Briggs Plastic Cam Gear

[@philipclarke9303]

Hi Bruce, I've always wanted to know how my mower works, have loved your videos and was waiting for a video on the workings in the crank casing. Keep up the great videos, enjoying from the UK.

[@BrucesShop]

You are so welcome. I love taking stuff apart.

[@Tobi08150]

i hate plastic in Motors

[@metoon3092]

Fascinating ! My little repair shop had a mower come in (Exact match to your donor mower- Yellow & Black brute ), Zero compression. All combustion pressure was forcing out the intake tube to the carb. Flywheel key fine, so I pulled the sump cover, removed the cam gear --and there it was , the compression release smashed, and the cam lobe *not* aligning with the tooth on the main gear. I recalled watching Mr. Bruce's video pertaining to this, and Bam! I retrieved another used cam gear, buttoned up the sump, bolted her back to the deck, She fired on the _First_ pull ! Thank You sir for the guidance and wisdom to put another quantum back into service. 😊

[@BrucesShop]

You just made my day

[@mogdefender8520]

Bruce, as long as the lobes are not worn, place the cam in the proper position like you did and the just put the cam in a mill and drill a hole right through the plastic cam and steel shaft. Then pin the plastic cam to the shaft. No issues with it slipping on the shaft anymore. You could use a roller pin or use a mild steel cylindrical pin and pen it on both sides with a ball pen hammer. Opening up a donor engine only to find another worn or loose camshaft would be a waste of time.

[@BrucesShop]

You are right. Good point.

[@JOEZEP54]

I was ready to make this comment & then saw yours. I did not try this (yet) just thought it should work. Did you have a chance to try it out?

[@ray8burnett905]

Briggs and Station has been using those cam gears for at least 20 years now. I know because I have several older B&S MOTORS

[@BrucesShop]

Yes Thanks a lot.

[@alexanderchuyko4889]

Oh! It`s the nice tutorial! Is there any clear symptoms when you have to suspect that this is probably this issue, please? Thank you

[@BrucesShop]

Well there was no pressure release on the rope when it was pulled. When the rope was pulled the entire mower woud move with the rope.

[@stoolie10]

Bruce I just replaced the plastic gear that failed on a friend’s pressure washer with a metal one that goes over the shaft and it ran fine when I tested it out for the first time. I gave it back to my friend it started once for him then locked on him. I got it unstuck but it won’t run now. Lots of time into this project 🤔.

[@BrucesShop]

Sorry. It is hard to comment on the pressure washer when I am not there

[@stoolie10]

@@BrucesShop I understand. Thanks for always listening to my issues. It’s always good to share with you.

[@gdbonney]

Tango Yankee Bruce. I always learn how to fix stuff watching your diy. I'm now fixing lawn mowers out of my garage. You're on my short list of teachers that help me take care of problems with mowers.

[@BrucesShop]

Cool Glen.

[@blackjack98enterprises]

Just did a 6hp craftsman myself yesterday and today. Got the engine running just fine. Your is very similar.

[@BrucesShop]

Thanks

[@mrwhy8073]

Just had the same problem with my daughters lawnmower. 7 years young. Piston ring broke too. Big gouge in the wall. Knew it was timing issue air was being pushed out the carb when pulling it over.know I know why rocks and sticks or hitting the ground can destroy the engine! Plastic fantastic!!

[@BrucesShop]

Yes i have seen this a few times.

[@alexanderchuyko4889]

Some people says it must be a small bump or a click at the end of compression cycle. If we pull the cord slowly or rotate the engine shaft. That`s how this pressure release works. Is this method effective for this type of Briggs engines, please, or it was for bigger motors for tractors or raid on machines only? I have noticed a very strange thing. Yes, I can start the engine initially when its cold, but no chance to repeat it later. However, when I removed its air filter and its lid, I can start it many times in a row... If put the filter, or even empty lid back- no chance to start... Tried many times. That`s out of logic... Is it something magical ?! :)

[@BrucesShop]

Wow that is weird that even with the air filter assebly is empty it still affects the starting. The age of the Briggs may be an issue. The older ones (pre 1982) need the air filter to be on as the filter bolt closes a hole. But i am guessing you have a newer one. Briggs Classic or quantum. You issue is new t me.

[@alexanderchuyko4889]

@@BrucesShop The engine itself, like the mower is not to old. Its manufacturing date is: 19/03/2018. Engine model is: 104m02-0010-f1 pretty typical. I starter to tune with this issue... It can potentially be a breather problem. Before engine starts, it has a fresh air to intake, but after some cycles, a dirty, oily air from the engine comes via this breather an reducing oxygen concentration. If the air filter volume is open- the engine can take fresh air, if closed (with filter or without), the circuit is semi-enclosed and this breather tube is inside... It was my guessing only... Otherwise, I have no idea :))) I tried even spray "easy start" - doesn`t work at all. Taking off filter assembly is only the way :)))

[@robbflynn4325]

Since being a kid I always loved taking stuff apart. Never been good at putting it back together though😢

[@BrucesShop]

It is a learning process. You are doing great.

