A Murray ELECTRIC 20 Snow Thrower

A roadside find.

Overall from the outside, it looks to be in remarkably good condition. It's a 12A, 20 inch swath single stage machine.

Model No. is 620000X30NA
S/N 735492872S2C050C
D.O.M. 2002.10.14

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Something looks and feels fishy about the 'On' trigger though. There appears to be a missing safety interlock key, and the trigger's action doesn't feel right.

And sure enough, plugging in the snow thrower and trying it results in nothing. 'Time to investigate how the mystery interlock operates.

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It turns out that that hexagon at about the centre of the above photo has to be turned slightly in the CW direction to enable the switch lever. The machine does run with that detail attended to. So, now I know that the machine only needs a replacement key (P/N 583356) in order to be operable. The next question is, "What's the condition of the drive belt?"

If the belt is good, this may be a saleable machine. If belt replacement is called for, a new belt may be too much money. (Belt P/N is 760976MA.) We'll see. 'Time to get the belt cover off for a look see.

Belt Cover Removal

It's quite an array of fasteners that hold the belt cover in place.

1. At the front there are five 10-24 x 1/2" hex washerhead bolts, 5/16" across flats (A/F) with 3/8" A/F prevailing torque hex nuts.
2. At the bottom-front, there is one 10-24 x 1/2" hex washerhead bolt, 5/16" A/F with a 3/8" A/F prevailing torque hex nut.
3. At the upper-rear there are two 1/4" x 3/4" hex washerhead threading screws, 3/8" A/F.
4. At the lower-rear toward the front, there's a 1/4"-20 x 1/2" hex head screw, 7/16" A/F, with a flat washer. It's important that this 1/2" long screw be reinstalled at its correct location. A longer screw here might interfere with the drive belt.
5. At the lower-rear toward the rear, there's a 1/4" x 3/4" hex washerhead threading screw, 3/8" A/F, with a flat washer.

And with those ten fasteners removed, one has access to the drive belt, like so.

And as it fortunately turns out, the belt is in fine condition, and all is in good order with its pulleys.

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So, if I can obtain a safety interlock key, I'll have a saleable machine here.

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FEEDBACK

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A Zippo Lighter Fluid Hack

If you're an incorrigible smoker, and you're buying your lighter fluid in 12 ounce or smaller containers, you're paying way too much. Here's a work-around that saves money.

Get yourself a Yankee gallon (3.780 ml) of Coleman camp fuel, and you'll have plenty of lighter fluid for way less^[1] than you've been paying for the little bottles of Ronsonol or Zippo lighter fluid.

You will need a small Ronsonol bottle for the sake of its convenient cap/spout. The Ronsonol bottle pictured above is the 341 ml size. Its cap can be pried off with a suitable plain slot screwdriver. Then, with a suitable small funnel,^[2] the Ronsonol bottle can be refilled from the big can of camp fuel. Snap the cap/spout back on the Ronsonol bottle and you're away.

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Notes:

[1] I won't bore the reader with the math, but the camp fuel is less than half the price of the lighter fluid.

[2] The funnel pictured is an elderly Coleman No. 0, which I don't believe is available anymore. Try a dollar store or a hardware outlet for funnels.

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FEEDBACK

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A Toro Power Curve 1800 Snow Thrower

Someone brought me an electric snow thrower to repair. It's a Toro model No. 38025, S/N 290008995 -- an 18" swath, 12 amp machine.

It's missing its final drive belt, and the toothed primary drive belt is looking a bit frayed. Here's a view of the left side of the unit, where the belts reside.

Final drive belt replacement looks like it should be a breeze. Primary drive belt replacement will involve removing a pulley.

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Intermediate Pulley Removal

That 9/16" A/F (across flats) hex is the head of the intermediate pulley's spindle. It has a left-hand thread, so it's CW to remove it. Removing the spindle with its pulley gets you to here.

The toothed belt's Toro P/N is 73-0160. Belt width is 19mm. On close inspection, the belt appears to be in good condition, and needn't be replaced.

