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I have a GT5000 Series craftsman mower with a Briggs&Statton 26 Hp engine. Engine Model # 446777
Type 0126 E1, Code 040910YG. I have adjusted the valves on the mower a couple of times and it appears
that the left side is continually coming out of adjustment. What would be causing this or could it be that the
key is broken in flywheel and I think the engine is on top dead center and it really isn't when I adjust the valves.
Any help or suggestions would be greatly appreciated.

https://www.briggsandstratton.com/us/en/support/manuals/results?NTT=446777-0126* engine operators manual & parts list, see page 6 in operators manual for specs. on valves. Engine cold for valve adjustment. Remove spark plugs & valve covers. Have a long blade screwdriver handy. Rotate engine clockwise, from top looking down, one hand on engine screen, gently install screwdriver in spark plug hole touching top of piston, keep rotating until piston is 1/4" inches past TDC, check rocker arms & see if both valves are closed, both rocker arms should be loose, if not loose you're on wrong stroke for that cylinder, so go around again until both rocker arms are loose & valves are closed. Make sure to identify intake & exhaust valves for adjustment, do not assume anything, as intake & exhaust valves for your engine have different measurements. Let us know how it goes, thanks.

When valves are adjusted correctly you should be able to feel a slight drag on feeler gauge when inserting between push rod & rocker arm. Be sure to recheck after adjusting, it takes patience & time.

Thanks Mechanic Mark. I will reset valves to these setting and try again. The repair manual I have says set both at .005 in
But I will reset to these specs and see if this helps. It just seems odd it's only on left side of engine. It will start and run but
if you pull plug wire off from left side engine continues to run but if I pull plug wire off of right side it will cut engine off.
Left side plug wiring firing hot and plug seems ok also. Crazy stuff but it's to good of a mower to give up on.
Thanks again. I will try anything to get going.

Do what mechanic mark said if that doesn't fix it try this take both plugs out put your thumb over hole of good side and spin engine with starter, now that you see how much pressure that was do same on side that makes engine die when you unplug spark, (if you do have a compression test gauge check both sides) if it feels same then put plug wire on side not running hold end of plug against metal where plug screws in spin engine and look for spark (if you're afraid of shock hold plug wire end with insulated pliers)


If you have no spark more than likely you have a coil problem. (Check known good side for spark if you get none on side that shuts engine down and make sure it is sparking)
You will need to have someone sitting on seat so safety will let engine get fire.

If the valve clearances keep changing after adjustment, the first thing I would check is to take a close look at the valve guides. Are they both at the same height, same amount sticking out the cylinder head. Also, pull each push rod and make sure it isn't bent.

All good advice. I will chime in (again) to say how tricky a pushed guide is. My Intek slowly pushed its guide up over (months?). As it did this the valve gear stacked up (valve could not open fully) and the cam lobe was slowly reduced to a circle (think lifter acting as lathe bit). The motor ran until that cyl would not fire. It had perfect compression , but the valve lift had been reduced to about .100" from normal ? .300+" ? Why this...? Well, with little support in the forum I theorized the head over heated and softened the aluminum. The guide and press fit dims were ok. Either it softened or Briggs supplier provided a sub standard casting (alloy content?). The pros here are quiet, perhaps due to their relationships with Briggs. This failure is somewhat common.

Motoman, most of the time I agree with you, but your last post is one I need to reply to. With the number of Briggs engines out there, I doubt it is a substandard alloy. Just about every time I have seen guide movement, I have also found cooling fins which were packed with debris. This will not allow the heads to cool properly and raise the temp of the alloy. The alloy and steel guide are designed to work together at the proper temperatures and if you change the operating temps, something is going to happen. Even though I have worked with most of the engine manufacturers and a few of the equipment manufacturers in the last 40 years, I know I am not in bed with any manufacturer and I doubt any of the other "pro" are there either. That comment was out of bounds. Read my signature.

Rivets said:

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Motoman, most of the time I agree with you,

Click to expand...

Ditto...though not always as it can be what one reads differently in a post
that can provoke separate thought trains. Regardless, it is experience
that most rely on here, and Motoman sure exhibits plenty of that.

but your last post is one I need to reply to.

Click to expand...

u
... likewise me to yorn.
It fair gives me the irrits to read a response as yours which so much mirrors
that dealers/manufacturers/warranty rebuilders (and the like) offer when THEIR
work/product fails. "Oh you didn't clean your teeth so now you got decay and
you want to blame God!"
To wit..

