All-Terrain Lawn Tractor Forum
Would you like to react to this message? Create an account in a few clicks or log in to continue.

All-Terrain Lawn Tractor Forum

Like riding lawn tractors through mud, woods, rocks, and snow? Then this is the place for you! Share your ideas, Post your projects and more!
 
PortalHomeSite RulesEventsFAQSearchRegisterLog inBuild-Off

 

 engine knock

Go down 
+3
matt-man
xxXMowerdudeXxx
crazykid1994
7 posters
AuthorMessage
crazykid1994
Established Member
crazykid1994
Established Member

500+ Posts
500+ Posts

Age : 29
Join date : 2013-03-18
Points : 4877
Posts : 618
Location : loxahatchee, florida

engine knock Empty
PostSubject: engine knock   engine knock Icon_minitimeAugust 17th 2013, 11:12 am

17.5 hp ohv intek has nasty knock on start up. i think its a piston knock because the valves open and close good and the push rods arent bent. never been taken apart. its on a pony. never seen mud or anything. lawn mower for mowing. any idea what could have caused it or is causing it? maybe a grenaded piston or rod?
Back to top Go down
xxXMowerdudeXxx
Established Member

Established Member

500+ Posts
500+ Posts
2014 Build-Off Entrant
2014 Build-Off Entrant

Join date : 2013-01-28
Points : 4889
Posts : 599

engine knock Empty
PostSubject: Re: engine knock   engine knock Icon_minitimeAugust 17th 2013, 2:25 pm

worn crank, rods or bearings
Back to top Go down
crazykid1994
Established Member
crazykid1994
Established Member

500+ Posts
500+ Posts

Age : 29
Join date : 2013-03-18
Points : 4877
Posts : 618
Location : loxahatchee, florida

engine knock Empty
PostSubject: Re: engine knock   engine knock Icon_minitimeAugust 17th 2013, 3:04 pm

Ok. Thank you
Back to top Go down
matt-man
Member
matt-man
Member


Age : 27
Join date : 2013-07-26
Points : 4343
Posts : 221
Location : North Fort Myers, Florida

engine knock Empty
PostSubject: Re: engine knock   engine knock Icon_minitimeAugust 17th 2013, 4:05 pm

Those crank weights tend to go on those engines so check them if you open it up
Back to top Go down
crazykid1994
Established Member
crazykid1994
Established Member

500+ Posts
500+ Posts

Age : 29
Join date : 2013-03-18
Points : 4877
Posts : 618
Location : loxahatchee, florida

engine knock Empty
PostSubject: Re: engine knock   engine knock Icon_minitimeAugust 17th 2013, 4:47 pm

i think it is the weight. im not opening it up since it is not mine to do that too. because when i start it it knocks and shakes the tractor. might be bearings tho since it is slowly getting worse
Back to top Go down
matt-man
Member
matt-man
Member


Age : 27
Join date : 2013-07-26
Points : 4343
Posts : 221
Location : North Fort Myers, Florida

engine knock Empty
PostSubject: Re: engine knock   engine knock Icon_minitimeAugust 17th 2013, 5:31 pm

crazykid1994 wrote:
i think it is the weight. im not opening it up since it is not mine to do that too. because when i start it it knocks and shakes the tractor. might be bearings tho since it is slowly getting worse
I had an 18hp that was doing the same thing and the top weight let go and knocked a big whole in the block so if I was you I'd get permission from who owns it and catch it before its to late
Back to top Go down
crazykid1994
Established Member
crazykid1994
Established Member

500+ Posts
500+ Posts

Age : 29
Join date : 2013-03-18
Points : 4877
Posts : 618
Location : loxahatchee, florida

engine knock Empty
PostSubject: Re: engine knock   engine knock Icon_minitimeAugust 17th 2013, 6:39 pm

Well. Maybe. Ill mention it too him
Back to top Go down
Stretch44875
Administrator
Stretch44875
Administrator

500+ Posts
500+ Posts

Age : 49
Join date : 2012-04-05
Points : 5653
Posts : 959
Location : Mansfield, Ohio

engine knock Empty
PostSubject: Re: engine knock   engine knock Icon_minitimeAugust 17th 2013, 9:08 pm

Check the engine mount bolts. I have had engines that knocked bad, bolts were just loose.
Back to top Go down
crazykid1994
Established Member
crazykid1994
Established Member

500+ Posts
500+ Posts

Age : 29
Join date : 2013-03-18
Points : 4877
Posts : 618
Location : loxahatchee, florida

engine knock Empty
PostSubject: Re: engine knock   engine knock Icon_minitimeAugust 17th 2013, 10:32 pm

Ok. Ill do that
Back to top Go down
MudKing01
New Member

New Member


Age : 25
Join date : 2013-08-17
Points : 4071
Posts : 4
Location : Georgia

engine knock Empty
PostSubject: Re: engine knock   engine knock Icon_minitimeAugust 17th 2013, 10:35 pm

If its a knock its either the engine bolts are loose or the bores have a groove in them it it does best thing to do is get a new engine is costs about $600 just to rebore the holes
Back to top Go down
matt-man
Member
matt-man
Member


Age : 27
Join date : 2013-07-26
Points : 4343
Posts : 221
Location : North Fort Myers, Florida

engine knock Empty
PostSubject: Re: engine knock   engine knock Icon_minitimeAugust 17th 2013, 11:20 pm

MudKing01 wrote:
If its a knock its either the engine bolts are loose or the bores have a groove in them it it does best thing to do is get a new engine is costs about $600 just to rebore the holes
Or you can get a used block in good shape its alot cheaper
Back to top Go down
Doc Sprocket
Site VIP
Doc Sprocket
Site VIP

