With a noise like you describe, I would check the coupler or drive between the engine crankshaft and the generator armature shaft. Are you simply running the engine without an electrical load on the generator? If you have been running it unloaded, put some sort of hefty electrical load on the generator and see what that does to the sound. It is also possible that an intake valve is trying to stick. You may want to add a bit of Seafoam Gasoline treatment/fuel system cleaner as well as some Marvel Mystery Oil to your fuel. This will help clean up and lube the intake valve stems in the cylinder head. Engines that sit dead in storage are pretty notorious about sticking valves.

If it were me, I would have a technician familiar with generators listen to it and make some decisions from there. Maybe a stethoscope would help possibly. It all gets expensive if something is awry. BTW, I think your model is a 350445.

mownie,

I did add Seafoam to the first gallon I ran through it. I can add some more Seafoam, and also maybe add it to the oil. Or I can get some Marvel Mystery Oil, if you think that's better to add to the oil. I have Sta-bil in the gas at the moment, but I think it's still OK to add Seafoam. I will take a look at the coupling between the engine & generator, but that seems pretty solid, and the noise sounds like a smaller object, not a big shaft. I have hooked up what I can, a 1000W work light, and a 1600W hair dryer, but it's a 10,000W unit, so that didn't make much of a load. I don't have anything really big that I can plug in easily, but I'll see what I can come up with. It only has 2 normal, 110V 20A plugs, so I can only plug in so many "normal" household items, without going to more exotic plugs.

tomplum,

That's a good thought. I did go around with a screwdriver up against the engine, and the other end to my hand & ear, it wasn't really conclusive. I think it's the engine, not the generator, but pinpointing it was difficult. It sounded to me like maybe it was more towards the "front" of the engine, closer to the flywheel, but it's tough to tell. It's an intermittent sound, so it's difficult to track, since it's not always there, and when it is, it's just a quick "clack". I thought I heard "secondary" noises, like it bouncing off something else, but it could be my imagination. With the exhaust roar, there's a lot of other noise around. Oh, and my apologies for the typo, you're right, the model is 350445.

Thank you for your help!

try adjusting the valve and see if that helps. The clacking sound sounds like a rocker smacking the valve. I think mownie might be right, could be a sticking valve

That would be great if it were an occasionally sticking valve. Seafoam in the oil and fuel and even squirt Marvel or Seafoam down the carb as it is running. I usually start w/ carb spray first. It fits with the sitting as Mownie said. One would think a pop or something related to runability would happen at the the same time. Seems hard to say without hearing it run, and then maybe even be stumped. We used to have one of those sound probe things, they worked pretty well, but not always conclusive. Try plastic pipe /tubing put to your ear.

If it actually is caused by a sticking (or slow moving when trying to seat) intake valve, the noise being heard would be likely be a mixture of different sounds. (1) Piston "tapping" the intake valve (2) valve stem tapping the rocker arm (3) rocker arm tapping pushrod (4) pushrod tapping lifter (5) hiss and/or pop as compression tries to escape backward into the intake port. At times, I and other folks where I work have made "po boy" stethoscopes by taking a length of 1/4" plastic tubing and inserting a piece of straightened coat hanger wire into one end. The coat hanger wire only needs to be 3/4 as long as the plastic tubing (tubing= 24", coat hanger= 18" or even a bit shorter). The end with the coat hanger is used to probe locations on the engine (or other) to pick up sounds. The tubing sort of acts as sound insulation from picking up "ambient noise" on the outside, but helps to "conduit" the noise along on the inside. The plastic tubing also minimizes the chance of shorting an exposed electrical terminal to ground if you are listening near something that has any. Hold the open tube end close to your best ear and probe the engine surfaces with the coat hanger end. The coat hanger can be bent to fit around objects. To help keep your hands from damping the noise, wear a pair of cotton "brown jersey" gloves.
Yes, Marvel Mystery Oil should be added to the gas tank too. The portion of the intake valve stem immediately above the valve face will benefit from the little bit of lube afforded by the small amount of oil added to the fuel. Realistically, you can use a dab of 2-cycle fuel mix oil to the tank instead of MMM if you like. The key word here is "Dab". As little as 2 or 3 capfuls (cap from oil bottle) per gallon of gas is plenty for this purpose.

