small engine cats

[DavidBarkey]

Anyone have any experience with small engine catalytic converters ? ? I spent over 17 years doing Drive Clean repair on cars and light trucks so I am familiar with automotive cat systems . I am kicking around the idea of making a direct fit cat for both the Kohler and the Onan engines to go in place of the muffler as the muffling capabilities of cats are quiet good if done right .
I am looking at getting sub-straight that is made to insert in motorcycle pipes or one half of a small V6 setup from a auto recyclers . There are still some shops with 5 gas analyzers near by I can get it tested before and after . A serious reduction in CO would greatly help guys running cabs in the winter . Thoughts / comments.

Dave

[Eugen]

I like your thinking Dave! Both the noise and the exhaust fumes bother me, but the fumes much more, so if anything would help with that, I'd be happy to adopt it too.

These are the things I'd keep in mind. Catalytic converters get fouled quickly by either rich running or oil burning. Otherwise, why not. Not sure it helps with the noise though, for that I think you need a really good (read large) muffler.

BTW I got somewhere in my junk pile a portable exhaust analyzer. Not sure if or how it works, found it outside the chemistry building at the university.

[DavidBarkey]

I like your thinking Dave! Both the noise and the exhaust fumes bother me, but the fumes much more, so if anything would help with that, I'd be happy to adopt it too.

These are the things I'd keep in mind. Catalytic converters get fouled quickly by either rich running or oil burning. Otherwise, why not. Not sure it helps with the noise though, for that I think you need a really good (read large) muffler.

BTW I got somewhere in my junk pile a portable exhaust analyzer. Not sure if or how it works, found it outside the chemistry building at the university.

Good point Eugen , I know there are 3 way cat that are specifically designed for carbs. Or even a diesel cat ?
As for muffling , I am thinking a muffler chamber backing up the cat chamber all in the same body shell. Kinda like the way an exhaust on a car is only all in one package .

Dave

[Eugen]

I've no experience with diesel. I do have my old catalytic converters I replaced on my truck. If I can find them in the junk pile you can have one of them if you want. Obviously I replaced them because they weren't doing the job 100%, so the truck threw a code.
Relu

[DavidBarkey]

I've no experience with diesel. I do have my old catalytic converters I replaced on my truck. If I can find them in the junk pile you can have one of them if you want. Obviously I replaced them because they weren't doing the job 100%, so the truck threw a code.
Relu

Ok thanks , it is worth takin a look at them
Dave

[Gordy]

I've no experience with diesel. I do have my old catalytic converters I replaced on my truck. If I can find them in the junk pile you can have one of them if you want. Obviously I replaced them because they weren't doing the job 100%, so the truck threw a code.
Relu

I recently watched a mechanic's video, He was told by a cat converter manufacturers rep that most bad cats. would be serisable again with just a good cleaning. Fill the cat with a mix of Dawn dish soap and water, let soap 24 hours then flush with water and air. Just need to get the soot out, as noted running rich or brunning oil will soot them up again though. I need to try it, better to repeat that than spend the $800 GM wants for a cat for my 03 blazer


Gordy

[Eugen]

Well @Gordy , before I forked out good cash for new converters I did try a few various ways of cleaning mine. I think it's worth a try, you have nothing to lose but the time to take them off and put them on again. Incidentally mine were like a royal pita to take out. Didn't work for me. However I did not buy new ones from the dealer, instead got 3rd party from ebay. The general thinking is that they won't last as long as the OEM. That was three years ago and no codes knock in wood. They were much much cheaper than the OEM though.I also did replace all four o2 sensors with OEM, valves adjusted, and a number of other things, to make sure it runs clean.

[DavidBarkey]

The 3 major causes of "cat failures" is actually not the cat its self but rather bad O2 sensors, Dirty Mass Air Flow sensors , and leaky exhaust manifolds . Understanding that a 5-10 year old Cat. may only be running at 75% efficiency and dropping below the threshold setting a code . Where a new cat will bring it above threshold and "solve the problem ".During my 17+ years in drive clean repair I "repaired" many , many faulty Cat.s by cleaning the MAS and running Sea Foam through the engine and out the exhaust . 1 in the tank and 1 dripped into the intake behind the throttle body . No disassembly required and not a mosquito to be found for miles . lol The other is the broken bolt syndrome not unlike my own truck at the exhaust manifold ahead of the O2 sensor affecting the O2 readings and the mixture as a result . An exhaust leak ahead of the upstream O2 sensor will kill your fuel economy as well . For every pulse out is a vacuum and false air leak in skewing the O2 sensor readings too the lean side causing the PCM to riches up the mixture .
Dave

[Gordy]

Well @Gordy , before I forked out good cash for new converters I did try a few various ways of cleaning mine. I think it's worth a try, you have nothing to lose but the time to take them off and put them on again. Incidentally mine were like a royal pita to take out. Didn't work for me. However I did not buy new ones from the dealer, instead got 3rd party from ebay. The general thinking is that they won't last as long as the OEM. That was three years ago and no codes knock in wood. They were much much cheaper than the OEM though.I also did replace all four o2 sensors with OEM, valves adjusted, and a number of other things, to make sure it runs clean.

I am glad it worked out for you. But 3 trusted mechanics told me not to waste my money on the 3rd party cats. They had done as you described, but ended up taking the 3rd party cat off and putting a OEM cat on and the code went away.


Gordy

[Gordy]

The 3 major causes of "cat failures" is actually not the cat its self but rather bad O2 sensors, Dirty Mass Air Flow sensors , and leaky exhaust manifolds . Understanding that a 5-10 year old Cat. may only be running at 75% efficiency and dropping below the threshold setting a code . Where a new cat will bring it above threshold and "solve the problem ".During my 17+ years in drive clean repair I "repaired" many , many faulty Cat.s by cleaning the MAS and running Sea Foam through the engine and out the exhaust . 1 in the tank and 1 dripped into the intake behind the throttle body . No disassembly required and not a mosquito to be found for miles . lol The other is the broken bolt syndrome not unlike my own truck at the exhaust manifold ahead of the O2 sensor affecting the O2 readings and the mixture as a result . An exhaust leak ahead of the upstream O2 sensor will kill your fuel economy as well . For every pulse out is a vacuum and false air leak in skewing the O2 sensor readings too the lean side causing the PCM to riches up the mixture .
Dave

I run seafoam in the gas 3-4 times a year,will have to try it down the throttle body. I changed the o2 sensors, but have not cleaned the MAS. Thanks


Gordy