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Thread ID: 146174	2018-05-12 00:34:00	Briggs and Stratton Valve removal and Ring replacement	kahawai chaser (3545)	PC World Chat

Post ID	Timestamp	Content	User
1449464	2018-05-12 00:34:00	Anyone removed or know valve removal on BS vertical pull start mower engine (187 cc, 3.5 HP) and replaced the rings? I decided to strip down a low compression engine (35 psi). This is after replacing a fractured flywheel key on another engine (about 65 psi) lying under my house for 5 years. Got that going OK on a Masport base, as a spare mower. I don't want to buy the B&S valve spring compressor (about 80 dollars at least, anywhere online) and buy the spring compressor too. I think I can pry the springs out, so as to lap the valves - but might be a pain to replace by hand - unless a few tricks or certain hand tools... Also the rings - Do you need to work out the thickness required so as to get a good fit and compression for the cylinder? some pics, with valve chamber cover removed of the and piston with rings,of my teardown...	kahawai chaser (3545)
1449465	2018-05-12 07:38:00	Without special tools This is how I have done it in the past. Put a piece wood under the valve head to hold it closed(wood on the bench and head on top of the wood to hold the valve against the seat) and using a ring spanner big enough to fit on the valve keeper, compress the spring and have someone remove the 2 collets once spring is compressed(may need to use long nosed pliers). Use reverse procedure to refit collets. A large hose clip will help with the piston rings. Just ensure they have the correct clearance. Old school but the rule of thumb was 3 thou/inch of bore diameter. the rings should move freely all around the ring grove. If anyone has a better way, please post it	Colpol (444)
1449466	2018-05-12 10:37:00	Thanks Colpol. Never thought of flipping the valves over to rest against wood/bench. Also the hose clamp - good and cheap tip. Might wrap the clamp around a semi rigid plastic strip also. then tap the piston down. I'll practice with the old/removed rings firat...	kahawai chaser (3545)
1449467	2018-05-12 19:10:00	Oooops! This is a double post - can a kind and benevolent person delete the first one and leave this one? Please? IGNORE FIRST POST - THIS IT THE TRUE POST AS I WANT IT TO APPEAR! I just a month or two ago did this very same thing for a friend . @kahawai chaser - you've helped me so much in my forays to Linuxland, that I feel compelled to write this to you with probably 'way more info than you need - but I will anyway . First - a SIDEBAR: That white-ish plastic 'gear' in your pic tells me that you engine is not pressure lube, but 'sling-splatter-splash' lubed instead . As ugly as it looks, it works . Go figger! Inasmuch, be sure to keep the oil level precisely up to the dipstick demarcation so you won't starve the moving surfaces of cooling and lubricating oil . The oil level is correctly measured by NOT screwing the cap back into position - instead, just lower the dipstick into the tube until the cap touches the top of the tube and draw it back out quickly to read the oil level . Screwing the cap down to get the oil level reading will short the oil 'pan' or reservoir of sufficient oil to protect the engine as it leans into turns, sidewise on hills or sudden stops and starts . I am flabbergasted by the price of the spring compressor in Upsidedown land . Was that a typo? I paid just $18 . 00USD (Smile . Amazon) for it and it was an official KD tool . . . . . from the company that builds many of the special application tools for Ford, GM or Chrysler, Fiat, Go-Go Mobile, etc . . . . including Kohler and B$S . The bench-trick works well - but will try one's patience anyway . Be calm . Drink non-caffeine drinks and remember that alcohol is for AFTER accomplishing putting the retainers back into the valve . SOME Kohler and B&S small engines use a new design 1-piece retainer for the springs and this is a very nice improvement . You only have to release the valve stem from the spring pressure and slide the whole top of the retainer to the enlarged hole they provide to slip the valve stem out of the keeper area . The older - two-piece keepers were miserable to handle even with the correct tool . In the absence of a real ring compressor - the large screw-type hose clamp works very well - even if you might have to reposition it as the bottom ring goes into the bore and you need to compress the next ring - etc . I don't believe that you can get the plastic insert to comply with the rings all the way to the cylinder bore either . I'd just use the clamp . I have never had to put a buffer or padding, etc . , between the rings and the clamp, as you will see that even if the clamp holds SOME of