Thank you very much, this is a huge help. For what it's worth, I don't hear any engine hiccups when it makes the clack sound. It doesn't miss, or backfire or anything. I like the idea of a sticking valve, especially if it could be fixed by adding stuff to the tank & oil :) I have one of those cheap engine-stethoscope things, I can try that. I could remove the valve covers and look under those as well. I will pick up some Marvel Mystery Oil and definitely try that first, as well as more Seafoam. Thank you again for all of the help so far!

I added some Seafoam to the oil, and the gas. I ran it for about an hour, at idle, to hopefully circulate the Seafoam, without being as likely to cause the noise. I have only noticed the noise when it's at full speed. I brought it up to speed a few times, but it was mainly at idle. I then added some Marvel Mystery Oil to the gas (which already had Seafoam), and ran it for about 10 minutes. It was getting late, didn't want to alienate the neighbors, so had to call it a night. I did notice some apparent misfiring, seemingly from just 1 cylinder, before I shut it down. I don't recall noticing that before. I will run it some more tomorrow. I may add some Marvel Mystery Oil to the oil as well, if that's acceptable to mix it with the Seafoam already in the oil. I'd like to spray some into the intake, but I have to move the gas tank, I think, to get enough access to the intake area, as there is not much clearance above the air filter, to the bottom of the tank. Thank you again guys.

Don't be too anxious to spray (or squirt) oil into the intake. I think the MMM added to the fuel tank will be sufficient. This is not neccessarily a case of "more is better". Here is what you are trying to accomplish. The intake valve stem becomes coated with a gummy, resinous layer of varnish, mixed with a slight amount of combustion by products that inevitably make their way into the intake through the crankcase ventilator and from being leaked back through the intake valve just before the valve closes. This stuff can become "sticky enough" to slow, or stop, the movement of a valve. The Seafoam and the MMM will clean the varnish off and leave a light coat of lube on the valve stem. It is not going to clean the valves instantaneously, but over a period of running time. The mess will be cleaned better if the cleaning agents (Seafoam & MMM) are carried past the valves in very dilute quantities over time, by normal action of the engine. Trying to pour a lot of stuff in all at once will only result in wasting the bulk of the product.
The"apparent misfiring" may be due to a sticky valve as described earlier.

Guys,

I've added Marvel Mystery Oil to the oil, in addition to the Seafoam that was already in there. I also added MMO to the gas. I've run it for probably another 3+ hours, mainly at idle. I did pull the air filter, and sprayed Seafoam into the intake while running, then shut it off. I let that soak for about an hour, and have run it for about 2 hours afterwards. I pulled the air cleaner again, and this time sprayed MMO into the intake, while cranking it with the choke pulled, and the ignition off. I let that soak overnight. I ran it today, it smoked for a while when I started it (presumably from the MMO), then that cleared up. I have not heard the clack noise in a while. Granted, I have mainly been running it at idle, to let the Seafoam, etc, circulate, but when I bring it up to speed, I have not been hearing the noise. That's definite progress. Now I can't decide if I'm just being paranoid about how the rest of it sounds. I hear mechanical noise when it's at full speed. That's of course to be expected, but I could hear a consistent ticking sound today. But, again, now I'm listening for anything, and this, spinning at 3600 RPM, seems to turn faster than my other engines, so therefore makes louder mechanical sounds.

I could take off the OHV rocker covers and look for rocker arm damage underneath, if that would be a good idea. I'd learn the most by taking off the heads, and looking for valve marks on the top of the pistons. I'm just trying to avoid taking apart more of the engine than needed.

Thank you guys very much for all the help so far, this seems to have made a definite improvement. I have not been hearing the clack (though *not* hearing it isn't 100% conclusive, as it was intermittent), and I did not notice the misfire today. Also, a few days ago, before running the MMO, etc, I realized I had seen the exhaust manifold pipe glowing by the 2nd cylinder (the one on the exhaust side). It was dark out, which helped me see it. This was at idle, as I recall. Watching it run over the last few days, I have not seen it glowing. I presume that glowing could be a symptom of a sticking valve.

