Robin EY21 Engine Replacement?

[Mr Mower Man]

I have a very interesting project that may be coming into my shop. A guy has a parking lot sweeper (AA-Tach PV-II) powered by this 21HP Robin engine (EY21 135270). He said it runs good & strong for about 3 minutes, and then it starts to labor like it's under a heavy load, and then it dies. He even says it locks up sometimes, so he wonders if it's losing oil pressure or something. He's prepared to replace the whole engine. I asked him if it ever smoked when it ran, and he said no. It doesn't make sense to me that it can run good and strong at all without smoking if it's been locking up inside, so I believe we've got another issue that could be repairable. The whole unit was in the back of his truck, and it left when he left a few minutes ago. I just looked it over for a few minutes and wrote down numbers and took some pictures. I've never seen one of these contraptions before. But I told him I'd research it and see if there was anything I might be able to do with it. He took it to my chief competitor first, and they don't want any part of it. Maybe I should say the same, but I have a golden opportunity here to win a new customer who has other equipment that needs maintenance!

Any of you have experience with these engines? Any ideas on what to look for with the symptoms I described? I know it probably isn't much to go on. The owner tried to start it up for me today so I could hear it run, but when he pushed the starter button, nothing happened. He said that had never happened to him before. Then he grabbed the starter pulley and tried to turn the engine by hand, but he couldn't move it, and he said it had locked up again. Sounds confusing to me.

So first of all, I'd like an idea or two on where to start diagnosing this engine. I can probably figure it out, except it has a strange looking ignition system that I'm not accustomed to (I'm not experienced at all with older type ignition styles). If that's causing his problem, I might not know how to figure that out.

Second, I'd like some direction in case we need to replace the engine. I've never seen an engine before that has a flywheel at the PTO end like this one. The crankshaft runs the flywheel, and then there's a drive shaft that bolts onto the outside of the flywheel. Can I even get a new engine that will fit? I don't even know how long the crank would have to be, and I'm afraid the current drive shaft is too long for any crankshaft to match up with.

What do you guys think about all this?

[bgsengine]

first link on a google search http://www.subarupower.com/media/manual ... 536250.pdf

[bgsengine]

But, almost sounds like you may have something in the enclosed flywheel area that is working like a cam clutch - a rolled up ball of debris or dried grease&dirt like a ball bearing that can cam into between the flywheel and engine would lock it up intermittently until something shakes it loose and then it runs normally.. I would start by removing the plugs and roll over by hand and feel for any resistance , listen or feel for anything that seems loose - tip engine one way or the other while turning over by hand - try to duplicate the lock up situation and then start removing covers , etc - I doubt you have an internal engine problem (unless something broke loose in the crankcase and jams in gear teeth?)

Oh yeah , if necessary , as a Subaru-Robin dealer we can get you specific info, parts, etc if I know what to dig out for you (beyond that service manual) if the info is available through our access (and our distributor)

[Mr Mower Man]

Hey, thanks for the service manual! I'd found online IPL's but not a service manual. That's a good idea about something in the enclosed flywheel area binding things up. Since the engine seems to run well when it runs (according to the owner), without smoking, I think I'll definitely focus on repairing this engine rather than looking for a replacement. Especially since you can provide me with any parts I might need. That was one of my big concerns, since I'm not a Robin dealer. I can run compression checks, leakdown tests, etc., to get a general idea of the engine's condition. And then I can do what you were saying. It looks like a good little bit of work just to get the engine loose!

[Mr Mower Man]

OK, I do have an update on this project. I let the customer bring the big monstrosity here.

I ran the engine for about 5 or 6 minutes, and it started to labor. A few seconds before it stopped running altogether, I could hear a squeaking noise. I did also hear a knock of some kind the whole time it ran, but I couldn't tell which cylinder it came from. The engine was locked up, and I couldn't turn it by hand, but the electric starter could turn it. Then I turned it by hand and I discovered that there was a "tight" spot at one point on every revolution. I thought it may be carbon buildup in the heads causing the problem when the piston was all the way up, so I removed the heads to inspect. That wasn't it, and the tight spot was happening when the pistons had been pulled down about a half inch. The valves weren't tight either, as I suspected they may be. But I did find that the piston seemed loose in one of the cylinders. I could move it back and forth. I could still detect a little bit of hatch marks. The other cylinder was much better, with no slop in the piston and the hatch marks very pronounced.

To make a very long story short, I got the engine removed from the equipment. I pulled flywheels and couldn't find anything that would be causing the binding it was experiencing. I basically did everything but tear into the crankcase to look inside. I buttoned the engine back together with fresh SAE30 oil (the oil that was in it was coal black), mounted it to a workbench, and started it up. I heard the knock immediately, and it seemed louder than before. After running about 3 or 4 minutes, I heard a loud breaking noise and one cylinder stopped running. The knocking also stopped. I stopped the engine and did a compression check and the cylinder that had the loose piston had zero compression, so the rod must've broken.

So now I've either got a rebuild or I can replace the engine. I haven't taken it apart yet to see the damage, so I'm not sure what a rebuild would entail. I can get a 20HP Kohler that retails for $1750, and I believe my customer would go for that. This thing has a 1-7/16" diameter shaft, so the smallest Briggs I could replace it with (which is usually what I try to do) is a 31HP that retails for over $2500. It would work, but it's overkill, so I'm looking at Kohler. I haven't looked into repair parts for the Robin, which may be hard to get and very expensive. Would you guys look to rebuild, or replace?

[bgsengine]

I vote RePower it - you get the engine warranty , as opposed to a rebuild in which YOU have to cover any warranty yourself.

[Mr Mower Man]

I vote RePower it - you get the engine warranty , as opposed to a rebuild in which YOU have to cover any warranty yourself.

Yeah, and it's more fun anyway! (in my humble opinion)

[RoyM]

This could get interesting. Is that a flat (horizontally opposed) twin? If so, is there room to install an ohv twin which is all that is currently available? Can you post some pictures?

[Mr Mower Man]

Yes, this is an opposed twin cylinder engine. I don't have any pictures of the engine mounted on the equipment, but it isn't very confined at all, so I'm pretty sure I'll be OK with a v-twin. It looks like although the v-twins may be taller, they won't be quite as long or quite as deep. And there's nothing above the engine at all. Heck, the original has smoke stacks!