symptoms of a clogged cat converter

Got a phone call from a friend who is looking to buy a used 1990 Civc
with 100K.
MT and the car has been well maintained. The seller says the cat
converter is
"going bad and the exhaust is blowing by the converter".

I doubted that even being posible unitl I looked at my service manual.
I see that the
exhaust manifold goes to " EX pipe A" which connects to "MIDDLE EX
PIPE" which
is fastened to the cat converter with a set of bolts that are spring
loadd.

Could exhaust gas bypass a clogged converter in this manor?

I will be taking a look at this car Friday afternoon and thought I
would ask if anyone in
the group has seen this before. My first thought was the gasket had
failed, or the middle
exhaust pipe had cracked. I haven't done any work that far up the
exhaust train since I
quite ridding motorcycles. Seeing a set of spring loaded bolts holding
the converter to the
middle exhaust pipe surprised me.

I plan using a longish tube to listen for the leak to pin point it. I
don't think it wise to try to
feel for hot exhaust gasses.

Terry

 

if the cat really is clogged, i'd be beware of buying the car because it
will either have had a serious injection problem /or/ will have spent
its whole life pottering about on 3 mile journeys where the engine never
got hot. both scenarios wreck a motor pdq.

otoh, it may be just a blowing exhaust, in which case, it's easily fixed
and the problem goes away. inspection will reveal all.

and if your friend still wants to take their chances on whether the
motor was in 3 mile heck, make sure the easy things are fixed like
ignition, o2 sensor, etc., change the oil, makes sure there are no
coolant leaks, /then/ take the car on a good hard run on some nice steep
hills. red line, full throttle. that will burn out a bunch of the
accumulated carbon from the engine and the cat. you'd be amazed how
much better it can be after a couple of hundred miles of running at
"full working temperature".

then change the oil again.

 

++++++++++++++++++++++++++++++++++++++++++++++
The inspection will have to wait until the middle of next week.
I managed to scratch my cornea with an allen wrench today.

Don't ask, it was rather silly and it hurts like hell so I learned
a valued leason.

I was using my hand and "pounding" on a 3/8" allen over my head,
it slipped out of the screw and spun nto my eay.

Ouch! on steroids.

No permanent damage, but the pain is too real. I wondered why they,
ER MD, gave me so many and such "pain pills". About 5:00 I learned
why. My wife says the patch reveals the true me. And my idiot cat
stays about 15' away and just looks at me in a truely unique way.

Terry

 

Cats are either plugged or poisened. The former is tested by a vacuum
gauge, the latter by your state emmissions test.