best way to remove exhaust to inspect?

Was told to check out my exhaust/cat to see if maybe that was my problem.
How hard is it to remove and take a look?
How long would it take a rookie, and should i do it?
I got some serious crackle going on after a short drive, and i used to smell what hinted too rotten eggs in the cab about a year ago, but not anymore.

VinCecil said:

Was told to check out my exhaust/cat to see if maybe that was my problem.
How hard is it to remove and take a look?
How long would it take a rookie, and should i do it?
I got some serious crackle going on after a short drive, and i used to smell what hinted too rotten eggs in the cab about a year ago, but not anymore.

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Good luck. At least on my '95 the rear bolts came out no problem (minus the "flags" shearing off the old nuts, I had to use a wrench on the nuts themselves) but the three front ones (joining the cat to the Y pipe) were very rusted to the point of probably not coming out without an oxy torch and an impact wrench.

However, you may have more luck removing the bolts from the Y pipes to the manifolds and removing the y pipe and cats assembly as one unit. My father in law did that when we had to pull back my tranny to inspect some recent engine work (rear main seal may have been leaking). The muffler and tailpipe IIRC are one unit, so once the two big bolts with flag nuts are off, it's just a bunch of rubber hangers and maneuvering to remove those.

I'd suspect one of the graphite gaskets more than anything. There is one between the muffler and the cats, and one between the cats and y pipe. Rust holes tend to leak and leak more and more. Graphite I'd think would be more likely to leak and reseal.

Leave the bolts to the y-pipe/exhaust manifolds alone. Don't touch them, don't think about touching them.

They have been there for so many years that you will break off at least one of them. Then you will get to pull the manifold(s) and you will then probably break bolts in the head(s) taking them off, so you get to pull the head(s) and have a machine shop fix all the stuff you broke.

Taking an exhaust system apart is always a crap shoot (if you are not an exhaust system person that has the tools and knowledge) and you may/probably will break stuff!! I would take it to a local exhaust shop and pay them loosen the bolts you need to remove to get the cat out (and snug them back). Then you will be good to go.

At the very least stay away from the engine/y-pipe end of things.

enjr44 said:

Leave the bolts to the y-pipe/exhaust manifolds alone. Don't touch them, don't think about touching them.

They have been there for so many years that you will break off at least one of them. Then you will get to pull the manifold(s) and you will then probably break bolts in the head(s) taking them off, so you get to pull the head(s) and have a machine shop fix all the stuff you broke.

Taking an exhaust system apart is always a crap shoot (if you are not an exhaust system person that has the tools and knowledge) and you may/probably will break stuff!! I would take it to a local exhaust shop and pay them loosen the bolts you need to remove to get the cat out (and snug them back). Then you will be good to go.

At the very least stay away from the engine/y-pipe end of things.

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Personally I didn't have that issue with the y pipe bolts. In my case the engine was coming out she to busted manifold to head studs/bolts and while the studs/bolts were a royal Pita (I had to use backing nuts on the studs since metric helicoil isn't cheap), the manifold to pipe bolts weren't to bad given adequate leverage and pb blast. That said, my motor had (according to the previous owner) had been replaced with a junk yard special so the bolts may have not been in long enough to rust in.

VinCecil said:

Was told to check out my exhaust/cat to see if maybe that was my problem.
How hard is it to remove and take a look?
How long would it take a rookie, and should i do it?
I got some serious crackle going on after a short drive, and i used to smell what hinted too rotten eggs in the cab about a year ago, but not anymore.

Click to expand...

The crackle is the Cat getting hot, and it gets hot when engine is running too rich.
Pull out at least 2 spark plugs and look at the tips, very light brown means good burns, blackish is Rich burn.

How old are the O2 sensors?
They are good for about 100k miles, after that they can start to make engine run richer and richer as they get older, so new ones will pay for themselves over the next 100k miles in MPG.
Only the 2 Upstream O2 sensors need to be replaced, the Downstream O2 sees cleaner exhaust, after the Cat, so usually lasts twice as long, but up to you.

To check exhaust flow it is best to use a vacuum gauge($25)
Read here for what and how to test: http://www.gregsengine.com/using-a-vacuum-gauge.html

Gasoline engines are still air pumps, engineers can add fuel injection, run with no distributors, and add a sh!t load of sensors and controls, but engines are still just air pumps, so vacuum gauge can tell you ALOT about engine condition, and if it is pumping air IN and OUT(exhaust) efficiently.

Clogged exhaust will cause slow acceleration and limited power at higher speed/RPMs, idle would be fine.

You can also bang on the pipes, Cat and muffler with rubber mallet or if cold your hand and listen for rattling, rattles are broken off pieces inside the exhaust system.............a bad thing.

When you burn gasoline(Hydrocarbons) with Oxygen, one of the by-produces is H2O(water), so exhaust systems rust from the inside out, and also why you often see water dripping from tailpipes.

RonD said:

How old are the O2 sensors?
They are good for about 100k miles, after that they can start to make engine run richer and richer as they get older, so new ones will pay for themselves over the next 100k miles in MPG.

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This. Like we talked about in your previous thread, replace your stinkin O2s already!
1. They've been giving you fault codes.
2. Your truck is running fine in open loop, but poorly in closed loop.
3. They've got a ton of miles on them and are more than due for replacement.
4. They can only improve the way your truck is running at this point.

Don't worry about anything else until they're replaced.

stmitch said:

This. Like we talked about in your previous thread, replace your stinkin O2s already!
1. They've been giving you fault codes.
2. Your truck is running fine in open loop, but poorly in closed loop.
3. They've got a ton of miles on them and are more than due for replacement.
4. They can only improve the way your truck is running at this point.

Don't worry about anything else until they're replaced.

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Found vacuum leak in the egr pipe. Made a ghetto patch, 02 code went away. Still think i should start with replacing them?

Take it to your local ma and pa muffeler shop and get a inspection. Slap the muffeler with your hand if you hear stuff inside it is probably the cooked cat material. Another quick test is have someone give it throttle with your hand behind the tailpipe. The exhaust should increase equally with rpms.

kimcrwbr1 said:

Another quick test is have someone give it throttle with your hand behind the tailpipe. The exhaust should increase equally with rpms.

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Im sure my 5 year old would love to redline the truck. Am i just feeling for an even increase in flow coming out?

I attempted to gut the cats today. Time was limited so i didnt get far. Got it off at the flange started beating it. Its like a brick wall in there. Next time I'll do it right and take it off amd beat from the front, but im a little worried about taking it off at the y pipe after someonea comment.

VinCecil said:

Found vacuum leak in the egr pipe. Made a ghetto patch, 02 code went away. Still think i should start with replacing them?

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Yeah. They're way past due. O2s have to cycle quickly to be effective. New sensors do this very well. 16 year old sensors with tons of miles do not. They slow down, which makes the PCM struggle to know exactly what's going on in a reasonable time and that costs you fuel economy at a minimum and can have significant effects on driveability.