I thought I'd throw out a bit of "learnt knowledge".

About 3 months ago I started hearing the telltale signs of an exhaust leak. One of those things that you only hear as you drive close to a curb on the driver's side since the curb will reflect the sound back to your ear.

It was a little "pfffffffft" at speed... I knew what it was, and I figured I knew where it was coming from (well, let's just say that I HOPED it wasn't coming from where I FEARED it to be from!).

After my headers (Downey's) went on, I had the shop re-work what they did with the crossover since the new one blocked my access to the tranny pan. The Downey headers install with the crossover running under the truck - not over like stock. The rework left the crossover under the pan, but now it drops out as a bolt-in section. Not my favored solution (since the crossover is still lower than the pan) but it works and I was kinda' fed up with them being idiots.

Anyway... My hope was that the leak was coming from the new bolt-on flanges, my fear was that it was the headers themselves.

I got my hope...

It took me about 3 months to get time to deal with this - all the while the "pffffffffft" got louder - but never really obnoxious. I just knew it was there, so it became easier to tune into.

So, I got some high-temp gasket material, dropped the old gasket, cut a new one, and fitted everything back together. fwiw, the old gasket looked like swiss cheese - there are a number of little (about 1/64") holes around the sides and out through the edges. weird.


(now here's the "learnt knowledge" part)

_WOW_. First off, it's a lot quieter than I thought it would be, which means that it was a lot louder than I realized. Second off, the truck runs a LOT better. It's smoother, there's more torque around the "highway passing" zone, and just feels more responsive.

Bottom line - I was surprised at what a little leak like this could do.


Interesting stuff!

 

Yeah, the leak on my 1st gen was wide open before and when I got a temporary fix on there I was VERY surprised at how much more oomph was behind the pedal! It's still a 4banger so I wasn't expecting much but it was a welcome surprise

Maybe I should look into copper gasketing when I do my headers...?

 

I have TRD headers and I have a serious exhaust leak. I'm pretty sure its those damn TRD gaskets. Also I noticed that the casing for the 1st cat is craked open along the seam from wheeling carnage. The truck sounds like a tractor now. But I don't have time for someone to look at it just yet. Maybe in another month or so.

 

Maybe... I keep hearing though that the best gaskets to use are the stock manifold gaskets from the 3.4L (i.e., NOT the TRDs). The latest back info to that though is that it depends on who's headers you go with.

So confusing...

 

Tell me about it!

Well, someone with LC Engineering headers (I think it was Seaflea) mentioned that he hasn't had problems after doublegasketing.
I may just do that.

Oh yeah, glad to hear that you've got the problem solved

 

mark,

this is fantastic news for me to read this b/c i have an exhaust leak somewhere too. it sounds like its coming from the right side of my 4runner. i'll have to do this sometime soon too.

bob

 

Good info Mark.

Yep, Edelbrock's require the use of their gaskets.

Good idea about the removable cross-under section. I need to weld some type of brace near the cross-under pipe, after all it is currently the lowest point on the rig (towards the front anyway)