Cracked exhaust manifold question V8
 

I've been reading up on the cracked exhaust manifold issue for the past hour or so. I recently bought my 06 and have paperwork that shows it has already been replaced. I do still noticed a tick on cold start, and also if my back window is down, I do smell the sulfur smell under load. Neither of which really bother me.

2 questions I wasn't able to answer while reading other threads.

If this was replaced under warranty, and Toyota is aware of the issue are they replacing the exhaust manifold with the same OEM part, or has it been upgraded not to crack?

Also, does the cracked manifold affect performance?

I am pretty sure they are replacing it with the same OEM manifold.

I been driving with the crack for 2 years now and there has been no performance loss.

I doubt if affects performance.

It doesn't throw codes or affect emission tests, either. Add to that the fact that it's very hard to observe the assumed cracks directly, and I remain a little skeptical that we can say with certainty that the ticks are a definite result of manifold cracks.

YMMV

has anybody replaced the stock with the Aftermarket headers - and relocated the Catalytic converter?

Aftermarket headers don't exist.

Well, they don't exist for the 4Runner...but they do exist for other 4.7L vehicles and some people have used those on the 4Runner with some modification to make them fit.

Personally, the Pacesetter stainless direct fit replacements look like the way to go to me. The engine in mine sounds horrible unless it's hot. Just awful. It's embarrassing.

This is what I'm talking about.

Is the problem w/ the aftermarket headers the actual fitment or the fact that the OEM catalytic converters are built into them?

I am surprised that there aren't some aftermarket options available that are designed for the 4runner. Personally I would like to move the cats backward anyways, or Y-pipe them into 1 cat.

I am surprised that this hasn't been explored more especially when people are having issues with the manifolds cracking.

There is a TSB-0346-09 for 2006 to 2009 4Runners. It says to replace the converters if the customer is complaining of the egg smell. The old numbers are still used in production, but it says to replace if the customer is complaining of the smell. New numbers 17410-31600 & 17450-31060.
I would assume that if got the headers replaced because of cracks you probably get the production numbers.
The reason the first catalytic converters are close to the heads is so they heat up faster and start working sooner. I remember my 1979 Firebird had the one converter under the floor pan. They also started grass fires on trucks when they were off road. I know the 4Runners have the 3rd cat low; I don’t think it operates as hot as the 1st ones.

Is it a tick or a knock? Could if possible be this: http://www.toyota-4runner.org/4th-ge...fix-first.html

Do you have a theory as to where the tick comes from? People have taken stethoscopes and the noise was coming from the manifolds, then they replaced the manifold and no longer have the tick. Sounds like case closed to me Grissom.

The issue is a combination of the catalytic converters being part of the exhuast manifold, the lack of space to work with in the cramped 4Runner engine bay (witha 2UZ-FE shoehorned in there,) and lack of demand.

There's been one or two people who have made some modded headers and talked about custom products, but I haven't really seen it take off. Hell you need to drop the motor slight IIRC just to get the damned headers off.

For what it's worth.. ALL Toyota vehicles have the egg smell. I used to joke with my buddy that if we were climbing a hill on the highway and we started smelling eggs...there must be a Toyota in front of us and 99% of the time there was. They all stink when under load. It's a Toyota thing.

That would be good evidence. I took a look and have yet to find the reference. Happen to have a link?

Of course I can't find it, pretty sure it was in that monster 50 page thread about the exhaust tick which is no where to be found.

I did find examples but unfortunately none of them use stethoscopes and not all examples would hold up in court but its the best I could do without spending hours:

See posts #6, #13, #15 here: http://www.toyota-4runner.org/proble...fold-tick.html

See posts by Tuscon T4R here: 2004 V8 4Runner cracked exhaust manifold - Page 2 - Expedition Portal

See picture (its of a Tundra manifold but they suffer the same problem, as do the Land Cruiser and Sequoia) in post #24 here: http://www.toyota-4runner.org/4th-ge...ak-tick-2.html

See post #22 here: http://www.toyota-4runner.org/4th-ge...anifold-2.html

The theory is that the crack is open when the metal is cold so you get a slight leak. Then once the metal expands from heat, it closes the gap and stops the leak.

I have the tick and there's no doubt in my mind I have cracked manifolds but I do see where your coming from because other things can be mistaken for the cracked manifold like: piston slap, valve tick, fuel injection tick etc.

If the cracks do not affect performance, why would you pay a grand to fix it?

The thread where I put headers on my truck and thoroughly described how I had an awful tick prior to doing, which the headers fixed pretty much covers it.