# B&S engine struggles when warm



## zero_gravity (Nov 14, 2007)

hello everyone, my first post here.

a lot of this info is second hand as i do not live at home with my mom anymore, and its her lawn tractor thats acting up. i've been learning a lot about car repair but havnt touched a small engine much.

the engine is a B&S model #281707 12 hp. what seems to happen is it will run fine when cold but when it warms up the engine will begin to struggle and run worse and worse to the point where it will barely make it back to the garage.

the spark plug is ok and intake seems clean enough. the air filter is still good and i also did a compression test - that was about 25 psi so i started laughing my ass off.

i've also been told that it could be the spark igniter. putting oil in the cylinder didn't change the c.test and it doesn't seem to be burning oil so that problem points to either valves or the head gasket.

so what i'm hoping to find is where do i start with this? i'd like to rule out the igniter before i do anything else, how would i test that? maybe warm it up with a heatgun and see if thats causing problems? any other ideas?

also and maybe most importantly, where can i get drawings, repair info and torque specs for this engine? any flatness specs for the head/block if i end up replacing the head gasket? i know almost nothing about this engine other than its old haha.

thanks for the help!


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## 30yearTech (Sep 14, 2006)

Do you have the type and code numbers for this engine?? That may help a little with recommendations.

I would start by checking the fuel cap and fuel delivery, make sure fuel cap is venting alright and fuel is flowing to the carburetor when it starts running bad.

The next thing I would check, would be the valve clearance on both valves, but particularly the intake and make sure there is adequate clearance. If clearances check out alright, then I would check the valve seats too make sure they are not loose.

Your description of the problem does not point to the ignition module, but it cannot be ruled completely out.


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## sluggermike (Apr 19, 2007)

I always like reading what the 30yearTech has to say. When I have a problem I most often think of a major overhaul. He, I assume he is a guy, but if I'm wrong excuse me, suggests something simpler and he is always right. He has saved me a lot of time and money repairing small gas engines, and I appreciate his help. Thanks 30yearTech.
Sluggermike


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## zero_gravity (Nov 14, 2007)

yeah thanks for the help its a start at least. yes i do have that info.

type: 0411 01
code: 90011631

ok so i know nothing about small engines....how do i check for these things? whats the valve clearance range? assuming check with feeler gauge. valve seats? i wish i had an exploded drawing....would help so much lol.


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## 30yearTech (Sep 14, 2006)

Go to the Briggs and Stratton website. You will find illustrated parts lists in pdf format. There is also a check chart in pdf format that will have specifications for most Briggs engines, such as valve clearance settings, torque specs etc...

The Briggs website is www.briggsandstratton.com

Just in case you don't locate the check chart, your valve clearances should be .005" - .007" for the intake valve and .009" - .011" for the exhaust.

You will find general service information but you will not find a service manual. (unless of course you want to buy one)


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## glenjudy (Aug 26, 2006)

With model and type, go here for owners manual, which has valve lash and, the illustrated parts list
https://www.briggsandstratton.com/m...e=Illustrated Parts Lists&menu=nav3&subMenu=3
hope this helps.
thanks,


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## justin3 (Apr 10, 2007)

Well according to my handy dandy notebook your valve lash should be .005-.007 Intake, .009-.011 exhaust measured in Inches. Its very well possibly a valve could be hanging up when the engine gets hot and everything expands. I would start by removing the head, cleaning it up, check valve lash then grind the stems as necessary then replace the head gasket and torque head bolts to 165 inch pounds. Another thing to check is the carburetor, see next time when the engine starts to die out if the carb is flooding out or shooting up gas.


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## 30yearTech (Sep 14, 2006)

sluggermike said:


> I always like reading what the 30yearTech has to say. When I have a problem I most often think of a major overhaul. He, I assume he is a guy, but if I'm wrong excuse me, suggests something simpler and he is always right. He has saved me a lot of time and money repairing small gas engines, and I appreciate his help. Thanks 30yearTech.
> Sluggermike


Your welcome Sluggermike and yes, he would be the correct terminology as I am a guy. I like to tell my wife " I may not always be right, but I am never wrong" lol, don't let my wife hear this, but I am quite frequently wrong about some things.


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## zero_gravity (Nov 14, 2007)

thanks for the help, you guys are awesome 

sounds like i may have to pull the engine and bring it home for the winter....damn! oh well, gives me a project to work on. yay!


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## oscaryu1 (Mar 25, 2007)

Might wanna look at the valves too if their not all the way down 



> Your welcome Sluggermike and yes, he would be the correct terminology as I am a guy. I like to tell my wife " I may not always be right, but I am never wrong" lol, don't let my wife hear this, but I am quite frequently wrong about some things.


Can I have her AIM? Just wanna show her something... 

[on this page *ahem*]


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## zero_gravity (Nov 14, 2007)

so i took a look at the thing this weekend, definitely something wrong in the head. turning the engine by hand i could hear air wooshing by the valves on compression stroke....couldn't get it started either, kept stalling out on me very quickly.

so i figure at this point its time for a rebuild! pulled the engine and brought it back home with me, since my mom really needs the lawn tractor (large lawn and her health isn't good) i'm going to be doing new valves, springs, seals, new HG, rod bearing, and new piston rings. oh and probably get the bore rehoned. if that doesn't fix it i'll be getting a shotgun

thanks for the help guys, if valves weren't suggested to me i may not have bothered to try listening to the old thing while turning by hand. its too noisy to hear something like that while its running.


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## 30yearTech (Sep 14, 2006)

Good Luck with the rebuild. Let us know how it all turns out... :thumbsup:


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