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Final Drive Belt

It's Toro P/N 61-8802; a five-ribbed belt. The belt is a tight fit -- it takes a bit of doing to get it on its pulleys. You may want to unspring the tension idler to make installation a little easier. Belt tension seems excessive to me, but it is the correct belt.

Here's a view of the installed belt.

Left Side Cover

The cover was missing its three fastening screws, and an associated skid plate. I replaced the screws with No. 8 x 3/4" hex washerhead sheet metal screws, GC Electronics P/N 11-206-C. The machine will have to do without its left side skid plate, unless the owner can find what's become of it. Here's a view of the left side cover installed with its replacement screws

Discharge Chute

The upper deflector portion of the chute is loose on its pivots.

The 5/16" x 1" carriage bolts aren't seated in their square recesses, and the prevailing torque of the nyloc nuts is too great for the plastic material to resist. Trying to tighten the nyloc nuts only causes the bolts to turn. The bolts' shanks won't seat in the square recesses. The pivoting/tensioning scheme cannot work as designed.

I replaced the carriage bolts with 1" hex head bolts with 5/16" plate washers under the heads. That makes it possible to snug up the bolts so the deflector is properly tensioned.

In Conclusion

A worthwhile repair, I suppose, although the price of the replacement final drive belt struck me as outrageous -- $46.46 CDN + HST came to $52.50! A new replacement machine, same make and model, is $449.00 CDN + HST at the Home Depot, so repair cost here was within reason.

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Missing Left Side Skid Plate Dealt With -- WEDNESDAY, NOVEMBER 20, 2019

That missing left side skid was bothering me, so I came up with a fix. Here's a view of the skid that's on the right side leading edge of the auger housing.

Note the two tabs that employ two right side cover screws to fasten the skid in place.

I could see no practicable way to fabricate a truly equivalent part.^[1] So, I fabricated a skid with a different fastening scheme. Here's a view of what I came up with for the left side.

That's a 5" length of 1/8" x 1/2" steel flat, rolled to conform to the auger housing's profile. Three countersunk holes accept No. 5 x 1/2" flat head wood screws. It looks to me like a sound arrangement -- I'm quite pleased with it.

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Addendum -- FRIDAY, NOVEMBER 29, 2019 -- Get The Idler Tension Spring Hooked On Right!

You want the idler tension spring to be securely hooked. Here's how it ought to look.

If the spring is hooked the other way around, the hooking won't be nearly as secure.

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Note:

[1] "So why not just obtain an OEM replacement for the missing skid?", you may ask.

Too much aggravation and expense is why. Another trip out to the small engines place in Pickering, where they'd be unlikely to stock such an item. Then, if the part were available to be ordered, another trip out to Pickering to collect it, plus the cost of the part itself.

By fabricating a functionally equivalent part from material I had on hand, I bypassed all that and I now have a truly finished repair that I can return to the customer right now. An outcome well worth the effort of part fabrication.

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FEEDBACK

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A Freakish Knife Failure

Found in the dishwasher after a wash cycle.

A supposedly high quality Cuisine de France chef's knife. It just up and broke in two -- quite mind boggling.

And it was one of my wife's favourites.

Anyway, there's no conceivable way of repairing that, that's for sure.

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FEEDBACK

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Honda HS621 Snow Thrower Oil Change

Changing the oil in a Honda HS621 snow thrower is a bit awkward owing to the placement of the drain plug and the filler neck. Here are a couple of items that make the job relatively easy.

First is a suitable drain pan. In Canadian Tire's kitchenwares section, I found a Lagostina cake pan that's 9" square by about 1 1/2" deep. It's perfectly suited to the task. The pan was on special so the price was reasonable. A dollar store might have something similar for even less money, though. Here's a view of the pan in position for draining the oil.

The drain plug's hex takes a 10mm socket wrench.

Second, you'll need a funnel with a 9" length of tubing for a neck extension. Here's what I cobbled together from what I had on hand.

That solves the difficulty of getting to the engine's oil filler neck.

Honda's oil recommendation is 5W30. Sump capacity is 600ml. With a full sump, oil should just be visible at the opening of the filler neck.

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FEEDBACK

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A No-Name 19" Push Lawnmower

A roadside find, in rough condition, possibly destined to be scrap metal.

