My PT-422 mods

[KMA]

Customized a cheap, garden tractor box scraper for use with my PT. It's a Brinly, which I ordered on Amazon for an extremely good price ($170.99 with free Prime shipping):

Amazon.com : Brinly BS-38BH Sleeve Hitch Tow Behind Box Scraper, 38-Inch : Lawn And Garden Towable Tools : Patio, Lawn & Garden

It can be angled 30 degrees either way and is meant to be used with a sleeve hitch, but I replaced it with a 2" receiver mount. I went to HF to pick up the following adapter:

2" to 1-1/4" Hitch Adapter

The plan was to drill holes and bolt it to the box scraper in place of the sleeve hitch, but they were out of stock so I had to get this one:

2" Ball Mount Hitch with 0 Drop

You'll notice the 2" ball hanging down. It won't allow you to rotate the blade all the way around. Not a big deal for me (could cut it off I guess), but if fully rotated it could be used to push dirt or snow. I didn't get a chance to really use it, but as-is the removable scarifier bar's teeth don't hang down quite far enough. This is mostly due to the limit on how much you can "curl" the plate, since it is not quite horizontal when all the way to the ground. I think if I pick up a drop down adapter like the following, it would allow me to get the teeth to dig in better:

Dual Hitch Extender

Another option is to weld longer "teeth" up against the existing ones, or maybe even add more while I'm at it. I'll see how it goes and make changes as necessary. Here are some pics:

 

[coolconnection]

Robin OEM engine filter replacement:

This was done to avoid having to purchase expense OEM filters over the web. You should be able to save a few bucks and go to the local tractor supply store and find a Kohler filter to use. I believe this should work on the 18, 22 and 25 hp versions, but the one in the pictures is a PT422. I based the following on an email from forum member washita although I did my mine slightly different, but the idea is the same... remove the metal cover from the OEM and use it with a more readily available filter element.

First, separate the paper element from the stock filter metal plate. There will likely be some rubber residue along the edge of the plate, so I just ran a wide blade screw driver along it to lift it up. Some of it would pull away in chunks making it easier. I don't think it has to be perfectly clean, but it needs to make a good seal with the top of the replacement filter. Be careful not to jam the tool into your hand while peeling up the residue, or cut your fingers on the wire mesh surrounding the paper element.

Washita suggested I use air filter #47 883 03-s1 for Kohler Command CH18-23 hp and CV17-23 hp engines. I used a slightly different model as seen in the following picture since it was all Tractor Supply Co had yesterday. The other model numbers may or may not be a better fit. I noticed the one I used (4708303) mated with the metal plate well, but was a tight fit onto the carburetor housing. The cost was $12.49 and included a prefilter.

You'll need to push down with enough even pressure to get the filter onto the carb housing without crushing it. This ensures a good seal, and allows the nut to reach the the threads when tightening it all down... but more on that later.

Here's a pic showing the metal plate over the installed filter, along with the prefilter. The nut is screwed on just to show how the metal plate makes a good seal with the new filter.

Since the filter I purchased had a slightly smaller inside diameter, I needed to push the element down onto the carb body with some force to get it to sit lower. Even after doing this, the filter was a bit higher and and wouldn't allow the nut to reach the threads when everything was installed, so I had to remove some material on the bench grinder.

Here's the last pic with the cover in place. The total time to do the mod was about 15 mins. Hope this helps someone else too.

I know this is a really old post but has anyone tried to use a K&N filter in this paper filters place and what were your experiences using one? I have done this mod to my old Robin filter and been using a filter I picked up at TSC since but I can get a K&N filter for $30 on line and I can wash it too and keep it like new.

 

[KMA]

IMHO, I wouldn't use a K&N style filter in the dirty/dusty conditions my PT sees. At the very least you would need to add a really good prefilter or two. I think K&N claims it is okay to use in these conditions, but if you search around you'll find many claim it is not ideal after oil testing, etc. I have one on the '83 CJ7 I'm rebuilding, and it just doesn't look like it would be good at all for filtering fine particles... even after a fresh oiling/recharge.

 

[coolconnection]

Thanks, I wondering about that.

 

[KMA]

iRe: My PT-422 mods

After replacing the original EH65 engine (when it died) with the EH72FI, and then having its fuel pump go after around 50 hours of use, I realized (as many of us PT4xx owners have) that the Robin engines and cramped tub space of the PT do no go well together. More recently, the replacement fuel pump started acting up and it was time to order a new one. In all honesty, the last fuel pump was only meant to be temporary and wasn't designed for this application (i.e., fuel injection), but it was a cheap test to make sure it fixed my issue. Buying an OEM fuel pump is expensive, only to have it fail a few months later... so I looked at Airtex's universal models intended for fuel injected motors.

I also started noticing the 10" fan I added to the side of the engine cover years ago only spun sometimes, so I figured I'd replace that too. While I was at it, I decided to add another small fan to move more air, so I picked up a cheap 7" unit along with a 12" to take over the dying 10" fan's duties. I made a jumper wire to take the thermostat out of the circuit, and have the hydraulic oil cooler fan run all the time along with the others. Here are the parts I ordered:

Pump:
Amazon.com: Airtex E8445 Universal Replacement In-Line Electric Fuel Pump for Fuel Injected Systems: Automotive

12" fan:
Amazon.com: Upgr8 Universal High Performance 12V Slim Electric Cooling Radiator Fan With Fan Mounting Kit (12 Inch, Black): Automotive

7" fan:
Amazon.com: 7 Inch High Performance Black Electric Radiator Cooling Fan Assembly Kit: Automotive

It's interesting to note that the 7" fan is a direct fit for the hydraulic oil cooler fan on top of the engine cover. I actually swapped it out with the OE Spal fan because I wanted to use the much narrower Spal on the back of the tub to push air across the engine's oil cooler. That allowed me to make a guard that didn't stick out too much. So far so good, but I'll need more time on it to know if things are any better cooling-wise. I had a theory that the weaker fuel pump was causing the engine to run lean (read: hotter), but the new one moves a lot of fuel. When I swapped engines, I re-routed the fuel line to the other side way from the muffler and oil cooler to cut down on vapor lock. The new pump is mounted on the same side again, but now its up under the fuel tank due to its larger size. Here are some pics:

 

[Frank Sorbello]

Thanks Tim, The fan I have looks the same but is an 11.5" or 12" fan. They have two types, push and pull. I am confused. I want the cold air to be pushed on to the cooler, right?

 

[MossRoad]

The stock cooling fan that is mounted on top of the engine cover over the hydraulic cooler pulls air UP. At least on mine it does.

 

[KMA]

This model pulls by default (which is what the OE fan does), but can be configured to push.

 

[Frank Sorbello]

I purchased two 12" new 12volt slim fans that are pretty much identical to the original for $34 plus free shipping on ebay. Only problem two of the four mounting holes don't match up. Not a big deal. Not sure how the seller can make money with a deal like that!

 

[stray]

Tell me if i'm wrong but i am pretty sure that if you reverse the leads to reverse the fan you need to take the blade of and turn it over. If you don't it won't blow near as well. You can just run it to test.