really loud like hole in muffler and running horrible

[phunter]

i have a 4500 with kubota engine. all of a sudden it is super loud like a hole in the muffler and has diminished power with acting like going to backfire. a burning smell like maybe heating the fabric covering the muffler. when I turned it off after limping back to the garage there was a red glow noted inside the muffler. the engine never heated up according to the gauge, since it started doing this just a few minutes after starting to mow. the gas is fresh and plenty in it. I limped back to the garage to put it away and now am writing this thread. could it be a hole in the muffler causing this? somehow changing back pressure? is it running rough and needs a new spark plugs? Is it something else I could handle? I am not a mechanic but would love to be able to fix myself. thanks for any comments? with sincere thanks.

 

[npalen]

The Kubota M4500 is a diesel tractor as is the Deere 4410. Are you running gasoline?

 

[phunter]

it is gasoline engine. i thought kubota since it takes kubota oil filter

 

[npalen]

The Deere 4500 is also a diesel tractor so what make of tractor is yours?

 

[phunter]

it is 4500 z with 700 hours. i have not changed the plugs. just oil changes and hydraulic filters air filters.

 

[phunter]

it is ventrac 4500 z

 

[MountainBuck]

I see in your posts that you have replaced the air filters, but I would take a close look at that again. If you have just blown them out with air before, I would go ahead and replace both of them.

Next check the ignition coils and spark plugs. Problems here can cause the muffler to overheat.

Beyond that I'd want to look at a compression test.

The Z also has optional propane. Does yours have the propane option?

The Z has the WG972-GL Kubota engine.

 

[tomplum]

I have a customer with a 4500 and a Kawasaki engine. In any case, if these twins lose a rocker, pushrod etc. they will do that. I'd pop a valve cover or two. A compression test will be telling as well.

 

[phunter]

I am not smart enough to do internal assessment but I think that is my problem. I have super clean air filters and no loose connections at coils or water near plugs.
Does engine rebuild work out very often or is a multi thousand dollar repair? The dealer cannot look at if for two weeks. I’m on a bad way wondering. Thanks for any and all comments

 

[tomplum]

It can be simple like loose rockers or more involved like a head. Removing the valve covers itself if they are accessible could tell you a lot.