the ring into position, it will be enough to get it into the bore anyway . Scratches and damage to the ring is almost impossible unless you tighten the clamp too much or use a big hammer . Be sure to turn your rings 180 degrees apart from each other - gap-wise, that is . . . . and make sure to not allow the ring gaps to be directly over the wrist pins either . That's old-school talk there - but it's something to which I adhere, always . PS: If you have a multi-piece oil (lower) ring, try to turn the individual parts 180 degrees apart also - but obey the 'never over the pins' rule . During assembly - I apply a liberal amount of 80/90 or 90/120 wt gear oil - yeah, the stinky sulfur-based, thick gearbox and differential lube oil - to the moving parts . It will ferociously to cling to the metal and will supply terrific protection to the sliding, grind-y parts until oil flow (or splash) is established . One CAN buy assembly lubricants - but good ol' 90-weight works every time for me . It also contains zinc and some other heavy metals to establish smooth rolling over and pressing very firmly to the gear teeth to protect them - and will do the same thing in your engine reassembly procedure . It will not harm the engine oil at all - it might even give it some more body . One more old-timey mechanic's rule was to use 30 wt or 40 wt detergent oil in any air-cooled engines . . . . . . . I've rebuilt more than a few air cooled engines that had had multi-weight oils in them - and the crankshaft was fine - but the cam and followers/lifters were all galled and brinnelled from metal swapping as the multi-weight oils have seriously lower sheer strength than single weight oils IMO . It also seems that ALL oils - even my favorite Castrol - have been adding synthetics to the mix . It's inevitable that you'll likely get some too, and although I admonish my customers to shy away from them in air cooled engines - it's gonna happen anyway . Lifters on the cam face exert tons of pressure in a very small point of contact and if the lube oil sheers easily, the cam and followers/lifters die a quick death and contaminate the lube oil with shards of bearing-eating metal flakes and splinters (as seen under a microscope . If Upsidedown Land has Lucas Break-In Lubricant ( . com/products/engine-oil-additives/engine-break-in-oil-additive-tb-zinc-plus" target="_blank">lucasoil . com) - I put it into my flat lifter engines as the most important additive available for a working engine of early, non-roller design . Crankshafts and piston skirts can be lubricated and protected with penguin urine, but the cam and followers/lifters is where the rubber meets the road, so to speak, for oil anti-sheer composition and protect-ability of sliding parts . :devil	SurferJoe46 (51)
1449468	2018-05-13 11:45:00	Your post Joe reads like an extract from Zen and the Art of Motorcycle maintenance (which was set in Montana!) The book describes a craftsman with empathy for things mechanical (but I don't think he used penguin urine :)) . He's in harmony with his work and would use a puller to remove a flywheel, whereas an impostor would just whack the shaft with 4 lb hammer . I confess to being in the impostor camp . I came home from the rubbish tip one day with an old B & S lawnmower and tried to fix it . It was hard to start so I filed a bit off the cam to make sure a valve was properly shut before the next one opened etc . Voila! The engine started so easily I could almost do it with one finger . And it ticked over REAL smooth I was thinking how clever I was as I gave it some throttle, But nothing happened! It just continued to tick over real smooth . The next week I took it back to the tip	BBCmicro (15761)
1449469	2018-05-13 11:53:00	Thanks Surfer Joe (46).Never noticed the 46 before... I buy B&S parts from SES direct NZ (includes genuine parts) and eBay. Compressor priced over 80 dollars (SES (sesdirect.co.nz)) in NZ and eBay - as most selling are from the USA. Shipping costs seem to be quite high similar to UK. The keepers as you say were one piece - so no pesky collets - keepers have a little indent opposite the larger hole. So pushing/pressing that popped it off easily for one valve(< minute) The indent for the other was facing rearward (took 15 mins). Took a while to find the timing mark too - a "hairline" mark (no dot) on the crank gear. Quite visible dot on the timing sprocket. Though I 'm sure I aligned them correct before finding the mark - took a while re-inserting the gears.. Proof I think is you can rotate the shaft fully without the cams - jamming the lifters I assume. Did not think of starting oil/compound. I do have 80/90 pennzoil diff gear oil. But have had nearly 20 years. Lucas break in oil is sold locally though. Ok some questions/observations... 