Exhaust Question

So I'm replacing everything from the cat. back, but I'm curious about the converter itself now. How do you tell if it needs replaced? The truck has 208K on it, but I don't ever detect any rotten egg smell, etc. The outside
condition of the converter is good, but I'm sure it is original.
Thanks,
John Manner 4.3L 4x4 1989 S10 Blazer
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Rotten egg smell is a sign of lead in the catalyst. Back pressure is about the only way to check for a plugged converter. Remember this, converters don't commit suicide, they are murdered! About the only way for a converter to go bad is something in front of it(engine, induction, etc) to be wrong!
My best suggestion, cut off the original converter and replace it with a new high flow converter and make sure everything is running relatively perfect in front of the converter. Or just leave the thing off...your choice!
| So I'm replacing everything from the cat. back, but I'm curious about the | converter itself now. How do you tell if it needs replaced? The truck has | 208K on it, but I don't ever detect any rotten egg smell, etc. The outside | condition of the converter is good, but I'm sure it is original. | | Thanks, | | John Manner | 4.3L 4x4 | 1989 S10 Blazer | |
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With the engine hot, at idle, in park, hook up a vacuum gauge to one of the TB vacuum ports. Should have between 17-22in/hg. Tweak the throttle a few times. Vacuum should drop 2in/hg then pop right back to where it was at idle. Next, hold the throttle at 2k rpm for 5 seconds, then 3k rpm for 5 seconds. Vacuum shouldn't budge more than 2in/hg from the idle marker. If it doesm this indicates resistance/backpressure in exhaust and likely a plugged cat.
Doc

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KOOL!!! Thanx Doc...It never dawned on me to do a vacuum test on the engine to test for low exhaust flow!
That's why your the 'Doc'!
| > So I'm replacing everything from the cat. back, but I'm curious about the | > converter itself now. How do you tell if it needs replaced? The truck has | > 208K on it, but I don't ever detect any rotten egg smell, etc. The outside | > condition of the converter is good, but I'm sure it is original. | > | > Thanks, | > | > John Manner | > 4.3L 4x4 | > 1989 S10 Blazer | | With the engine hot, at idle, in park, hook up a vacuum gauge to one of the | TB vacuum ports. Should have between 17-22in/hg. Tweak the throttle a few | times. Vacuum should drop 2in/hg then pop right back to where it was at | idle. Next, hold the throttle at 2k rpm for 5 seconds, then 3k rpm for 5 | seconds. Vacuum shouldn't budge more than 2in/hg from the idle marker. If | it doesm this indicates resistance/backpressure in exhaust and likely a | plugged cat. | | Doc | | > | > | |
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The Doc rules j00!
he helped me a great deal with my 89 S-Blazer, same situation.
Now if I could just get another 3mpg out of the old girl.....

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