pt 425 robin engine pipes glowing

[Rivco]

At the request of a Fellow member I am Re-posting a picture of the dual exhaust conversion I did on my PT 180.

Here's how I did it:
1- duplicated muffler cutout on other side of engine cover.
2- Fabricated new exhaust manifold flanges.
3- Welded a short peice of 1" black pipe nipple to flange.
4- Added 1" to 1 1/4" 90 degree elbow.
5- Added a 6" x 1 1/4" black pipe nipple to elbow.
6- Added a second 90 degree elbow just outside of the engine cover.
7- Added a short black pipe nipple and then welded it to a USA made 12" glasspack muffler.
8- Welded 1 SuperTrapp 3S tip to the ends of the 2 glasspacks. My PT 180 was 18 HP. so I ordered a total of 12 Diffuser disks with the two SuperTrapp tips. ( 6 per. side )

CORRECTION... I ordered and installed a total of 6 diffuser disks ( 3 on each side ). The disks are rated at 1 disk per. 3 Hp. It's been a few years since I did that conversion

 

[Marks481]

At the request of a Fellow member I am Re-posting a picture of the dual exhaust conversion I did on my PT 180.

Thanks Rivco, as always, your work is incredible. In retrospect, would you have done anything different if you had to do the mod again? Other then sell your PT180 before you did all that work? Did you use normal schedule 40 black pipe?

I am weighing the benefits of going two mufflers vs trying to adapt the OEM side discharge muffler header like Gravy did (although I would probably move the opening in the canopy higher to avoid making the dogleg on the header to make it exit out the existing canopy hole).

http://www.tractorbynet.com/forums/power-trac/100127-robin-exhaust.html

Every time I turn off my PT, and it diesels and/or backfires for several seconds, I move the mod a little higher up my list...

 

[Gravy]

Tim,

Along with the dogleg issue, my muffler setup has another weakness. The original muffler sat above the rear tire, which cooked the fuel pump. Mine sits behind the rear tire, where it gets
smashed into rocks & stumps when I back up. It still works, but it ain't pretty, and it'll probably break off eventually.

It DID fix the backfire problem.

 

[MossRoad]

There are two designs for the PT400 series that I like.

The first one is mine! The engine in the middle with the tram pump up front and the two PTO pumps behind the engine. The only drawbacks of mine that I can see are:
A. The stock Kohler muffler has to be removed to change the battery (4 bolts).
B. The plastic fuel tank could be a problem in the future. If it ever fails I will weld up a metal one in the same shape and put a sight gauge on the side.

The second design that I like is the one with the engine in the rear and all three pumps out front. The fuel tank is in the lid. The battery is up on top for easy access. The only drawbacks of that design, to me at least, are:
A. The fuel tank in the lid. I think is would be easy to spill fuel if the tank was full and you tipped the lid. Also, it is harder to fill since the filler is far from one edge. Both of those problems could be minimized if the filler was on a tube in front of the tank and to one side.
B. The muffler on that design is fabricated by PowerTrac and requires heat shielding, etc...

I really wonder why Power Trac switched from Kohler engines and the stock Kohler exhaust. It seemed like a winner to me.

 

[SnowRidge]

There are two designs for the PT400 series that I like.

The first one is mine! The engine in the middle with the tram pump up front and the two PTO pumps behind the engine. The only drawbacks of mine that I can see are:
A. The stock Kohler muffler has to be removed to change the battery (4 bolts).

1. There are two variants, one with a Kohler muffler and one with a Power Trac attempt at a muffler. Junking the PT muffler and installing the Kohler muffler is the first step for those with the second variant.

2. Not to quibble , but there are six bolts, two of which will be frozen on.

B. The plastic fuel tank could be a problem in the future. If it ever fails I will weld up a metal one in the same shape and put a sight gauge on the side.

The tank is polyethylene. I think it is more likely to be a problem when new (it was for me, crappy fitment), than in the future. Polyethylene is pretty stable stuff.

 

[Gravy]

I really wonder why Power Trac switched from Kohler engines and the stock Kohler exhaust. It seemed like a winner to me.

Quick answer: $$$$$$$$$$$$$$$$

Kohler costs quite a bit more than Robin for the same rated horsepower. Both companies have generally very good reputations for quality. Cut costs and still provide a good product...

On this forum, we have a sampling of maybe several dozen 400 series owners at most? There are more complaints about Robin engines, but I think more of us HAVE Robin engines. We'd need hard numbers to make any fair judgments.

I've had 3 problems with my Robin engine: An oil cooler hose came loose (I caught it in time); it is hard to start when cold (weak ignition/cranks too slowly), and the air filter failed, allowing dust into the engine.

OTOH, I've heard of Kohlers dropping valve seats and self-destructing. My Robin still runs, but blows oil out the breather.

I've spent way too many hours on the internet looking for the perfect replacement engine. I've found various engines, each with it's own shortcomings. I haven't found anything that looks like The Answer.

If anybody knows of an affordable/available replacement engine that fits, makes at least as much power as the Robin, that is at least as reliable, and doesn't cost too much more, please let me know.

Extra points for diesel.

Gravy

 

[MossRoad]

Not to quibble , but there are six bolts, two of which will be frozen on.

Yeah, I forgot about those bracket bolts!

 

[MuncyBob]

Another Power Trac built muffler, I presume.

I junked mine and put a stock Kohler muffler on. Much better performance, no run on, and lower fuel consumption.

What modification (if any) did you have to do for the Kohler muffler to fit? Any pics?

 

[SnowRidge]

What modification (if any) did you have to do for the Kohler muffler to fit? Any pics?

I cut about an inch off of the outlet pipe. I'm travelling now, so don't have access to my pics. Just look at Moss Road's web site. His muffler is identical to mine. PT also cut the tail pipe.

I bought the muffler kit (for lack of a better term). It included the muffler, gaskets, mounting bracket, and hardware. You can buy the muffler alone, but you need the bracket, too. There is also a heat shield. I don't remember if it comes with the basic muffler or not. It certainly did come with the muffler in the kit.

 

[Marks481]

3- Welded a short peice of 1" black pipe nipple to flange.
4- Added 1" to 1 1/4" 90 degree elbow.
5- Added a 6" x 1 1/4" black pipe nipple to elbow.

A couple of questions....

1. I measure the existing stubs between the flange and the square manifold on the PT muffler as 1" OD, which probably means 3/4" pipe (rated by ID). Did you have a problem fitting 1" pipe on the flanges and still getting bolts through? Obviously bigger is better for this application.
2. Why did you use the 1" to 1 1/4" 90 degree elbow instead of just keeping it at 1"? And where did you find butt-weld 1" to 1 1/4" 90 degree elbows?

Thanks... just trying to follow in your footsteps here.