It's also easily the ugliest lawnmower I've ever seen -- a dreadful colour scheme.

Anyway, the first order of business is to deal with the stuck starter. It won't recoil. The starter cord's handle is some sort of steel bracket.

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Starter Working

The spring needed winding up. The cord is too short to be parked up on the handlebar as it ought to be, but it's long enough to work so I can test for spark.

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Starter Update -- SUNDAY, NOVEMBER 24, 2019

I installed a new cord -- an 88" MTD/Atlas item from Canadian Tire. Canadian Tire P/N 60-7553-8. $5.99 CDN + HST. I had a salvaged grip on hand. The new arrangement works fine. The 88" cord length is adequate for parking the grip up on the handlebar.

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Spark Plug

It's a Champion RJ19LM, which is correct for the engine. The plug is in reasonably good condition, but the gap is oversize. I set the gap to a snug 0.030". A spark test reveals that I do have spark.

Engine

Engine is a Tecumseh. As best I can make out the codes embossed on the front of the cowl, it's a TVS90 43368F SER 80686.

Compression Test

I got a reading of about 42 PSI. That's pretty lame. A well worn engine may exhibit 50 PSI, so this engine is past it. Just for the heckuvit, I'll see if I can get it to start and run.

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Compression Test Update -- THURSDAY, NOVEMBER 7, 2019

I did get the engine to start and run. After running the engine for a brief while, I did another compression test. That test returned a reading of almost 60 PSI. I imagine that the piston rings got a good shakeup, and started to seat better in the cylinder's bore. 60 PSI is still not great compression, but in my experience, 60 PSI is viable compression -- the engine still has useful life in it.

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Fuel Tank

The fuel tank lifts off two ways at the rear of the cowl. There's a spring-type hose clamp to be dealt with at the fuel line nipple.

The tank is all but empty. There doesn't appear to be water or sludge in it. The cap is cracked. The cap's gasket is ill-fitting, and falls out easily.

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Fuel Tank Update -- SUNDAY, NOVEMBER 24, 2019

New red fuel tank cap. Tecumseh P/N 34210.

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Air Cleaner

The air cleaner is mis-installed, and missing its cover. Two special 10-32 shoulder screws with 1/4" A/F (across flats) hex heads with No. 2 Phillips recesses fasten the air cleaner's body to the carburetor. There's a round gasket in the air cleaner's air horn where it contacts the carburetor. The gasket is inclined to stay in its groove and not come loose.

Cowl

At the front, two 10-24 x 1/2" hex washerhead screws with captive external tooth washers, 5/16" A/F.

At the rear, two 1/4"-20 hex washerhead screws, 3/8" A/F.

Governor/Throttle Control Plate On Top Of Carburetor

Note the positions of the adjustable features of the plate -- the throttle cable jacket's position and the plate's position.

• Throttle cable. Loosen off the clamp (1/4" A/F hex) and unhook the cable.
• Control plate. Two 10-24 x 1/2" hex washerhead screws with captive external tooth washers, 5/16" A/F.
• Unhook the governor spring link.

Carburetor

• Two 1/4"-28 x 7/8" hex head screws, 3/8" A/F with two 7/16" A/F KEPS nuts.
• Note the position of the governor link in the throttle lever, and unhook the link.
• Float Bowl Screw. 1/2" A/F hex.

The carburetor is a float bowl type, as simple a design as one will ever see. There are no adjustments aside from float level. There is no idle jetting. Pressing the primer bulb forces a visible squirt of fuel up and out of the main jet into the venturi.

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Start Up Trial

'Put some fuel in it, gave it three primes and it started on the first pull. So, even with compression as low as 42 PSI, a four-stroke engine will start and run.

That doesn't save this lawnmower from the scrapyard, though. It's too ugly and too far gone to sell.

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Oh, What The Hey -- SATURDAY, NOVEMBER 23, 2019

For want of anything better to do, I decided to go ahead and try to make a serviceable, saleable mower out of this piece of junk. That took a fair bit of doing. Here's what I've done.

