Briggs 13.5HP Intek Snow (Simplicity P1732 Snow Thrower)

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  #1  
Old 01-25-14, 09:33 AM
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Briggs 13.5HP Intek Snow (Simplicity P1732 Snow Thrower)

Group,

Have a Briggs question here.

Briggs 13.5 HP (16.5 ftlbs torque) Intek Snow engine on a Simplicity P1732 snow thrower.

Four (4) years in service.

Engine and blower have run flawlessly since purchase up until about the first or second use of this winter season.

Engine pull-over now seems very hard on part of the pull cycle, I'm assuming compression stroke. User has to really pull hard and steady to roll it past this point. Engine still starts reliably once past this point (jumps right to life).

The pull start (sometimes kick-back with blowback through carb intake) happens at start (cold) after priming the carb circuit, and also pulls over hard (hot) after use with fuel valve off and residual fuel burnt out of carb until stall.

The AC electric starter also has a hard time rolling the flywheel past this point also.

Historically it pulled over smooth (always) with no kickback.

Issue onset suddenly and was not a gradual degradation.

I'm suspecting maybe a valve issue or decompression control issue.

Does this behavior sound familiar to anyone?
Is there anything I can correct from the OHV cover? (valve lash of course)
other decompression parts?

Any insights would be greatly appreciated.

Briggs Intek Snowmax model 210000
 
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  #2  
Old 01-25-14, 09:37 AM
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Briggs 1650 series engine.
 
  #3  
Old 01-25-14, 10:01 AM
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Engine runs fine as always once it starts. No hiccups, smoke, loss of power, sputter, or other anomalous behavior.
 
  #4  
Old 01-25-14, 11:54 AM
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Certainly sounds like your valve lashes may need to be adjusted. The specification for your model is to have the intake valve gap at 0.004"-0.006" and the exhaust valve 0.004"-0.006".

The specs and procedure can be found in this service manual.

http://dl.dropboxusercontent.com/u/1...ylinderOHV.pdf

In short, you remove the valve cover. You remove the spark plug. You turn the flywheel clockwise and observe the movement of the valves to determine which one is intake and which is exhaust. When the piston is moving on the compression stroke, place the rubber end of a pencil in the cylinder onto the piston and observe when the piston is at top dead center. Now make a mark on the pencil and another mark 1/4" above it. Now turn the flywheel so that the piston is 1/4" past top dead center (roughly. You are just ensuring that both valves are fully closed).

Now I like to measure the valve lash before and after adjustment so do that now. Now simply take a torx screw driver and loosen the lock on the hex nut. I think it is a 10mm wrench that turns the hex nut. Once the lock is off, place a 0.005" feeler guage into the valve lash and turn the 10mm wrench until the valve is very snug against the 0.005" feeler guage. Once set, tighten the torx screw to about 4 ft/lbs. Do this for both valves (although the intake is where the compression release will be) and then replace the valve cover.

Put the spark plug back in and try it again.

Here is a video to help if you have never done this before.

Lawn Mower Repair Valve Adjustment V-Twin - YouTube

In summary, your motor has a compression release mechanism built into the camshaft and the intake valve. As the valve lash widens with use, the amount of movement in the intake valve during the compression stroke reduces. If the compression on that motor is not released, it will be very difficult to get the motor cranked past that compression, during starting. It will create no problem while running (probably will even run a little better) but you will have the darndest time trying to get it to start.

You can observe all this when you have the valve cover off. Once you set the valve, before you put the spark plug back in, turn the flywheel a couple times and observe the intake valve very closely. You will see a large movement as the valve opens to let in fuel and then closes to begin the compression stroke. Keep a very close eye on it and move the flywheel very slowly and you should be able to observe a very small bump in the valve. This is the compression release working. If you don't see a bump, you have an even bigger problem, but it is rare.
 
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Old 01-25-14, 12:34 PM
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Awesome write-up with supporting manuals. Much obliged.
 
  #6  
Old 02-01-14, 12:52 PM
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Well, mixed results.

Before adjusting the valves, I managed to bust the plastic pawls out of the original pull starter, so I had to procure another pull starter.

Got the valve cover off this AM. Gauged the "as-was" clearance to be no more than .006. One valve was a bit tighter, maybe in the range of .004 to .005 ish.

So I pulled the spark plug and with the pull start off, hand rolled it over to TDC and then just past watching the valves and feeling for slack on both rockers.

All was as expected per procedure, and I reset both to .005 with my trusty SK feeler gauge.

electric starter rolled it over just fine. Put new pull starter on and it pulled over to TDC then rolled hard.

Took the pull starter off again, pulled spark plug, reset valves on the snug side of the spec to .004

Reassembled, electric start worked fine. Pull start seemed to roll over fine.

Ran engine for a while with fresh oil. Warmed it up.

electric start still worked fine... pull start worked fine.

Put the unit away.. Returned 4 hours later out of curiosity, grabbed the pull start and busted the pawls in the new starter just like the old one.

Not certain why the behavior is variable, but is still not right.

Not sure if I should tear this down or shoot it and find a Honda engine for it.

Wondering if I can D&R the decomp pawl without removing the engine from the blower.
Probable not.

This B&S engine has turned into a huge disappointment.
 
  #7  
Old 02-01-14, 07:51 PM
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I've had 2 of these briggs style engines this year & had to replace cams.. Watch the valve operation & you should see the decompression work.. if it doesen't bump the exhaust valve open on the compression stroke, you will need a cam. Sorry, Roger
 
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