| engine knock | |
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+3matt-man xxXMowerdudeXxx crazykid1994 7 posters |
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crazykid1994 Established Member
Age : 29 Join date : 2013-03-18 Points : 4877 Posts : 618 Location : loxahatchee, florida
| Subject: engine knock August 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? | |
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xxXMowerdudeXxx Established Member
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Join date : 2013-01-28 Points : 4889 Posts : 599
| Subject: Re: engine knock August 17th 2013, 2:25 pm | |
| worn crank, rods or bearings | |
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crazykid1994 Established Member
Age : 29 Join date : 2013-03-18 Points : 4877 Posts : 618 Location : loxahatchee, florida
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matt-man Member
Age : 27 Join date : 2013-07-26 Points : 4343 Posts : 221 Location : North Fort Myers, Florida
| Subject: Re: engine knock August 17th 2013, 4:05 pm | |
| Those crank weights tend to go on those engines so check them if you open it up | |
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crazykid1994 Established Member
Age : 29 Join date : 2013-03-18 Points : 4877 Posts : 618 Location : loxahatchee, florida
| Subject: Re: engine knock August 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
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matt-man Member
Age : 27 Join date : 2013-07-26 Points : 4343 Posts : 221 Location : North Fort Myers, Florida
| Subject: Re: engine knock August 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 | |
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crazykid1994 Established Member
Age : 29 Join date : 2013-03-18 Points : 4877 Posts : 618 Location : loxahatchee, florida
| Subject: Re: engine knock August 17th 2013, 6:39 pm | |
| Well. Maybe. Ill mention it too him | |
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Stretch44875 Administrator
Age : 49 Join date : 2012-04-05 Points : 5653 Posts : 959 Location : Mansfield, Ohio
| Subject: Re: engine knock August 17th 2013, 9:08 pm | |
| Check the engine mount bolts. I have had engines that knocked bad, bolts were just loose. | |
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crazykid1994 Established Member
Age : 29 Join date : 2013-03-18 Points : 4877 Posts : 618 Location : loxahatchee, florida
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MudKing01 New Member
Age : 25 Join date : 2013-08-17 Points : 4071 Posts : 4 Location : Georgia
| Subject: Re: engine knock August 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 | |
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matt-man Member
Age : 27 Join date : 2013-07-26 Points : 4343 Posts : 221 Location : North Fort Myers, Florida
| Subject: Re: engine knock August 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 | |
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Doc Sprocket Site VIP
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Age : 51 Join date : 2013-04-21 Points : 7270 Posts : 2914 Location : Ontario Canada
| Subject: Re: engine knock August 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. | |
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crazykid1994 Established Member
Age : 29 Join date : 2013-03-18 Points : 4877 Posts : 618 Location : loxahatchee, florida
| Subject: Re: engine knock August 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.... | |
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matt-man Member
Age : 27 Join date : 2013-07-26 Points : 4343 Posts : 221 Location : North Fort Myers, Florida
| Subject: Re: engine knock August 18th 2013, 6:22 pm | |
| Sounds to me like the weights they will come and go as far as the knock in concerned | |
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crazykid1994 Established Member
Age : 29 Join date : 2013-03-18 Points : 4877 Posts : 618 Location : loxahatchee, florida
| Subject: Re: engine knock August 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 | |
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Doc Sprocket Site VIP
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Age : 51 Join date : 2013-04-21 Points : 7270 Posts : 2914 Location : Ontario Canada
| Subject: Re: engine knock August 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? | |
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crazykid1994 Established Member
Age : 29 Join date : 2013-03-18 Points : 4877 Posts : 618 Location : loxahatchee, florida
| Subject: Re: engine knock August 19th 2013, 10:24 am | |
| Splash. And I know its just coincidence but now I can't figure out what was knocking
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jack9102 Member
Age : 28 Join date : 2013-03-17 Points : 4364 Posts : 103 Location : Sudbury, ON, Canada
| Subject: Re: engine knock August 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! | |
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| engine knock | |
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