PT422 Engine shaking / sputtering

[woodlandfarms]

Do you even use your PT? those are the cleanest 425 pictures I have seen except for someone who has a new baby rolled off the back of a delivery truck.

Great job on the mod. You have a bunch of 425 owners very very excited. Wonder if this should all go into a new thread for easy searching.

Carl

 

[Vacuous_One]

J_J: Thought about that...but, my P/T is an older model. With the later 425 models being "beefed" up, I don't think it's fair to call a 422 with a bigger engine a 428. Honestly, I don't know what would be fair!

woodlandfarms: Yes, we do use it. It's just that those photos were taken right after I changed out the engine. And, since I had the engine out...I tore it all down and repainted it. So, it's repainted and unused in those photos! I promise it doesn't look like that anymore, though! :laughing:

 

[BobRip]

Beautiful! This is the way to upgrade. Can you give us part numbers and suppliers for any parts you added. Like the fitting for the return gas line.

 

[Vacuous_One]

BobRip,

Yes, I can...but it will take a while! Thought I had that all nice & organized, but...I can't find it all!

I'll have to do a little searching and organizing before answering!

 

[ponytug]

This looks like a fantastic job! It looks like a great solution to a chronic problem for many people. I hope it returns many years of service.

Does your return hose go to the bottom of the gas tank? If not, I have a small heads up. If you get foaming (aeration) issues in warm weather (similar to vapor lock), you might want to consider adding a hose in the tank to get the return submerged. (I don't know how much fuel the Robbins recycle to the tank and at what rate, but I know it is a general concern for fuel injection returns in cars.)

It may be totally irrelevant here...

The close clearance on the dipstick looks like it would be easy to fix with a vise on the mounting brackets.

All the best,

Peter

 

[Vacuous_One]

ponytug: No, the return doesn't go to the bottom of the tank. It stops just inside the top of the tank. Haven't run into any issues yet, but thanks for the heads-up...I'll keep it in mind if I do!

Parts used in the modifications are per the attached files. I replaced the coupling for the wheel drive on the front end of the motor and both spiders (due to wear/damage...not because of any issue with the new motor), added the grommet and "L" fitting for the fuel injection return line, and - thanks to this forum - been able to identify and replace the fan switch.

If I think of anything else, I'll let you know...

 

[Marks481]

I'd negotiate with P/T to pay the difference and upgrade to the fuel injected engine on any new machine!

Good thought. That would definitely be a worthwhile option for a customer to think about. The difference between the new 25 and 28HP engine is only about $700.

Of course, from Power Trac's perspective, it blurs the lines between the models they offer. Having such an option available might convince a PT1430 shopper to go the cheaper route (a "PT428"). That would mean a lot less $$$ in both tractor and attachments. I know a 28 hp air cooled engine is not really in the same ballpark as a 30 hp diesel engine, but not everyone would see it that way.

Thanks for the pictures and model numbers. I know alot of us will be looking for reports on your engine over the next couple of years. It is nice to have a clearly defined path to follow when we have to upgrade.

 

[Clumber]

Good thought. That would definitely be a worthwhile option for a customer to think about. The difference between the new 25 and 28HP engine is only about $700.

Of course, from Power Trac's perspective, it blurs the lines between the models they offer. Having such an option available might convince a PT1430 shopper to go the cheaper route (a "PT428"). That would mean a lot less $$$ in both tractor and attachments. I know a 28 hp air cooled engine is not really in the same ballpark as a 30 hp diesel engine, but not everyone would see it that way.

Thanks for the pictures and model numbers. I know alot of us will be looking for reports on your engine over the next couple of years. It is nice to have a clearly defined path to follow when we have to upgrade.

I just bought a PT 425. Is swapping the engine really possible? There is no mention of this on there site.

Patrick

 

[Marks481]

Power Trac on occasion customized their product for customers, such as installing different capacity wheel motors.

I suspect that their willingness to entertain requests is very dependant on the the economy and how many orders they have received recently. Sometimes they categorically refuse anything like this, other times they agree.

The last time somone (as reported on this forum) asked for a different engine, they refused. I suspect that usually they will not agree to the alternate engine, even if it is a drop-in replacement. They would prefer you buy the PT1430 if you want more hp. And pay significantly more for the attachments.

Consider this: if you really want to replace your EH72 25 hp with the 28 hp version, you can probably ebay your new engine for $1000-1100.

Maybe they haven't loaded up the truck yet... call Terry and ask him.

 

[coolconnection]

I wonder how much a fuel injection kit would cost to upgrade the 25 horse robin engine. Do you think it is doable and a worthwile upgrade or do you think it is just for new engines?

Just wondering:anyone:

 

[Clumber]

Power Trac on occasion customized their product for customers, such as installing different capacity wheel motors.

I suspect that their willingness to entertain requests is very dependant on the the economy and how many orders they have received recently. Sometimes they categorically refuse anything like this, other times they agree.

The last time somone (as reported on this forum) asked for a different engine, they refused. I suspect that usually they will not agree to the alternate engine, even if it is a drop-in replacement. They would prefer you buy the PT1430 if you want more hp. And pay significantly more for the attachments.

