Hustler Sport 48" 21HP B&S Intek Problem

wascator

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Hi, I have owned this machine about 3 years and it's a nice smaller machine. I have a problem now with the 21 HP Intek single. When I got on it to change the blades yesterday, it cranked over like the battery was weak, or it had unusually high compression. I started it by jumping it and it ran smoothly, but with reduced speed and power. When I stopped it would not crank over as before.
Reading on forums, I learned this engine can have problems with the intake rocker arm stud getting loose and backing out. I looked and, sure enough, mine was badly loose. I tightened it and reset the valves, but this did not improve the cranking and I could not get it to crank over and start even jumping it. The engine will turn by hand and it seems not too tight except in one position, like really high compression. Any ideas or experiences? I may just order a new engine: about $550 I think. Is there a better replacement engine? Kawasaki?
 

Lawnranger

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Hi, I have owned this machine about 3 years and it's a nice smaller machine. I have a problem now with the 21 HP Intek single. When I got on it to change the blades yesterday, it cranked over like the battery was weak, or it had unusually high compression. I started it by jumping it and it ran smoothly, but with reduced speed and power. When I stopped it would not crank over as before.
Reading on forums, I learned this engine can have problems with the intake rocker arm stud getting loose and backing out. I looked and, sure enough, mine was badly loose. I tightened it and reset the valves, but this did not improve the cranking and I could not get it to crank over and start even jumping it. The engine will turn by hand and it seems not too tight except in one position, like really high compression. Any ideas or experiences? I may just order a new engine: about $550 I think. Is there a better replacement engine? Kawasaki?

When you did your final valve adjustment, please tell me, in detail, the procedure you used.
 

wascator

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The stud and rocker arm involved were the lower, intake, the stud was almost backed out of the head.
I removed the stud and rocker arm by turning the ball stud counterclockwise, of course the entire stud backed on out. I then installed the stud only back into the head, and snugged it with a 10mm wrench, intending to further snug it later in the process.
I reinstalled the rocker arm adn replaced the ball stud very loosely.
I barred the engine while observing the valve action until I knew I was on the compression stroke and I was off both cam lobes. I then loosened the setscrew in the ball stud using an Allen wrench and a larger wrench on the ball stud for backup. I selected my 0.003, 0.004, and 0.005 inch feelers. By manipulating the setscrew with the Allen wrench and the ball stud by hand, I set the clearance at the valve end to a tight 0.004". I snugged the setscrew while holding the ball stud with a wrench, the rechecked the clearance to confirm it had not changed. I then barred the engine around, by turning the flywheel screen by hand and checked the clearance again, still OK.
The engine turned freely, except it still has a tight place which feels like an unusual amount of compression. The starter will not turn it through a complete cycle without stopping.
Regards,Randy
 

Lawnranger

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Hi Randy,

Thanks for the detailed reply. Some Briggs engines need to be turned 1/4" past T.D.C. and I use a skinny screwdriver in the spark plug hole to measure piston movement. I don't have a service manual to look up the procedure for you and you haven't posted engine numbers yet but please post the numbers as someone else may be able to tell you if you need to go past T.D.C. for proper valve adjustment.

I had one come into the shop last week with the exact same symptom and it was valve adjustment. The valves were over three times the spec for the engine and the starter could not complete a crankshaft revolution. The battery tested good and as soon as I set the valve clearance the engine started just fine. I see this problem all the time but some folks on this forum poo-poo the very idea.

Try this: remove the valve cover and spark plug so you can rotate the engine by hand. As the engine is on the compression stroke, carefully observe the valve rockers for a slight movement as the piston is coming up. The movement is very little but necessary as this is the automatic compression release performing its job. If you don't see the movement, you may have a case where the ACR is not working.

Have you removed the spark plug and turned the engine by hand to feel if there is any excessive resistance?

A three year old battery could be on its way to the junkyard so make sure to have it load tested to be sure.

Check all electrical connections in the starting circuit and perform a voltage drop test across the positive and negative side of the system to eliminate any possible cause there.

You could have a starter going bad, too, so don't rule anything out until you positively determine the condition.

Good luck and I hope you get the engine fixed soon.
 

wascator

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Hi, I believe you have an important point about the compression release.
When the valve rocker stud came loose, of course this would disable the acr and at the same time have the effect of throttling the engine down because the intake valve is not opening very much. I did get it running by jumping it, but it had not much power, even though it was running smoothly.
I do not have the procedure for setting the valves properly; I only used what I know about engines in general to get as close as I could. I believe that, with a correct valve setting and the acr working, my machine will be back at work soon.
I have an appointment with a local man who is reputed to be good with these; in fact he either works or has worked at the dealer where i bought this machine.
Thanks a bunch!
RR
 

Lawnranger

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Hi, I believe you have an important point about the compression release.
When the valve rocker stud came loose, of course this would disable the acr and at the same time have the effect of throttling the engine down because the intake valve is not opening very much. I did get it running by jumping it, but it had not much power, even though it was running smoothly.
I do not have the procedure for setting the valves properly; I only used what I know about engines in general to get as close as I could. I believe that, with a correct valve setting and the acr working, my machine will be back at work soon.
I have an appointment with a local man who is reputed to be good with these; in fact he either works or has worked at the dealer where i bought this machine.
Thanks a bunch!
RR


All the best to you, neighbor. Please do come back and tell us what ultimately fixes your engine.
 

wascator

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I speculate on reflection that the loose rocker arm might somehow have damaged the cam lobe.
I will pass along whatever I learn.
My mower is now in "the system": a repair shop with a lot full of broken mowers where the occasional triage is performed, and where one may or may not ever see one's mower again...
 

wascator

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Re: Hustler Sport 48" 21HP B&S Intek Problem SOLVED

Hi, got a call from my repairman Carl: there was a cap on the intake valve stem, between it and the rocker arm, and it had fallen out when the stud got loose. I did not see it when I tightened up the intake rocker stud, and I did not know what I was doing so I put 'er together without it.
He got it back together and it is fine and for a very reasonable charge. Yahoo! :biggrin:
Thanks everyone!
 
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