Wease Posted December 7, 2010 Report Share Posted December 7, 2010 I've got what sounds like an exhaust leak on my '98 SVT Contour. It's coming from the driver's side. I was under the car about a month ago changing the oil and saw nothing that hinted the exhaust was rusting out, but that can be missed. Now, I've started throwing Check Engine lights as well. Then this week, I've noticed the car can kind of lag performance-wise. Like not accelerate like it should and seems to stutter. Then I got out of the car yesterday and smelled something that didn't seem right. Could this be a blocked cat? I've had issues with the O2 sensors before and I'll admit, I'm not the best at replacing them when I should. Thoughts? Quote Link to comment Share on other sites More sharing options...
spankis Posted December 7, 2010 Report Share Posted December 7, 2010 I just recently had one in my 265k mile Dakota. It was very odd, honestly. It did throw an o2 sensor code, but it just honestly felt like it was choking the truck to death. The exhaust quieted down noticeably, but gradually over time. It got to the point where it would be clearly laboring to maintain speeds going up slight grades on the freeway. First thing I noticed was quieted exhaust, and as a result it was replaced with a hissing/air escaping sound, because all the backpressure was forcing air out every gasket and flange ahead of the cat.... I understand it can burn up your pre-cat o2 sensor too in some cases, although mine seems to have survived the ordeal. If I recall the 2.5L contours have 4 of them. Quote Link to comment Share on other sites More sharing options...
SpaceGhost Posted December 7, 2010 Report Share Posted December 7, 2010 I had one in my 88 Fiero GT, car became slow as hell. The acceleration was noticeably slower. Quote Link to comment Share on other sites More sharing options...
99FLHRCI Posted December 7, 2010 Report Share Posted December 7, 2010 Cat should also be noticeably warmer then the rest of the exhaust, I have literally seen them cherry red. Quote Link to comment Share on other sites More sharing options...
AJ Posted December 7, 2010 Report Share Posted December 7, 2010 a clogged cat can force the exhaust gasses past the manifold gasket and cause a leak. seen it a few times before. you will also have poor performance and could cause damage to the engine if you drive it too long without fixing it. Quote Link to comment Share on other sites More sharing options...
Not Brian Posted December 7, 2010 Report Share Posted December 7, 2010 One of the cats on my old subaru literally broke apart into pieces while driving, which flew down the Y-pipe into a main cat, blocking it completely. The car instantly started studdering and was barely able to drive, felt like it had about 20 horsepower. When I finally gimped it home I looked under the car and the pipes were bright red from hot exhaust gasses being trapped in there. Quote Link to comment Share on other sites More sharing options...
Wease Posted December 7, 2010 Author Report Share Posted December 7, 2010 Well I've had a Check Engine light for a while for an O2 sensor that I hadn't gotten to. I'm wondering if that damaged the cat and now I'm hearing the results of that? Quote Link to comment Share on other sites More sharing options...
Mr. Jones Posted December 7, 2010 Report Share Posted December 7, 2010 Well I've had a Check Engine light for a while for an O2 sensor that I hadn't gotten to. I'm wondering if that damaged the cat and now I'm hearing the results of that? No cat = win. This is your reminder to mod. Quote Link to comment Share on other sites More sharing options...
Wease Posted December 7, 2010 Author Report Share Posted December 7, 2010 No cat = win. This is your reminder to mod. LOL, I don't mod this car. Just the others... Quote Link to comment Share on other sites More sharing options...
fRAZER Posted December 14, 2010 Report Share Posted December 14, 2010 that does sound like a blocked cat, just start the engine and put a t shirt in the muffler then feel for any leaks, if you can't find anything theres a good chance its the cat. If your cat is bad then i highly recommend replacing the o2 sensor with it. 1 Quote Link to comment Share on other sites More sharing options...
