Hi everyone,

It has been a good few months since I have been on here, but as of today I am a little bit baffled about one of the gaskets that goes from the CAT to the center silencer pipe.

After a long winter here in the northeast, my exhaust system from the CAT to the muffler was shot. I went to Rockauto.com and purchased a new Bosal cat, Bosal center silencer pipe, and Bosal muffler. I matched up the gasekts via Bosal's parts diagram for my 1994 Accord EX with an automatic transmission. Upon receiving the parts, everything checked out perfect EXCEPT the gasket I mentioned above. Bosal's diagrams, Carquest's and Honda's OEM diagrams all show a metal oring style gasket to join those 2 pieces. However, upon ordering that "called for" gasket, I realized that is not the part for it whatsoever. The oring is way too big and it just looks as though even a smaller one should not. See the picture below of what I am referring to.






In realizing I had the wrong gasket, or so I think, I picked up this flat gasket from Advanced Auto. The only parts diagram that called for this flat gasket was the Walker diagram for my year model and make. This gasket fit on and joint the pipes. But what has me confused is why would all the diagram show it to be a metal oring gasket and not the flat gasket Walker calls for? See the picture below circled in red of what I am referring to.

Here is a pic of the flat gasket I used:



Here is a pic of the oring gasket I originally purchased:



Can someone set the record straight for me on this one. I am quite baffled at this point.

The 2nd problem I ran into with my exhaust install was with the donut gasket that joins the center silencer pipe to the muffler pipe. I ordered the wrong part and realized it immediately. So, I went to Autozone and they didn't have the correct Bosal donut (256-305) in stock. So, haphazardly I found a very close donut from a Mazda that "seemed to fit on the car. See pic below of Mazda gasket joining my 2 pipes.

(Keep in mind the bolts are not tight, this was just a test fit inside my apartment, notice the 2 yellow arrows pointing to the gap I am referring to)



After installation, the exhaust is quiet like she rolled off the showroom floor in 1994 EXCEPT when I am 1900-2000 rpm and only during this time. When at these RPM's I get a terrible rattle/chatter from that area where those 2 pipes are joined. Is this because I used a Mazda gasket? Should the gasket sit more inside the muffler pipe, unlike my gasket in the pic above? Also, there seems to be a gap between where the bracket is on the silencer pipe and the flange where the donut gasket sits. Is this normal, or is it a factory defect?

Sorry for all the questions but this is my first exhaust install from CAT to muffler on this car and with so many diagrams and variations, I am pulling my hair out.

I hope everyone is well and 2014 is treating them great. I look forward to chatting with everyone soon!

Thanks for reading!

-Craig

 

edit: sorry I meant to circle part #30 instead of the one currently circled.

 

I'm thinking it is the cat? Meaning that when I had to replace that "middle pipe" from the cat back to the muffler, my 95 EX auto OE cat had the o-ring type. There was a "groove" in the cat where the o-ring sat into. I had to put a small dab of silicone on it to hold it on/in the groove as I fitted the middle pipe to it.

That gap between the two pipes looks about right to me.

 

There are places that will pay you for the old cat. Call around or search the internet, I'm pretty sure some have been paid ~$100 for the old cat.

 

So you're thinking the rattling/chattering is coming from the cat connected to the silencer pipe area? From the sound of it, it doesnt seem to be coming from there. It is coming where the silencer meets the muffler in the flex joint. I am curious if the wrong donut gasket is the cause of that noise...

 

Well I found the source of my rattle! It had nothing to do with the flex gasket. It was actually the hanger on the silencer pipe that was hitting the hanger area welded to the car. Looks like Bosal's hanger specs were off by just a tad. I bent it a little and rattling is gone! I also hear a teeny weeny little rattle where the muffler curves around the gas tank. The pipe is actually hitting the suspension arm just a tad due to vibration. Looks like Bosal's specs were off just a tad on that too! My fix for that is to buy a little longer of a rubber hanger to drop the exhaust about a 1/2 an inch lower so it doesn't tap that metal peice.