Robin Exhaust

[SnowRidge]

You know, I always thougth my 2001 PT425 with the Kohler engine was loud until a few weeks ago. I let my daughter mow the lawn with it and I stood back and realized it is about as loud as my neighbor's Wheelhorse and my other neighbor's Deere lawn tractors. It may be that my steel canopy just traps the noise in there with the operator, but from a distance, it is just like the rest.

Mine was actually quieter with the restrictive PT built muffler. With the Kohler muffler, like you have, it is a little louder, but nothing objectionable or unusual.

 

[J_J]

I believe that Kohler does make a quite muffler, but it would have to match up with what you have such as mounting direction, length and so forth.

 

[BobRip]

You know, I always thougth my 2001 PT425 with the Kohler engine was loud until a few weeks ago. I let my daughter mow the lawn with it and I stood back and realized it is about as loud as my neighbor's Wheelhorse and my other neighbor's Deere lawn tractors. It may be that my steel canopy just traps the noise in there with the operator, but from a distance, it is just like the rest.

I put some sound absorbent foam underneath my ROPS and it helped some. Clint Blake has no ROPs and his machine is a lot quieter.

 

[catsco]

You are correct about the ROPS metal roof making the 425 SEEM louder.

My old Samurai stopped all of its nasty transmission, axle, and engine sounds after I removed the roof (yes, the roll bar stayed).

Two large mortar mixers being used in our area have the same engine as my 425, and the noise seems about the same from a distance.

So, it seems that the noise could be reduced drastically by something to avoid reflecting the sound from the roof, such as foam (as has been suggested) or some kind of flexible vertical piece from the rear of the canopy made so as to not hit anything when turning.

Mark H.

 

[ponytug]

Depending upon how much you want to spend, there is a lot out there, and many of the products wil insulate against transmitted heat as well. e.g. Dynamat, etc. If you put it on the ROPS, just make sure that you get one that is good for vertical or roof mounting.

Of course, you can put some under the engine cover as well. My V8 truck got a lot quieter with a little bit of extra insulation under the hood. A lot quieter. On the PT, I would get an insulation that is sealed so that an oil spray doesn't turn into a major mess.

All the best,

Peter

You are correct about the ROPS metal roof making the 425 SEEM louder.

My old Samurai stopped all of its nasty transmission, axle, and engine sounds after I removed the roof (yes, the roll bar stayed).

Two large mortar mixers being used in our area have the same engine as my 425, and the noise seems about the same from a distance.

So, it seems that the noise could be reduced drastically by something to avoid reflecting the sound from the roof, such as foam (as has been suggested) or some kind of flexible vertical piece from the rear of the canopy made so as to not hit anything when turning.

Mark H.

 

[BobRip]

Depending upon how much you want to spend, there is a lot out there, and many of the products wil insulate against transmitted heat as well. e.g. Dynamat, etc. If you put it on the ROPS, just make sure that you get one that is good for vertical or roof mounting.

Of course, you can put some under the engine cover as well. My V8 truck got a lot quieter with a little bit of extra insulation under the hood. A lot quieter. On the PT, I would get an insulation that is sealed so that an oil spray doesn't turn into a major mess.

Peter

I put some Dynamat on the corners of the engine cover. I did not want to block the expanded metal for air flow reasons. If there was a difference it was subtle. I have some left and will try it on the sides of the engine compartment on either side of the engine, if I can get it in their. There is not a lot of clearance.

 

[BobRip]

I put some Dynamat on the corners of the engine cover. I did not want to block the expanded metal for air flow reasons. If there was a difference it was subtle. I have some left and will try it on the sides of the engine compartment on either side of the engine, if I can get it in their. There is not a lot of clearance.

I added a piece of Dynamat to the right side of the engine compartment. I could not easily do it on the left. I did not see a noticeable difference. I wonder if Dynamat works when added to a 1/8 inch plate. It is really made to work on sheet metal. It was certainly worth a try.

 

[woodlandfarms]

My problem with Dynamat is the weight. The lid on the 1850 is really, really heavy. Any extra pounds would make it nearly impossible to lift.

Then again, I have been called a whimp by many...

 

[ponytug]

Unfortunately, it works best in the center of the metal, in large pieces, where it gets the best damping effect.

And, yes, you are right, it works better on sheet metal, but it will still absorb vibrations on thicker metal. Did you try some on the ROPS?

All the best,

Peter

I put some Dynamat on the corners of the engine cover. I did not want to block the expanded metal for air flow reasons. If there was a difference it was subtle. I have some left and will try it on the sides of the engine compartment on either side of the engine, if I can get it in their. There is not a lot of clearance.

 

[BobRip]

Unfortunately, it works best in the center of the metal, in large pieces, where it gets the best damping effect.

And, yes, you are right, it works better on sheet metal, but it will still absorb vibrations on thicker metal. Did you try some on the ROPS?

All the best,

Peter

I have a sound absorbing foam under the ROPS. I did notice a change in sound when I did th is. Is this the best choice for that location?

