OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Tecumseh / Kirby Engines Yardman Mower with tecumseh flywheel trouble

Hi sparker, what sort of blade carrier does it have, I bet it has a bar and my belief is they don't give enough spinning weight and so much inertia is required on the keyway to help it spin. The other issue is the key should not be taking that much load, it is only so the timing can be set. My gut feel is there is a problem with the taper and it is not being tightened down hard enough on the taper. It may require a bit ground off the inside of the wheel to allow it to come down just a fraction on the taper, doesn't need much

It has a very large blade holder with 4 blades. It's a 21" cut, from memory. You might have a point there Norm, maybe I hadn't put the correct torque on the nut, I just tightened it down using "the force". I have since looked up the correct torque. Torque Specification is 45-65.5 NM for the aluminium flywheel.

Sparker, being tight on the taper is just as important as the torque on the nut

The flywheel I am using came off another old tecumseh mower and there may be a difference as you say. I have to buy a new key for it on monday.

Sparker it broke the original keyway so I'm thinking taper problem. Before you fit the keyway, fit the flywheel and see if it grabs on the taper and if there is enough thread left so the nut is not bottoming out on the end of the thread. If it is you will need a washer under the nut. Also check that the underside on the flywheel is not bottoming out on a shoulder on the taper.

My mower shop didn't have a key for it. Ebay cheapest was $9.00. I ordered 20 from the USA for about $21.00. So now I will have to wait a couple of weeks. I'll sell the extra ones on ebay or so my cunning plan goes.

Sparker you can make up a temporary keyway just to test and prove that it will hold on the taper ok while you wait for the ones from the States. It is only required to set the timing and if it tightened up fine in the right spot it should hold without the keyway if you really wanted to test it.

Blast! My old torque wrench only goes up to 20 Nm. The torque shown in the manual is "Flywheel Nut (Aluminum) 400-500 45-56.5" Nm.

It's back to using the "force".

Hit it with the rattle gun sparker

Now the thread on the nut is stripped. I have to get another one and I have to clean up the thread on the crank. I think I damaged the nut when I had to get the flywheel off....I like red neck style methods. No rattle gun Norm.

Ok sparker, seems like a couple of things going on here, why did you strip the thread, was the nut bottoming out on the end of the thread before it tightened down on the flywheel, this could account for the broken keyways with the flywheel not being tightened down properly. Does it need a washer under the nut that can fit over the end of the shaft, not just over the threaded section

Two reasons it is stripped. The first one is because when I was getting the flywheel off I put the nut back on level with the crank and hit it with a hammer! The second one is when I was putting the nut back onto the crank I must have over-tightened it and stripped it out altogether. As a mechanic I would make a great ballet dancer.

Sparker,

Have you ever of flywheel knockers? I use several different ones here on my 2 handheld two cycles. I read in Tecumseh engine service manuals that they made them for the larger mower engines. They are basically a solid piece of metal that is drilled and tapped to the thread size you need. This done deeper than current threaded shaft length as to not bottom on the shaft end. Mine are made of hex stock so I can easily install and remove them.

They are higher than the flywheel fins [much less chance breaking fins with a hammer] and are screwed on until seated, then backed off one thread [maybe two at the most], and you smack the knockers with a heavy hammer. This jars the flywheel off the taper. No damaged threads or mushroomed crankshaft ends. It might a few hits with the hammer depend how stuck the flywheel is on the taper.

As for over tightening that is why you should be using a torque wrench as over tightening not strip threads and not an impact gun, its damages the flywheel.

I prefer pullers but there are flywheels that don't have puller holes and these flywheel knockers work fine for loosening the flywheel.

You may have done damage to the shaft that you won't be able to repair without special tools. There is obviously something very wrong going on here that we are not able to see. I can't see how you could over tighten the nut , unless you had the fanwheel or the blade carrier locked up solid, or the threads in the nut had been destroyed by the hammering and you were using an 18 inch breaker bar on it.

AVB, when I use my rattle gun, and I have been using it for probably 40 years, I only allow it to impact about 3 times and it never causes me any problems. I only use my low impact gun for tightening, never the 1150nm one, that is used only for undoing things

NormK,

You probably got common sense than most...I have seen cast iron nearly split in half by DIYers. The one DIYer try to get me to replace his flywheel for free saying I did it. I know better than to use an impact though it is tempting at times. The last Briggs opposed was so stuck on by the use an impact I never got it off.

Hi AVB. I hadn't heard of them but since you mentioned it I did a google search and there are lots on ebay - specifically for 1/2" Tecumseh threads too. As usual I learn these things hen it's too late!

...and Norm, I think the thread on the crank is OK but I can't find a nut to fit it. Bunnings only had coarse threaded 1/2 inch nuts but I think this one is 20 tpi.

Sparker I have a number of earlier Tecumesh motors here, not sure if they are the same but going by the way Aus Post charges it is not worth posting a nut because they would charge $8.55 to send it

Yes. It is cheaper sometimes to get something from Asia delivered to my door (including postage) then to just pay Auspost charges.