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General Forums => The Mess Hall => Topic started by: bumati on December 22, 2009, 07:15:37 AM

Title: Flex Pipe?
Post by: bumati on December 22, 2009, 07:15:37 AM

Is any body running a peice of stainless flex pipe on the  down tube?  has this helped with the manifold cracks?

thanks

Title: Re: Flex Pipe?
Post by: jfrabat on December 22, 2009, 10:46:23 AM

I have one, but it is not on the downpipe; it is actualy before the cat, as there was not enough space.  No issues with cracked headers (mins is stock and missing the last stud).

Title: Re: Flex Pipe?
Post by: dwtaylorpdx on December 27, 2009, 08:24:56 PM

The cracking is due to the over-expansion of the cast iron, besides cracking the manifold mine broke the rear stud of 3 times.

The newer inline 6 engines have flex section in the factory tubular manifold because they broke bolts too.

I found that running the earlier full length intake and exhaust manifold gasket seemed to help...
About 93 they used a gasket under the exhaust only and just sealer on the intake.

Dave

Title: Re: Flex Pipe?
Post by: jfrabat on December 28, 2009, 01:23:47 PM

Quote from: dwtaylorpdx on December 27, 2009, 08:24:56 PM

The cracking is due to the over-expansion of the cast iron, besides cracking the manifold mine broke the rear stud of 3 times.

The newer inline 6 engines have flex section in the factory tubular manifold because they broke bolts too.

I found that running the earlier full length intake and exhaust manifold gasket seemed to help...
About 93 they used a gasket under the exhaust only and just sealer on the intake.

Dave

My rearmost stud was broken since the day I got the Jeep, so now I need to replace it.  Hobe the flex pipe helps keep it in one piece from now on...

Title: Re: Flex Pipe?
Post by: dwtaylorpdx on December 28, 2009, 08:01:43 PM

Don't hold your breath, the manifold cracks are from local expansion,
(Between the exhaust bolts)
A flex joint may help but I'm on the 6th complete exhaust (Only 1 header)
since I've owned my YJ (Bought new in 1994). It destroys cats, mufflers, hangers pipes, the 2.5
produces pretty harsh exhaust pulses and a stock one is not smooth at all.
My current one is lasting pretty good, its heavy aluminised tube,
welded steel muffler and a matrix/random tech cat. Its about 3 years old now, a new record for me.
The flex pipe probably would have helprd the issues I've had downstream from teh manifold though...

My Thorley header is like 7 years old and still in great shape.

Dave