Again, thank you for all of the help so far, I really, really appreciate it. You kept me from chasing my tail, looking for something loose inside the engine. I'd welcome suggestions on what to do next. Leave it alone and run it? (I plan to keep adding MMO to the gas for a while, to be safe) Pull the rocker covers off and look underneath? Something further?

You can pull the valve covers and survey the general appearance of everything (crud, varnish) if you want to. I don't recommend pulling the heads because nothing really indicates the need to. It couldn't hurt to adjust the valves...........unless you do it incorrectly, but here again nothing indicates you actually have a valve adjustment issue.
The red exhaust may have indicated a sticking valve, but probably not in the same way you think. I presume you think a sticky exhaust valve on the cylinder that had the red glow would be the culprit. Probably not. The liklier scenario would be that the opposite cylinder had the sticky valve (intake valve), resulting in too little combustion to redden the exhaust on that side. Because the engine governor would be able to open the throttle and keep the RPM at max without a load on the engine, the GOOD cylinder was working harder than if both cylinders were making equal power (and heat). This engine may just be trying to "shake off" the effects of a long period of inactivity. What are your plans for this genset? Emergency standby power? Regular use in situations where utility power is unavailable? Or both?

mownie, thank you very much for the quick reply. If I were to pull the valve covers, would it be OK to pour/spray some Seafoam on the valve components to help loosen any varnish? You're right, I had assumed the glowing-exhaust cylinder would be the one with the problem, either due to the exhaust valve not sealing fully (and leaking during combustion), or the intake valve closing late, after blowing some of the intake charge back out (as the piston came up), and running lean. My plans for the generator are simply for emergency power if we have an outage. In the New England ice storm last winter, we had no power for 3 days, so it got me thinking about a backup. But that event was really the exception, rather than the rule. More common would be several hours every few months. I don't expect to be using it all that often, but of course I do want it to be reliable when I do need it.

You can do more good by simply running the engine with the additives you now have in place (in the fuel and oil). Trust me, spraying copious amounts of stuff ONTO the parts is not what the engine needs. Anything you simply spray onto the surface of the components will be gone in seconds. This engine needs some run time. The mechanical action of the moving parts in the presence of dilute amounts of Seafoam and MMM does more good than any direct aplication of the concentrated additives. Does "synergy" mean anything to you? (An interaction of several things that results in a greater effect than the sum of the "things" individual effects.) Essentially, that means a little dab will do ya if combined with exercising the components (or something like that) :^)

mownie, OK, no problem, I will plan to just keep running additives through the gas. They do seem to have helped over the hours I have let it run so far. I ran it some more tonight, and unfortunately, I may not be entirely out of the woods.

I connected the biggest load I could manage, about 3600W, and ran it for 5-10 minutes like that, after warming up at idle for several minutes. It handled it fine, which was good, but I did seem to hear the clack again at one point. It was dark, and I shut off the outside lights. I could see a very faint glow from the pipe coming from the starter-side cylinder, which got brighter when it got to the exhaust-side cylinder. The center of the muffler (looking in through it) was an even brighter orange. One thing that occurred to me is that the first cylinder has introduced hot air to the exhaust manifold already, then the second cylinder is adding even more. Could that help account for the pipe glowing more at the 2nd cylinder? Is this perhaps normal? With the setup of this engine, the muffler is at one end of the exhaust manifold. The IPL seems to show that with some configurations, the exhaust is at the center of the engine, with 2 inlets to the muffler, presumably. My muffler is off to the side, and has 1 inlet.

I noticed something else that was odd as well. As I was wheeling it back into the garage, I noticed a different noise. It's the same one I hear sometimes when I let off the electric starter (if I had the ignition off), or when it slows to a stop when you shut it down. I pulled the plugs, so it would turn more easily, and poked around with my mechanic's stethoscope, while pulling/cranking the engine. It sounds to me like a noise from one of the bearings, as you hear it when you turn the engine over. I think it's louder with the stethoscope on the generator head, vs. when I have it on the engine. My next step may be to try and separate the two, to try and isolate which is making the noise. It's difficult to describe, the bearing is not squealing or anything. The best I could say is it makes me think of the balls rolling around in the bearings, kind of as if it were just noisy. I took a video with the digital camera, I'm going to include a link to the video, below.

