Ariens Tractor Burning Smell

[lefty]

This is going to read like a story and I apologize for that but I figure this is the best way to report my observations.

Ariens: 936046
Serial: 041910C012688

Briggs: 31G777 1413 B1 091103ZD

This came to me because it wouldn't start. It is owned by a woman who is not very mechanical. The first thing I noticed was a huge mouse next under the cover on top of the cylinder. I'm told that it has cut the lawn 3 or 4 times this season like this. About a 1/2 acre. The first thing I did is remove the mouse nest and clean it out. I checked the valves and did a leak down and noticed a bit escaping from the intake. But I wanted to see if it would run so I didn't go any deeper than cleaning it out. It came to me with decent looking oil but the level was at the bottom line. So I added to get to the right level. Once cleaned and with the proper amount of oil, I started it up and it started just fine and ran great for about a minute. It's very likely that the owner, who inherited this and is not very knowledgeable, just didn't know how to start it correctly. But once I noticed the mouse nest, I wanted to get it squared away before trying to run it.

During cleaning it out, I noticed some black tar-like substance on the metal shield under the flywheel. I was thinking that maybe they overheated it and either blew some out the seal under the flywheel, or it was just old oil that tarred up from the engine running too hot with the mouse nest.

Once all cleaned up, I started it up with the intention of warming up the oil for a change and let it run for about 4 minutes, at which point I started smelling something burning, not a smell I've noticed in the past. It was kind of like a burning rubber smell but not quite. I did see some thin smoke in my garage and the smell was pretty bad. I figured it was that tar and maybe some dirt / oil burning off. but it got pretty bad and I started noticing it not quite running right. She turned a little rough and I shut it down. This may have been in my head but given the smell, I became hesitant to let it run any more. Once it shut down, I turned the flywheel by hand and things seemed good. Started it again for a second with no problem after a few minutes. I have a laser therm and can check the temp on the engine if that info helps. I wish I could describe the smell a little better.

I got the right amount of decent oil in this. I'm not sure how to proceed. Is this the old burnt oil burning off the engine or do I have a bigger problem here? I know this is a tough question but thought I'd report my observations and see if it rings a bell for anyone.

[KE4AVB]

One thing with being a 310000 series is when you do the leak down test have the valve cover and listen at the push rod galley for air leakage pass a blown head gasket. Other than that anything could be wrong with an engine that has been overheated.

[bgsengine]

I'd bet on a burned out alternator stator (melting which might explain the black substance found) and if it got bad enough could be feeding back and burning the coil.. I'd suggest popping the flywheel off and inspect (and resistance check) of the alternator, and close look at coil for any bulging black plastic (and check the ignition ground wire at engine connector for possible 12 volts feeding back - which could happen if stator wires and coil ground were close enough together that hot melted charging wire could have shorted the ground wire) I'd also suggest a close check of the alternator magnets too (I would not be surprised if you found loose magnets, caused by overheated engine) what you describe by that odor, might also be called electrical burning.. a strong acrid smell much like burning rubber..

[lefty]

Thanks. I'll pull the flywheel today and report back.

[lefty]

Here's a top-down look. The red arrow is showing where the bulk of the caramelized substance is. May be oil? Mouse poop and pee? Whatever it is, the smell closely resembles what I smelled burning. You can see where I scraped some away with a screwdriver. There's also some burned up blackness around the shaft on the top of the engine.


Maybe the owner spilled some oil on top last filled? He's passed away so we can't ask him.

As far as the stator, magnets, and wiring, I can't see anything out of wack. Should I try to scrape as much off as I can and let the rest burn off?

https://photos.app.goo.gl/ATLHc4woGfMu1sf8A

[lefty]

Making progress. So I cleaned all that stuff out and eliminated the smoke from the engine. But was still picking up the smell. So I let it run a little longer and to my surprise, I heard the blades start to spin. Long story short, I think the rubber smell may have been rubber from the belt. I took the deck off and the tension pulley mechanism seems to be a little screwed up. It's very tight and there are a couple of bearings attached to the blade brakes that are pretty gone. Feels to me like the pulley mechanism is not operating smoothly, not letting the blade brake levers to ride smoothly over the notches and take all the slack out of the belt?

So once it heats up, maybe the belt gets tacky and starts to grab because there's not enough slack since the belt still has some tension on it?

The system itself seems to be set up properly. It's just that the tensioning pulley is very tight and notchy, if you know what I mean. Those little bearings are very worn out. There's a lot of slop in them. I can't think of any other reason why I would have friction like this on the belt without the blade engaged. Is this something that happens over time?

[lefty]

Well I found a berm on something that I thought was holding things up and filed it down. So now I have, what I think is, full relaxation of the tensioning pulley for the blade belt system. But I'm still having the same results. The machine starts up, runs good for a minute or so, then the blade engages on its own. Which makes me think that the belt is too tight for some reason. I'm super confused.

[lefty]

I should clarify, the engagement lever itself remains in the disengaged position. It's just that the pullies start the belt moving. I feel like there should be more slack in the belt in the disengaged position.

[bgsengine]

proper belt guides present up front at engine pulley and in correct place? It is not uncommon to find these bent out of place or removed entirely after somebody too lazy to loosen the guides attacks them with a prybar....sometimes they just break off and/or go missing (or someone forgot to tighten them back up after belt replacement) also verify the return spring is in place on the movable idler bracket, may want to unbolt that bracket and check pivot bushings, clean out rust and debris from the entire mechanism, lubricate bushings... check that there is a bit of slack in cable when things are fully disengaged (there's 2 or 3 cables that can fit, but a short cable might cause your problem too.. lack of any slack in the cable would be a clue to that)

[lefty]

proper belt guides present up front at engine pulley and in correct place? It is not uncommon to find these bent out of place or removed entirely after somebody too lazy to loosen the guides attacks them with a prybar....sometimes they just break off and/or go missing (or someone forgot to tighten them back up after belt replacement) also verify the return spring is in place on the movable idler bracket, may want to unbolt that bracket and check pivot bushings, clean out rust and debris from the entire mechanism, lubricate bushings... check that there is a bit of slack in cable when things are fully disengaged (there's 2 or 3 cables that can fit, but a short cable might cause your problem too.. lack of any slack in the cable would be a clue to that)

All of the above. That spring is missing. And the machine does need some TLC. Thank you. Not a very failsafe design is it?