Buying Advice wish to buy a new suburu robin engine to replace current one

[MossRoad]

I think a more useful modification would be a clutch between the engine and pumps so you could disengage the load to start. That would probably cure any Subaru cold weather starting issues.

 

[joshlee]

With the Subaru motors starting so hard in cold weather, I'm wondering if using synthetic oil for the hydraulic tank would make any difference? They say it doesn't thicken up as much as your conventional oils. There was someone on here that said how theres not a huge difference with viscosity between 20w and 10w in cold weather, but synthetics? I wonder?

Yeah, those Power Trac exhaust pipes would have to generate excessive heat at those 90 degree bends along with restriction in flow, and I really liked Kent's forum so much that I went and purchased a Subaru exhaust header and muffler.

Thanks for your opinion on the Kohler/ Subaru swap idea.

Josh

Well, since I don't have a Subaru, and am biased by my Kohler's dependability, I'd have to think long and hard about it.

From what I've heard, the Subaru's don't start well when its cold outside. And by cold, I mean way below freezing down to -5 or so. That's when I need the machine the most, as I have to plow the drive to get out to go to work to make money to support my family. So does my wife, so she's counting on me as well. In summer, its no big deal if the machine doesn't start. I can mow the lawn tomorrow. Not so much with snow.

My garage is unattached, un-insulated and unheated. I don't want to go out there and apply special means to get it started. Block heaters, tank heaters, space heaters, quilts, blankets, etc... its bad enough that I occasionally use starting fluid below -5 if it doesn't pop after a couple tries, as I have to open the hood and remove the air cleaner, start it, and then put everything back.

I do not know which engine is made better, will last longer, is easier to service, etc... I know I can get parts for the Kohler locally at several sources. The Subaru, not as many places, but they are getting more common.

Now to the question of the electronic fuel injection, and this isn't specific to either brand.... Supposed to start easier (does it?), and use less fuel. However, I cringe at electronics in lawn and garden (and AG) equipment. When it fails, how do you diagnose it and are the parts available, and, most importantly, how expensive are they compared to a carb?

If I had one with a Subaru, I'd probably go for another Subaru with more HP and EFI, put a Subaru exhaust system on it and modify the hood to make it fit. I'd put in plenty of heat shielding to keep the muffler heat directed away from the engine and hydraulics. My Kohler has a Kohler exhaust system and the pipe exits directly out the center of the rear of the machine. There's a Kohler heat shield between the muffler and the engine, too. In my opinion, their home-brewed exhaust systems are a problem. They're restrictive, too many bends and corners and probably hinder performance. They need to seriously re-think using the Subaru in this application.

Anyhow, its all speculation until I get my hands on one with a Subaru, so take it for what it is... my opinion, not fact.

 

[KMA]

I have a modified exhaust header and Subaru muffler, and use synthetic oil in the engine and hydraulics. The oil may help a bit (e.g., start a few degrees colder), but the switch to the EFI engine helped by about 10-15 degrees. The exhaust modifications help with heat, but it is still an issue and always will be due to the PT4xx tub design. IMHO, the only "real" solution on current models is a cooler running engine or lots of customization.

 

[MossRoad]

Here's a photo of how my 2001 model year PT425 is laid out (no, the tractor has never been that clean again).
You can see the rear facing muffler with the two-section PTO pump beneath it. The VVP is in front of the engine, almost under the gas tank.
I really like this setup. Only thing I have to watch for is hot exhaust exiting the rear of the tractor has melted the plastic on a few cheap implements! :laughing:

 

[MossRoad]

View from other side.

 

[MossRoad]

PTO and steering pump.
Notice the pump adapter mounted to the Kohler engine. This is the business end of the Kohler, so, in essence, it is mounted backwards in the engine compartment. Well, not sure about backwards, but the fan is at the front in this application.

 

[MossRoad]

The variable volume pump. Notice it is mounted to the shaft through a hole cut in the fan shroud of the Kohler engine. Can't see how the pump is attached to the motor.
View attachment 422904

 

[joshlee]

Wow! Thats an awesome idea! No doubt, that definitely would work.

I think a more useful modification would be a clutch between the engine and pumps so you could disengage the load to start. That would probably cure any Subaru cold weather starting issues.

 

[joshlee]

Do you think these Subaru engines in the PT's can get 1500 hrs before an overhaul? With the heat, do you think your engine is running at about the same temperatures as Kent's? According to the readings he took, it seems that machine of his is set up pretty good? As far as the temps , that is.

I have a modified exhaust header and Subaru mffler, and use synthetic oil in the engine and hydraulics. The oil may help a bit (e.g., start a few degrees colder), but the switch to the EFI engine helped by about 10-15 degrees. The exhaust modifications help with heat, but it is still an issue and always will be due to the PT4xx tub design. IMHO, the only "real" solution on current models is a cooler running engine or lots of customization.

 

[joshlee]

I see. I notice you don't have a heat shield either. The pumps are right underneath the muffler? In that respect, I might prefer the Robin/Subaru set up, but thats nice to see how the engineering changed from 2001 and obviously that year they built a durable, good running machine.Not that it would be anything significant, but I wonder if the newer PT-425 can lift more than yours, because of there being more weight in the rear of the tub? It looks like you have more available room to work on your engine than mine too?