With the number of Briggs engines out there, I doubt it is a substandard alloy. Just about every time I have seen guide movement, I have also found cooling fins which were packed with debris. This will not allow the heads to cool properly and raise the temp of the alloy. The alloy and steel guide are designed to work together at the proper temperatures and if you change the operating temps, something is going to happen.

Click to expand...

Soooo... in your learned'd opinion the possibilty Motoman raises is null because you
say it's more likely an experienced mech. is going to run a motor hot from
ignorance or laziness or both?!
Excuse me for noting You are well out of order, Sir.

Motoman is likely waaaay too much of a genl'menz to pull you into line, not I.
I earnt my scars the hard way.

Read my thread and tell me my fins are "packed with debri", Sir.
http://www.lawnmowerforum.com/small...a-fr541v-top-end-bobbins-rocker-assembly.html

Even though I have worked with most of the engine manufacturers and a few of the equipment manufacturers in the last 40 years, I know I am not in bed with any manufacturer and I doubt any of the other "pro" are there either. That comment was out of bounds.

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It is all speculation, other than "Robert/Honda" who is to know who's who?
It would be highly unusual for sponsers of LMF not to have 'moles' at least
monitoring posts. I am going to leave that (your affdavit) as it stands.
I simply find it interesting you chose to make it.

Read my signature.

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This...?
This is only my opinion, and many will say it ain't worth a darn, as I'm only a retired grease monkey instructor and not a professional mechanic. Use what I post at your own risk as you know teachers only know book knowledge.

Wellllll,, may I have space to comment....
Aussies, generally, are not inclined towards chest beating, Tarzanism.
My quals would likely give you even more palpitations then you are already
moved to. Suffice to say I got broken fingernails AND paper on the wall, plus
many an hour spent with manufacturer's international reps working through
some significant problems - not combustion engine related.
Never at that level have I experienced any paricipant being handed a tube of
Colgate and a toothbrush in answer to a theoretical proposition or even more
of a testimonial to a component failure.
Now where that, by your mantra, is what you have been instructing
"grease monkeys" to do when faced with complex outcomes reported then
gawwwd help those buying into these mower machines who own an OCD in
respect of cleanliness...the psycho wards will overflow!
The exit lanes of mower repair shops littered with corpses!

Sorry Motoman,, if I stole yer thunder
Post as read fairly got my goat as it is precisely what Kawa agents are trying
to sell me. It aint workin' :/

KK

KK, please post in the Kings English so someone can understand what you are talking about.

I will say again this forum is providing something none other does as well. Restrained dialog among really diverse interests and backgrounds. And in the process educating because there's nothing as good as the "lab" experience (your lawnmower) and the knowledgeable people who respond.

Clarification of "relationships" with manufacturers. This is meant to merely say that restraint is common sense when a person's livelihood is at stake. One does not criticize the golden goose. Regarding possible casting problems: Not that it is intentional , but that any supplier stream of parts can have problems over time . They machine up fine and look identical, but may react differently at e.g. 300+ F?

I am plagued to keep trying to understand. These AC engines are really remarkable to last as long as they do and sell for the "price point."
Somewhere (Wisconsin?) there is a design center "test bed" where all temperatures and failure analyses are performed on running Briggs motors. They know the weaknesses and try to eliminate them while staying competitive. IMO

motoman said:

[...]
I am plagued to keep trying to understand. These AC engines are really remarkable to last as long as they do and sell for the "price point."

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And exactly why I am not getting overly excited
around Kawa failure... I understand why it is so, simply wish Kawa pay more attention to what they offer as "quality" engines. They fixed their entry into the bike market, they can fix QA in the mower market.
Remember these?
"Winni" Winconson.
http://www.youtube.com/watch?v=xkOiHTUlbS8
Tecumseh.
https://touch.trademe.co.nz/listing/view/906700757
Both those early AC engines were robust in service and both cost a bomb at the time. However there was little competition - Villiers made something similar as I recall - and both went by the wayside as Honda tooled up for "stationary" outside of bike successes in this Country. And why?
Still today, any small powershop or hire centre stocks only Honda as a preference. Franchises scream for Honda affiliation.
And the price has always been "right".
Beats me how they (Honda) do it.

And just as a generalisation?
This forum and others list way less "help help me Honda" posts over Kawa and Kohler or B&S.
As their sales are huge the anomaly in pleas has to say Honda is still doing it right.
And that is Global, as LMF reflects.

KK

Rivets said:

KK, please post in the Kings English so someone can understand what you are talking about.

Click to expand...

Goooogle returned no list on any Kings family in respect of dictionary.



Have you lost an apostrophe, I wonder?
Here... have two, a 'freebie' :dance1:

Trust that helps a learnd'd one some.


KK