You hear it best as the engine slows to a stop. I pulled the spark plugs out for the video, to let it turn over more easily. I don't know whether it's coming from the generator head or the engine, but I guess I'll try to find out, if I can manage to separate the two somehow. I don't know that the noise is a big problem, but it's disconcerting, at least. Thank you again for your help!

The link to the video is http://tinypic.com/r/14t2e6p/4

Here is a link that might be useful: Engine noise video

I'm concerned about the piece of black plastic you found on the dipstick. Do you have a picture? There are things that could be broken off in the engine that will not stick to a magnet.

The sound I hear in the video (that I believe to be the noise you're chasing) sounds like the metal to metal noise that happens when a non-metallic "spider" of a coupler is absent. If the engine and generator are connected by a "Lovejoy coupler", there should be a 6-lobed non-metallic cushioning device that meshes between the 2 "three lobed" coupler halves. One coupler half on engine crankshaft, the other coupler half on the generator shaft.

rdaystrom, unfortunately, I foolishly discarded the black piece of plastic, at the previous owner's house. I was excited about my find (the generator itself), it did not hit me until I was on the road how dumb that was. It looked kind of like it might have originally been round, maybe something like a washer, that had been chewed up somewhat. It was thin, probably previously-round, around 1" long if you straightened it out.

mownie, the governor would not, presumably, make any audible noise as the engine turns over, right? The governor seems to be working OK (it kept the engine speed as I added a load, including bringing it back up when I started my circular saw), it just crossed my mind. I did see last night that there is a slight misalignment between the engine and the generator head. You can see in the video that the gap between the bottom of them changes slightly as the engine turns. But a misalignment is presumably somewhat normal, and the reason for a coupling like that. Though in looking at the exploded view quickly, I'm not noticing a coupler on the list.

Slight misalignment is unavoidable, but it is desirable to have the centerlines of crankshaft and rotor shaft as close as possible, the same holds true for the angle of approach for the two members as well. A coupler of some sort makes it possible to tolerate very slight misalignment issues without damaging the engine or the generator. Excessive misalignment can result in damage/wear to the coupler members.
Can you post the exploded view illustration?
The governor would not produce any sounds that would be audible outside the crankcase.

mownie,

I had been able to download a copy of the manual from Generac, so I extracted the exploded view & parts list pages. I uploaded them to:

http://www.yourfilelink.com/get.php?fid=513771

I hope this may help. I'm going to try and separate the generator head from the engine, if I can. That way I can at least try and isolate where the sound is coming from. Though I fear this may be easier said than done. It sounds as though there may be a taper on the end of the crankshaft.

Here is a link that might be useful: Exploded views of Generac 10000EXL

Well, there certainly does not appear to be a separate coupler. And, the PTO end of crankshaft looks tapered. The generator fan, along with the rotor, are furnished as one assembly and maybe there is a tapered socket on the fan to mate to the crankshaft taper along with a keyway.

Too bad, I was hoping the sticky valve issue. Maybe something as simple as the adapter plate to the engine isn't fully secure. Or an odd spot in a bearing. Are you going to pull the pan regardless to determine what the mystery piece was? If you need help pulling the rotor, let us know.

tomplum,

I started looking at the generator head last night, and some more tonight. Tonight I took off the Rear Bearing Carrier, the "face plate" at the end opposite the engine. I'll confess, it's daunting looking inside. There are a number of wires coming off the stator, going to the Power Regulator, and a number of them go up into the electrical box (with the outlets), which I have not yet opened. I cannot really move the Bearing Carrier much, without running out of slack on these wires.

There is apparently no bearing in the generator near the engine. There is only a bearing at the far end. I looked at that bearing tonight, it looks good to me, it turns smoothly, etc. That makes the turning-the-engine-over noise potentially more likely to be coming from the engine itself.

It's a good thought about the adapter plate not being tight to the engine. If I can get enough of the generator off, I will definitely check that. But I am concerned about trying to disassemble the generator. The wiring is my first concern, I'm worried about shearing off a wire, or causing similar damage. Removing the rotor also sounds like it can be kind of a challenge.