2500+ Posts
2500+ Posts!
2018 Build-Off Entrant
2018 Build-Off Entrant
2021 Winner of Winners
2021 Winner of Winners
1st Place Build-Off 2016
1st Place Build-Off Winner 2016

Age : 51
Join date : 2013-04-21
Points : 7270
Posts : 2914
Location : Ontario Canada

engine knock Empty
PostSubject: Re: engine knock   engine knock Icon_minitimeAugust 18th 2013, 7:38 am

matt-man wrote:

Or you can get a used block in good shape its alot cheaper
Agreed. If yours turns out to be physically damaged, just source another used one that's in good physical condition. It doesn't even have to run as long as you are well-enough informed to be able to check it. Get a similar enough match and just swap whatever parts over that you need to. Think of is as buying a short block. The new one doesn't need to have a functioning starter, coil, carb, whatever- just swap them over from the bad one.
Back to top Go down
crazykid1994
Established Member
crazykid1994
Established Member

500+ Posts
500+ Posts

Age : 29
Join date : 2013-03-18
Points : 4877
Posts : 618
Location : loxahatchee, florida

engine knock Empty
PostSubject: Re: engine knock   engine knock Icon_minitimeAugust 18th 2013, 4:40 pm

checked all the engine bolts. they are tight. its not knocking anymore. and its running again since i cleaned the carb... idk what caused the knock honestly....
Back to top Go down
matt-man
Member
matt-man
Member


Age : 27
Join date : 2013-07-26
Points : 4343
Posts : 221
Location : North Fort Myers, Florida

engine knock Empty
PostSubject: Re: engine knock   engine knock Icon_minitimeAugust 18th 2013, 6:22 pm

Sounds to me like the weights they will come and go as far as the knock in concerned
Back to top Go down
crazykid1994
Established Member
crazykid1994
Established Member

500+ Posts
500+ Posts

Age : 29
Join date : 2013-03-18
Points : 4877
Posts : 618
Location : loxahatchee, florida

engine knock Empty
PostSubject: Re: engine knock   engine knock Icon_minitimeAugust 18th 2013, 6:41 pm

the engine had been sitting for 9 months so we tried starting it and it knocked and would then start and the knocking stopped and it only ran on choke so i cleaned the carb today and made sure all the bolts were tight. and started it and it runs. no knock
Back to top Go down
Doc Sprocket
Site VIP
Doc Sprocket
Site VIP

2500+ Posts
2500+ Posts!
2018 Build-Off Entrant
2018 Build-Off Entrant
2021 Winner of Winners
2021 Winner of Winners
1st Place Build-Off 2016
1st Place Build-Off Winner 2016

Age : 51
Join date : 2013-04-21
Points : 7270
Posts : 2914
Location : Ontario Canada

engine knock Empty
PostSubject: Re: engine knock   engine knock Icon_minitimeAugust 19th 2013, 7:24 am

The fact that the knock disappeared after you cleaned the carb is most likely coincidence. Is this a pressure-lubed engine, or a splash-lube?
Back to top Go down
crazykid1994
Established Member
crazykid1994
Established Member

500+ Posts
500+ Posts

Age : 29
Join date : 2013-03-18
Points : 4877
Posts : 618
Location : loxahatchee, florida

engine knock Empty
PostSubject: Re: engine knock   engine knock Icon_minitimeAugust 19th 2013, 10:24 am

Splash. And I know its just coincidence but now I can't figure out what was knocking
Back to top Go down
jack9102
Member
jack9102
Member


Age : 28
Join date : 2013-03-17
Points : 4364
Posts : 103
Location : Sudbury, ON, Canada

engine knock Empty
PostSubject: Re: engine knock   engine knock Icon_minitimeAugust 24th 2013, 8:34 am

Now hold up, mechanical collisions internally arent the only thing that makes a 'knock' sound. Briggs OHV engines generally have a high compression ratio, so older 87 octane gasoline may cause it to detonate and make it sound like a rod knock.

Also if youre exhaust valve isnt seating perfectly, the combustion whoosh goes past the valve heating it up. The orange hot valve acts like a glow plug and can cause preignition. Running rich on bronze grade gas can cause detonation as well.

Check your plug. If pieces of porcelain are broken off, and/or the insulator is bleached white, youve got a detonation problem. If the plug looks almost mechanically damaged check the piston face. You may find it has a hole or peppered surface.

Preignition shows similar signs, but is caused by over advanced ignition timing. (broken flywheel key). They can shear off if the flywheel nut is loose.

I had a 4hp tecumseh prism push mower with a TVS115 flatty on it. Got it for nothing. Ran great, smooth. But knocked so bad I thought the rod would come thru the block. I also found, if I cut the motor warm, and pulled the rope slow it ripped the handle out of my hand backfiring. Took the flywheel off, key partially sheared giving a bad timing of about 46* BTDC.

Check your keys if all else fails gentlemen!
Back to top Go down
Sponsored content





engine knock Empty
PostSubject: Re: engine knock   engine knock Icon_minitime

Back to top Go down
 
engine knock
Back to top 
Page 1 of 1
 Similar topics
-
» Knock Knock!
» Is a tecumseh formula engine big enough for a rear engine Murray law tractor?
»  engine will not run right
» B & S Which engine do I have?
» How man cc is an 11hp engine?

Permissions in this forum:You cannot reply to topics in this forum
All-Terrain Lawn Tractor Forum :: Technical Forum :: Engine Tech :: Briggs and Stratton-
Jump to: