Briggs 19.5 HP Engine Repair - JD LA115

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  #1  
Old 09-15-10, 06:21 AM
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Exclamation Briggs 19.5 HP Engine Repair - JD LA115

Thanks in advance for your help on this one guys.

Good friend of mine thinks he blew his 2006 Home Cheapo JD LA115. Tells me he thinks he heard something snap during routine mowing, and the motor stopped abruptly.

Subsequent cranking by him, he hears what he describes as violent metal-on-metal sounds. My buddy is not handy, and frankly down on his luck right now with work, etc. So before you say go buy another one (not in budget), I thought I'd try to help him out.

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Engine now cranks, but does not fire. No noises.
Essentially just spins.

Been a while since I've rebuilt one, but going to try to open it up to see.

As a double-check, appreciate any steps I may have overlooked troubleshooting before I start the tear-down.

Troubleshooting

1. Good spark w/ new plug. Coil, alternator, flywheel and starter fine.

2. Fuel flow good. Fuel filter, lines and carb receiving fuel.

3. Intake manifold pulled, fuel appears in intake chamber.

4. Valve cover pulled and inspected. Hand turn flywheel - both valves working.

5. Removed the plug. Placed small wooden dowel in chamber and turned flywheel. Not feeling piston move. (Believe I felt the valve moving.) Suspect the piston connecting rod snapped?

6. Drained oil. Removed filter. No signs of any metal.

Anything I missing before I start tear-down?

--Max
 
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  #2  
Old 09-15-10, 09:05 AM
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If you turned the crank and the piston is not moving I think you are correct about the connecting rod. Since the valves it sounds like the other internals should be OK as long as pieces of the broken crank did not do any damage as they slapped around.
 
  #3  
Old 09-15-10, 11:00 AM
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@PilotDane - thanks. Followup pls. This motor is a typical single cylinder Briggs OHV.

Are there any issues with yanking that head, relative to the valves and lifters?


Looks like 6 bolts holding the head now... should I just be able to remove with disassembling valves/everything under the valve cove for a further look?
 
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Old 09-15-10, 07:41 PM
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Originally Posted by MyBlueDog View Post
Looks like 6 bolts holding the head now... should I just be able to remove with disassembling valves/everything under the valve cove for a further look?

Hello MyBlueDog,

You have the right idea above, But just off the top of my head..... Watch for any valve stem buckets under the rockers, You don't want them to drop out and miss putting them back in. Also mark the push-rods so they go back into the same hole on re-assembly.

If you need any other assistance, The model and type numbers may be helpful.


Good Luck
 
  #5  
Old 09-16-10, 12:33 AM
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When you get it open, look closely at the area of the block behind the starter and the boss in the block where the cam shaft fits. These areas seem to be the most prone to cracking when the engine blows.
 
  #6  
Old 09-16-10, 05:28 AM
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-----------
Update
----------

Briggs 31P877 - 0110E1

Head pulled.

1. Intake push rod (aluminum) bent.

2. Piston in tact but does not move when turning crank.
-- Pushed it in as far as it would go to examine cylinder. 1 minor gouge on cylinder wall, looks to be from ring.

Definitely have a snapped piston rod.

Onward...
 
  #7  
Old 09-22-10, 08:27 AM
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======
Update - Videos
======

I shot some videos of the troubleshooting and tear-down guys. If you want to see the damage, jump to vids 5-8.

Appreciate you leaving a comment and/or voting after you watch.

Briggs Engine Repair

YouTube - BriggsRepair's Channel
 
  #8  
Old 09-22-10, 08:57 PM
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Originally Posted by MyBlueDog View Post
======
Update - Videos
======

I shot some videos of the troubleshooting and tear-down guys. If you want to see the damage, jump to vids 5-8.

Appreciate you leaving a comment and/or voting after you watch.

Briggs Engine Repair

YouTube - BriggsRepair's Channel
video 2 pretty much showed there was no compression
 
  #9  
Old 09-22-10, 09:05 PM
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that note on video 3 about no fuel because carb sucks it in is way off base. Pump must fill carb bowl (or gravity flow) there was no fuel because engine had no compression and no crankcase vacuum pulse which operates the fuel pump
 
  #10  
Old 09-23-10, 07:05 AM
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I agree with 38racing on the second vid. With the spark plug in, if you can spin the flywheel by hand easily one complete revolution, with little to no resistance or bounce-back, compression should be checked.

4 steps in 4 minutes I use for general diagnoses.
1. Check oil for level and condition.
2. Add teaspoon of fuel to carb, if engine fires a fuel delivery issue should be suspect. If no fire,
3. Check for spark-no spark, diagnose ignition beginning with spark plug. If spark is evident, and fuel test failed-
4. Compression, possibly timing, which in most cases with small engines is simply a shear key.
 
  #11  
Old 09-27-10, 10:31 AM
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Excellent job with the videos !!
 
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