[@SteveRobReviews]

Nice one Bruce. I had one like that last year. The owner didn't want to spend any money on it. The exhaust valve was opening slightly too early , I ground it down and it ran for about a month. They threw out the mower. I would have liked to try drilling into the plastic and into the cam and drive a small roll pin and see if it holds.

[@BrucesShop]

Yes so dd I but the decompression release was so bent. I could have bent everything back and given it a try though.

[@josephpuchel6497]

Hey Bruce It’s been awhile. I’m working on similar issue but also believe governor needs replacement also. So while inside it’s get replaced. Hope you’re well. Happy Easter

[@BrucesShop]

Right on. Good for you.

[@RobertPerrigoOkiechopper]

Bruce , what I like about plastic parts is its a type of fuse to cut down on metal to metal damage. But thats just my opinion .

[@BrucesShop]

Thanks for the great comment. I remember my first encounter with a plastic cam gear in a Honda and I thought is was so awful but now i am OK with it. It is like stress relief.

[@martindesmarais7158]

Tried to find a full steel one replacement, I failed, can you link me if it's available,,, Appreciate tnx.

[@BrucesShop]

I think the steek ones don't have the decompression release. They are also very old. like you i have note even seen one. Sorry

[@not2fast4u2c]

Well...I learned something new today...I knew they had a plastic gear but that is the first plastic cam I've seen and the if the crank is not bent It's gotta be tough to have the blade adapter part shear like that

[@BrucesShop]

They really must have hit something hard eh!!!

[@dfields9511]

Hey Bruce. From your southern neighbors. I have a craftsman Briggs 6.25 in which I think the same thing happened to. Timing seems to be off but flywheel key is fine. It only runs for a few seconds on a prime, and carb is clean also. It s giving the symptoms of a broken fw key. I was wonder if I could open it up and reset the timing but thanks to your vid I now know I may not if my cam gear got broken like yours. I paid only $5 for the lawnmower but there is at least 80+ of good parts on it .

[@BrucesShop]

Cool. I don't hesitate on using a non running mower for parts.

[@prostreetgsxr]

I know that the plastic cams give a lot of problems but I have never heard of that happening because the engine came to a sudden stop. Usually it would be a bend the crankshaft or flywheel key sheared off. There’s not much inertia stored in that light weight Camshafts.

[@BrucesShop]

Well the cam lobes were out at least 20 degrees. i just showed what i found.

[@prostreetgsxr]

Bruce Pender I believe you 100% that the cam timing is off I’m just wondering if it is off because the engine came to a sudden stop or because mounting plastic to metal is just a bad idea and it’s going to happen either way. Keep up the great videos!

[@davegeorge7094]

The E valve opens @ 100 d past TDC closes@about 260 dlater. The cam tips are 225 apart(about 1/4 rotation of big gear.) Intake opens @ 360d past TDC for about 225 d. Too early, too late it seems but valves just crack open slowly and I think exhaust is quieter because. I measure 24.5 mm max lobe diameter each. If a pushrod get shortened, valve can't open fully and long enough. KEEP CYLINDER FINS OPEN TO AIR FLOW, grass oil wasp nest clogs fins.

[@BrucesShop]

Thanks WOW!!!

[@stevecase8634]

Great vid Bruce, that explains why the pull rope is so hard to use. I am going to take the sump cover off and see what I see. I may have an old cam gear that will have the valve decompressor still attached. Something to do over the warm winters we have here in FLA...thanks so much for the tutorial..best from us down south

[@BrucesShop]

Thanks for the kind comment Steve

[@stevecase8634]

Thank you Bruce,,you strike me as a person with the heart of a teacher. Thanks for making it easy to do these things..best from all of us

[@ZippoVarga]

Briggs and these other companies are not doing anything out of the ordinary with plastic components. Governor gear sets have been plastic for over 50 years, cams, for about 30. In fact, my 1966 Buick had a nylon timing gear on the cam and it worked great for 200,000 miles. A lot of people seem surprised, but the cam, under normal conditions, is a low impact part that is perfectly suited for plastics. Less weight means more efficient operation. Not cheaper manufacturing. Good explanation and video my Friend! Cheers! Sean~

[@BrucesShop]

Thanks a lot. Okie has a good point about the plastic nylon parts actually helping.

[@BrucesShop]

Some how I am OK with the nylon gears and other parts of my brain don't like it.

[@tombruce6398]

Hi Bruce REALY liked your video it REALY helps people like me who are on a fixed income thanks would you post part number of the cam I can’t find it any where

[@BrucesShop]

I am sorry Goole will work if you type in the model and make of the engine.