Painting

I stripped the blue paint off the handlebars with paint remover. The handlebars, engine cowl and discharge chute all got painted gloss black. 'Looks much better.

Primer was Canadian Tire Armor Coat grey primer P/N 048-0621-0. Paint (two coats) was Canadian Tire Armor Coat gloss black enamel P/N 048-0314-2.

Deck Cracks Behind Rear Wheels

I cut two patch plates from 1 1/2" wide steel flat, and installed them with 1/8" hollow aluminum rivets, like so.

I also used the same 1 1/2" wide steel flat to fabricate two rectangular 'washers' for underneath the handlebar brackets.

The rear of the deck is now rigid as it ought to be.

Trailing Flap

The original flap was completely torn off. The pictured flap that I've installed is the same as that used on my own lawnmower. The parts breakdown in my user's manual gave me the part number -- MTD P/N 731-06953 -- so I was able to order one from the small engines place in Pickering.

For hinges, I used 1/2" All Round strapping. The hinges are anchored by two 10-24 aluminum threaded inserts, with 1/2" long hex socket head screws.

Air Cleaner Cover

The air cleaner cover was missing altogether. I had a salvaged one with a broken tab on it, so I made up for the broken tab with a 10-24 x 1" screw and another 10-24 aluminum threaded insert.

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So there we are -- the mower is now a serviceable machine. I'll try peddling it on Kijiji come spring.

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FEEDBACK

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A YARD MACHINES by MTD 4.5HP/21" Snow Thrower

My son picked this up in working condition for $20.00 CDN. He's asked me to look it over before he tries flipping it for a profit.

It's an MTD MODEL 31A-150-500. MFG. CODE 21-074-4411

It's a single stage machine with a two-stroke engine. Fuel mix ratio is 50:1. There's a 120 VAC electric starter feature.

Engine is a Tecumseh:

• ENGINE MODEL HSK845 8204D (H)
• ENGINE FAMILY VTP139UB25RA
• DISPLACEMENT 139
• D.O.M. 7254G

Let's have a look-see and discover what sort of condition the machine is in.

A Motley Collection Of Auger Drive Cover Screws

The heads of the screws fastening the auger drive cover are all different. I'm almost afraid to discover what the screws' threads are. There's a cross-slot, a slot, a PoziDriv and a slotted hex head. there's one screw missing down below.

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The screws are a mixed bag -- mostly threading (sheet metal) screws. I think they should all be 1/4"-20, so I chased the holes with a tap, and now I've got uniform 1/4"-20 screw locations at all five places. I'll install 1/2" long hex socket head screws, split lockwashers and flat washers at final reassembly.

The Auger Drive

The V-belt looks to be more-or-less ok. The tension idler feels lubricant-starved. I'll take that off and oil it as best I can.

Belt Tension Adjustment

The clutch control cable terminates in an extension spring that hooks onto the idler pulley bracket. There are three holes in the idler pulley bracket for the spring to hook into. The lowest hole affords the least belt tension. The two higher up holes afford progressively greater belt tension. Here's a view of that.

Note that the spring in the photo above is hooked into the lowest of the three holes, for least belt tension. That belt tension seemed marginal to me, so I hooked the spring into the middle hole.

Note also the second extension spring higher up. That's the idler pulley bracket return spring. The spring seen in the photo is not factory -- it's someone's kludged replacement. The return spring is not supposed to be hooked into a tension spring hole; it's supposed to hook onto that notch in the bracket that's just below the tensioning spring holes. I don't have a better replacement for the return spring, so I'll just have to leave that be.

The Top Cover

Remove nine threading screws to unfasten the top cover. Remove the fuel tank cap and the discharge chute's wingnut. The cover will be free to come away, though some forceful coaxing will be needed to get the cover past the exhaust pipe. Here's a view of the machine with the top cover off.

Note the electric starter motor directly below the muffler.

The Carburetor

The carburetor is a float bowl type, with no adjustments aside from float level. The float bowl is readily accessible from below, as can be seen in the following photograph.

I took the float bowl off for inspection. (A 1/2" wrench is needed.) There was some sediment in the bowl that I rinsed out. Float level looked satisfactory.

