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Hi everyone,
Last week I picked up a 2006 Husqvarna YTH2448 with 445 hours on it. Test drive on the seller's level lawn seemed to go great, then I got it home to my hilly lawn and found issues. First, when moving, the hydrostatic transmission was quite loud on hills. Then, shortly after I started cutting, I tried to go in reverse with the blades engaged and the engine nearly stalled, then backfired loudly. I continued to cut, but shut off the blades in reverse and it did OK. After a few minutes, occasional white smoke started coming from the engine. The more I cut, the more white smoke I got and the more the mower starting missing.

Recapping the issues:
1) Loud-ish hydrostatic sounds
2) Loss of power in reverse (especially with blades on)
3) Loss of power in reverse resulting in big backfire
4) Increasing amounts of white smoke from engine after the backfire
5) After a bit more time, the mower sounds like it is starting to miss

After the backfire I changed the oil, oil filter, fuel filter, and spark plugs to see if it would improve the lack of power in reverse issue. There was no change.

I appreciate any advice you can offer me.

There is usually a safety that will prevent you from cutting in reverse, so maybe someone has cut into the wiring to remedy this
and is not done well. To help more, we need all of the model numbers off of the tag under/behind the seat, and off of the engine.

Fish said:

To help more, we need all of the model numbers off of the tag under/behind the seat, and off of the engine.

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Mower: Product = 279201, Serial = 022306B001337, Model = YTH2448

Engine: Model = 445677, Type = 0413 E1, Code = 050614 YH


Thanks again!!

Well the smoke could be a separate issue, like excess gas getting into the crankcase from a flooding carb, or a head gasket starting to blow. Here is a pic of your wiring, just for an initial test, unplug the kill wire going to your coils and mow with it
backwards etc., see if anything changes. The fuel shutoff should still shut your engine off when you turn the key off, if not, you will need to choke it down, or carefully pull the plug wires with insulated pliers.

Fish said:

Here is a pic of your wiring.

Click to expand...

The picture didn't work. Can you try to repost it so I know which wire to pull? Thanks.

After you start the engine are you turning the key back to the first position as that's where it needs to be to mow in reverse ?

When you pulled the plugs was there oil on them.

Carscw said:

After you start the engine are you turning the key back to the first position as that's where it needs to be to mow in reverse ?

When you pulled the plugs was there oil on them.

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Good call on the key. This is exactly why the mower wanted to stall in reverse. This is my first riding mower and I should have spent more time learning about such "features". So, after I screwed up and ran it in reverse without turning the key to the correct position, it caused a backfire, and since then it has been discharging white smoke and running roughly. Not super rough, but something is clearly wrong.

I just started it, ran it for a couple of minutes, and checked the plugs. Neither were wet with oil, but one had more black buildup on it than the other, although both were quite dark. Those plugs had about 30 minutes of run time on them.

Re: 2006 YTH2448 - Several issues

I'll be out of the country for the next 6 days for business and will have limited internet access, but I would really appreciate it if anyone could post any opinions about what could be causing the rough running and white smoke that I'm seeing. Please read through previous posts to get the whole story. I'll reply to anyone that posts a suggestion once I get back. Thanks again for sharing your expertise.

Re: 2006 YTH2448 - Several issues

MichFish86 said:

I'll be out of the country for the next 6 days for business and will have limited internet access, but I would really appreciate it if anyone could post any opinions about what could be causing the rough running and white smoke that I'm seeing. Please read through previous posts to get the whole story. I'll reply to anyone that posts a suggestion once I get back. Thanks again for sharing your expertise.

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The rough running and smoke are from the valve guides sliding out of place. When running the 24hp Briggs and Stratton in hot temperatures the valve guide/seals slide out of place. Eventually you will lose one cylinder, then you will know for sure.

I rebuilt mine but there's no way to stop it. The only solution is to put on new heads/valves from a newer model year where they fixed the problem.

MichFish86 said:

Good call on the key. This is exactly why the mower wanted to stall in reverse. This is my first riding mower and I should have spent more time learning about such "features". So, after I screwed up and ran it in reverse without turning the key to the correct position, it caused a backfire, and since then it has been discharging white smoke and running roughly. Not super rough, but something is clearly wrong.

I just started it, ran it for a couple of minutes, and checked the plugs. Neither were wet with oil, but one had more black buildup on it than the other, although both were quite dark. Those plugs had about 30 minutes of run time on them.

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Check your air filters and make sure they are clean. New plugs with only 30 minutes on them shouldn't be black.

Thanks for the additional replies. Flyin2low- thats good to know about the valve guides. I'll keep that in mind, but I'm hoping for an easier solution.

detel - The air filter looks pretty good.

What else could cause plugs to blacken after only 30 minutes of running? I really feel like this might be tied to the big backfire, but maybe not. Anyone agree that it could be the bad valve guides? I'm hoping for somethings I could try to check on in my garage instead of taking it to a mechanic. I'm fairly handy with smaller, push mower sized briggs and stratton engines, but I don't know much about this v-tek.

I was just out running the mower for a few minutes and I realized that I forgot to mention that there is a "pop" or "Poof-poof-poof" sound rapidly, especially once it warms up a bit. The sound is not in a regular pattern - "poof---poof-poof--poof". Sounds like it is missing or something because it seems to slightly loose power each moment that it "poof"s.

I have the same model and insane smoke/issues. I read what a respondent said about adjusting valves and have heard the same suggestion locally. I think it's crazy that these Briggs units have so much issues with smoke. I wish there were non cost-prohibitive way to repair this. All I ever hear locally is it's cheaper to buy a new mower.

An update: I haven't posted on this for awhile because it took almost 3 weeks to get the mower back from the mechanic.

The mechanic cleaned the carb which helped the mower a lot. It is much more power and it made the bigger problem come into focus better. Obviously the mechanic didn't test it long enough because if he let it get hot he would have noticed the problem.

Now the mower runs perfectly until it get hot. Once its hot it starts blowing white smoke (burning oil?) and missing. What would make a mower blow white smoke and miss only when its hot??

Thanks again for lending your expertise.

Sounds like you have a head gasket that is starting to blow. Remove both valve covers and push out into the yard and start and run on low. Oil will drip out where the heads are off, and you can visually see if you have a bad head gasket, as it will be apparent where the compression is escaping.
What happens, is that the escaping compression goes into the pushrod gallery which goes into the crankcase, and forces oil into the breather then carb.

They almost always blow in this area, as there is a huge gap between the head bolts and not much gasket area.

Fish said:

Sounds like you have a head gasket that is starting to blow. Remove both valve covers and push out into the yard and start and run on low. Oil will drip out where the heads are off, and you can visually see if you have a bad head gasket, as it will be apparent where the compression is escaping.
What happens, is that the escaping compression goes into the pushrod gallery which goes into the crankcase, and forces oil into the breather then carb.

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I thought this was a great suggestion so I went ahead and replaced both the head gaskets. I figured it was due anyway at 450 hours. Unfortunately, both the head gaskets looked good and after reassembling it with the new gaskets, the mower is still burning a lot of oil. I also adjusted the valve clearance while I was at it. Any other ideas for why the mower is burning a lot of oil? Its going through about 1/2 qt per hour. Again, it only starts smoking once it gets hot.

While I had it torn apart, I noticed the left cylinder had way more carbon build up. Also, the left cylinder has 2 black valves, while the right cylinder had a white exhaust valve. Therefore, I think the oil burning is coming from just the left cylinder.