Heymow - Lawnmower Racing Forum

Engine Help => Briggs OHV & Vanguard => Topic started by: refteck on July 16, 2018, 10:22:05 am

Title: 20hp Vanguard rattles when shutting off.
Post by: refteck on July 16, 2018, 10:22:05 am
Hi everyone
I have a model 35 Vanguard, a Performance V Twins short block with stock heads, shimmed springs, ARC flywheel and 2 bbl carb on gas.  If I run hard, when I shut it down it makes a rattle sound and a puff of smoke out the carb, it will do this once every 5 -6 races.
 It all started when my bumper got pushed into my rear tire and finished the race not realizing it was working harder than usual. I have checked the usual, flywheel key, valves, compression.

Any ideas what is happening?
Title: Re: 20hp Vanguard rattles when shutting off.
Post by: refteck on July 16, 2018, 01:08:45 pm
After reading it above,  the sound is more like when a motor runs on or tries to run backwards.   Is there a way to test the diodes?
Title: Re: 20hp Vanguard rattles when shutting off.
Post by: nolids on July 26, 2018, 09:02:45 pm
Yes, your engine is running backwards when you shut it off.  It is not diodes from your charging system, that is a completely different subject.  I think you have your timing off on your engine.
Title: Re: 20hp Vanguard rattles when shutting off.
Post by: refteck on July 28, 2018, 09:25:11 am
Thank you Nolids.  I spoke to my builder and we figure that I am not letting it idle down long enough before shutting it off. We have been cancelled here due to rain, I will try it next time.
Title: Re: 20hp Vanguard rattles when shutting off.
Post by: rotten ron on July 29, 2018, 12:04:52 am
It is called  dieseling ,it is firing without using the ignition ,it will happen if the idle is too high when you try to shut it off, if the idle is slower it won't do that. It could cause damage to the engine so it is not good.
Title: Re: 20hp Vanguard rattles when shutting off.
Post by: refteck on August 06, 2018, 07:22:41 pm
Thank you Rotten Ron. It has not happened again since I give it 30-40 sec to idle down after a race.