Consider this: if you really want to replace your EH72 25 hp with the 28 hp version, you can probably ebay your new engine for $1000-1100.

Maybe they haven't loaded up the truck yet... call Terry and ask him.

Very interesting! My objective is to have an engine that is easier to start in cold weather. I think I remember reading in this forum that all the engines were difficult getting started in the cold, especially the diesels. Having more power would also be good.

Patrick

 

[MossRoad]

Very interesting! My objective is to have an engine that is easier to start in cold weather. I think I remember reading in this forum that all the engines were difficult getting started in the cold, especially the diesels. Having more power would also be good.

Patrick

The Kohler gas engines do not have difficulty starting in cold weather. I cannot figure out why Power Trac stopped using them and switched to the Robin. Hopefully, the F.I. Robin will solve this once and for all.

 

[J_J]

They probably contracted for a lot of Robin engines and got them for less money, thus more profit.

 

[Clumber]

My new PT 425 arrived last evening after a 5 hour drive from Tazwell on an open trailer. It was below 30 degrees here with a winchill of 19. The tarctor started on 3-4th try and ran great. I started it on the first try today about noon at 30 degrees. This after a night at 25 in an unheated garage. I am feeling very good about that so far.

 

[Vacuous_One]

Clumber: That's excellent! Glad to hear that Robin/Subaru may have a better engine now that Powertrac is using in the 425 than the older models some of us have/had!

 

[MossRoad]

My new PT 425 arrived last evening after a 5 hour drive from Tazwell on an open trailer. It was below 30 degrees here with a winchill of 19. The tarctor started on 3-4th try and ran great. I started it on the first try today about noon at 30 degrees. This after a night at 25 in an unheated garage. I am feeling very good about that so far.

That is sure good news for all future owners. :thumbsup:

 

[KMA]

My new PT 425 arrived last evening after a 5 hour drive from Tazwell on an open trailer. It was below 30 degrees here with a winchill of 19. The tarctor started on 3-4th try and ran great. I started it on the first try today about noon at 30 degrees. This after a night at 25 in an unheated garage. I am feeling very good about that so far.

Maybe the newer engines have an updated ignition?

 

[Clumber]

The engine manual says its the EH72D.

This morning it was 23 degrees F. It took 4 tries to start. Let it run for 2-3 mins, ran great.

 

[KMA]

I think it is going to come down to a Kohler Command Pro 25hp and the Robin EH72 FI, but the Kohler is ahead by a nose.

Kohler Command Pro CH730
+ automatic compression release and electronic ignition
+ good reputation
+ wide array of accessories/parts easily available
- tighter fit
- difficult to interpret "spec numbers" and find best version
Kohler Engines: CH730: Command PRO: Product Detail: Engines

Robin EH72 Fuel Injection
+ Fuel injection
+ Same size block for drop-in fit
+ Easy to translate known PT spec number to FI model
- harder to service/understand?
- Potentially higher price
- Need to purchase new coupling for smaller shaft diameter
Subaru Robin - Features and Benefits

The price for the CH730 varies quite a bit depending on spec number... Here's a good price on one that might work, but I'll need to do some more researching before knowing for sure:
Kohler Engine Number PA-CH730-0038, 25.0 HP Model: CH730S-0038 Command Series - On sale with free shipping at Tulsa Engine Warehouse!

Okay, the weather should start warming up here soon so its time to get an engine ordered for my PT422 so I can get it running again. I'm still bouncing back and forth between the Kohler CH730 and EH72 FI. The CH730 is about $200 or so cheaper, but I will likely need to replace the muffler assembly. I'm fairly certain I can get it to fit in the tub. The Robin should almost drop in and Vacuous_One was successful in putting the fuel injected model into his 422. I'm convinced my cold weather starting issues will improve with either choice, but I'm still a bit nervous about the long term reliability of the Robin engines. Maybe mine dying within a couple of hundred hours is a fluke, but I can't help but feel like they are not as reliable as Kohler, Honda, Kawasaki, etc. I wish I didn't feel this way because I'd pay the extra few hundred bucks to be able to drop something with little modification.

Any thoughts/opinions? Thanks.

 

[toy]

Not too long ago maybe a month or two I was up there to get them to rebuild [clean up and replaced one part of it] my tram pedal valve, and I asked them why they quite using koehler engines in their machines on the gas models. The person that I was talking to at their show room told me that the koehler quite selling direct to them and said that they would have to go through a distributor to get the engines, and to do that it would drive up the costs a lot. I made a suggestion for them to get a distributorship from Koehler, as many engines that they would sell it would be beneficial to give them a dealer distributorship to pt. I hope they consider it a good suggestion, and something happens positive for our machines.

Since a lot of you are having robin engine problems, I believe I would just as soon have a briggs and stratton engine. I have a Sears lawn and garden tractor 18 hp and it is about a 1989 year model and I have mowed our yard once a week every week during mowing season and haven't had any troubles with it.