On reassembly, I ended up with a leak at the float bowl screw's gasket. The gasket is an ill-fitting thing. Reassembly and re-tightening solved the leak.

Carburetor Removal

Carburetor removal on this machine looks like a nasty bit of business -- not to be undertaken without a pressing reason for it.

It appears that in order to remove the carburetor, one must unfasten the dashboard to get it out of the way. Then, a ball-ended hex key might be needed to loosen off the carburetor's two fasteners, and I don't have any of those. Since this machine starts and runs satisfactorily, I'm going to leave well enough alone.

The Spark Plug

The spark plug is accessible via a hole in the dashboard. The spark plug in this machine's engine is an NGK BPMR7A, with a 3/4" hex and a 0.025" gap. The plug shows some evidence of oil fouling, but is in good condition. (The oil fouling may be from having run with too oily a fuel mix.)

And That's It

The machine starts and runs, and auger drive looks ok. It can go on Kijiji.

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Update -- SATURDAY, MARCH 8, 2020

I never did put the machine up for sale. Instead, I let it sit unused all winter under the carport. I tried starting it today and it was no go -- the machine absolutely refused to start.

I dragged it into the workshop and checked for spark; that was ok. I uncovered the carburetor's intake and checked for priming. There was no evidence of priming spurts whatsoever. I upended the machine on the front of its auger housing and tried the primer bulb. Fuel emerged from around the float bowl's ring gasket. Bingo!

That explained a lot. With the float bowl's ring gasket leaking, pressing the primer bulb only blew air past the ring gasket; the float bowl wasn't being pressurized so that fuel would be forced up the main jet into the venturi. The priming function was rendered inoperative by the leaky float bowl ring gasket.

A replacement ring gasket solved the problem. A reminder that a small, normally invisible detail can disable an engine.

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FEEDBACK

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A McCulloch Model MT2026 Corded String Trimmer

The trimmer hub is a disaster, and replacement parts are no longer available. There'll be no restoring this item to operability. I figure I'll take it to pieces just for the heckuvit. Maybe there'll be something of it that's worth salvaging.

The Hub

The hub's outer shell is a piece of wreckage. It appears that a repair to the torn out trimmer line exit holes has been attempted, to poor effect. The hub spring is an ill-fitting kludge -- not the original spring. I don't know what to make of the translucent sleeve over the trimmer line spool. How that arrangement could ever bump-feed trimmer line is beyond me.

The Business End

There's a steel rod bail holding the safety guard in place. (The bail rod is 4mm diameter.) With that bail pried loose and removed, the safety guard can be removed. The motor housing can then be opened up.

Opening Up The Motor Housing

The motor housing is fastened together by ten 4mm threading screws, No. 2 Phillips recess. One of the screws is concealed under the ID label. The two uppermost screws are 13mm long. The other eight screws are all 18 mm long.

Opening up the motor housing reveals two prominent features of the machine -- the handle length adjuster and the motor itself.

Handle Length Adjuster

There's a latch/detent affair that enables the handle shaft to have one of four different lengths. The length increments are just shy of one inch.

The latch and the detent lever are spring loaded by coil springs. (I'll salvage the springs.) It's a diabolical thing to reassemble if it springs apart on you, which it's very likely to do.

The Motor

The motor is quite robust looking. (It still works, by the way.) Motor rating is 120 VAC, 3.2 A, 10,000 rpm.

The motor mount bracket is fastened to the housing by two 4mm threading screws, No. 2 Phillips recess. That fan/hub on the output end of the motor appears to be press-fitted on. I can see no non-destructive way to remove it.

Motor Fan/Hub Removed

I bored into the centre of the plastic fan/hub so I could get a puller's nose to contact the motor's shaft. That got the fan/hub started coming off. From there, I was able to pry the fan/hub off the rest of the way. Here's a view of the motor out of its housing along with its detached fan/hub.

The motor's shaft is 8mm diameter, with splines that make for an interference fit with the fan/hub's bore. Shaft length is 15/16".

I rigged the motor for a no load current draw measurement, and a photo-tachometer reading. I got about 650 mA  at about 27,000 rpm. Evidently, the 3.2 A, 10,000 rpm rating represents full load values.

