Hi,
I have now reached my limit on buying and replacing manifolds.

My first set cracked in 2011, so I replaced then with stock manifolds, they cracked again about 3 months later. This time I got smart and replaced then with headers from Borla.... 6 sets of spark plug wires, three rolls of heat wrap tape and modified heat shields later, it too cracked... Driver and passenger....

So I went back to stock manifolds and the last set lasted about a year before I realized it had been cracked for a while.

So I jump on Morris 4x4 center's website looking at the description trying to find warranty info and the page says to install a flex pipe in the down pipe...

Now here is the question, anyone do this and how? Does it last/work?

 

Why do so many people crack their manifolds?

 

Well the torque from the motor, twists the manifolds since the earlier model JKU's have single "Y" piece catalytic converters...
The website says a flex pipe needs to be installed...

That's why I asked if someone has done this, and has it lasted?

This is the quote from their website:

Product Name:
Exhaust Manifold, Right (Right Side)
Fits:

• 2007-2011 Jeep Wrangler JK
• 2007-2011 Jeep Wrangler Unlimited JK

Please Read:The exhaust systems on the JK Wranglers allow very little flex. This causes the forces that the exhaust sees from the engine torqueing to twist the exhaust system instead of allowing it to flex. Over time the weakest part of the exhaust system (the manifolds) fails, causing cracks to develop. It is highly recommend that a flex-pipe is installed into the down-pipe of exhaust system with the installation of replacement manifolds. This will allow the forces that the exhaust sees to be absorbed by the flex-pipe instead of passed onto the manifolds.

Product Details:

• Right side
• 3.8L 6 cylinder
• Fits 2 and 4-door models

 

I agree it's stress, but I wonder why most manifolds don't crack, mine included.

 

My originals cracked, no sure if my current ones are or not. Its easy to tell with a SeaFoam treatment through a vac line. It will smoke in the engine compartment as opposed to out of the exhaust.

 

I've heard of the flex pipe for the but none for the JK yet. The Dorman manifolds didn't have that in the fine print and they've got a lifetime warranty.