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?