Collection, Preservation and Display of Old Lawn Mowers
As requested the gasket paper used for the side plate gaskets was 0.15 mm, and the sump gasket also paper was 0.25 mm.
The engine was originally fitted with four gaskets but we did notice a fair amount of end float so measurements will made as we reassemble.
Re the missing clutch linings I suspect that a donor machine could well be your easiest option.
Clutch linings are available https://www.ebay.co.uk/itm/163176802324?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1555.l2649
I wouldn't worry about the valve stem / guide wear. Unless you are going for a complete engine recon - re-bore etc just live with it.
Exhaust . Removing that stub will be a source of entertainment / grief in varying proportions. It may be worth trying to square up the step so that the new washer sits properly and seals against the muffler box. Stubs, washers and boxes are all available.
The washer under the breather body looks OK . My earlier reference was for the breather valve disc that sits loose under the cap.
Thanks Wristpin, I've sent you a reply. I do indeed have the paxolin disc from the breather, a few more pics
If anyone needs to make up a replacement disc, if it's any use, the dimensions of my disc are 0.018" x 0.535"
Exhaust value on the left is more corroded and pitted than the inlet valve on the right
After a cleanup
After cleaning up the valve seats, would lapping the valves help to shift the contact area on the valve further away from the margin and back to where it should be?
Hmm, that exhaust valve might reface without leaving too than a margin but may be easier to find a better valve. Surprisingly the exhaust seat doesn't look too bad .
Refacing Trimming valve stem Seat cutting Not ideal, contact patch should be
nearer the centre of the face
to increase clearance
EDIT The above was created on the PC but when viewed on the iPad the captions have moved and refuse to be edited !!
Hillsider - thanks very much for posting the gasket material thickness that you used, very helpful.
Wristpin - thanks for posting those pictures - what a useful machine and tool to have! I have access to a bench grinder but that's it, so no way of controlling the angle accurately to ensure it's concentric to the valve stem etc. I've seen a couple of companies advertising valve refacing online for a few pounds per valve, so if I can't source a better condition exhaust valve I may get that done, and then I can hopefully manage the lapping myself on both valves.
It's difficult being my first engine restoration not to want to just replace everything with new and get the cylinder bored for a new oversized piston and rings etc, so I know that everything is going to work as it should and not burn oil or have play. But i have to be realistic with the age of the engine and the limited 'new' engine parts available, and as long as the engine runs smoothly enough to allow the mower to be used for it's intended purpose, I'll be happy with that.
Would you be happy to use the crankshaft as it stands with the journal face having the score mark, adn the con rod bearing having matching score marks right down the middle, that you can feel with your finger let alone your nail? Is that likely to cause major problems in future, or will things still run ok like with regular oil changes and inspection? Could that sort of scoring cause something to bind up for example?
I've found a new con rod and bearing cap online, and if I can source a better condition crankshaft, then would that be the recommended way forward? Just trying to draw on the knowledge of much more experienced people on this forum as I'd rather swap out now if it is likely to need sorting sooner rather than later, or likely to cause engine failure.
Taking into account that crack in the crank a better used one may be a good idea. Be aware that very early versions of your engine had a different taper as well as some other dimensional differences. If the seller of your replacement crank has the flywheel a comparison of the casting/part number embossed on it would be as good a check as any.
Scott, I have to compliment you with the quality of the photo's, really _stunning_ and educational.
Thanks for the kind words Henno. I'm hoping the pictures will help both myself when the time comes to rebuild and put everything back together, as well as helping others who are looking to do the same thing or struggling trying to find references and pictures for what the parts should look like and how they all fit together. Before I started, I found many threads that people had started but then seemed to abandon and never reply with updates. I couldn't find much in the way of full restoration threads on a similar mower/engine, that went into enough detail for a complete beginner like myself, so hopefully my thread will help others looking for such information.
While I wait for a suitable replacement crankshaft to turn up, I'm turning my attention to the cylinder. I've been measuring the ring gaps to see how much the rings and the bore have worn.
Using feeler gauges I have measured the following:
Can anyone tell me if these gaps look ok, and how far away from new ring gaps the measurements are? Also, these measurements indicate bore wear of 0.1mm / 0.0039" - again is this acceptable wear, or does this indicate oversized piston and rings would be required? I have absolutely nothing to compare these figures to in order to know if they are 'ok' or not. Can anyone help please?
Measuring worn rings in a worn bore only says one thing - the combination show a worn engine. However we know that from other equally obvious signs that it’s had a hard life.
