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Scotts S2046 with B&S 20HP Intek will not start

Posted by Josmoe (My Page) on
Mon, Nov 14, 11 at 22:21

Hi,

I have a Scotts S2046 ride on mower with a Briggs and Stratton 20HP Intek 2 cylinder engine that I am having difficulty starting. The battery is a few weeks old, has been charged and has 12V output. With the engine cover off to expose the fly wheel I can see when the ignition is on the starter cog rises up the spindle and engages with the fly wheel but cannot turn the engine. I have removed the spark plugs and the starter can turn the engine. The spark plugs are also new. Previously the engine had been turning but not starting until after a few tries it would no longer turn. Now it does not turn unless the spark plugs are out.

From reading other posts this appeared to be a valve setting issue causing too high a compression. Using that advice I have reset the valves to 0.004" on both cylinders for intake and exhaust. Even with that the starter cannot turn the engine.

I have taken the starter off and connected directly to the battery. It turns, but not what I would call fast .... not sure what it is meant to be like however as I have never seen a "good one".

Any ideas what I should try next or what could be wrong ? Should I get a new starter motor and try that ? Any way to test a starter to see if it is almost dud ? Perhaps the starter has been damaged by all the times I have used the tractor with the valves incorrectly set ?

Thanks for your help.

Josmoe


Follow-Up Postings:

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RE: Scotts S2046 with B&S 20HP Intek will not start

Starters are pretty torquey when you hit them with a good battery. The best way is to make your final connection by hitting the ground to the casing. It sounds to me that maybe your battery itself may be low in power. If you have another battery, try that and see if there is a difference. In fall, I always have at least a couple tractors I work on that the person just replaced the battery and they were the problem. Likely old stock. It is possible to have a lazy starter. Especially if the engine has been hard to crank for a while. They are pretty tough though. I suppose you could bring the starter by the dealer and get an opinion from them.
Back to the valve adjustments. Normally your engine is set at .006 on the exhaust. Some set the valves .003 and .005. The compression release is on the intake side BTW. In either case, the valves are adjusted 1/4" after the compression stroke. Meaning, locate the intake valve and after that valve closes,the piston reaches the top of it's stroke- go that 1/4" further. Keep us posted.


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RE: Scotts S2046 with B&S 20HP Intek will not start

to add to tom's good advice, take your battery to a qualified shop that can LOAD test it and run a hydrometer test on the cells. even new tractor batteries can be marginal as purchased.

M/W, clean the battery leads (both ends) to bright metal with crocus cloth or sandpaper - don't be fooled by giving it a quick look - may still have enuff invisible corrosion to severely limit batt output....


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RE: Scotts S2046 with B&S 20HP Intek will not start

"Previously the engine had been turning but not starting until after a few tries it would no longer turn. Now it does not turn unless the spark plugs are out."

"I have taken the starter off and connected directly to the battery. It turns, but not what I would call fast ."

Could be battery but he says it is just a few weeks old, could be bad new battery but not likely. IF the start has been being forced for a period of time, could be the starter has been overheated.

With a good set of jumper cables, jump directly from each post of the battery to the starter, grounding on the starter. IF it turns now, problem is between battery and starter. IF not, jump from known good battery, car battery for instance, to the starter. IF it works now, battery is weak IF not starter OR still valve issue.

Directly from B&S Service Bulletin #729 - Use the following procedure to correctly adjust the valve lash on subject engines.
Correct valve lash settings on a cold engine are:
o Intake .004-.006" (.10 - .15 mm)
o Exhaust .004-.006" (.10 - .15 mm)
(with piston 1/4" down past TDC.)

NOTE, IF the Intake Valve Cam lobe is worn off, compression will not be released. Unlikely BOTH Intake Valve lobes are worn off that bad at the same time. Remove spark plugs, remove valve cover, rotate engine by hand in normal direction of rotation, clockwise, and notice the Intake Valves, they should make a final little bit of closing motion as piston is perhaps half way up on compression stroke. EACH piston, each Intake Valve. No final motion at all, bad camshaft OR clearance not set properly.

Walt Conner


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RE: Scotts S2046 with B&S 20HP Intek will not start

OK thanks for the good advice.

I have already jumped the starter directly from the battery to the starter skipping the solenoid etc and it still would not turn.

Sounds like I need to jump from a car battery and reset the valves to 0.004 on the intake and 0.006 on the exhaust.

I may be a few days getting back to you with what.

JoSmoe


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RE: Scotts S2046 with B&S 20HP Intek will not start

"Sounds like I need to jump from a car battery and reset the valves to 0.004 on the intake and 0.006 on the exhaust."

The Intake Valve clearance is what is critical. I set as close to the min. as I can on the engines which relieve compression via the Intake Valve which is MOST B&S engines but not all.

These engines have a history of camshaft failure,see my test.

I can send you a PDF of the B&S Service Manual for this engine IF you like, address below, put in proper format and remind me. (Lots of requests and bad memory)

Walt Conner
wconner5 at frontier dot com


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RE: Scotts S2046 with B&S 20HP Intek will not start

Hi,

I have finally had time to work on the tractor again (had to recover from some knee surgery).

Thanks to your great suggestions I now have it working ! ... purring like a cat :)

I tried jumping the starter directly from a car battery and it turned the engine no problem even without touching the valves. So that confirmed there must have been something wrong with the battery. It was new, only a few weeks old at the beginning of this posting. We took it back to Sears and they confirmed it was bad and replaced with a new battery no problems. The new battery would not however turn the engine.

Thanks to Walt's emails I then reset the valves to 0.004" on the intake using the service instructions. It seemed to be what I did before except the order I did the cylinders in. Previously I had set the valves randomly picking the furthest from the starter first. This time I followed the instructions and set the cylinder closest to the starter first and the opposite one next. Not sure what difference the order of setting the cylinders in makes, but it seemed to make a difference for me, either that or when I repeated the procedure I did a better job of it this time. After buttoning it all back up again it started with relative ease !

Thanks again for your help, and now I know a little bit more about my tractor engine ! :)

Happy Holidays, Josmoe


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