2.7s but not many 3.4s. if i had a crack in mine, would you suggest i go with another OEM manifold or get headers...im not S/C btw.