You either need to beg or borrow some bore measuring equipment - telescopic bore gauges and a digital vernier needn’t cost a fortune , or, as an absolute minimum a new ring set to give you a comparison.
That said, it’s amazing how those little old cast iron SIF lumps will run even when completely shot; but taking into account of all the known nasties, I would be on the look out for a less worn engine.
Thanks Wristpin. I didn't want to buy a new set of standard rings just to check the ring wear, if the already measured cylinder bore wear was considered too much. From what I can find online, 0.1mm bore wear seems to be the limit for some cylinders, therefore this would indicate a rebore and oversized piston and rings would be required for my engine. I see you can get oversized piston which is 2" + 0.060" / 50.799mm + 1.524mm.
Going down the route of getting another less worn engine, surely it's just a gamble until you get the engine and strip it down? It could have less wear but could have as much if not more wear that my current one. Would it not be better getting hold of a better condition crankshaft, new con rod and oversized piston, knowing that the engine is then in good condition, bar potentially worn valve stems and or guides? I guess if an engine or complete mower turns up nearby cheap enough, it could be worth the gamble in the hope of using the best bits from each one and making one good engine?
Trouble is, you are trying to measure something potentially worn with something that is also potentially worn. I think you will get a better result with new rings, your max difference with the original rings is 4 thou and this is likely to decrease with new rings, I would be tempted to glazebust the bore and fit new rings. As Wristpin says, you can only really measure a bore with the correct tools and these will also allow you to measure if the bore is out of round i.e. is it oval.
Thanks Hortimech, appreciated. I figured, with my limited knowledge, no matter how much wear a ring has, measuring the gap near the top and bottom of the cylinder would still give you the amount of taper/cylinder wear. If this wear was too much and needed a rebore, then standard rings would he no good, as I'd need oversized pistons and rings following a rebore.
I'll get some standard rings and see how much wear my rings have.
Although I have digital verniers, I've seen proper bore gauges online in videos now, so will see about hiring or buying second hand perhaps, or finding a garage/engine repair shop that could measure for me.
What would an acceptable level of wear be before requiring oversized piston/rings/rebore?
Maybe I'm overthinking this given the age of the engine . I do have tendancy to want everything to be perfect and correct which probably isnt helping. Perhaps better crankshaft, new con rod and standard rings will suffice and just be prepared for the engine to burn a bit of oil - as long as it runs and the mower works......
The cast iron Suffolk will run when other engines wont. Provided that there are no scores in the bore or piston, I would just re-ring it.
That's good to know. Starting out for the first time on this level of engine stripping down and rebuilding, it's easy for things to spiral a bit. New valves and guides are available, but going down that route I'd have to find tools to remove the old guides (ream and thread a bolt down into them and extract) but then the guides may need a light honing, so more tools, then the valve seats would need recut, again more tools I dont have. Then I start looking at granite surfacing plates so I can get a nice flat clean surface on the cylinder block and head mating surfaces. Not to mention the fact new piston rings may still have too big a gap due to the cylinder bore wear, so I start thinking I should give to the engine to an engine shop to carry out all the necessary work!
On one hand I'd love for it to all be reconditioned and build up as near to new condition as possible, but I really know that its unrealistic for the money Involved, as it wont be a museum piece, I just want something to be proud of that I have restored to a high degree that works well. Maybe if I had more tools or had done similar projects before it would be easier to do the full works on it!
Re surface plate, you can get 300 x 300mm granite allegedly at 3 micron flatness for $38 from alibaba china.
Took a tip from Wristpin and got some 8mm thick glass big enough to do twins and singles, been oil tight on the few I have done.
Work with what you have. Forget the valve guides , just sort the valves, rough up the bore with a cheap flap wheel; that’s what Cords sell as a glaze buster. Fit a set of standard rings . If you want a cheap surface plate, visit your local shop window glaziers a blag a bit of heavy plate glass . I did that about 40 years ago and made a wooden case for it - still have the same piece. As both Hortimech and I have said, it will probably run.
When you fit the new rings to the piston take care to fit the compression rings with the corner cut outs in their correct locations.
one thing that I have not seen mentioned here yet is that you should measure the ring gaps in the unworn areas at the top or bottom of the bore as well as the upper and lower worn areas, as you have already noticed there is a clearly defined area of travel for the piston rings using this method you can get a fairly good idea about the amount of wear in the cylinder.
As as been said previously these engines are very forgiving.
Chris - thanks very much for the link to the surface plate, that doesn't look bad for the money compared with a lot of other options! As Wristpin also mentioned, the glazing option will be worth investigating locally as well.
Wristpin - thank you, I have ordered a set of standard rings and am looking for a suitable diameter flap wheel - would something around 300 grit be the sort of grade i'm looking for? I've seen those 'bottle brush' looking devices called flex-hone which look a lot less dangerous for a novice than say the 3 legged devices with spring loaded cutting stones advertised as honing tools, but if a flap wheel is going to give the same results if used correctly, then that's going to be much cheaper.
Hillsider - I made a note of the orientation of the existing compression rings in the piston before removing them - thankfully, as I would no doubt have forgotten by now! Also, the current ring gap measurements I posted above were taken using the worn top section of the cylinder around 15mm down, and the bottom readings were all taken in the unworn part of the cylinder at the bottom.
I will post up the difference using the same locations with the new rings, as I can't find any info online about what the 'new' gaps should be (in the unworn area at least), so will hopefully be a reference for others in future.
Something mysterious (yet again!) I noticed with the sump - where are what appear to be hundreds of tiny metal curly 'shavings' sat down inside one of the main sump bolt threaded holes?!
I would welcome suggestions as to what on earth these shavings could be and where they have potentially come from? I didn't find them anywhere else in the sump or drained oil, just this one threaded hole. Using a tiny magnet I removed them and washed out the entire sump, and the threaded hole looks perfect, so it can't have been an incorrect sized bolt used and the threads were stripped or anything like that. Stumped!
Another curious thing I have noticed - the oil splasher has what looks to be a 'worn' side - almost as if it has been hitting the bottom of the sump? I wouldn't have thought it would be designed to do this, but I take it these are not normally smoothed off on one side like this...
The bolts holding the splasher to the bearing cap were tight and the splasher looks like the genuine part. There's a tiny mark on the sump but this looks more like where the oil dipstick would sit. Other than that, some strange looking texture to the upright 'columns' either side of the sump...
No idea on the flicker Im afraid.
Are you sure that thread where the swarf was has not been helicoiled? - It does not look it but...
Given its the only place where the swarf has accumulated I would assume it must have been a result of bolt/thread action..
The sump markings would just be a result of casting, nothing too worry about unless its a crack.
No idea about the shavings in the bolt hole. I suppose that they could have been trapped there since the original machining of the sump. Ive never seen a sump as poorly finished as yours but, there again, could well have been that way for ever.
Oil splasher/ dipper. Does look a bit rough. They came in four lengths to match the sump depth, usually with a number stamped into them. From memory the sumps came in four configurations; four bolt with transverse grooves to sit on the tie bars of the early cast iron Colts; Shallow flat bottomed with three bolt fixing used on the Qualcast Commmodore but with a groove to accommodate a clutch cable that ran under the engine. Shallow four bolt used on later Colt / Super Colt and a deep four bolt used on the 98cc engines on Super Punches etc. There were other variations to accommodate oil drain plugs and even a short split pin dip stick before the cylinder block was modified to provide an oil fill/dip stick plug.
EDIT found another one!!
The oil thrower (like the sump) comes in different sizes, so it might be worth checking that the thrower does clear the sump internal surface.
As for an helicoil being fitted, then the swarf would have been aluminium, which isn't magnetic, so I would look for something that looks like it has been machined.
Timesert then, but unlikely
Deglazing. I would think that 300 grit is a bit fine - perhaps 180. As you say, the cheap (ish) spring loaded three stone hones can be a bit difficult to control and one has to be careful, particularly at the bottom of the bore, not to go too deep and have the stones flip over. The professional ones with the universal joint and parallel action are far better - at a price. The flu-brush Flex Hones are mainly used for finishing - reducing asperities- in newly cut re-bores and would be hard to justify for a one off.
The Cord flap wheel glaze busters are crudely effective at a justifiable price for a mower engine - the biggest problem now is finding them. One used to be able to find them in Halfords and some of the old school motor factors and Cords themselves don't seem to be geared to deal with Joe Public. however they are still in their catalogue. I've still got a selection of well worn Cords ones and some diy flap wheels used with a wood bit extension shaft . Around 350rpm with a steady stroke produces a nice cross-hatch.
Thanks for all the advice and suggestions - I would be well and truly stuck without all the knowledge and experience of the members on here!
