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?