Back Pressure Problems from Baffle in New Garden Tractor "Muffler"?

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SteveHGraham
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Back Pressure Problems from Baffle in New Garden Tractor "Muffler"?

Post by SteveHGraham »

I'm about to weld a homegrown exhaust onto my John Deere 430 garden tractor. The tractor has a 1.5" exhaust system, and I am welding a 1.5" exhaust tip onto it. I am putting a 4" baffle inside the tip to see if it cuts the noise at all.

Question: am I likely to have back pressure problems because of the baffle? I don't know how restrictive the old factory muffler was.

Once the baffle is in there, I will have to grind and weld to remove it.
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warmstrong1955
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Re: Back Pressure Problems from Baffle in New Garden Tractor "Muffler"?

Post by warmstrong1955 »

Hard sayin'.....no idea what kind of baffle you are putting in, or it's flow characteristics.

Have you thought about measuring it? Maybe a quick test with a manometer when everything is just tac'd together?
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SteveHGraham
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Re: Back Pressure Problems from Baffle in New Garden Tractor "Muffler"?

Post by SteveHGraham »

Unfortunately, I left my manometer in my other pants.

Now I have to look up "manometer."
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warmstrong1955
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Re: Back Pressure Problems from Baffle in New Garden Tractor "Muffler"?

Post by warmstrong1955 »

SteveHGraham wrote: Sat Aug 17, 2019 12:53 pm Unfortunately, I left my manometer in my other pants.

Now I have to look up "manometer."
It's nothing but a clear plastic hose with a tape measure on it.
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John Evans
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Re: Back Pressure Problems from Baffle in New Garden Tractor "Muffler"?

Post by John Evans »

A picture of the baffle would help.
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liveaboard
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Re: Back Pressure Problems from Baffle in New Garden Tractor "Muffler"?

Post by liveaboard »

On a finicky computer controlled high spec motor you might have to be careful, but you're very unlikely to have any back pressure problems with that sort of engine.
Mufflers aren't rocket science.
I've made my own in the past, mixed and matched them, etc.
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Re: Back Pressure Problems from Baffle in New Garden Tractor "Muffler"?

Post by spro »

As I recall there is a resonator then an actual muffler. Mufflers have many baffles and the exhaust takes a route around them all. That is why the older mufflers are off set from the input to the output- well, part of the reason- if you cut one apart. When they rust inside, certain baffles break off and clog the exhaust. I can't see one baffle plate doing anything but heating the engine.
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SteveHGraham
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Re: Back Pressure Problems from Baffle in New Garden Tractor "Muffler"?

Post by SteveHGraham »

Here is a photo of the baffle. The tractor sounds much better. It used to roar. Now it's merely too loud to use without hearing protection.

I have had an interesting time with the tractor. I'm glad no one was filming me.

First, the belt came off, and I had to fix that. Then I discovered my muffler wasn't actually attached. Then I found out a new muffler would probably fail, too. Then I cobbled together my own exhaust.

I took the tractor out to try the new exhaust. Things seemed to be going well. Then I felt the tractor going over something, and I saw a big green object emerge from under the right front tire. It was the tractor's grill.

I had loosened the grill in order to get the side cover off, so I could install the exhaust. Evidently, I failed to secure it properly when I tested the exhaust. Now I get to test my sheet metal repair skills. The grill was bent into a pleasing shape, not unlike a Moebius strip.

The really wonderful thing about this accident is that I ran over the grill twice. When I saw it coming out from under the tire, I threw the tractor into reverse. I wanted to get away from it before it went under the blades.

After I put the grill aside, I got back on the tractor, and it wouldn't start. "No problem" I thought, "it must have some kind of switch that prevents it from starting when you shut it down with the PTO engaged." Of course, that was wrong. The battery had chosen exactly that moment to take a dump.

I spend more time working on this tractor than using it. I assume that won't always be true. Otherwise, I may get myself a new Kubota subcompact with a belly mower. I can't continue with a schedule of 3 hours of tractor repair to every hour of mowing.

The extremely poor design of the detachable belly mower is something to behold. Yesterday it took me 45 minutes or so to reattach it. I had to use a deadblow hammer and a pry bar. This was AFTER taking an angle grinder to the defective part that connects the deck to the rear of the frame.

I welded the new exhaust with a Titanium Unlimited 200 welder from Harbor Freight. I had been wanting a decent 120V MIG, so now I have one. I could have gone with the MIG-only version, but for $200 more, I got DC TIG and stick. Hard to turn that down. Seems very nice for the price. It may be a while before I use the Lincoln again.
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John Evans
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Re: Back Pressure Problems from Baffle in New Garden Tractor "Muffler"?

Post by John Evans »

I would not worry about back pressure with that baffle,should flow just fine. You know to do TIG you must have argon ! not CO2-Argon mix for MIG unless you are using flux core wire -no gas needed there.
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SteveHGraham
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Re: Back Pressure Problems from Baffle in New Garden Tractor "Muffler"?

Post by SteveHGraham »

I am pretty sure I used argon. At some point, I got the idea that I had used C25, but then I seemed to recall using my tallest tank, and that's argon.
Every hard-fried egg began life sunny-side up.
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