spider0735

I have a problem that I couldn't find the answers to.. not yet. Awhile back, I swopped my cat with my brother's cat, the same car essentially.. or perhaps different by a year. mine is a 92 and his might be a 93. I swopped it and it was running fine until there are gas leaks under my car. I traced it back to the catalytic coverter. It seems like the flexible pipe on the catalytic converter has a pretty bad hole under the shield. well...I want to cut the flex pipe away and replace it with another one. ... but I can't figure out how to do it. I tried thinking about sawing it off...but I couldn't find the ends. maybe there could be bolts under the cover plates, or do I have to take the cover plates off first? Any help would be nice.
Thanks.

Tyler's 1st Car

We ran into an exhaust leak on our car - it was at the front and the rear of the flex pipe.
We have the H23A motor with the stock 4 into 2 into 1 header pipe.
The flex pipe is actually part of the 2 into 1 section of the header.
I bought Exhaust Flex Pipe - Universal, 13 7/8"; 9 7/8"
Product Line: NAPA Exhaust

Part Number: EXH 42216

Price: Price
Unit
:
:
48.49
Each
and used a cut off wheel to cut the old one in half and removed it.
Wear foam surround goggles for this, as the stainless wire mesh will be thrown all over and it is nasty and sharp.
When you completely remove the center section of the flex pipe - you will be left with 2 attached flanges.
Then I measured the distance between the flex portion remaining flanges and took those notes along with holding up the new one and made marks on it where I will need to cut some of the flex tube away for the oxygen sensor.
The rear portion of the flex pipe will need to be welded to the catalytic converter tube.
That has the front mount attached to it.
I will be cutting the mount off of it along with the remaining flange and weld the flex pipe to it.
I'm un-sure at this point if I need to have the new flex pipe swagged - not sure of the spelling of that - also known as - re-sized at a muffler shop.
The i.d of the flex tube may not slide into the front portion of the catalytic converter tube.
So I may need to have it stepped up a size to get it to slide over it.
Currently - just tonight - we removed the flex pipe - like I said - with a cut off wheel.
Then we removed all of the rubber hangers (have fun) and lowered the rest of the exhaust down and removed it from the car.
This is from the flex flange all the way to the muffler tips - laying it on the floor, we are wire brushing it and will be painting it with high temp paint to try and make it last as long as we can.
This is the actual process below...
The catalytic front portion with the mount will be taken off, using a 4 inch grinder to grind the welds of the mount and the remaining flange and remove it.
Then we will remove the 2 into one pipe - 2 bolts on the rear motor mount side and the 2 bolts that attach it to the main header - you get to them from the underside.
Then we will take our dimensions and cut a U notch out for the oxygen sensor.
Then we will cut and grind off the remaining flange and weld the flex pipe on the 2 into one front header.
This is the point where I'm uncertain if the diameter of the new flex pipe will slide on and be able to weld it - like I said - it may need to be sized up a tad to slide on - we'll see.
Dont weld the mount back on - wait until you get the entire system in place to tack weld that back on.
Then we will temporarily bolt it in.
Then we will slide the newly painted exhaust system from the rear and slide that into the flex pipe.
The portion of the pipe that we will be welding will be bare metal and will be painted after all welding and grinding is completed.
Making certain it is exactly where we want it.
Then we will weld the flex pipe to the tube which comes out forward of the catalytic converter, making it one solid piece.
Now is the time to tack weld that front mount back on.
Then - we will un-bolt the 2 into one header and slide off the temporarily installed exhaust hanger rubber bushings that hold the rear of the exhaust system in place and finalize the welding of the flex pipe and front mount.
Then give it an nice coat of high temperature paint and raise it up in place securing it with the rubber hangers and then using anti-seaze - tighten down the header motor mount bolts and the 2, 4 into 2 header bolts.
Dont forget to use new gaskets on the 2 - into 1 header - It is Napa part # EXH 31377 QTY-2.
This should work out great.
I hope this helps you out in repairing / replacing that flex pipe without buying a whole new 2 into one header / flex pipe assembly.
I believe by doing it this way - I will save many hundreds of dollars - as it's such a domino effect - I would've had to buy everything new except for the muffler - which on our car is in excellent condition.
All of the flanges between the catalytic converter, mid-pipe and muffler are pretty much one rusted piece - so I didnt want to replace it all and wire brush and paint it to make it last as long as we can.
On top of all that... the oxygen sensor would've had to be purchased also - as its rusted in the 2 into 1 pipe as well....
Some of you are probably asking yourself - why dont they just go buy a catback system and be done with it?
Well - 1 is - we dont want a fart can on the car - we're making this a reliable stock Prelude for as little coin as possible and saving the rest towards books, room and board and school.
2 - I'm paying for all of this, as my son is going through college - $ isnt a factor when it comes to some things - but I have other projects for bigger dollar investments.
You may only own one car - I pay and maintain for 3 - 1 car - 1 suv and 1 truck.
Then I have a Harley, a Honda sportbike, a Yamaha Zuma, a Pontiac Ventura street strip car and a Ford model A street rod project.
So I dont wanna hear - just go buy a cat back system - LOL
You all can tweak and tune on your stuff - which is very cool - I happen to be on here to help and learn from others to maintain stock style vehicles.
I hope you understand this.
Thanks for reading this way to long post!
Have fun...
Take Care - Jeff