It feels like a long road ahead at the moment, even just with the engine, let alone the rest of the mower that needs addressed. If I can get the engine sorted mechanically and put back together that will be a big milestone for me. I haven't even opened up the carb to check the state of that yet, and I'm constantly wishing I had so many tools like valve seat cutting tools, an ultrasonic cleaner, glazebuster etc.
I'm certainly prepared to invest in a few bits and pieces as I'm really enjoying learning about the engine and if I make a success of it, I may even do another!
Looking more carefully at the other end of the valves, it appears the inlet valve has been filed/ground at some point, to presumably increase valve clearance due to wear and tear - not a particularly square job! It's missing the slight chamfer that the exhaust valve has at the end of the stem
Angus - do you think it's still worth grinding these valves? I suppose I could refit them once ground and see what clearances I have, and then it it's too much, I could look at replacing the valve/s if necessary?
Who knows - maybe this valve was sourced from another engine at some point.
Also, I can't see any wear anywhere else around the engine internals which gives any clue as the where the swarf came from. Threaded holes look original to me, no sign of any fettling
Regarding the oil splasher, one side is certainly longer than the other, which would seem to be why it has been worn smooth. My splasher has the number '4' engraved on it - would there be any references anywhere which might confirm what number splasher should be on my particular engine? The con rod has a number '2' on it before the main part number E3520 if that bears any relation to what number the splasher should be? Or would that be too easy..
Angus, thank you very much for tracking down Cords and asking about the GlazeBusters, really appreciate that! Looks like I'll have to try the 3 stone sprung tool and just go very carefully with it
Looks like we’ve nearly got a matched set of dippers !
Just go carefully with the sprung tool but with the crank out you can put a block of wood or polystyrene in the crankcase to act as a bottom stop. The top is easier to judge , just keep the pivot points of the stones below the top of the bore on the up stroke.
Its quite common to find that the ends of the valves mauled about . My B &D grinds them square but can’t put back metal that someone else has hacked off. I think that the face of your inlet will clean up nicely and in doing so will close its clearance slightly . Your exhaust shows all the signs of having stood a while, open and in a damp atmosphere - hence all the corrosion and pitting. How much has got to come off the face to find good metal will only show up during the process. The danger is that to get to good metal the margin will become too thin . Nothing to loose by trying though.
I’ve got s jar of Suffolk valves from scrapped engines but it’s been raided so often “ to find a better one” that good’uns are a bit thin on the ground.
While on the subject of valves . When prepping a four stroke for the winter lay up it is good practice to turn the engine over to just past TDC so that both valves and the points faces are shut. Then a good spray of WD 40 ( others available etc!) into the exhaust and up through the carb. Then bung the exhaust and inlet with a bit of oil soaked rag or workshop towel. Leave a good bit sticking out to remind you it’s there in the Spring.
Now if you can just find a number 2 dipper, that will be the whole set!! I've found a picture of the new con rod I was going to buy, however although it has the same E3520 part number, it has the number 4 just before this (my current rod has number 2) and the shape of the tapers along the shaft of the rod are different to my current one
A lot of rods I'm finding online have the number 4 on them, and not 2 like my current one. Would the engine number be of any use to anyone to help identify which one should be used on my engine?
I'm guessing that the 2 and 4 numbers are batch numbers or even a factory date code.
That seems likely - perhaps the number on big end bearing cap is similar - mine has B7 on there
In other news, one of the two metal dowels that sits between the engine block and the sump, part number E3819, has a crack running down the side, opposite to the split that is supposed to be there
It still seems solid, so hopefully won't be an issue. It would be nice to find something that's actually not broken on this machine!!
I believe that the original dowels were solid; those appear to be roll or spirol pins.
Going back to the con rod - part number E 3519 covers the rod, cap, screws and locking strip - E 3520 just is the bare rod.
Ultrasonic cleaners are a very handy thing, a decent 2.5l can be had for around £60 and the bigger ones are coming down in price, although 2,5 has done me fine so far. End up using it for all sorts of things.
Easy for me too say and not sure of the criticality, I would buy new dowels if available or get some made
So the dowels are a makeshift replacement then - originals either broken or lost in the past. The part number for the dowels doesn't return any results on google so looks like I may have to fabricate some. Finding out the dimensions of the originals isn't going to be possible, and rather than trying to copy the makeshift ones, am I best measuring the depth of the locating holes in both the sump and the engine block, and then making some slightly shorter and narrower so they are a tight fit in the hole but with a few mm gap height wise? Sorry if it's obvious, but what material would be best here?