1. Why no bearings on crank shaft. But seals are present. Bearings are present on my Ryobi weed eater/line trimmer (see pic) - which I also stripped - waiting for oil/compression piston ring kit from eBay 2. Why the hole in the cam gear? 3. I noticed in this YT vid (www.youtube.com) there are claws/pointers in the middle of oil slinger 4. Also the cam gear is plastic in that vid - though slotted over metal shaft I think (Hence perhaps little metal shavings produced) 5....Then why not have plastic lifters as well? 6. Exhaust port bit carbonised - dunno whether to dremel it with mini wire brushes and burring bits. Might end up gouging the port. 7. Realised that the lower and wider piston groove still had a pentagon wavy shaped metal band present. This I assume meshed with the two con-joined rings removed from that lower slot 8. Just realised also that one of the upper rings has a bevel - or rather another angled ring/step integrated. I guess it faces upward on the top groove. The other ring is just flat or level. will stagger the gaps when re-inserting both old rings then new ones later... Before adding starting oils - have to clean the cylinder bore (and fins) and oily crank case. Though dunno whether to use the cheap degreaser spray cans (takes ages to dry off, strong smell, and often use rags to dry off) or more costly but evaporative parts/brake cleaner, or carb cleaner. Any thoughts? 8827	kahawai chaser (3545)
1449470	2018-05-13 13:10:00	Some observations on the Briggs motor in your attachment. This motor has an aluminium block, so bearings are quite unnecessary as aluminium is a very good bearing material (as used in Caterpillar diesel engines). You can ream out the block to fit bronze bushes, but I have never had to do this. Likewise with the valve guides. As there are no collets it is possible to slide the keepers sideways to free them from the valves. NOTE that the springs are different, the exhaust spring is stronger & thicker than the inlet spring. Some springs have closer coils at one end. This end is placed towards the block to reduce the un-sprung weight of the valve assy. The piston is chrome plated because the bore is aluminium, as opposed to a chrome plated bore. The idea is to avoid metal pick up which would occur if they were both the same metal. If you use genuine B&S rings they will already be gapped. The top ring will have a tapered upper edge (to clear the wear ridge) and will be chromed, the second ring will be sharp edged and chromed. The oil control ring will have chrome rails. NOTE: If you get cheap 3rd party rings, only the top ring will be chromed, not recommended. DO NOT use oversized rings in a standard bore. They will become oval when compressed and will burn oil. Use a broken piece of ring to scrape the carbon out of the ring grooves. Set governor speed to 3600 RPM maximum.	mzee (3324)
1449471	2018-05-13 18:42:00	@ mzee - that's great information for kawaii . . . . and I approve/endorse it all heartily . That any piston ring has an observable 'abnormality' in it's design - eg: a groove, a chamfer, a dot or a taper - indicates that it is the side of the ring that sits UP in the piston . I've never seen any change in that information in all my years . Oh - yeah - ONE exception: There are rings that have a scraper concavity right out at the ring face (toward the cylinder wall) which would put it to the underside of the ring --- that is/are designed to literally scrape the residual oil off the cylinder walls . So far, I have mostly seen that in low RPM engines - but them Koreans are tricky and might try it in a Hyundai someday - if not already so! TTBOMK - this is the only reversal of 'all oddities and marks to the top of the ring' theory and I believe this was on a two-cycle or steam engine anyway . This was also on a single ring piston that had no secondary compression ring either . The total lack of bearings on the big ends of the rod and/or the bosses that support the crankshaft is indeed from a desire to simplify the whole machining and assembly process in the factory . There MIGHT be a bean-counter in the woodpile too, trying to lower costs . These rods are, of course: aluminum . The crankshaft is steel . They will not swap metal very easily . That then the oil's sheer wall and advancing Tsunami-like wave is not broken nor is it much more than one or two oil molecules thick - lessening roilling (not a typo) qualities too . It CAN happen - but oil keeps these two adverse parties apart if it is in sufficient quantity, good quality and not severely contaminated . - hopefully . Currently - many of the newest automobile engines do not have bearings either . They are capable of machining the block so carefully that bearings would be a downgrade to the efficiency of the engine at least with drag coefficients and 'oil sheer wall sticktion' qualities dragging miles per gallon to lower levels . My first foray into bearing-less engines was a 3 . 