[@ranger1244]

I wonder if someone else tried to fix it because in a previous video about the trash picked mowers you showed the flywheel key was ok but in this video the blade adapter key was sheared off which is insane!!! With what must have been an extremely violent blade strike I'm surprised the shaft wasn't bent too and the blade made into a pretzel!!!

[@BrucesShop]

Could be. But with close looking at the key it looks a little crooked in there. If I fix it i will replace the key too.

[@kenhilson786]

just found this on a search. I have a 01 quantum from neighbour of a friend. he put ohv plug in this flat head. exhaust valve hit the plug. when cam shaft stopped the crank gear spun the cam gear on the shaft cracking gear hub. I found this on disassembly after I replaced exhaust valve and then noticed piston to valve timing was way off. new cam $140 cdn. found used on ebay for 65. i have a 91 which has different cam part number but going to pull it and compare.

[@BrucesShop]

Very cool! Best of luck

[@lamarkelley4058]

I'm working on the exact same problem on a Briggs and Stratton 3.5 HP , thanks for the video/info , it's a big help.

[@BrucesShop]

Best of luck. Enjoy the job too.

[@jcondon1]

Just picked up what looks like the same mower. Timing of the compression stroke vs position of the magnet in relation to the coil is way off. Have a feeling that it is the same issue :( Was second guessing what I was seeing. Plastic cam gear and lobes says it all.

[@BrucesShop]

Let me know. i am always interested in what others find. Thanks James.

[@robertbrown8396]

I keep seeing guys turn those crankshafts with their hands... You should make a note to tell them to carefully feel the keyway slot... I grabbed hold of one and turned it and it sliced my hand open. Some of those edges can be as sharp as razor blades. The edges was so sharp I didn't even feel it cut my hand open, until I noticed there was blood all over the bench and floor. Now, on any I have on the bench, I take a small file and knock the edges down.

[@BrucesShop]

That is experience talking. Thanks Robert.

[@tavo24vv19]

Makes me wonder what kind of damage would happen if that wasn't a plastic camshaft. Bent valves and valve marking on the piston head maybe🤔.

[@BrucesShop]

Right I still think that flywheel key should have sheared but you just never really know what happened.

[@conner5611]

Can't bend valves on a flathead you can float the valves all day long

[@renadog1]

If it wasnt made of plastic it probably would not of been a problem. Just got rid of my fathers 40 year old mower and bought one of these plastic mowers, lasted 2 years!

[@JeffTheHokie]

I have a Briggs quantum-style that did its job and died of old age, and a newer-generation plastic everything (carb, crankcase, recoil cup) Briggs that most likely has a bad camshaft because it went to crap about a month after hitting a pipe, but key is intact. Do the two use the same camshafts, or has that part changed as well? I don't want to put any money into the "just check and add" POS, but if I can build a frankenengine from the two that might be an option.

[@dominiquehaines-86SquareBody]

I completely rebuilt my 550ex Briggs and Stratton engine.. New Fly wheel key, plug, filter.. lined up the cam gears an cleaned the housing.. as well as the carburetor.. still a dead pull..

[@BrucesShop]

Well did you find the issue ?

[@dominiquehaines-86SquareBody]

@@BrucesShop nope.. just picked up another engine for it.. still tryna figure it out though.. I was thinking of putting a fuel filter on it to see if it makes a difference

[@robertsmith2956]

Back in the 70's all you had was a paddle inside to splash the oil around for lubrication. I guess i'll find out about the chinese engines. Just ordered one and got a second mower free. So spare gear. LOL But I'll open mine still. Think I have round lobe, pulled valve cover and the exhaust rocker wasn't even on the rod. I have a little movement, but rocker is very lose, and easy to knock off again. Are the lobes the same dimension? I can't find a service book to look up the specs for valve lash, or lobe size.

[@BrucesShop]

I am sorry I can't help you.

[@stevecase8634]

Very interesting Bruce..wonder if the plastic cam gear saved the crankshaft from bending..I have seen my share of wobble and vibration in the ones with the bent shafts..

[@BrucesShop]

I bet it did. Shearing that blade adaptor must have put some stress on that crank eh!!

[@ericdixon2898]

It appears that the gear slipped on the spindle. Bent the counterweight on the centrifical compression release. First time I cracked mine open I couldn't believe it was plastic but I figured hell it must be tough.. guess not.

[@BrucesShop]

The majority of them are great. I blame the hard flywheel keys on the Briggs.

[@kelvinbrooks9588]

Hey Bruce!! Awesome Video! I ruined my mower running over a large tree root. Now I know how to go in and see what's what! Thanks again!

[@BrucesShop]

As you have to open the engine ----just check everything else first. Check the flywheel key first !!!!!! They go before the cam gear.

