Shop Jeep Mufflers

I've got a 1981 Jeep CJ7 (6 cyl) that needs a new muffler due to the rotted out old one. Easy enough to replace, right? WRONG!

The previous owner had everything from the catalytic convertor to the exhaust pipe welded together. He also had Headman Headers installed on the manifold.

The only piece that has not been welded on the exhaust, is on the pipe that comes out of the cat that connects to the headers via nuts and bolts.

So, it would appear that this is my only option at cleanly removing the exhaust. But where do I find all of the connection pipes? My main problem is finding a pipe that I can reconnect to the header and then to the catalytic converter (that I must replace due to the welding). I'd like to do this without welding. Any ideas out there?

ps- i would like to use a cat rather than omitting it entirely.

Arggh! This sounds so custom that you can't count on OE parts to work or fit without some cutting or add on short pieces. If you don't have torches this is going to be tough.

You may find it cost efficient to have a muffler shop just weld in another muffler if the rest is ok to save.

Where I live you can't eliminate a converter from any vehicle that was made with one new -- could be different where you live,

T

1996 jeep cherokee sport, 4.0 liter, 82000 miles Just purchased vehicle 2 weeks ago went for vehicle emmisions failed, previous owner cut off converter, is there a quick fix to problem since i am low on cash, will get original oem by next inspection>

A converter is you only choice. After market converters can be had for cheap and can work just as affectively as OEM for emmissions testing. Usually wont last as long but half the price or less. Find a good local muffler shop that can cut and weld a new one in. Good Luck.

I have a 99 jeep wrangler with the 4.0 6cyl. yesterday I was driving it was running fine and then all of a sudden it bucked a couple of times and then ran like it was only on 2 cylinders. when I found a place to pull over I started seeing smoke coming out from underneath the car. When i looked under the muffler was cherry red erom the heat. I shut it off and sat for about a half hour and then tried to start it, it started right up and I drove it a few miles home without any problem. trying to figure out what would cause this to happen.

That's an engine problem, not an exhaust problem. It had to be running pretty bad before that happened.

It could be, but It runs great, it's my daily driver and I keep up on the maintenance and put 100 miles a day on it. this came out of the blue.

As HT said it had to be running real lousy for a while but still burning fuel in exhaust = the cherry red. Wild guess but IMO worthy of ruling out some reasons why and now runs fine..........

#1 Get codes read. Yup even the so called old style real Jeep stores codes. Near has to have some info in there.

My gut says now that you said you drive that much defaults to what happens or could with this engine layout by looks still a 258 C.I.D. straight six. Nothing really wrong and were used for ages.

I'm thinking valve timing. If I hadn't witnessed a few the OE (likely) timing chain set actually can jump by surprise and by some miracle jump back to on time. Well cared for is great but they just don't last forever most lose it to a nylon cam gear. Set looks like this.....
/
You can't see this but can check for how much lash it has. Take off distributor cap. Note position of the rotor, leave cap off. Put a socket on crank bolt and turn both ways noting on harmonic balancer how much it can turn if you need to reference it with just a scratch on it and one on nearby mounted part. Might have timing marks or not.

If so use that. Even if it does might be hard to see them. Doing this pulls slack/lash one way then when turned the other way shows how much slack/lash is there. If no marks I'll say it shouldn't move more than perhaps 1/2" max or 5 degrees if marked.

Might not be the issue at all but at age and presumed higher miles this is a weak link that can be erratic though most just fail and become obvious.

These can take some pounding high miles with a few known weak spots that can be dealt with. I'd rule that out and if a keeper for more do that chain anytime work is needed that is near it,

T

Was the check engine light on or flashing when it was running bad? If so, it would be interesting to see what code(s) were stored.

My o2 sensor on my '95 jeep keeps faulting. when i hook up the code reader it says something about high voltage something or other (sorry, don't have the code reader with me, and my memory is worthless).

i replaced the sensor, but it keeps happening. any suggestions as to what to look for?

The exact code is

21
Oxygen sensor bank 1 position 1 shorted to high voltage


I just replaced this sensor about 2 weeks prior to the code showing up. I notice a foul smell in the exhaust, plus it seems to be putting out a nasty blackness (dang, new muffler and cat. conv too!!)

The check engine light comes on/off intermittantly, the engine runs much worse when the check engine light is on, so I do think it is a "real" problem.

1996 Jeep Grand Cherokee Laredo 4.0 (160,500 miles)
-What I’ve replaced thus far-
STARTER (TWICE)
IGNITION COIL (TWICE)
BOTH OXYGEN SENSORS
CATALYTIC CONVERTER
MUFFLER AND TAIL PIPE
CRANKSHAFT POSITION SENSOR
CLEANED THROTTLE BODY
CLEANED IDLE AIR CONTROL VALVE
AIR FILTER
FUEL FILTER
RAN LUCAS THREW ENGINE SEVERAL TIMES
RAN OCTANE BOOST THROUGH ENGINE SEVERAL TIMES
SPARK PLUGS
WIRES
CAP
FUEL PUMP RELAY
STARTER RELAY
BATTERY
REPLACED TWO SCREWS ON PCM (READ THAT THIS REMEDY WORKED FOR SOME, BUT NOT FOR ME)
HAD JEEP CHECKED FOR VACUUM LEAK, NONE REPORTED
CHECKED PCV VALVE AND CLEANED IT (ALL LOOKED GOOD)
CHECKED MANIFOLD FOR LEAKS, NONE REPORTED
HAD FUEL PRESSURE CHECKED-REPORTED IN NORMAL RANGE

*HAD JEEP CHECKED BY FIVE DIFFERENT MECHANICS (ONE WAS EVEN THE DEALERSHIP) AND HAD IT HOOKED UP TO MANY DIFFERENT DIAGNOSTIC TESTING EQUIPMENT-ALL SAID THAT THERE WAS NOTHING WRONG WITH MY JEEP.


*At this time I have no check engine light.


*The issue is that my jeep will run great, but when I take it on long distance trips (1-2 hours) it starts to act up. The problem is that approximately an hour (usually) into the trip I will come to a stop light and have to stop and my jeep will idle at abnormal rpms (between 100 and 200). My jeep never stalls, however. When I give it gas the rpms increase just like normal, or if I shift it into neutral the rpms will shoot up to normal ranges as well. Also, I am experiencing terrible gas mileage and I can smell the exhaust inside of my car. Finally, I am experiencing somewhat hard shifting while at higher speeds and sometimes when I’m in a lower gear and the engine is working to downshift to maintain a certain speed at which I’m traveling. This has been a ten month annoyance of mine and all the mechanics I have been to at this point have failed. I am looking for the answer to my problem, but any help is appreciated. Thanks so much!

Also, would a bad chain cause me to have poor gas mileage?

Thanks

A very high percentage of jeeps were indeed fixed with the pcm screws , Go back and try backing out those screws a couple of turns .If no change ,go to a salvage yard and get a pcm harness and swap it out. One other thing ,look down at front of eng in the opening in front of #1 exhaust tube and see if the harness is stuck to it.

I think this engine uses a timing chain. They can be erratic and fool techs.


Check for lash in that chain. 160K is enough even for real chains vs known maint for the rubber ones,

T