6 Speed S4 Posted December 14, 2010 Report Share Posted December 14, 2010 The cat will glow red if its really clogged. You will notice lack of acceleration, bad fuel mileage, and engine light may come on depending if the ecu is smart enough lol. Quote Link to comment Share on other sites More sharing options...
Nitrousbird Posted December 14, 2010 Report Share Posted December 14, 2010 Sean, bring it over, I have a handheld OBD-II scanner. That will make troubleshooting the problem a lot easier. Quote Link to comment Share on other sites More sharing options...
gmann Posted December 15, 2010 Report Share Posted December 15, 2010 Red cat =/= to clogged cat. red cat means the catalyst material is burning hotter than it should usually because of wayy overfueling. Also, cat's should be warmer than the rest of the exhaust for two reasons. 1: it's closer to the engine than the muffler's. 2: it's performing a chemical reaction to burn off unburned hydrocarbons that didn't get ignited in the combustion cycle. Try to take out your pre-cat oxygen sensor if the car is chugging along, that should allow enough exhaust gasses to escape for the car to run better than it was. Quote Link to comment Share on other sites More sharing options...
Guest 614Streets Posted December 15, 2010 Report Share Posted December 15, 2010 If your cat is blocked and it sounds like it is, just remember cats don't clog up , malfunctions in the rest of the engine cause cats to go bad. Quote Link to comment Share on other sites More sharing options...
AJ Posted December 15, 2010 Report Share Posted December 15, 2010 The cat will glow red if its really clogged. You will notice lack of acceleration, bad fuel mileage, and engine light may come on depending if the ecu is smart enough lol. not always. If your cat is blocked and it sounds like it is, just remember cats don't clog up , malfunctions in the rest of the engine cause cats to go bad. not always. Quote Link to comment Share on other sites More sharing options...
99FLHRCI Posted December 15, 2010 Report Share Posted December 15, 2010 Red cat =/= to clogged cat. Also, cat's should be warmer than the rest of the exhaust for two reasons. 1: it's closer to the engine than the muffler's. 2: it's performing a chemical reaction to burn off unburned hydrocarbons that didn't get ignited in the combustion cycle. quoted because all it takes to make an exhaust is cats and mufflers Quote Link to comment Share on other sites More sharing options...
Not Brian Posted December 15, 2010 Report Share Posted December 15, 2010 A blocked cat would scratch and meow until you open the door for him. Quote Link to comment Share on other sites More sharing options...
gmann Posted December 15, 2010 Report Share Posted December 15, 2010 quoted because all it takes to make an exhaust is cats and mufflers quoted because you don't get what I said. Cat should also be noticeably warmer then the rest of the exhaust, I have literally seen them cherry red. What I took from what you originally said was that the part behind the cat should be colder than the rest of the exhaust. You are correct in saying that for the reasons I stated. But what you said is easily misinterpreted as the cat should/could glow cherry red just because it gets warmer than the rest of the exhaust when that is wrong. It only glows cherry red when there is an uncontrollable amount of hydrocarbons getting into the exhaust system that is not being burned off in the combustion cycle. Obviously what I wrote is misinterpreted as well if you pick pepper out of fly shit as most people on the interwebz do. Hope this clears the air. Quote Link to comment Share on other sites More sharing options...
spankis Posted December 15, 2010 Report Share Posted December 15, 2010 For what its worth I just last week replaced my cat, and once I cut it out you could see that the media inside it had fractured/broken up and big chunks were sitting in the case all kinds of directions, inhibiting flow drastically. Mine did not ever glow red as some have suggested always happens. Point here is that engine malfunction is not always the cause of cat failure - as has been said. Mine was just old and VERY worn. Quote Link to comment Share on other sites More sharing options...
TTQ B4U Posted December 15, 2010 Report Share Posted December 15, 2010 What Would A Blocked Cat Sound Like / Do? would look like this and probably be making a bunch of farting sounds http://www.funnyfartsounds.org/wp-content/uploads/2010/01/evil-farting-cat.jpg Quote Link to comment Share on other sites More sharing options...
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