Strong Exhaust Smell

[OutbackL130]

I have a 1980's john deere 420 like in this pic that I've been restoring. I'm just now starting to ride and use it more and am noticing the exhaust smell is very strong. The engine runs great and does not smoke at all. I've never had a riding mower that smelled this bad. The exhaust on the 318's and 420's blows out of the right fender in relatively close proximity to your face. I just wanted to check with other 318 or 420 owners and see if this strong smell is normal? to be honest I'm concerned about the carbon monoxide levels while riding it. When the wind blows from your right all the exhaust comes back on you. I tested with a carbon monoxide meter and it averages 50 pmm and spikes to over 100 ppm at head level. Is this safe??

 

[George2615]

I don't own one but it sounds like its running a little rich. I assume the muffler itself and the gasket where it bolts to the engine are good. Hard to tell from the pic but the exhaust pipe looks a little black. I would also think it should be sticking out a little further from the body plastic. I don't know how long it was down during your restoration but did you replace the old gas with fresh gas.

 

[OutbackL130]

I think you might be right about it running rich, although I've had it looked at by a john deere dealer and another tractor repair shop and they said it appears to run fine after adjusting the carb. The engine surges very slightly at idle and they told me it is because of ethanol in the gas. My 420 has a new OEM muffler and gaskets. The gas tank was drained when I replaced the fuel lines.

I dont like how john deere designed the exhaust outlet on these mowers. When you drive forward the wind blows exhaust right in you face. These are very popular tractors. It must be safe right?

 

[George2615]

Maybe adding a down tube to the exhaust pipe would help. Was the carb rebuilt? Float replaced? If not, the main jet could be enlarged due to age and use causing it to run rich. No fine tuning on the carb will correct that. An old float with a pinhole in it will fill with gas causing it to sit lower not letting the needle seat to close when it should. Just grasping at straws here.

 

[OutbackL130]

I took the original carb apart and cleaned it. Didn't see anything wrong with the float.

I just googled 318 - 420 exhaust smell and apparently it is very common for the older onan engines to leave a strong exhaust smell on you after mowing. I dont know if its normal but it definitely is very common.

 

[bigtiller]

I always smelled like cigarettes when I finished mowing with my 318 many years ago. But I don't recommend you try that. I seen a few of them running around work back then with a copper ell screwed to the exhaust tip.

 

[Kish318420]

How many hours on it? Usually it means that the engine has a lot of hours and will need at minimum pistons, rings, valve job, (decarbon). Do a compression test. If it is low 80-85 PSI yeah it needs attention. Mine (3000+ hours) cylinders were egged, could see rings at the tops side of cylinder (horizontal engine), Cylinders needed to be bored and honed, valves seats ground, new valve seals, new rod, pistons (will have to over, because of boring)

You may not see smoke, Is it consuming a qt of oil per 4 hours of running? Then it does need work or you may find it dead in the back (way back yard).

To each his/her own

 

[ovrszd]

If it's not smoking badly when running don't tear it down and overhaul it. Horrible expense that you don't need.

They do emit an odor. After all it has no emissions system at all.

Don't worry about it unless it's unbearable to run. If so, then do as others have said and add a turn pipe pointing the exhaust down and away from you. Don't point it up. You'll leave it sitting out in the rain some day and the engine will be full of water. That's way worse. But, hey, you won't worry about exhaust smell anymore cause it won't produce any.

 

[beenthere]

Kish picked up on an old thread, and the OP hasn't been active in the last 6 or more months. Just FYI

 

[ovrszd]

Posting for future readers.