Export thread

I could not figure out from the other posts whether my jammed-on Lawn-Boy 5024 blade collar is threaded onto the engine shaft or is pressed on. Some say to use a puller to remove it and other show it being tapped off as if threaded on. I had no luck with a puller and heat. All I want to do is replace the lower seal. Thanks. Mark Kinsler kinsler33@gmail.com Lancaster, Ohio USA.

From what can see in the image below it is not threaded. Looks to more of a tapered fit.

Thank you. The mower would run only intermittently, and I suspected an air leak. After elaborately sealing the carburetor I thought I'd look at the crankshaft seals. Behold, the top one had blown out completely, but the bottom one remains inaccessible. If I can get the blade flange un-bent I may make an executive decision to leave it alone and just put the top seal back in place.

Mark Kinsler

What i was using 2 feet pipe and big hammer.Plase that pipe on corner of that blade adapter and whack with the hammer.

Sort of like removing a tie rod or ball joint. Whack the adapter on the side of the collar with a hammer and drift while 'bucking' it on the opposite side. The compression will pop it loose.

Thanks. I was afraid for what I assume is a delicate magnesium mower deck. It wasn't clear how the long pipe and hammer was supposed to work, for it looked like Mr BogdaN was trying to unscrew it.

In any event, nothing worked, including a three-jaw puller that merely served to bend the plate. And so, armed with my propane torch and a wood-handled monkey wrench my father was given around 1925 I heated the plate, bent it to what might have been its original shape, let it cool and re-mounted the blade and stiffener. In the hope that the bottom seal is okay I shall deal with it another day.

The top seal, however, had blown completely out of the magneto mounting plate and was hanging on the shaft when I took the cover off. Everything was soaked with oil, including the electronic ignition module I finally purchased after horsing with the points for a year. Cleaned everything out with carb cleaner, pushed the seal back in (rubber was fine) and secured it with green penetrating threadlocker plus a hearty application of Dap Rapid Fuse, a terrifying variant on cyanoacrylate glue.

I haven't tried starting the venerable machine just yet.

Mark Kinsler

Well, that didn't work. Reseating the top seal didn't do a thing, and the mower only runs on the ether starting fluid I'm able to squirt into its air intake. I think I'm out of ideas, but I like this mower a lot. Clearly it's not getting fuel.

Some facts: The entire governor and spark advance have been removed because part of the governor mechanism demolished itself some years ago. I wired the throttle open and it's run fine that way, and I apologize for doing that.

When it began to fail last year I trouble-shot everything for weeks, discovering among other things that the ignition points had stopped conducting electric current due to rust between the moving arm and the contact that's riveted into it. I finally decided to try an electronic module,which has worked splendidly except that it increases gas consumption.

I tried to adapt a throttle control, but that's not nearly as straightforward as I'd like and research continues. Meanwhile I have the throttle just wired open. It ran okay like that for a while, and then failed again. Fuel delivery is the problem.

It has a new float and needle and seat, and I've polished and re-set everything. I noticed that it would sometimes revive when the intake was partially blocked, and I was able to get it to run by madly pumping the primer plunger. Now that doesn't work, either.

Searching for an air leak, I carefully sealed the carburetor to the reed plate and the reed plate to the crank case. Are the weird-looking passages beneath the reed-plate-to-crankcase gasket critical? I may have filled them with gasket sealer.

Yesterday I found that the top crankshaft seal had become unseated, so I shoved it back in and (I hope) glued it securely into place. I was unable to get to the bottom seal because I can't pull the blade stabilizer thing off without bending it. So I re-assembled everything and here I am. There is spark, it runs fine on ether spray, and the fuel primer pump is in poor shape despite my attempts to repair it.

Any and all advice will be appreciated.

Mark Kinsler

Does this carb have the little screen/filter in the fuel inlet? Have to look close to see it. Worth a look.

You have to get that blade collar off. While it is on you can't clean the exhaust ports or muffler. Twice (different mowers) I broke the welds removing the blade collar from shafts using a pulley puller. These collars are not that expensive. You can find used ones and new ones easily online. After than experience, I figured that these things automatically jam on, but that is not the case. They get jammed on when people use impact drivers to install blades. I have found that they do not jam on if you clean the shaft and use anti-sieze between the collar and shaft. But the most important part of that is to torque the nut properly: 50 ft-lb The last time I removed the blade (to sharpen it) after I had installed it properly, the blade collar FELL OFF. Talk about a grinning happy surprise!

FuzzyDriver said:

You have to get that blade collar off. While it is on you can't clean the exhaust ports or muffler. Twice (different mowers) I broke the welds removing the blade collar from shafts using a pulley puller. These collars are not that expensive. You can find used ones and new ones easily online. After than experience, I figured that these things automatically jam on, but that is not the case. They get jammed on when people use impact drivers to install blades. I have found that they do not jam on if you clean the shaft and use anti-sieze between the collar and shaft. But the most important part of that is to torque the nut properly: 50 ft-lb The last time I removed the blade (to sharpen it) after I had installed it properly, the blade collar FELL OFF. Talk about a grinning happy surprise!