[@notajp]

I just ran into this on an Intek 5.5 hp horizontal engine that was given to me last year. It came off a chipper/shredder, and supposedly needed a valve job. I started working on it and found that the valves were not moving. Pulled it down expecting to find missing teeth on the cam gear, but they were intact. I was puzzled until I removed the cam. It also has a plastic gear, but with individual plastic lobes. It also had a slipping cam gear, but it was worse than yours. I could hold the shaft in one hand and twist the gear with the other hand. Didn't even need the vice. Pretty crappy design. It appears that the gear and lobes are merely pressed onto the shaft, with only friction to hold them in place. You have to wonder what the engineers were thinking!

[@BrucesShop]

What bugs me is that gear should be stronger that the flywheel key. That should shear off first.

[@dfabeagle718]

@@BrucesShopFWIW, the cam will turn loose without hitting anything. Just a bad design.

[@MegaFlaxman]

MegaFlaxman I hope I can get a response on this question. I have a 2008 Honda clone 6.5 horizontal shaft. It was in the original box till just recently when I aquired it. I filled with oil and gas and wouldn’t start. I checked the compression and it’s 28 psi. Checked the rockers and they’re moving like they should. I removed the rockers and physically moved the valves up and down, both seem to be seating properly. Filled cylinder with oil and tried again, still 28 psi. What’s my next move, remove the head and check the valves?

[@BrucesShop]

No don't. All newer engines of that size have a compression release on the exhaust valve. It is internal to the engine. So at very low RPM yo will always read a low compression. I would just make sure the oil is good level and start it up. Don't "fill "the cylinder with oil. Is the motor new?

[@2003cinman]

Top vid fella, many thx :). I’ve been trying to sort a timing prob with my 725 series b&s engine for ages, just didn’t consider the cam lobes could rotate about the camshaft. Shite quality though, not b&s best moment!

[@BrucesShop]

They all use plastic cam gears now.

[@2003cinman]

Bruce Pender Oh, fair enough. I guess the plastic lobes are somehow “bonded” to the steel shaft, and only come undone when the blade hits a solid object of some kind.

[@BrucesShop]

​@@2003cinman Exactly

[@2003cinman]

Bruce Pender I wonder how realistic it would be to drill a small hole through the plastic area between the two cams, through the steel cam and out the other side, then insert a tiny split pin. Maybe it’d prevent such a cam-slip happening again?

[@BrucesShop]

@@2003cinman I thought about it.

[@Pyridox]

Interesting Bruce. I guess some of these engines are not worth repairing when the internals have issues.

[@BrucesShop]

Well a couple of years ago when the economy was great they were a throw away item. Now that money is tight more are getting fixed.

[@danielauen7790]

Seeing as how the camshaft seems like its mostly plastic, i wonder if you can 3d print a hotter cam.

[@BrucesShop]

I wouldn't but i am 66 years old. LOL

[@hoss1947]

I have a 2009 John Deere riding mower with a 19 HP Briggs single cylinder engine. I was driving on my driveway heading to the road where I was going to start mowing as always. The engine stopped and would not restart. I pulled the top cover, and flywheel off and found a sheared keyway, don't know how that happened on concrete without blades engaged. I changed the keyway, and a second later it sheared another key way. I made some phone calls and was told that the engine might have a nylon cam gear that slipped on it's shaft. Now I have to crack it open and see what the problem might be. I'll probably fix it, and get rid of it. No more Briggs engines for me. Nylon gear and cam on a steel shaft...shame on you Briggs.

[@BrucesShop]

Well even the older 6HP mowers have that. I have only changed 1. Have you checked that electric clutch?

[@davessmallenginerevival2847]

Very interesting Bruce. I don't think I've ever seen that happen before

[@BrucesShop]

It is more common up here in push mower land. Thanks for the comment Dave

[@megaengineeringsolution1911]

Thank you sir for the video,but I still have some question to ask. From nigeria

[@BrucesShop]

OK

[@megaengineeringsolution1911]

Mr Bruce,I discover there a crack on the cam shaft,could that cause the machine to decompress.

[@BrucesShop]

Yes. do the lobs line up with the notch on the wheel?

[@campbellpaul]

Valuable information and nice tutorial! E-replacement Parts is only good for carb kits, filters, gaskets, valves, piston rings, cables and the occasional bolt (if they raised the price on those, they'd be out of business) Most small engine repair shops won't even waste their time with a repair like that, knowing it's not worth the fix.

[@BrucesShop]

You are right but I just fix for myself. I use E replacement Parts to get part numbers.

[@campbellpaul]

Yeah, I notice they are just a middle man. I do like their ability to ship fast when they have the parts in stock, however.

[@lmalino695]

Hanging on to old parts turns into its own project and becomes a trade off on where time is better spent obtaining a needed part. Did you make your discarded parts available to others or just trash them?

[@BrucesShop]

Used parts are the key to my little operation. In western Canada it takes 2 weeks to get something from amazon. Folks don't realise it but i am a 9 hour drive north of Helena Montana.