 

[ponytug]

My question would be how much of the noise is reflected, and how much is caused by the ROPS vibrating?

Dynamat reduces vibration, and transmission of sound from one side of the surface to the other.

Foam will reduce reflected noise pretty well. It isn't as good at reducing vibration.

They aren't mutually exclusive.

Since the sound is probably reflecting off of the ROPS down to you, I would hazard a guess that it is a good location. I really wouldn't want it in the engine compartment, where it would probably decompose, absorb oil, and catch fire.

Personally, I wear Pelltor earmuffs, but they don't obviate the need for ameliorating the sound in general.

All the best,

Peter

I have a sound absorbing foam under the ROPS. I did notice a change in sound when I did th is. Is this the best choice for that location?

 

[MossRoad]

I wear ear protection, too. I suppose one way to check would be to get a sound level meter and hold it in front of your face and take a reading. Then, loosen the ROPS bolts and swing it down in front of the tractor and repeat the test.

I have access to a sound level meter, but I don't have the time to do the experiment this weekend. The only sounds you will hear at my house for the next few days are :

Munch, crunch, slurp, burb and zzzzzzznnnnxxxxxxzzzzzzz!

 

[SnowRidge]

Foam will reduce reflected noise pretty well. It isn't as good at reducing vibration.

They aren't mutually exclusive.

Since the sound is probably reflecting off of the ROPS down to you, I would hazard a guess that it is a good location. I really wouldn't want it in the engine compartment, where it would probably decompose, absorb oil, and catch fire.

I had lead impregnated sound absorbing foam in a boat's engine compartment. While it didn't catch fire, it did decompose.

 

[BobRip]

My question would be how much of the noise is reflected, and how much is caused by the ROPS vibrating?

Dynamat reduces vibration, and transmission of sound from one side of the surface to the other.

Foam will reduce reflected noise pretty well. It isn't as good at reducing vibration.

They aren't mutually exclusive.

Since the sound is probably reflecting off of the ROPS down to you, I would hazard a guess that it is a good location. I really wouldn't want it in the engine compartment, where it would probably decompose, absorb oil, and catch fire.

Personally, I wear Pelltor earmuffs, but they don't obviate the need for ameliorating the sound in general.

All the best,

Peter

I always wear ear protction to, and would even if I reduced the sound. I just don't like that much noise around and don't like to disturb the neighbors even though they would never complain.

I have a slow vehicle triangle on the back of the engine cover. I wonder if the dynamat would help on the back of it.

 

[woodlandfarms]

I don't mind (and I wear) my earmuffs with ipod earbuds underneath. I do want to find a set of earmuffs that take an Ipod signal (in stereo) and hopefully with no wires..

Anyway, what I wanted to say is earmuffs are great until I mow. I have hit so much stuff and not heard it until it was way too late. So, I am going to add a second muffler as well as foam on the underside roof of the tractor canopy...

 

[KMA]

I do want to find a set of earmuffs that take an Ipod signal (in stereo) and hopefully with no wires..

How about these? They're called "iMuffs".

Wi-Gear iMuffs - Wireless headphones for your iPod and Bluetooth phone!

 

[ponytug]

Just get a Griffin or Belkin FM transmitter for your iPod, and put it in a safe place. Then you can use these;
Peltor WorkTunes

Having done a lot of mowing without earmuffs in the old days, I don't know how much turning down the sound on the tractor is going to help you. I used to hear a small ting, as the first blade glanced over the monster rock, and then the next second, it was WHAMMO, but perhaps your reactions are faster than mine.

All the best,

Peter

I don't mind (and I wear) my earmuffs with ipod earbuds underneath. I do want to find a set of earmuffs that take an Ipod signal (in stereo) and hopefully with no wires..

Anyway, what I wanted to say is earmuffs are great until I mow. I have hit so much stuff and not heard it until it was way too late. So, I am going to add a second muffler as well as foam on the underside roof of the tractor canopy...

 

[MossRoad]

... I used to hear a small ting, as the first blade glanced over the monster rock, and then the next second, it was WHAMMO, but perhaps your reactions are faster than mine....

I love that sound!

 

[woodlandfarms]

Well. Lets put it this way. With the Ipod going alone, I can hear things, and with the Earmuffs, i can kinda hear things, but with both going it takes me smoking my belt to realize things have gone south...

Carl

 

[Marks481]

I do want to find a set of earmuffs that take an Ipod signal (in stereo) and hopefully with no wires..

AO safety also makes earmuffs with built in speakers that take a 3.5mm jack, but they are kind of pricey:
Amazon.com: Peltor Listen-Only Headset #HTB79A-02: Home Improvement

I would rather buy their Electronic Surround headset (mostly for the wood shop or when grinding). It blocks loud noises and amplifies low noises, and also has a 3.5mm jack to plug in your ipod. At $185, it might be just a little TOO expensive... especially cause if I buy one, I will have to buy two (my 5yo generally gets to wear my safety gear first, so if I actually want to use something I gotta buy two... which is why I now have two autodarkening helmets):

http://www.peltor.com/pdf/comm/surround.pdf