Click to expand...

Thank you. After much labor, It's off, albeit in poor condition. How do you get to the bottom seal?

If you don't already have it, you should get a copy of the Lawn-Boy service manual. It will give you quick answers to most questions you have: 1950-2000 Lawn-Boy Service Manual
Yours is a D engine and I am familiar with F engines. The last bottom seal I replaced I had the engine out already, so it was super-easy to get to. If you search the manual for "seal" you'll find lots of information on seal replacement. You should be able to pick the seal out and slide it off the shaft since you have the collar off.

The only luck I've had with collar plate rework was one where the previous owner had put on a blade with holes that were too small to go over the ridges on the collar holes, which bent the collar evenly toward the engine. It sounds like you really had to booger yours up to get it off, so you should probably just replace it.

You mention the stiffener, Do you still have an original, flat blade on? Your photo has the blade off already, so I can't tell. If you've replaced the blade with a Tri-Cut blade (i.e.your blade is newer than 1982), you should not be using the stiffener and washer. Search manual for "9-15" (without the quotes) and you'll jump right to the page.

It goes without saying that since you are down there working on it already, you should clean your exhaust ports.

Thanks. I should be able to rebuild the collar if I can't find a new one. This mower is from 1975, and I did not post a photograph. My guess is that there's a lower plate that I can unbolt to get at the seal, for I cannot think of a seal puller that would pull a seal from a hole several inches deep--unless the seal was somehow displaced. The remnants of a fuel filter remain around the main jet, but rather than fight with parts I just installed an in-line filter on the gas line.

I'll report on further progress.

Mark Kinsler

OK, good luck. Like I said, I haven't worked on D engines, and looking at your photo I see that yours is self-propelled so there's also that assembly in the way. Did you find the D-engine seal replacement procedure in the manual? There's a guy here that knows a ton more than me on these mowers, RivetS, Maybe he'll join the conversation.

Been a while but seems like on my mower the actual bottom of the motor is about an inch above the deck plate. Might be much easier if you just pull the motor off the mower?

My mower is the two-stroke non-self-propelled 'brick top' Lawn Boy, or Lawn Bo because the 'y' got obliterated by gasoline. The photograph was posted by someone else. The blade shaft pokes out of a fairly long snout at the bottom of the engine, and the bottom seal is a few inches inside said snout. You can take off the muffler and clean the exhaust port without removing blade or blade collar, but in this case I've got very low crankcase vacuum. I don't know where the leak is: I re-set the top seal, which had blown out of place and was hanging on the upper shaft (the rubber was fine, so I just sort of glued it back in) but that did not solve the problem. Wondering if the bottom seal could be at fault I did a test consisting of a plastic bag stuffed down the carburetor's craw and the air cleaner foam stuffed upon that. Surprise: the motor started and ran, albeit slowly. So it's getting air from somewhere: either through the lower seal or through the throttle pivots or perhaps somehow through the fuel primer plunger, which I've just thought of. Is that a possibility?

Mark Kinsler

Oh, my. Until your latest post I was thinking that was a photo of your mower! You've got some good attention on your other thread, so I think I need to move to that one.

FuzzyDriver said:

Oh, my. Until your latest post I was thinking that was a photo of your mower! You've got some good attention on your other thread, so I think I need to move to that one.

Click to expand...

I finally removed the blade collar by drilling a pair of holes in it, bolting the thing to my heavy-duty puller, and using such brute strength as I can summon up at my advanced age. By this point the blade collar was about as bunged up as one could imagine, so I reinforced it with a piece of iron pipe and a lot of brazing.

The rest was more straightforward than I'd thought. I un-bolted the lower muffler casting and then the aluminum plate that lies under the engine. I also unbolted the engine itself--just three bolts.

To remove the lower seal I used a long sheet-rock screw to punch a small hole in the seal's metal housing and then drilled out that hole to about 3/32" or 1/8" or so with my hand drill. Then I firmly screwed the sheet-rock screw into the hole I'd made and used the claw on a crowbar (the claw on a claw hammer works, too) to pull the seal right out of the engine casing. Part of the seal seemed to have been damaged--the rubber had torn--so that might have been the difficulty.

After assembling everything I find that I still have fuel-delivery problems. The mower will run for a while while there's fuel in the bowl, but it won't stay filled. I replaced the fuel bowl drain with a nylon fitting that would accommodate some very thin clear plastic tubing, and this arrangement allows me to look at the fuel level in the carburetor bowl. (The tube is formed into a U-shape).

So research continues. I think I've still got a real air leak somewhere, so I've applied o-rings to the throttle-plate shaft and to top of the primer pump. I shall re-assemble things tomorrow and maybe matters will improve. Advice is always welcome.

Mark Kinsler (and it turns out that all my message notifications from this group were in my spam box.).

Wow, you have gone through a lot of work on that mower. Good job so far! Be sure to use anti-seize on the color and threads when you put it back together, and torque it to 50 ft-lbs.