[@lmalino695]

My question was prompted by your narration where you say 'I just cleaned up my yard and got rid of my old motors'. Did I misunderstand? I save stuff, maybe obsessively, because my stuff is so old and I figure evolving technology may be able to revitalize damaged components when a replacement is unobtainable. My oldest mower was purchased in 1957 as a share between my father and a neighbor.

[@BrucesShop]

Ah yes. I have a shed with a lot of parts but i do tend to recycle the motors that are toast. The ones that have some hope i get running. I have for example 2 Honda boxes, 2 Briggs boxes etc. I am doing good on the reusable parts. Thanks for the great input.

[@dano5814]

there's a pile of used ones on ebay dirt cheap in the states. one as low as 6.45 shipped. aren't they available to you up north?

[@BrucesShop]

Shipping. We use Ebay.ca not Ebay.com

[@grahambird1570]

Hi Bruce, I found a fix for this slipping Plastic Gear, remove the Gear, cut a small 'Key way' and cut a small key way by hand and re-assemble >. Bingo !

[@BrucesShop]

Cool, thanks

[@ZombieDaveAZ]

Great point made by Ranger. If the strike was hard enough to shear the blade key and the timing gear probably the flywheel key as well. I'm willing to bet the crankshaft has a little wobble to it too. Nice of doublewide to offer up the part. That's brotherhood of a dying breed. Thanks for sharing Bruce. PS. Save those parts for the next zombie.

[@BrucesShop]

I am going to try and fix this one. I couldn't detect any wobble in the crank. I just used a straight edge though. (old School)

[@ZombieDaveAZ]

+Bruce Pender ,I have zero doubt that you will make that mower usable again. You have all the skills to bring it back from the dead. Have a great weekend. It will reach 114° in Southern AZ by Monday! SMH

[@BrucesShop]

Thanks Dave It is going to 18 Celsius today here in Alberta Canada which is about 65 F.

[@ZombieDaveAZ]

+Bruce Pender, It sucks to be me. Not really. lol

[@SouthpawDavey]

Thats very interesting. I am sure there is hope ;-) Hefty price for the part.. I was talking to a guy just the other day about how new stuff is made to fail so you have to buy parts. Although what happened to that mower is not in that category.

[@BrucesShop]

Yes it hit something bad.

[@travisnichols8683]

Bruce I would like to ask you where do you find your briggs parts at when you show us the bag and part number?

[@BrucesShop]

There are lots. Just google Briggs and Stratton Engine parts. The bags are supplied by the seller. For example Craftsman or Yard Machines.

[@805ROADKING]

Great video Mate!! It wasn't that long ago when Briggs made quality engines!! But like you said, everybody is making junk now!!☺

[@BrucesShop]

They all use plastic.

[@josephpuchel6497]

Hey Bruce Buy a all metal one from older design engine. They are all the same.

[@BrucesShop]

Right I have one but does it have the compression release. The one I have has no little spring?? Great comment I will look again.

[@Trades46]

Camshafts are now made of plastic...I don't even know what to say. Heck given EPA emission regulations & corporate average fuel economy (CAFE), I expect this kind of shit to appear soon on automobiles.

[@Wayoutthere]

I know righ? I always feel somewhat insulted.. We the buyers, that keep purchasing these throw away mowers, are responsible.. Buy good stuff, kawasaki engines etc.

[@BrucesShop]

It already does. Lots of moving plastic parts in an auto engine and they seems to last. I feel both OK and sometimes disappointed with it.

[@campbellpaul]

Complete design flaw Bruce points out... That key should have saved the internals. Replacing it should be the only fix necessary!

[@Pro1er]

It was probably 30 or 40 years ago that I heard about an all plastic Ford engine - too lazy to look it up but I found this. blog.caranddriver.com/is-this-the-engine-of-the-future-in-depth-with-matti-holtzberg-and-his-composite-engine-block/ Plastic has its place - in kids toys.

[@edenpop5754]

Your videos really help me fix my mower. Thanks very much

[@BrucesShop]

You are welcome. This is why I got onto You Tube. :-)

[@megaengineeringsolution1911]

My mower is decompressing,I don't no what to do. Cam shaft is fix well to the timing of the grand shaft,yet no compressor

[@BrucesShop]

What is you valve lash? at Top Dead Centre on the compression stroke.

[@megaengineeringsolution1911]

Please how do I get to no the valve lash,can you send me a video via Facebook or whatsapp

[@cainsmale5988]

Just bought the exact same cam ..genuine briggs and Stratton quantum series off Amazon for $60.00 .. informative video btw :)

[@BrucesShop]

Thanks Cain

[@cainsmale5988]

@@BrucesShop welcome Bruce

[@jetgriff]

Hi Bruce.. following this video, on a 625exi... when I took the cam out the exhaust and intake pushers fell out followed by the push rods. are they supposed to be fixed in place?? John

[@BrucesShop]

On these the tappets contact right onto the valves. Is the exi overhead valves. This one is a flathead.

