Drove the Miata to work yesterday and it had no power and wouldn't rev past 5K. I removed the cat (OEM 1991 part) and discovered that half the internal ceramic "brick" was missing and what was left had turned sideways and blocked the outlet. I removed the blockage and bolted it back up and WOW, what a difference. I now realize that the car had been slowly losing power for months - maybe years - and like the proverbial frog in a pan of water, it happened so slowly I didn't really notice.
My question: what happens if you drive a car with a clogged cat indefinitely? What kind of engine damage would eventually result?
Usually the totally clogged cat will not allow the car to run... So usually, no damage done.
yamaha
UltimaDork
10/31/14 11:12 a.m.
In reply to bluebarchetta:
Not unless its a Sentra SER......
You can burn it to the ground.
Absolutely yes. Some engines are more sensitive than others, and nearby components can be damaged by the heat, and fire is a real possibility. So in short, will a clogged cat always cause damage? No. Can it cause damage? Definitely yes, and possibly severe.
yamaha wrote:
In reply to bluebarchetta:
Not unless its a Sentra SER......
Those cars and their Altima brethren ingest the cat... lol
Other than the heat issues mentioned, no physical damage to the engine will occur.
Just a restricted exhaust. Too much back pressure.
In reply to iceracer:
That not always the case. On some engines, like the Nissans already mentioned, that cat is very close to the head, when the cat breaks apart internally some of bits get pulled back into the engine. Also, on aluminum head engines that have the cat right up on the exhaust manifold, the heat of a clogged cat can harm the exhaust valves and seats.
I don't think that either of those scenarios are common, but both have happened.
Opti
Reader
11/1/14 9:56 p.m.
Doesnt clogged cats kill rotaries?
Clogged cats kill rotary engines. Restrictive cats kill rotary power.
Poorly running/tuned rotary engines also kill cats quickly, so it might be that it is correlation to poor running/low compression engines killing a cat and then dying instead of the direct cause.
Brett_Murphy wrote:
Clogged cats kill rotary engines. Restrictive cats kill rotary power.
Poorly running/tuned rotary engines also kill cats quickly, so it might be that it is correlation to poor running/low compression engines killing a cat and then dying instead of the direct cause.
Let's see if I have this straight...
As long as I'm driving my Miata, everything is fine, regardless of the condition of my cat.
But if I'm driving my fb, I'd be better of getting a dog?
Dogleg garboxes are a different discussion.
In reply to grafmiata:
No matter what you're driving, you're better off getting a dog. (drops the mic, runs like hell)
But seriously folks, thanks for the responses. I must have fixed the exhaust restriction before it did any damage, because the little 1.6 runs great now. I never understood why anyone would argue for the 1.6 over the 1.8 until now, as I think this '91 would give my dearly departed '96 a run for its money.