Anyway, I now have a very nice little universal motor that I can think of no possible use for.

The Handgrips

The lower handgrip is fastened by a single M6 x 52mm carriage bolt and wingnut. There's a flat washer under the wingnut.

The upper handgrip is held together by six 4mm threading screws, No. 2 Phillips recess. The two screws nearest the trigger are 13mm long; the remaining four screws are 18mm long

The Trigger Switch

The red trigger acts on a momentary slide switch. The slide switch is made by Defond. It's rated at 11 A, 125 VAC, 5.5 A, 250 VAC. Its terminals are 3/16" male spade terminals.

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So there we have it -- the whole thing dismantled. Here's what all I salvaged:

• Three compression springs.
• Motor.
• Slide switch.
• An M6 x 52mm carriage bolt with wingnut and flat washer.
• A 25 1/4" length of 7/8" diameter steel tubing.

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FEEDBACK

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Some Dollar Store Tools

The local Dollarama store has some remarkably neat stuff.

The 9mm utility knives are excellent; they even have spare blade storage for two spare blades.

I was only in the store for the sake of the knives, then the screwdriver and bit set caught my eye. I'm a sucker for such things, so I figured I could gamble $4.00 CDN + HST. There's no exchange or return at the Dollarama, so I'm hoping that the screwdriver bits are the real deal -- not overly brittle or soft. We'll see.

The socket wrenches are all metric -- 4mm to 14mm. The handle would really be something if it had ratchets, but it doesn't. The handle attaches to the shank in either a 'T' or an 'L' configuration. The 'L' configuration should provide an abundance of turning force.

'Looking forward to having need of the set.

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FEEDBACK

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Another Poulan 260 PRO 42cc 18" Chainsaw

My last attempt at getting one of these running was a washout.

We'll see how I make out with this one. It's another machine that was given to me by the small engines place that I frequent. It's a saw that wasn't worth the shop's while to repair, so the owner just abandoned it. It's in pretty rough shape by the looks of it -- the chain appears to be off its sprocket and jammed. I'll want to attend to that first thing.

I'd really like to get this saw going. I have three sickly cedar trees at the foot of my backyard that need to come down.

Anyway, here's the saw's ID label data:

FAMILY 2000US EPA PH1
                YPWES.0424CS:EM
DISP. 42CC
SERIAL # 00075D 100235-3

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Jammed Chain

Clutch/sprocket/bar access is by way of a single cover that's held on by the two bar clamp nuts. The nuts are hex washerface items, M8 x 1.25, 13mm A/F (across flats). Note that the chain brake must be disengaged in order for the cover to be removable.

The chain on this saw may have been run out of oil -- it had many seized links that wouldn't traverse around the sprocket without jamming. With penetrating oil and a good deal of persuasion, I've gotten the chain to where it will traverse complete circuits. On with examination of the saw.

Bar Oil Reservoir

It's bone dry. That may explain a lot. I won't fill it unless and until I can get the engine to run.

Fuel Tank

There's some fuel in it. The fuel takeup tube is iffy, but its filter is still in place..

Top Cover Removal

Three obvious screws, T25 Torx recess.

Spark Plug

The spark plug had been installed very tightly. I had to take an impact wrench to it to get it loose.

It's a Champion RCJ7Y. It's a bit sooty, but not in bad condition at all. Hex is 3/4" A/F. Gap is a loose 0.025". A spark test revealed that I do have spark.

Priming

The primer bulb is a bit stiff, but it appears to be intact. The thing won't prime, though.

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Problems/Solutions:

• A stiff metering diaphragm. The diaphragm in my scrapped Poulan 260 PRO was ok, so I swapped diaphragms.
• Embrittled fuel line tubing. The fuel takeup tube looks to be virtually impossible to replace by squeezing it through its hole in the top of the fuel tank. I drilled out that hole to 5/32" diameter so I could slip-fit a replacement tube through. The tube's interface with the fuel tank is no longer fluid-tight, but the arrangement will get me going.
• The bar and chain are past it. The bar and chain on my scrapped saw are good, so I swapped the bar and chain.