I really want to fix this properly, but I'm worried about the risk of destroying the whole thing in the process. If I do get the generator off, I'm thinking about opening the crankcase to look for the mystery piece, though I'm still kind of leery of opening the engine. It depends in part on whether I try and fully remove the generator.

Take pics, do diagrams, borrow the wife's nail polish to mark the connections- what ever gives you peace of mind. If you think it is beyond what you care to disassemble , now's the time to decide that too!

tomplum,

I looked at it more closely tonight, including opening the electrical box. Seeing where the wires go is somewhat reassuring, I think I can label them sufficiently, if they have to come off. For now, they're all still connected, from the stator to the Rear Bearing Carrier, and then into the electrical box. I had enough slack to simply move the Bearing Carrier to the side, for now.

However, I would welcome any tips on how to remove the rotor. I removed the long bolt, it came off easily. I had read something on another forum (http://www.broadbandreports.com/forum/r18965592-Portable-generator-disassembly-help-needed) where the person took his (different) genset to a shop. They threaded a longer bolt down through the rotor, into the crankshaft (so there was still "extra" bolt sticking out of the rotor). They then suspended it by the rotor, with the engine hanging down, and hit the bolt with a hammer, which succeeded in popping the engine off of the rotor. I tried something like that (the long bolts that hold the generator closed are the same thread, but a few inches longer), without success, so far. However, I can't hang it with the engine hanging below the rotor :) I still have the engine bolted down in the frame, but it's bolted onto the rubber mounts, so it could still briefly move away from the generator, if it wanted to. The generator is being supported from below by my car jack. I was leery of actually unbolting the engine, since the engine & generator could then slide out of the frame and fall on the floor.

The stator is still installed. Any thoughts on how to loosen this would be quite welcome :) Thank you!

Are there threads in the end of the rotor itself? That makes it easier. With this style you can buy a bolt and either do it hydraulically by standing the generator on end, filling the hole w/ oil and thread the bolt in w/ a bit of teflon tape on it and it will push it off. Or you can used that bolt to thread against the crank bolt and push it away. Some will also have threaded holes on either side of the center that you can use to push against the rod that goes down to the crank. Some you had to just let them hang and give them a rap on the bolt. An impact hammer will help to release it better.

No, unfortunately, the end of the rotor does not appear to be threaded. Nor are there any threaded holes near it, naturally :) Should the stator be removed before working on the rotor? Does the stator just pull off? It hasn't moved yet for me, tugging on it briefly.

I am not one of those guys that makes generator repairs look easy. It is a struggle at times for anyone. I used to work w/ a guy who would remove the rotor bolt, put the end cap back on and run the generator until it would break free. A head shaker for sure, but I never saw him kill one in the few times I saw him do it. That shop used to have a kit for threading the rotor inside and puller bolts. You may be able to do the same thing which could be another option. Some still whack the bearing end w/ a deadblow and a piece of hardwood. Or both sides of the lamination with dead blows at the same time to get them to pop. I am thinking that the stator casing is nestled tightly in the adapter. Hopefully you are holding 4 bolts in your hand...

Heh, yes, I did remove all 4 bolts that hold the generator closed, and all the visible ones that could be keeping things together. I agree that the running-it-until-it-breaks free approach is disconcerting, but it could have merit. I tried re-installing the rotor bolt, with it still loose, then I re-installed the Rear Bearing Cover, put 2 bolts on it, and pulled the starter cord several times (with the plugs out). Unfortunately, nothing wiggled free. But it was worth a shot. The inside diameter of the rotor shaft is 0.415", so it looks like maybe I could tap it to somewhere around 7/16-28 or 1/2-13, depending on where I read. I'd prefer not to have to drill the hole first, for fear of going at an angle. I could then try the oil & bolt trick.

What are the laminations you referred to? I did try hitting the sides of the stator casing with a rubber mallet, then tried a steel mallet onto a piece of pine, to try and wiggle it loose, to the left, then right. It did not seem to do anything. If I could remove one, the rotor or stator, it would presumably make the other one easier.

Oh, and I'm sorry, I figured out what the rotor laminates are.