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Replacing a clogged cataylic converter and exhaust on truck

Post in 'DIY and General non-hearth advice' started by Marster, Jan 26, 2009.

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  1. Marster

    Marster New Member

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    Anyone ever clean out a cataylic converter? I have one that has clogged and possible has clogged the muffler too. I wont know till I take everything apart. My truck is old enough not require emission testing, only a visual.........so as long as the shell is there, it will pass.

    I'm not sure what exhaust to go with. I may just stick to stock. Truck is old and I really dont want to put alot of money into her. She has 168000 on her now. Love to see 200,000.

    Is there any damage this could have caused the engine? It's not completely clogged but definitely higher reduced the airflow.

    Any advice will be greatly appreciated
    Marster

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  2. EatenByLimestone

    EatenByLimestone Minister of Fire

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    What year? Is it OBD-I or OBD-II emissions? Is there an O2 sensor behind the cat?

    Matt
  3. Marster

    Marster New Member

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    Not sure of the OBD-I or OBD-II.....but it's a 1994 Dodge Dakota V6 4WD. It does have an oxygen sensor behind the cat. I replaced it once and then after the cat started to go, I didnt replace knowing it would only blow the senor again.
  4. mayhem

    mayhem Minister of Fire

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    My guess is it would probably be cheaper and easier to replace the cat and sensors than to modify the truck so it can run properly without a cat.

    Do a little googling and see who makes aftermarket CAT pipes...you cut the old one out, swap in the new one and go on your way.

    Not sure about possible engine damage, but I know my old 2002 Nissan Altima 2.5 had a recall for the pre-cat (which think your truck does not have). They found over time that the pre cat was too close to the engine and they had a tendency to have their innards turn to powder which could then get sucked back into the motor in coasting sutiations. Odds are your truck motor is fine.
  5. beau5278

    beau5278 Member

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    All you need to do is,get the cat off then use a piece of tubing or solid bar stock and knock the catalyst loose,then pour it out.It shouldn't have gotten into the muffler at all,if it did,it should be a chunk that would come out if you turn it right.Catalytic converters,even the aftermarket ones have gotten ridiculously expensive in the past year or so because of the precious metals used to make the catalyst.If you don't need it for inspection,on that old of a vehicle,the cheapest way out,as long as your doing it yourself is to just empty it.Spray the bolts holding the cat on liberally with penetrating oil and they should come right out so you can just reinstall it after it's empty.If you have to ruin anything make sure it's the pipe between the cat and muffler or the muffler flange if there isn't a pipe,aftermarket mufflers are still fairly cheap.The engine shouldn't need any other modifications to run correctly although the check engine light may stay on but if the engine isn't worn badly and has good plugs and wires,it might not.
  6. Marster

    Marster New Member

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    Thanks for the replies! Yes, I really like to do it the cheapest way since the truck is so old and doesnt require emmission testing for inspection. The only thing the garage does is a fuel cap pressure check and a visual.

    I have a buddy of mine willing to help. He said he would cut the cat off and clean it out. There are no bolts holding this on. I guess he will weld it to put it back on.

    The motor in the truck has always been strong. It has good plugs and wires on that were just replaced last summer. As far as the engine check light, I'll ignore it or somehow get it to go off. It came on when the cat first started to go. I didnt have the monies to replace so somehow it ended up going off but I dont remember how.

    I heard it could fry the EGR valve......whatever that may be.......I have no idea so I hope to find this out as well. I know a good oil change will be needed but other than that, I have no idea what it did or didnt do to the motor. I read on different forums people that drove theres till the car wouldnt even go up a hill and had no damage......Mine isnt quite that bad.......yet. And i wont be driving it now at all. Love my truck and would hate to know i ruined it by being naieve.

    Thanks again for the replies
    Marster
  7. DAKSY

    DAKSY Patriot Guard Rider Staff Member

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    Google for the Dakota Mailing List (DML)
    Once you fill in the info on your truck (No charge for joining up...), post to the list...
    There's a couple of techs on there who can tell you yea or nay...
  8. Marster

    Marster New Member

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    THANKS! Just signed up!! Never knew this ever existed.
    Appreciate your help.
  9. Highbeam

    Highbeam Minister of Fire

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    I had a newer VW car with a bolt on cat. I attained a hollowed out cat to replace the original cat and when I went to do it discovered that the original cat had already been gutted and the old shell back in place.

    I ruined the 2 cats on my last chevy truck which had O2 sensors before and after each cat. Total of four O2 sensors. The after cat O2 sensor's only job is to report cleaner air than went into the cat so when you remove the cat's guts, the rear O2 sensor will alert the computer to set the SES light. Everything should run just fine but that gore light will come on.

    Honestly, I would check on the cat prices. They weren't that expensive and the original cats lived a long life at 168000. I would rather look at an SES light then run around with a plugged up cat if cash was that tight.
  10. DAKSY

    DAKSY Patriot Guard Rider Staff Member

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    You bet. The DML has saved my funky a$$ more than once...
    Not to mention the fact that the members have saved me about 6 bazillion $$ in repairs & mods...
    Plus, they're a good buncha folks who get together for things like trail rides & BBQs & the like...
    Welcome to the DML!
  11. EatenByLimestone

    EatenByLimestone Minister of Fire

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    I have a 92 Dakota with the 318. I believe you are still OBD-I and only have a pre cat O2 sensor which means you can modify it to your heart's content. When my truck came out there was an EGR valve, later models, due to a cam change, did not have an EGR valve. The DML will have instructions on removing it if you want to.