And after all that, I'm still getting nowhere. I can't get the saw to start, and I'm getting weary of putting in seemingly futile effort.

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Update -- MONDAY, OCTOBER 21, 2019

My son pointed out to me that I have plenty of time on my hands. So, I decided to return to the chainsaw and keep on attempting to get it running, however futile the attempt might be.

After an outrageous amount of fiddling, I got the thing to run for awhile. Now I'm back to being unable to start it again. It's exhibiting high compression -- compression so high that I can't get a decent pull on the starter cord. 'Next visit to the small engines place in Pickering, I'll ask about that. I'm hoping that they'll have an answer.

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Further Update -- TUESDAY, OCTOBER 22, 2019

I took the saw with me to Pickering yesterday to show it to the senior man at the shop. He deemed the saw to be normal. So, I have to confess that the problem is not excessive compression; the problem is my lack of upper body strength. When I got the saw home, I rigged a method whereby I could get both feet holding the saw down while I tugged on the starter cord with both hands. That got the saw started. Here's a view of my 'both feet' rig.

Right foot goes in the handle as per usual; left foot goes on the stick of wood. I can hoist the starter cord's handle with both hands, and away we go.

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I got my three ailing cedar trees taken down and limbed. Cutting up the trunks will have to keep for another day; it's raining today.

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FEEDBACK

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Roadside Find -- A Sears Craftsman 21" Rear-Bagging Lawnmower

My wife found this lawnmower just up the street while out walking with our granddaughter and hauled it home for me.

It's a Sears Canada Model 944.364372, Serial No. 050905M 005419. Engine is a Briggs & Stratton 6.75 MRS (Most Reliable Starting). No. 125K-0506-E1 05041258. (I don't know what to make of "6.75" -- evidently the engine has 6.75 of something, but there's no indication of what.)

The mower looks to be in not bad condition. The deck shows no rust bubbling up, and the safety bail is operative. Let's take a tour and see what's up with it.

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Muffler

An obvious fault is that the muffler is missing one of its two attachment screws.

That will likely call for a trip to the small engines place in Pickering, if I can't kludge a replacement.

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Muffler  Update -- WEDNESDAY, SEPTEMBER 25, 2019

The small engines place fixed me up with a salvaged screw. Here's a view of the complete fastener complement for the muffler.

The screws have 2 1/4" long, 3/8" diameter shoulders, with 1/2" long, 1/4"-20 threaded ends. The hex heads are 7/16" A/F (across flats).

And here's the completed muffler installation, with the keeper ends cinched. (I applied anti-seize compound to the screws' threads.)

Much better.

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Oil

The oil looks reasonably clean, but it measures way overfull on the dipstick -- overfull enough that I'll want to siphon some out if I can get the machine running.

Sump capacity is 591 ml or 20 US fluid ounces.

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Oil Update -- WEDNESDAY, SEPTEMBER 25, 2019

My siphoning rig's pickup tube wouldn't fit down the dipstick hole. The idea of tipping the entire machine to drain out oil didn't appeal to me, so I've left the engine overfull with oil. It doesn't blow smoke when it's running, so it should be ok with that.

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Fuel

The tank looks empty. On the fuel tank's cap there's written "FRESH START CONTINUOUS FUEL PRESERVER". On the underside of the cap there's a little vial affair attached that says "REPLACE WHEN EMPTY", like so.

It looks empty to me. I guess it had fuel stabilizer in it that's dispensed at some slow rate. That feature is a new one on me; I've never seen it before.

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Blade

The blade is on the right way around, and it doesn't appear to be distorted, or badly nicked and dull. A sharpening will be in order, though. The blade screw's hex head takes a 9/16" wrench.

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Spark Plug

The spark plug is a Champion RJ19HX. Hex size is 13/16" A/F. (An acceptable substitute for the RJ19HX is RJ19LM.)

It's in reasonably good condition. Gap is a snug 0.030", as it should be.

A spark test revealed that there is spark, so there's hope for the engine.

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Compression

Compression measures 60 psi, which in my experience is fairly typical for well used mower engines. The engine should still have plenty of useable life in it.