[@Tbizzh]

Man...I just went through taking this same engine apart twice with no luck in getting it running nicely. The first time it sputtered and never got up to speed, then I realized I threw it back together without setting the timing. So I took it back apart after that realization and set the timing just as you did here... And now it won't even start. The first pull gave a backfire and it won't start.I'm stumped, the carb is clean as well as the filter and new spark plug. The flywheel key is new and the flywheel went on easily. Any ideas? One part I'm hung up on is the tdc magnet on the flywheel. Since the flywheel is attached to the crankshaft with a key I'm not sure why you need to check that.

[@BrucesShop]

Did you try a different cam gear? Just wondering. Something is still off.

[@Tbizzh]

@@BrucesShop good question. I saw you pointed out the exhaust lobe is lined up with that feature on the gear. I'll have to take another look.

[@BrucesShop]

Great.

[@conner5611]

Almost every non commercial lawnmower has a nylon can gear these days even hondas they say its for weight saving

[@BrucesShop]

Right. They all do.

[@bobgreene2892]

Would it be easier to drain the crankcase oil before inverting the engine block?

[@BrucesShop]

Probably. It is easier to look back on a process.

[@fleetwin1]

$105 for a CPS cam! So, not only is the gear plastic, but it looks like the lobes are plastic as well, am I correct? I was expecting broken teeth, but the gears were aligned perfectly....Is the gear keyed to the shaft? Are the lobes keyed to the shaft? That plastic tab on the gear is supposed to line up with the top of the exhaust lobe, correct? I'm sure the manual would spell this out, but I could see me spending hours skipping over the plastic cam after seeing the teeth were not broken and aligned properly......So many of these plastic cam gear mowers/engines must scrapped after the owner receives the repair estimate for several hundred dollars. I guess Briggs thinks it is OK to produce such a flimsy part because other manufacturers are doing the same...Such a shame...Thanks for this valuable information, might save a lot of frustrating diagnosis time for many repairmen....

[@BrucesShop]

The gear is not keyed. The lobes are not keyed as far as I know. Most manufacturers use plastic cam gears, Honda too.

[@fleetwin1]

I just don't understand how they think the lobes and gear will stay properly oriented without being keyed in place somehow....Now, everytime an engine has a strange running issue that can not be easily resolved, the technician will be wondering if the cam gear/lobes are out of position....Oh well, I am probably over thinking all this, as usual....

[@francoannoni6252]

Bruce, when did they start using plastic parts on these mowers like this?

[@waltschannel7465]

franco annoni At least 40 years, Briggs has been using plastic cams and gears.

[@BrucesShop]

Thanks Walt yes they have been around a long time.

[@dfabeagle718]

@@waltschannel7465 Sorry to necro-post but I used to work on this junk in the mid / late 80's for a living. The 9 cubic inch and 11 cubic inch were not plastic in the 80's (3.5 and 4 hp verticals). The 5 hp back then was a 13 cubic inch monster and had a cousin 10 cubic inch vertical beast 4 hp "big block". They were commercial quality engines and were also not plastic. I do remember seeing a 3.5 hp (9 cubic inch) with a plastic cam but it was 90's vintage. I've seen this plastic cam failure in several 12 cubic inch motors though, rated anywhere from 4 to 6.75 hp. Several of them were on pressure washers, they didn't "hit" anything. The earliest one I have is a 1992 based on the "Code" numbers (first two are year of manufacture). The 12 cube stuff is easy to tell visually even without the cowling model numbers because they have a centrifugal governor arm sticking out of the block. Most of the older junk from the 80's back to probably sometime in the 50's had an air vane governor and a diaphragm "mixing valve" instead of a real carburetor. This cam failure makes me sick - 50 bucks for an engine that's worth 40 bucks when it's running. I'm seriously considering one of the comments made earlier, time it and pin it with a roll pin. I'm guessing the cam's shaft is hardened though, probably not worth the effort. I thought by now maybe the Chinese would have ripped off the design and cast up some iron cams, but no such luck. It's a pity to throw out blocks with bores and every other aspect in really good condition because some jack wagon accountant in charge at Briggs wanted to save 1.00 on the cam.

[@prestigelawncare6657]

Great insight to the engine Bruce, enjoyed watching thanks buddy.

[@BrucesShop]

You know how they work by the name of your company.

[@prestigelawncare6657]

absolutely I do but I never get bored with engineering and tbh not many film a engine in this way. Good stuff Bruce.

[@jonienglish3231]

parts not cheap i bought a 250cc single stage snow thrower with shredder auger owner ran with no oil seized the piston to cylinder wall cleaned the cylinder with muriatic acid , welded the scored piston and honed with red scotch brite pad . reassembling engine now !!! the Cam release for exhaust valve Cheaply made tab runs on lifter

[@BrucesShop]

Goos luck

[@BrucesShop]

good luck oops

[@jonienglish3231]

just finish reassembly today !!!!!!!!!!!!!!!! tomorrow try to start welded the scored piston , filed the skirt then painted skirt with dry graphite spray lube , then baked in oven 250c for 1/2 hr, aluminum transfer on cylinder cleaned with muriatic acid , then flapper wheel , then honed with red scotch brite pad, crank and rod ok Rings ok ( reused ), reused plastic Cam shaft

[@Z-Ack]

Thought that little spring thing was compression release.. not low rpm whatever..

