...and all of a sudden, BOOM!...followed by a BRADADADADADADADAH...

[rcecale]

Driving home from work yesterday, about 20 miles or so, my car, for the most part was acting just fine. I did, however, notice a couple of tiny back fires upon decelleration with the clutch still engaged. Not something I recalled ever hearing before, but they were tiny backfires, so they didn't concern me very much.

After 9 miles of freeway driving, some of which was stop-and-go, I left the freeway and began my surface-road part of my commute. Lights every half-mile or so, some even closer than that. Lots of drivers seemingly unsure of where they were going, which lane they wanted to be in, you know the deal...pick a lane, dude!!!

Anyway, making my way from light to light, rarely getting above 3rd gear, but it occasionaly would happen. Ahead of me is a red light, so I let of the throttle and there it was again, a little bitty backfire...sounding like a little pop. I had just noticed the car was seeming to feel a little "constipated". Not quite as responsive as she usually is. I mean, she's not a turbo, but for an 84 NA, she does alright.

I pull up to the red light, thinking maybe she's just a little hot. Nope, temp gage is pointing straight up. Not hot at all. Well, we'll see what she looks like when I get her home.

Light turns green. I ease off the clutch while applying throttle. She pulls out easy enough. through first gear, shift to second and and all of a sudden, BOOM!...followed by a BRADADADADADADADAH...

Several throughts race through my head: "What the he!! just happened?" followed by "Did I just blow my engine?", followed by a few more that I probably shouldn't type here.

Stepping on the gas causes this immense roar. Is that what it sounds like when the engine is blown, but still running? What the...?

I step on the clutch and look for a place to coast the car to. I then turn the engine off and coast. Damn! Nowhere to really pull the car out of traffic. Will she start back up. Turn the key, she fires back to life. Would that happen if the engine was toast? Nahhh, probably not. Maybe it's not the engine.

Engine is running, check the temp...looks fine there, gage is still pointing straight up. Blip the accelerator, the engine revs normally, it's just loud as hell. Lots of vibrations, though, seeming to come from directly below me. Hmmmm...

I think of the small backfires I was hearing and then reason to myself, perhaps the cat was clogged and I somehow blew a hole in it. Yeah, that's probably it. Only a couple of miles from home, the damage has been done, let me get her into the garage and have a look.

Loud as he!!, I make it home, pull into the garage and have a look. Didn't catch it at first, but on second glance, it's blatantly obvious. How did I miss that on the first glance.

Just before the actual cat, there is a 2 or 3 section of tubing that flanges against the exhaust. Well, that little section of tubing is where the damage occured, completely separating, not connected in the least.

My question now is where to find a good, used cat.

My car is 25 years old, and as such, no longer required to get emissions testing every year.

Randy

[earlr85944]

local exhaust shop, have them weld in a straight stainless pipe.

[speedracing944]

Post a WTB add on the 944 parts forum. I purchased a full stock exhaust from the manifold back for $60 shipped.

Speedy

[exitwound]

I picked up a 'universal' catalytic converter from Advanced Auto of all places that fit the car. I have a late model 944, but I'm sure they're not that different. Was like $50.

[944Spec_bound]

Glad it was just the cat.
Your title cracked me up though. I had to read what that was about. Could have been the describing a tire blowout, an engine blowing, a trip to a 50cent concert, my son driving up with his stereo cranked, the story of Battle of the Bulge....

[zedsn]

Hi, I picked up a universal cat and bought a stainlessexhaust band clamp to attach it to the pipe before the cat and had many trouble free miles after that.

[rcecale]

Sorry for the poor images, camera on the ohone isn't the best, I suppose...

Anywhoot, here's a shot of the separation point...


And the same shot with red indicating the two edges, for clarity...


Btw, what is that bolt there for, on the cat?

Randy

[zedsn]

Can't remember what the bung is for on the cat but it is a factory fitting.

[nightheart]

lot of universal cats are supposed to work. I picked one up on ebay for around $50, but haven't had it installed yet. I'm emissions except, so for now it's just a straight pipe through. I'm guessing you priced oem cats from $1000+, and thats insane.

[idontknow]

I replaced mine with a straight pipe as well. Cheaper, easier fix and you won't have to worry about blowing up a cat again

I thought the exhaust noise was going to be a lot higher but it wasn't. A noticeable increase yes, but no where near as loud as your trip home.

[maxiblu]

That bolt you're referring to is the test port for an exhaust gas analyzer. Comes in very handy for setting idle mixture etc.

[rcecale]

Looking more and more like I'll be having an exhaust shop do this one. The cat definitely failed on the forward weld, and there doen't seem to be enough room between the mounting bracket and the end of the pipe for me to use a coupling clamp to reassemble it.





Randy

[exitwound]

Just a note, you can get all the pipe you need at PepBoys or a similar store. (If you have the tools and room to do it, that is). The prior owner of my car cut the catalytic converter out and welded in a straight pipe (which is a no-no in PA). We cut out the pipe and used clamps and it's rock solid. Like $50 for the catalytic converter and $15 or so for the pipe and clamps.

[rcecale]

I'm just not sure if I have enough room here for a clamp to have enough traction to seal up right.
Using the pic below, there is approximately 1 inch of good pipe (between the two yellow lines) before the radius. Also, the weld is right on the edge (between the yellow and the red). It's raised, so that may prevent the clamp from sealing as well.



Also, I'd love to just replace it with a straight pipe, but I'm not so sure on the legalities of that. I'm no longer required to have emissions testing done, so chances are, it would never be discovered, but, I'm not the type to push my luck. Besides, is that something an exhaust shop would be willing to do?

Randy

[turbobrat930]

Randy, I am in Macon...and have a whole exhaust system to include the CC for $100.00 All I need to do is take it off the car...

[rcecale]

Finally got around to pulling the cat. Interestingly enough, I can see daylight through it...



The pic doesn't really show it well enough. There is actually more light coming through than what you can see. You can see a few screens throughout, and some of the screens have particles embedded into them, but it's definitely not clogged.

I understand they're supposed to make a noise like a baby rattle when shaken...well, that's certainly not the case. When I shake this one, I hear the noise of a single "pebble" being shaken around. This thing appears to be toast!

Randy

[legion]

I'd skip the cat if you can get away with it. You will see an increase in power and mileage without it.

[exitwound]

As well as pollutants too. Don't forget about Mother Earth!

[rcecale]

Originally Posted by exitwound

As well as pollutants too. Don't forget about Mother Earth!

click!

Randy

[exitwound]

I'm not following.

We put the catalytic converter back in after the previous owner took it out. I would never have passed emissions in PA without it. Actually, in PA, it doesn't have to be working, just has to be 'present and in place'.