Thanks for the info on the Ultrasonic cleaners Chris, definitely plenty of uses. I can probably swing it with the other half If play the 'jewellery cleaning' card too :)
I've actually just read through your 43SL restoration thread - it's certainly given me some inspiration!
Hi RL, if the 43 did not send you to sleep this might :-) - https://www.oldlawnmowerclub.co.uk/forum/history-and-technical/technical/starting-marquis-20
The U/S cleaner I have must have been through 8 carbs, loads of injectors, watch bands, jewellery etc, well worth it for me anyway. The U/S cleaning fluid can also be made cheaply instead of buying expensive stuff.
Re the dowels, I have no experience of this on mowers. On old motorbikes they are usually a strong interference fit on one side of the part ( like sumps, clutch cases etc) and will come away in place on the removing part. Given they are a locating dowels (I believe?) I'm really not sure of the criticality, if I were making new I would make them of similar or more malleable
Test the dowel hole diameter with a twist drill - probably Imperial . Then see if you can buy the appropriate diameter short length of Silver Steel . In this application they are probably fairly important to resist fretting between the block and sump as the bolt at either end does not provide much, if any, horizontal location.
An alternative to Silver Steel may be the plain shank part of a bolt.
EDIT Lots of Imperial Silver Steel rod on ebay
Thanks Chris - I've read through that thread you posted as well and found it interesting - certainly didn't start falling asleep! I'm trying to absorb as much information as possible, not coming from an engineering/mechanical background, so reading about ways people resolve issues, craft replacement parts from material they have lying around etc I find truly impressive.
Slowly trying to turn my garage into more of a workshop, so make it easier to work on things like this as I think I've caught the bug!
Angus, thanks for the suggestion on the dowel material, I'll get cracking and see what I can find/make and report back.
Meanwhile, something I've found on the mower which is actually in good condition (shocking I know) is the chain - positive news! After a good clean/soak, it's actually in excellent condition and must have been well lubed during it's lifetime - no sticky links or damage, and not a spot of rust
Well, the brief blip of good fortune with the chain didn't last long, after removal of the chain it was time to remove the upper and lower sprockets. Upon inspecting the larger sprocket, there appeared to be, what I initially thought might just be dried cracked grease, however this was sadly not the case...
Answers on a postcard as to what might have brutalised this poor sprocket so badly?!
It looks like it has been run with a loose retaining nut at some time, is there any damage to the shaft ?
In no particular order, poor quality sprocket, something jammed the cylinder and shocked it, or the nut loosened off a bit and the sprocket chattered away until it rotated enough to burst the boss.
Or a combination of all three.
I had something much less severe on a much later aluminium belt drive one, yours looks a lot more tortured. - worked for me but would not work on a steel one in that state I don't think, halfway down this post
The shaft condition is a good one, hows that?
Clearly a good used one would be the easiest route, a bit of mig or tig infill would be difficult on the inside and a pain to shape but the outside with a touch of mig could hold it up ok and some serious metal filler shaped on the inner with proper retaining nut and sprung washer and loctight could work if done well. But easier to find another..
On the upside the chain looks great.
Thank you for all the suggestions, I thought it would have taken quite some force to do that to it, and also going back to the crankshaft surface 'fracture' too, but I guess the speed things are rotating and the force behind it, to suddenly stop, all that energy has to go somewhere.
Speaking of which, closer examination of the other end of the crankshaft also shows a slight fracture, albeit to a lesser extent than the flywheel end - might have just been a manufacturing oddity though
In terms of the sprocket, thanks for the info there Chris, and sourcing a better condition one is definitely my only choice there. The non-built up side of my sprocket does look to have the tell tale sign of wear similar to the one you had, where the flats of the shaft must have been spinning slightly within the sprocket to give those wear marks on opposite ends. I've found some 19 tooth contenders on the bay so should be able to sort something out there.
Regarding the shaft condition, things appear to be in good condition at both ends. I have to admit, I've not taken any detailed pics when removing the cutting cylinder to remind me which way around it goes - oops. I've taken some pics of both ends to show the condition. Would someone be able to confirm which end is the drive side please? Also, should the bearing caps be able to be removed to clean up the races? Do these caps fit onto the bearings when reassembling, then the cylinder shaft goes through them? What I'm trying to ask is how do you get these bearing caps back up against the bearings when assembling? Should they slide on the cylinder shaft? Also assuming the 'wavy' shaped cap is deformed and requires straightening?