[@BrucesShop]

Well you are right. It opens the exhaust valve at low RPM

[@bodineh32]

Hi. I need to know what type of engines that I can find a replacement cam shaft in. NON PLASTIC!!

[@BrucesShop]

I think they all use them now.

[@thesmallenginenut135]

Thanks for the video that same thing happened on my greyhound engine

[@BrucesShop]

I have never heard of Greyhound

[@clauslundberg9224]

Really nice video Bruce. Always been a little intimidated of opening up the inner workings - but you make look like no problem at all. Thanks.

[@BrucesShop]

Well it was already broken so you can't break it by taking a look.

[@mikeip3191]

@@BrucesShop Great super instructive video sir (from a fellow Canuck, though dislocated). My camshaft on a 15 year old like engine had snapped in two pieces- it came 1 cutting after sitting idle for 3 years, and the self-propel v-belt wedged between the pulley and bottom of sump case. Thanks to your step by step guidance and commentary I mustered up the confidence to pull the engine apart and somehow get it all put back together again. Started up on first pull (well, once I remembered to gas it up).

[@carlodonnell146]

@@mikeip3191 I wouldn't buy a self propelled, it is just more things to go wrong

[@carlodonnell146]

I opened my briggs/stratton and I don't see anything that looks out of place but it still doesn't start NO SPARK is the problem the key is not sheared and I don;t see anything else at the moment ANY IDEAS WOULD BE APPRECIATED!!! Thanks

[@Smalltechguy]

I don't like those plastic gears and I also had a blade attachment torn up also. I have a few of these laying around. But I had gotten lucky and ordered one, but naturally sears messed it up and still haven't been sent the correct one.

[@BrucesShop]

Sears is now gone i Canada

[@Smalltechguy]

yeah most of them are shut down here also

[@Smalltechguy]

I have a wooden bench, so I frilled a hole in mine to have the engines stand up

[@BrucesShop]

Good idea. I finally cobbled up a table stand. It is primitive though.

[@Smalltechguy]

I think that I may try another cam as well. I have a donor motor from the replacement sump. I will check the cam to see if it has moved thus creating the recoil snap back action. I don't like black and blue fingers.@@BrucesShop

[@rayburnett3066]

I have seen those plastic cams on older motors too

[@BrucesShop]

You are right

[@1hjehje]

A great video! It's too bad that the replacement part is so expensive.

[@BrucesShop]

Yes. You have to be a good scrounger to work on small engines.

[@shanecorrigan1096]

Hi I have a 5.50 hp engine and I’m replacing the crankshaft and I was timing the camshaft but there was like 3 holes and I don’t know which one is which help please and thanks

[@BrucesShop]

At 7:02 in the video is the marks for this one.

[@Graham_lee]

Your link is that a metal replacement or plastic?

[@BrucesShop]

The replacement was plastic too if that is what you are asking. The link to the new part is yes plastic.

[@Graham_lee]

@@BrucesShop Thanks was just wondering if you can get a metal one for a degoverned engine

[@conner5611]

@@Graham_lee I wouldn't de govern a vertical shaft engine since the oil slinger is also the gov gear but a 5hp briggs metal cam should fit

[@ovenox5375]

I changed the flywheel key, cleaned carb and replaced diaphram, lapped the valves. Lawnmower starts first pull but overheats very very fast about 30seconds. I dont know what else I can do. So many hours wasted. :( Any ideas?

[@ovenox5375]

3.5hp briggs lawn mower

[@BrucesShop]

@@ovenox5375 Can I ask a dumb question Has someone changed the flywheel to one with no fins , like a solid cast iron one?

[@ovenox5375]

Bruce Pender Nope, they look good and very clean. Engine was overheating before and after I cleaned carb and changed diaphram. I changed oil, and after 30min of working(it had to cool off many times between) it got very black. I am not sure at all what else I can do. Maybe its sucking air from somewhere to run lean? And its very very weird, it sounds normal but it gets really hot after just 10seconds of use and my friend has pretty much the same mower and it doesnt get hot nearly as much. In those 30minutes, I know that first 1 minute engine runs okay.ish, but whet its gets super hot it starts popping from time to time. Thanks for reply

[@thesmallenginenut135]

Yeah the greyhound engine and Predator engine is the same thing as the Honda engine

[@BrucesShop]

I am familiar with the predator Thanks.

