I've just disassembled an MSV562 with a VEX60 engine. I removed the blade disc and I'm trying to remove the blade boss. The reason being, I was going to replace it with a boss designed for a non-reinforced disc, which can take 4 blades and also has the fins required for better uplift of the grass (CA09444G).
Unfortunately, the boss is very stuck on there. Unfortunately, I don't have any large/heavy and solid steel structure to hammer the boss against. I tried giving it a few light taps with a smaller hammer (Not wanting to damage the bearings), and of course, put some WD40 on the threads to seep down. No luck here, so I got a 3 jaw puller to try to remove the boss. It got to a certain point and I just couldn't turn it by hand anymore, and I didn't want to leverage the flywheel and potentially break something. So I thought I might be able to use my impact wrench. After all, the pressure being put on the crank should be offset by the pull of the jaws. I noticed the puller rotating slightly, but when I looked at the position of the boss it didn't appear to have changed.
At this point I wanted to stop, I was concerned that it was still moving and I was getting nowhere, and also decided I needed to come up with a new strategy. After removing the puller, however, and rotating the engine from the crank/boss, I noticed that the engine was more difficult to rotate :-/
So at this point, I'm both concerned and confused. My initial thought is that somehow I may have bent the conrod somehow, but how? If the pressure put on the crankshaft is being offset by the pressure put on the boss, shouldn't they cancel themselves out? Also, how on earth am I going to get the boss off now?
Paul not sure what has happened, are you sure it won't rotate, pull the plug out and see if that is the problem, remember you are trying to rotate the motor using a much smaller circumference than turning it using the blade carrier. Then comes my next question, why do you want to remove the boss if you just want to change the blade carrier. The boss is the same since I think back in the seventies, might have been back in the late sixties. Only ones that are different are the ones they fitted 4 strokes on Victa bases
The engine will rotate, it's just that at a particular point of the rotation it's slightly more difficult than it was, and it's definitely not compression related. I rotated it by hand before trying to pull the boss off, no issues, standard pressure when rotating (Approx. twice per rotation), but now, during one revolution at a single point, it will seem more difficult to turn. The only thing I can think of is that either the crank pin has moved, or the crank pin has moved and the conrod has been bent. I haven't gotten to the point of disassembling to find out why yet though.
For the boss, there are different versions depending on if you've got a disc with or without reinforcing. If you look at the original 2 blade disc, you'll note that it has wings on the side that turn up a little. I can only assume this is to create some sort of upward force. However, if you look at the 4 blade reinforced disc (CAO9445G), it has no such wings, which is why I went for disc CA09444G. The problem is that without the reinforcing, it's about half the thickness. One way to deal with this is to put a washer between the boss and disc, which I didn't really want to do or to replace the boss with one designed for both self-drive and a non-reinforced disc.
All of that said, I think I may have jumped the gun, because I'm now realising that while the push versions have a boss that's the same size, one for the reinforced disc and one for a non-reinforced disc, the self-propelled may only have a boss designed for a reinforced disc, which means that this may all be for nought :-/ I need to check more part numbers.
I would still like to know how on earth to get these off though. Has anyone had experience removing these without something like an anvil, and in a case where a 2-3 jaw puller has been unsuccessful?
Paul yes I forgot about the 560 having the reinforced blade carrier, you can just grind the tabs back about 2mm and it can take a standard blade carrier. As for removing the boss it just pops off if you support the underside of the boss with something like a steel block or mash hammer and give it a couple of swift hits with a hammer on the top side. I have fitted a standard blade carrier on a 560, but I did change the boss and then you can use the blades off the 24 inch, now they are a real blade, built for real work, I think that is what I did. Just check the Victa 24 blades are 140mm end to center
Norm, does that method work well on a PT where the boss fits over the alloy flywheel. I have used the 2 hammers method on a FC and it works really well but on a PT not so well. The blade boss seems to rust on pretty well to the alloy, Dissimilar metals I suppose. I ended up having to borrow a hydraulic puller. That got it off easily but the flywheel came with it. Then I could not get the boss off the flywheel. I would imagine thats its possible to break the alloy flywheel if it was hit hard enough even though its well supported by the other hammer.