As for the blades themselves, all look ok, except one, which has a slight 'twist' or 'bend' - hard to explain but the pictures show what I mean. How would I go about sorting this out? Adjustable wrench and a hammer to try to take the bend out somehow?? This could be a clue as to the other damage to the sprocket, crankshaft...
The cylinder bearing cone with the pin and large spring washer is the belt drive side (i.e. right hand side) and should just pull off. The other end is pressed onto the shaft and is only usually removed to replace it.
As for the bent cylinder blade, support it on something solid (we used an anvil) and hit it, the cylinder will need regrinding after this. Do not use any heat, it could take the temper out of the blade. The blade will have been bent when it hit something, on a golf green (where this happens fairly often) it is usually a spike out of a golfers shoe, but, on a normal lawn, it could be anything.
That bent blade is fairly typical of the condition of cylinders presented for grinding and possibly contributed to the failed sprocket. As Hortimech says, easily straightened ; I prefer to put the cylinder on a sand bag as that way they don’t jump about when hit, but each to his own.
Also, as observed, leave the drive end cone in place unless it is necessary to replace it. Take care of the tin dirt excluders; they used to be available as a separate part but will be hard to find now. I prefer to grind those cylinders on their own cones but with slave races and cups
To answer your specific questions. The fixed cone is on the sprocket end . The cone with the spring washer should be free to slide and is on the belt end.
The damage to the crank is very strange, I’ve never seen anything like it on a Suffolk engine and with a degree of certainty would say that it’s not related to the blade damage. As well as the sprocket absorbing shock loads those loads are also separated from the engine by the centrifugal clutch.
Thanks Hortimech and Wristpin for the clarification on the cylinder orientation, much appreciated. I should be able to tackle the bent blade in that case!
I gently removed the tin hat from the pressed on cone side, which came off after some penetrating spray and gentle wiggling. The cone doesn't look too bad at all all things considered
Out of interest, what are the small grooves/knurled area you can see just in front of the cone on the shaft? Does the pressed on cone locate onto these to prevent any rotation?
The other 'removable' cone at the other end was a bit more tricky, and had seized in place, so I had to leave it soaking in penetrating spray before gently persuading it to part company with the shaft. The face on this cone is more pitted and not nearly as good as the other end, so I don't know if I should try to seek a replacement or if it just means a slightly rougher feel to the cylinder spinning around, and wont affect the performance as such?
Starting to move...
The shaft cleaned up fine both ends, so I will clean up the tin hats and cone faces as best as possible. The ball races in the bearing houses were also in a somewhat neglected state.....
The ball races would also appear to have been previously fitted the wrong way around, as the balls should be facing into the pressed in cups, is that right?
The oilers (reference to Adam's Lubetech?) were completely blocked with old grass and general crusty gunk, so I cleared them both out and gave the whole assembly a clean up. New ball races to add to the growing list of parts required!
Races. Definitely look to have been the wrong way round. The cones will be OK but may rumble a bit. When you reassemble it I would give them good slug of heavy grease and then a squirt of oil when they are all back together. The grease Helps keep the oil in ! The shaped felt seals that go between the bearing blocks and the chassis side plates are still available or you can cut your own from sheet felt.
I see that there are a few sprockets on ebay - most as a pair with a chain bit one or two just the lower one.
Well looking at the cost of replacement cones, I will happily put up with a slight rumble from the bearings! Are you able to suggest any heavy grease that would be suitable? I've used 'Weldtite TF2' bike grease for cones and bearings on mountain bikes over the years, and it leaves a teflon coating, but I've always felt its been a bit too thin for long term bearing use.
On the subject of the 19 tooth sprocket, I note my mower did not have a washer behind the nut when disassembling -
Yet the parts diagram for both the Super Colt and the Atco both show a washer behind the nut. The sprocket is the same part number on both L8538 / L08538, however the washer differs between the two diagrams - IN564A / L18025 and I can't seem to locate this washer by part number online?
After a bit more digging online it looks like L18025 may translate to F016L17849, which does come up as a 'shim' or 'plain washer' in a couple of places, and seems to match teh washer used behind the flywheel nut on some models https://www.ebay.co.uk/itm/GENUINE-ATCO-COMMODORE-FLYWHEEL-NUT-WASHER-PART-NUMBERS-F016L17845-F016L17849-/163697394835
So this should be obtainable - probably similar to whatever washer is on the pulley end of the cylinder shaft