The other day I went to the exhaust shop, and asked them to replace the flexpipe with a resonator. They told me that removing the flex pipe is a bad idea... why? The reason they told me "it's there to keep the system from cracking due to vibrations"? is this true?

Has anyone on here replace the flex pipe with say a straight pipe or resonator of some sort? Anyone have any problems after taking off the flex? Hit me back, thanks!

 

agree with shop....lots of heavy components in modern low emissions exhaust system...expensive cat. converter is easily cracked and damaged....system is welded joints, all can crack....

solid from engine block to tailpipe with no give if flex is removed...far easier to replace flex than an exhaust manifold with broken off bolts....engine removal time

 

I agree also, all motors vibrate, and the v6 motors are no exception, in fact, they generate slighlty more vibration that I4 or v8 motors. If the flex was not needed then the ford engineers would has skipped it to save money.

 

Absolutely. My old MGB is a perfect example - it has no flex pipe and is forever twisting the exhaust system loose. Especially when it 'runs on' and the engine shakes itself like a wet dog.

 

Yes it is a very important part of the exhaust (especially with a transverse engine.) It is there to give the exhaust the ability to be twisted and move without cracking weld seems.


Just curious why you want to install a resinator?

 

Hmmmm....my muffler shop just eliminated my flexpipe about 2 months ago. He said it shouldn't be a problem. Now you got me thinking....

 

I would return it to the shop that did the service with a new flex pipe in hand and ask them to instal it because as stated by others in this thread it is vital to have some play in the exhaust or you'll have problemsI would also suggest to them they do it Labor-free,considering it should have been installed at the time of service.

 

The odd thing about the Aerostar exhaust is that the flex pipe is sooo far to the rear that I question how effective it reall is. That may have been what Wresleu's shop had thought too. Most cars have the flex joint right behind the engine and ahead of the cat, right at the y-pipe in a case like this. The Aerostar has it quite a bit farther back and behind the cat, which is itself a ways farther aft then on most cars. That means that even with the flex pipe in place, a fair portion of the exhaust system is still moving with the engine. It must work and past validation tests, but it is definately different from normal.

On my van, when the entire exhaust behind the cat rotted off (including the flex joint), I took it to a few places for a cat-back estimate. Mind you, the cat-back system on this van is relatively short because of the aft cat placement. Every estimate I got was $300-$400, with the primary reason being "that flex joint is expensive ($120)". I found someone selling a new Aerostar flex joint on eBay ($35), bought a Super-Turbo muffle from Advance Auto, some pipe sections, and a friend and I welded up a cat-back system with flex joint that exits ahead of the rear axle on the RH side. With such a short cat-back, I also thought about eliminating the flex joint, but I had it already...

 

Let me put it this way. I have a 1990 B2600i. A shop eliminated my flex pipe, and now I have a cracked exhaust manifold (stress cracks too), and the bolts that fasten the head pipe to the manifold both snapped off. The flex on the Aerostar is fairly effective where it is, but ahead of the cats would have been better, except that you would need 2.

 

okay, well if I can't take off the flex I'll try removing one of the cat converters. Which one can I eliminate, without having any funky smells coming out of my exhaust? I do have emission laws here, but no one here checks for that.

If I can I would probably take out the first cat by the Y pipe, hit me back with some feed back. Thanks!

 

getting caught with a removed cat. can be unhealthy for one's wallet....

 

You cannot remove the cat, but if you replace both cats with one cat that would be legal. If you removed just one converter then remaining one would not work. If you replaced them both with one aftermarket, it would work just fine.

The fine for removeing you converter is $2500 per incident, and people have been know to get caught because their vehicle either smelled, or failed an emissions test. And this is per incident. Last year a shop here was bankrupted, becuase they were removeing cats, and the health department caught them. And they fined them to the legal limit. I believe they had over 30 violations on record.

 

Check local laws, too. Not all states have any sort of emissions check or care to look for such a thing. Also, it is illegal to remove a cat on a vehicle that has less then 50K miles, and some age criterial that escapes me at the moment. On older vehicles with higher mileage, you can remove the cat - but only in order to replace it with a new one (but maybe a high flow one, eh?).

 

are you guy's talking about the spring loaded bolts on the joint just after the cat when you are talking about a flexi joint because if not then my 1991 4.0 V6 does not have a flexi joint in the system except for this joint with the springs on the bolts. Man I have been busy tonight in this forum.

 

cbr,
the exhaust flex joint is a 2" inner diameter section of stainless steel wire mesh 10" +- long, have internal corrigated flex tube of stainless steel
cooling exhaust gases produce some real nasties like sulfuric acid which collect in cooler parts of system and destroy from inside out.

the spring loaded bolts were an earlier attempt at solving exhaust system stress breakage

don't get caught in a emissions system required state on vacation with a modified cat removed vehicle...they even refuse first borns here....fresh blood only

service shops here are required to report all vehicles with altered or modified emissions systems or they loose their emissions systems certification and the state closes them up