Hi Jeff, always works for me but I don't really use a mash hammer on the underside, I have a piece of RSJ that I sit the boss on and then give it a good wack, but not everybody has a piece of RSJ kicking around. If you can sit the mash hammer on a brick or something solid on the concrete and then hit it, it will come off. I doubt you would break the flywheel as it is completely supported inside the boss and the shaft
support the underside of the boss with something like a steel block or mash hammer
HI Norm,
Thanks for the suggestion, I'll try using a sledge on one side and a hammer on the other and see how we go.
So, while curious to see what damage may have been done (If any), I removed the pull start. I found that when the piston gets right towards the top, there is quite a bit of resistance. I haven't disassembled the engine further than that at this point, but my next port of call would be removing the head. my initial thoughts are still that the conrod may have been bent, or, it could be that something is misaligned, like a ring issue. When I pull off the head and exhaust, hopefully tomorrow, I'll know more.
So the person I purchased the mower off has obviously done a bit of work on it. The body of the engine has fins consistent with the VE series, and the MSV562 is supposed to have the VEX60. Curious, the crank pin in place is the older style (4 notches). Further to this, the boss that's supposed to be on this model is EN73162B. The issue is that the boss that's on there looks different, and I feel would be quite difficult to remove. If you look at the aforementioned boss, you'll note that between the pulley and end of the boss, the shaft is tapered but straight. The boss installed on my crankshaft has a bit of a cup between the pully and shaft. So there's maybe an inch to hammer on, and about another inch that's rounded and I don't know that I can really hammer on that.
Yeah it was running originally. I had to remove it so I could flip the base upside down and drill out some bolts that were snapped off. Before trying to remove the odd shaped boss, the engine was rotating normally.
Paul I would like to see a pic of this "odd shaped " boss ? When you were trying to remove the boss what did you have jambed in the motor somewhere that may have put pressure on the rod? The ones with ears were fitted to the 4 stroke motors(straight shaft) that were fitted on Victas and using the Victa blade carrier.
Just getting everything set up and I'll send some pix. Nah no ears, though there are some pictures online of some that look a little similar that do have ears. I'll send the pic ASAP.
I wonder if you have dislodged the flywheel slightly so that its brushing on the coil. Take the coil off and see if the problem continues. I can not see how you could have done any other damage like that.
I wonder if you have dislodged the flywheel slightly so that its brushing on the coil. Take the coil off and see if the problem continues. I can not see how you could have done any other damage like that.
Hi Jeff,
My thoughts exactly. Thanks for the suggestion, once I'm setup I'll remove the coil and let you know how I go as well.
Hi Jeff I'm also curious as to how you used a puller to get the boss and flywheel off together, what did you hang onto, only thing I could use in this situation would be a bearing puller, but I'm, not even sure if that would do it.
Yes,a long shaft PT just a belt drive boss, same principle, sit the straight section of the boss on a block of steel and give it a good hit with a hammer on the opposite side and it will pop off the shaft
Sounds like you may have stretched or bent the crank. I did the same thing when removing the pulley from a tilt a cut with a dead Powertorque. Not sure how it happens, but I could only move the piston so far each way once I had the pulley off. I was told about this by a bloke at a mower shop I visit from time to time. Still have that motor sitting around, I haven’t bothered to inspect it any further yet.
If the only reason you want to get the boss off is so you can fit the thinner blade carrier it would be much simpler to fit a 2mm washer on the shaft before you put the blade carrier on, or grind the tabs back carefully
Norm I used a bearing puller. It was just thin enough to fit in between the boss and the flywheel. I think I just need an anvil or something very solid to hit against. Railway iron or similar. Can not believe how much people want for a decent anvil.
Paul, you must have moved the flywheel a little to cause that issue. They only clear by 20 thou or so so not much needed. If its loose at all do not run the engine at all or you might damage the flywheel where it fits over the crankshaft. I have done that once.
That boss must be off a self propelled mower hence the pulley. Can not change the boss anyway unless you can get another one with a pulley which will not be easy. I wonder if thats what the factory Super 24 Powertorque pulley is like.
