PT422 Engine shaking / sputtering
- Thread starter KMA
- Start date
- Views: 28531
MossRoad
Super Moderator
- Joined
- Aug 31, 2001
- Messages
- 57,924
- Location
- South Bend, Indiana (near)
- Tractor
- Power Trac PT425 2001 Model Year
Radiator, Muffler relocation, battery, fuel tank, hydraulic cooler, the swing of the engine cover, length of existing hydraulic hoses, engine shaft diameter, length, adapter for engine to pumps, cooling hoses, etc...
Yes, it can be done. My guess is you will end up removing the engine cover and cutting the rear out of the engine tub, mounting the engine, pump, radiator and battery to one big tray, slide it in as a unit, bolt it down, hook up all of the hoses, then put the engine cover and fuel tank back on, fabricate a new rear end to the engine tub, then hang a muffler out the back or side, which will promptly get ripped off or smashed on a tree. At least, that's what would happen to me! :laughing:
I'm not sure why you are saying all of that needs to change... am I missing something? The pumps, etc mate to the "front" shaft side on my PT422 so the engine is mounted at the back of the tub and everything else is in front of it. The location of the muffler, battery, fuel tank, etc should not change (in theory). I'll have to take some pics and post them here. Of course, this assumes the actual engine block size is similar to the Robin. For a liquid cooled engine, the radiator would need to be moved outside. Of course, a new muffler would need to be fabricated regardless, but that is probably a positive thing.
This isn't a particularly good pic, but you can see the engine is at the very back of the tub and the muffler is mounted outside the cover. The black metal thing on the right side is the heat shield between the exhaust pipe and fuel tank.
Last edited:
My goal is to find one that fits pretty close. Width seems to be where I have the least wiggle room on my version. I have a inch or two behind the Robin, and height shouldn't be a problem since the engine is currently sitting atop some spacer tubes, and I think I have some decent room above the current air filter. Depth/length is actually the biggest challenge since the Robin is particularly small in this dimension... so finding a replacement that fits depth-wise will be tough. As crazy as it sounds, the liquid cooled Kawasaki I linked to earlier might give me the best chance of fitting without modification (other than moving the radiator outside).
Regarding the time estimates... since my Robin didn't like to start below 55 degrees when it was running "good", I've gotten used to not having it available over the winter. So that leaves me roughly 6 months or so to work on it. If that's not enough time... I'm definitely in over my head.
Last edited:
Here's an interesting update from Terry at PT... he says there is absolutely no issue with dropping in a 25hp EH72 Robin in place of the original EH65. I asked him if I should be worried about the pumps, etc and he said "not at all". In fact, he seemed to recommend going for the EH72 instead. In case anyone is wondering, here are the two spec numbers for the engines:
EH720-DS0032
EH650-DC0303 (need to verify if that 'C' is supposed to be a 'Z'... Terry's accent got the best of me I think )
I think I can fit this Kohler Command 25hp:
http://www.smallenginewarehouse.com...16"x4-29/64" Keyed Shaft, OHV, Electric Start
What do you guys think about the trade off between that engine (which probably costs about $250 more than the Robin) and the "drop in" EH72 choice? I'm not particularly happy with the Robin and I'd really like to go for a better engine, particularly one that starts in colder weather and maybe even runs quieter. It appears the engine should be around 25hp and have a 1 7/16" shaft. I'm not seeing options from Honda or Kawasaki that would fit... Found this site for the EH72 with free shipping, still need to see if I can find a better price.
http://www.equipatron.com/subaru-horizontal-engine-sub8011.html
EH720-DS0032
EH650-DC0303 (need to verify if that 'C' is supposed to be a 'Z'... Terry's accent got the best of me I think
)I think I can fit this Kohler Command 25hp:
http://www.smallenginewarehouse.com...16"x4-29/64" Keyed Shaft, OHV, Electric Start
What do you guys think about the trade off between that engine (which probably costs about $250 more than the Robin) and the "drop in" EH72 choice? I'm not particularly happy with the Robin and I'd really like to go for a better engine, particularly one that starts in colder weather and maybe even runs quieter. It appears the engine should be around 25hp and have a 1 7/16" shaft. I'm not seeing options from Honda or Kawasaki that would fit... Found this site for the EH72 with free shipping, still need to see if I can find a better price.
http://www.equipatron.com/subaru-horizontal-engine-sub8011.html
Last edited:
Marks481
Platinum Member
- Joined
- May 29, 2005
- Messages
- 978
- Tractor
- Power Trac 422 (2005)
Not to surprising that the 25 hp robin fits... It is the same engine. :laughing:
Different carburetor, and an external oil filter. Smaller diameter cylinders. Same engine block.
The advantage of the EH72 is that you can get a fuel injected version. That way when it quits working, none of our small engine repair knowledge will get it going again.
As long as you are thinking about the FI version, maybe you can get the low profile 28 hp EH72 to fit. I think an extra 6 hp would really help.
Different carburetor, and an external oil filter. Smaller diameter cylinders. Same engine block.
The advantage of the EH72 is that you can get a fuel injected version. That way when it quits working, none of our small engine repair knowledge will get it going again.
As long as you are thinking about the FI version, maybe you can get the low profile 28 hp EH72 to fit. I think an extra 6 hp would really help.
Yeah, I knew that...
I was more surprised about the fact that there is apparently no issue with the extra power on the pumps, etc. I was under the impression we had to be careful about jumping up to 25hp.Even the "regular" EH72 FI version appears to be 28hp. Going up 6hp would make me pretty nervous about reliability, although more power + fuel injection does sound pretty cool. :licking: I'm with you on the fact that FI will give me even less chance at being able to fix these darn things.
Swapping out the EH65 for the EH72 is a no brainer since the cost isn't much more. Spending another few hundred dollars more at least to get a potentially "better" brand (e.g. Kohler Command) is a tougher decision, especially until I know I can get it to fit. Rest assured, I won't be buying anything until I get as much of it figured out as possible. :thumbsup:
Gravy
Platinum Member
As far as I can tell, the 28 hp Robin gets it's extra power by revving to 4000 rpms vs the standard 3600. At 3600 rpms it makes about the same power as the 25 hp. I don't know if the pumps will take 4000 rpms.
BobRip
Elite Member
I think the main reason the Robin engine has trouble starting when cold is that the starter must rotate the pumps and the engine. Is there any information to support that the Kohler will start better when cold? I think the fuel injection would help no matter who makes the engine. I am speculating here, so if anyone has seen a Kohler on a PT start reliably when cold (say below 32f) please less us know. If you are afraid of too much horsepower then reduce the top RPM.
Thanks guys. I'll have to give the EH72 FI some more thought. I guess I could adjust the stop on the throttle cable connection so that it only revs up to a point. Anyone find a place that sells them online? I can't seem to find the fuel injected model.
Regarding cold starts, I agree that the biggest problem is turning the pumps with all that cold hydraulic oil, but I couldn't even get the engine to start when it was 50-55 degrees out. I would have to put a heater on the hydraulic oil tank AND make sure the battery was fully charged to even stand a chance.
Thanks again for everyone's input. :thumbsup: I'll keep you posted.