    Matt
  12. EatenByLimestone

    EatenByLimestone Minister of Fire

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    Oh, I just re-read and see you have a sensor behind the cat. That would be OBD 2. Hogging out the cat will most certainly throw codes. Does anybody know if this will throw the computer into a limp home mode?

    Matt
  13. EatenByLimestone

    EatenByLimestone Minister of Fire

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  14. Marster

    Marster New Member

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    Just went into the site you specified. It doesnt show my truck as being OBD II. I have no idea what that stands for and the more I read, the more confused I got. Once it stops snowing here I'm going to pop the hood and see if there is a name plate of some sort under the hood making this reference. According to the site, it should make reference. What does this all mean?

    I do know on the Y pipe from the manifold is an oxygen sensor. Is this what determines if it's OBD I or II?

    Thanks for all your help. This is all new to me! Going to pick up a new exhaust system today. Buddy of mine said he will remove the cat and clean it out. Really like to know anout the OBD I or II reference.
  15. Marster

    Marster New Member

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    This would be sweet! Hopefully this is how my truck is set up. I have no idea about the ERG value. If i dont need it then that is great too. Where is it located at? While I'm under the hood, I'll look for it.
  16. Marster

    Marster New Member

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    Man, I hope not. Cat has been out for awhile as well as the osygen senor. It did throw a code back then but somehow it just stopped coming on. Even now I have no codes coming up or check engine light.

    Thanks so much for your help. The old girl has been so dependable that I hate to think I could have damaged the motor. I sure hope not..... She has always been oil changed ever 3000 miles since new.

    Marster
  17. Marster

    Marster New Member

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    I've browsed through a few post. I need to familiarize myself alittle and post there. Alot of good info. It's so hard to find someone who is willing to help especially for free. Thanks again!!
  18. Corey

    Corey Minister of Fire

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    Just my .02, but you may want to check the computer codes (Autozone and many other auto parts places will read them for free) then troubleshoot the issue which caused the plugged cat in the first place. If the light came on 'way back when' that is probably what caused the plugged cat in the first place. Even if the light is off, the codes should be stored in computer memory.

    In a modern vehicle, there is no reason normal operation would cause a plugged cat. But things such as leaking head gasket, stuck fuel injector, bad O2 sensor, bad fuel pressure regulator, misfiring plugs, etc can lead to a 'plugged cat' either by filling it up with foreign material, or causing a rich burn and actually melting the ceramic substrate.
  19. DAKSY

    DAKSY Patriot Guard Rider Staff Member

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    <>Just my .02, but you may want to check the computer codes (Autozone and many other auto parts places will read them for free) then troubleshoot the issue which caused the plugged cat in the first place. If the light came on 'way back when' that is probably what caused the plugged cat in the first place. Even if the light is off, the codes should be stored in computer memory.<>

    In the Dakotas, when you get a MIL, you can turn the key on/off three times & the codes will be displayed on the odometer.
    Once you get a code, you can either check the FSM for interpretation,
    or refer to any OBDI or II reference material...
    AFAIK, all diagnostic codes are interpreted the same way for all vehicles...
  20. Czech

    Czech Minister of Fire

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    Not a Dakota, but I 'modified' the cats on my 97' Yukon, it had over 210000 miles last summer. Other than the MIL staying on, the truck runs fine, now 231000 miles. I have the MIL read every so often just to be sure I'm not missing any other codes, always 'insufficient cat' so far. I did notice a preformance difference, the truck was having back pressure symptoms prior to the 'fix'.
  21. Czech

    Czech Minister of Fire

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    Hey you gearheads (count me in, at least armchair wise), nice Dakota site. Now what about a site for us GM'ers? Lot's of knowledge here too, just wondering if I should renew my alldata account or not. Thanks.
  22. DAKSY

    DAKSY Patriot Guard Rider Staff Member

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    The EGR valve is located on the top of the valve cover on the left (passenger) side of the engine.
    It plugs into a rubber grommet & has a tube coming off it to the carb.
    I ya wanna check it, unplug it & shake it...If it rattles, it's ok...
    If it doesn't rattle, drop it into a jar of gasoline & that should clear the gunk (technical term) out...
    EGRs very seldom go bad, they just get blocked...
  23. Marster

    Marster New Member

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    Update:

    Yesterday a buddy of mine replaced the exhaust on my truck and cleaned the cat out. It definitly was starting to block. The guts of the cat looked like a large brick that was busted into two pieces. You could see it was sliding back and forth inside for quite a while. He told me my truck was an OBD I and that I shouldnt have any codes being thrown.........and so far I dont. Truck runs better than it has for a long time!

    Thanks to everyone on here that gave me a helping hand! Oh, the EGR value is ok too! I think I caught it soon enough before it did any damage.

    Thanks again!
    Marster
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