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Air Filter

Loosening off a single, captive 5/16" A/F hex head screw gives access to the air filter.

This one is pretty dirty. A replacement is in order. (Replacement filter P/N is 491588.)

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Fueled Up And It's No Go

I took the air filter off so I could observe carburetor priming, and nothing happens. There's no evidence of fuel being pushed up out of the main jet when the primer bulb is pressed. The engine won't start. So, the carburetor has to come off for inspection.

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Carburetor Removal

• Air cleaner cover and filter element.
• Small black cover above the air filter -- one pan head No. 2 Phillips recess screw, 10-32 x 13/16".
• Air cleaner base -- three hex washerhead screws, 10-32 x 5/8", 5/16" A/F. Note the gasket, which will likely remain stuck to the carburetor. Note also the crankcase ventilation tube to be reconnected at reassembly.
• Fuel supply tube at carburetor -- one spring clamp. Be ready with a suitable plug to plug the end of the tube. A bit of 5/16" diameter rod, or the shank end of a 5/16" drill will do nicely.
• Carburetor -- two hex washerhead screws, 1/4"-20 x 5/8", 3/8" A/F. Unhook the governor link. Note the O-ring at the intake tube. That O-ring must be in place and intact.

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The Carburetor

The carburetor is an ultra simple float bowl type, having no adjustments. There's no idle circuit to get clogged up; there's only the main jet that's easily checked for clogs.

To remove the float bowl, use a 1/2" socket wrench on the bowl's fastener. The float bowl on my carburetor was clean and free of debris.

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The Primer Circuit

Some study of the air cleaner base and its gasket will reveal the operation of the primer circuit. Pressing the primer bulb closes off the bulb's vent hole, and forces air through a channel in the air cleaner base. Priming air is ultimately delivered to the carburetor via a small orifice at one side of the carburetor's mouth. From there, air is channeled within the carburetor to the float bowl, where it forces a dollop of fuel up the main jet and into the carburetor's throat.

Given that the primer bulb is sound, priming failure is most likely due to poor seating of the air cleaner base to its gasket and the carburetor's mouth. The integrity of that seating is absolutely crucial to primer operation. Replace the gasket if in doubt.

On my engine, the primer resumed working after I reinstalled the air cleaner base on the carburetor. The engine became startable. Something must have been amiss with the seating of the air cleaner base.

The engine ran poorly with the air filter element installed; the air filter element is evidently badly clogged. The engine runs fine with the air filter element removed.

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Update -- THURSDAY, SEPTEMBER 26, 2019

With a new filter element installed, the engine runs fine. I've never seen a filter element so badly clogged as the one that was on this engine.

Further to the matter of the air cleaner base gasket, I obtained and installed a new gasket (P/N 795629), and that didn't work -- with the new gasket, I had no priming. Reinstalling the old gasket restored priming. Here's a view of the inboard side of the air cleaner base, and the two gaskets.

The old gasket that works is at the left; the new gasket that doesn't work is at the right.

On the old gasket, note the full impression made in the gasket's surface by the priming air channel's ridges. That gasket fully seals the priming air channel; hence, priming is enabled.

On the new gasket, there's little impression from the priming air channel's ridges. The air channel leaks, and priming doesn't happen.

The fault lies in the design of the air cleaner base's fastening scheme, and the non-rigidity of the air cleaner base. The gasket doesn't get squeezed with uniform pressure all the way along the length of the air channel.

Maybe if I left the new gasket in place for long enough, the gasket would get squeezed sufficiently that it would seal the air channel. Another solution might be to install the gasket with a smear of silicone gasket maker.

Anyway, for now I've left the old gasket in place, ragged though it is.

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In Conclusion

The lawnmower was discarded on account of two minor faults that had a big impact on the machine's behaviour. The leaky primer circuit was causing failure to start, and the clogged air filter made for very poor engine performance when I did get it running.

I attribute the leaky primer circuit to questionable design. The clogged air filter was just neglect of routine maintenance.

With attention paid to those two faults, I've got a perfectly serviceable lawnmower, with plenty of life left in it.

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