[@gregoryhearne9427]

What is the part number for the gasket

[@BrucesShop]

just use google. Briggs sumo gasket

[@doublewide6]

Those 7HP and below engines are not worth fixing. It is $20 just to open up (gasket, oil seal, oil). I know you are opening it up for fun/interesting video reasons. I will send you one of those cams if I have it. Please send me the part number and engine info. Ebay is pretty good for finding parts like that cam for under $20. Nice video. Bob

[@BrucesShop]

One just came in that is a year older and has another really bent crank. It is a self propel and is throwing belts. I will use the cam gear from that. Thanks a lot though Bob. Ebay.ca here is a killer on the shipping in Canada but I do use it. You are so right about it not being worth the fix, I have a couple of motors around here in limbo.

[@snickerstorino]

nice shirt bruce, i see we share another similarity. :)

[@hunter1953]

Great video really enjoyed it as usual with all your videos

[@BrucesShop]

Thanks a lot hunter

[@billkrause4585]

Set the 7 year motor on the shelf and wait for the used part ...

[@BrucesShop]

I just don't have room for that. Thanks anyway.

[@639Beaver]

how much for new mower?

[@wirkal]

Plastic?...(?)... There are many people who no longer use B&S engines, the Kohler ones are the best these days.

[@BrucesShop]

Well most id not all small engines have plastic cam gears now. It drives me crazy. Even the old Briggs quantums as seen in ths video use a plastic cam gears as do Honda's

[@wirkal]

@@BrucesShop Almost everyone, not all, has entered the business of planned obsolescence, they know that it is counterproductive to lose trust in a brand, but since they are now so big and can easily create new brands... You have to think very well before and know choosing what to buy and what not to buy, consumers stopped putting pressure on the brands, personally I contact until I find a manager, in general they give me some solution, because it is about talking and reasoning face to face.

[@GlynRobinson]

Good Morning, BRUCE!!!

[@BrucesShop]

Good morning.

[@NotME535]

Wow! Plastic engine parts. I wasn't expecting that... It's high quality plastic though, but I doubt this would happen to a metal camshaft. The flywheel key should have broke too, but we know now what broke instead. Now 105$ is a huge price for a plastic part on a lawnmower, no wonder people don't repair engines. A Honda clone probably cost's less than that cam. Ridiculous.

[@BrucesShop]

Yes Honda clones are an option. They have improved. That is 105 Canadian about 80 U.S.

[@NotME535]

It is still a lot of money-

[@BrucesShop]

yes

[@carlodonnell146]

does the engine turn clock wise or counter?

[@BrucesShop]

Clockwise looking from the top

[@carlodonnell146]

@@BrucesShop thank you , I couldn't remember because I think of that only when I have a problem to solve; but I suppose when you pull the starter it turns it clockwise now that I think of it.

[@thesmallenginenut135]

Harbor freight sold it but now they sell Predator engines

[@BrucesShop]

OK We don't have Harbor Freight in Canada. Princess Auto is our go to store.

[@bigbadmower5283]

can u put a metal cam in even though its plastic

[@BrucesShop]

If I could find a motor old enough maybe. The plastic cams have been around a looooooong time.

[@bigbadmower5283]

i am shocked the fly wheel key isnt sheared

[@rustyrepairs2565]

Great info. Thank you!

[@jonienglish3231]

i have a honda gcv 160 plastic cam gear with rubber timing belt soaking in oil

[@BrucesShop]

Yes you do but they are pretty solid.

[@rogeroconnor5182]

when they hit whatever it was,i bet they soiled themselves.....lol nice shirt by the way,hopefully they dont cost as much as a cam does

[@BrucesShop]

My favourite colour Plaid Canadian spelling.

[@knighthawk86855]

Ebay it I bet you can find a cheap one there.

[@BrucesShop]

A beer shirt?

[@BrucesShop]

That was a joke :-)

[@DonovanBryant92]

this is why these engines have a short life span because of the plastic engine parts like this camshaft

[@BrucesShop]

They all do it now Honda, Briggs and on.

[@kenyoung5682]

Excellent, as usual.

[@BrucesShop]

Thanks so much.

[@kevinjohnson9736]

Great Video as Always!!

[@BrucesShop]

Thanks. This was a popular video.

[@Fridgemusa]

I'm not against using plastic for engine parts but why not overmold the plastic camshaft, cam gears and lobes onto a metal frame rather than just fitting plastic gears over a metal shaft that can easily spin? Just seems lazy to me :(

[@BrucesShop]

Like Okie says it is like a fuse but the flywheel key should take the stress.

[@jonienglish3231]

a piston cost $100 bucks plus shipping

[@BrucesShop]

I know

[@larryjones6049]

Very interesting.

[@BrucesShop]

You are watching a lot. Thanks.

[@Fakeus]

that can happened to anyone

[@BrucesShop]

Yes it can

[@robertyearian227]

Not Honda chonda not Kohler krohler

[@BrucesShop]

Sounds like Taryl

[@robertboykin6939]

Use softer keys.

[@BrucesShop]

I don't have a choice. They come in after they break.