8 Ford V6 that amazed me . However, there are no oversized (undersized, really) bearings for subsequent rebuilds - nor are there any crankshafts that are re-machineable either . They are nitrited and are so hard that they would require Blanchard or centerless grinding machine work at least - very expensive and slo-o-w! (see $$$ going down the tube?) Corporate bean-counters are known to suffer The Vapors at the mention of expensive processi (processis?) Besides, these designs pose another singularity: once-and-only-ONE TIME machined radiusses (radii?) in the journal areas where the vertical throw-wall meets the cylindrical bosses of the crankshaft throws for the big ends of the rods and the mains anyway . Once you cut those radiussesses (gotcha!) you destroy the integrity of the crankshaft and you'll have to 86 it in the end . But: +1 on the spring coil design and the tighter wound end going toward the block . +1 on the piston chrome plating - even though most people cannot discern any chrome at all . Not all chrome glistens! However: -1 on the top ring nomenclature - because that chamfer on the inside edge of the top ring is to allow compression to force the ring tighter to the cylinder walls by actually and not very incrementally to be sure ---> thereby increasing the surface area inside the upper ring groove and the ring itself . In design, it will redirect some of the compression gasses to that area and actually push the ring harder into the cylinder wall . In operation, this is pretty easy to see - mentally . During and right immediately after the fuel charge is fired, the advancing pressure wave will get between the piston head and the cylinder wall, seeking escape . It's a nature-thing! When that pressure wave encounters the ring, it tries to dislodge the ring from it's (the pressure wave's) run seeking any port outward to a lower pressure zone, and as presses the ring down, opening the ring's upper groove-to-ring clearance where the pressure then also pushes into the back area of the ring . In this attempt to get out of the cylinder any way it can it then pushes on the 45 degree chamfer and that sets another process into motion . The ring then moves both down in the piston ring groove, and also outward into the cylinder wall - further enhancing it's seal and attempting to do it's job of keeping the pressure inside the cylinder where it belongs, by assisting the sealed combustion chambered area and thereby pushing the piston down and ultimately rotating the crankshaft . Lots of mental animation - no? I love it! That's the ZEN of a chamfered upper piston ring .	SurferJoe46 (51)
1449472	2018-05-22 01:26:00	After averaging multiple meticulous readings, by leveling the rings with the inverted piston in the bore, the ring gaps - top to bottom - areapparently too wide: 34, 30, and 62 thou (at least 0.80mm) when measured near the top, and 24, 25, and 56 thou near the bottom. Youtube vids and forums mention higher than 30 thou for compression rings and 45 thou for lower control ring then rings are worn hence low compression and high oil consumption. New compression rings are about 3 thou to 10 though it seems. Perhaps 12 - 16 thou for used engine... Also appears that Briggs and Stratton don't give any ring gap values, and torque/spec readings on their web site. Apparently need (or buy) their very costly hardback spec manual. Though can download parts manual, but need submit the engine codes to do so. I discovered that they make the standard rings - which are easily available for the standard bore size (2.78 inch, where I measured 2.76 inch near top), but seems there are also a range of oversize and undersize rings - which I think are discontinued. But if standard rings result in small/no gap - it seems they can be filed at their ends. I used zip ties to compress/re-insert the valve springs, and long thin scalpel knife to cut them once springs/stems are aligned with the keepers.- indeed the exhaust spring is quite strong - why would that be? The lifters were vey newish - for A 1984 engine - as compared to the scruffy looking valves. There seems to be two tiny holes at the bottom and bottom edge of valve chamber - I guess for oil drainage? May get the rings new or swap some from other engines and mowers I have. Currently watching a few cheap used ones on Trademe...Funny I just remembered I assisted a little on mower engine repairs with my step dad around mid 70's- who was a mower contractor. Those mowers had vertical push/turn button prime/starter and rectangular engines I think..,	kahawai chaser (3545)
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