Question about Garden

1 Answer

Hit stump with lawn mower, engine has no compression, replaced particially sheared key, still no compression, what do i need to do? Engin is 12.5 briggs

Posted by on


1 Answer

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points


    An expert that got 20 achievements.


    An expert that got 10 achievements.


    An expert that got 5 achievements.

  • Master
  • 8,404 Answers

You may have a broken connecting rod. Remove the spark plug and see if you can observe movement in the piston. if you can turn the crank and the piston follows ... it is probably OK. You are saying no compression which would indicate no piston movement due to broken con rod.

I could be wrong ...

Thanks for your interest in

Posted on May 31, 2010

Testimonial: "Thanks, I removed the plug, can only see a valve moving in and out, could not see the piston."


1 Suggested Answer

  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

Hi there,
Save hours of searching online or wasting money on unnecessary repairs by talking to a 6YA Expert who can help you resolve this issue over the phone in a minute or two.

Best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.

Here's a link to this great service

Good luck!

Posted on Jan 02, 2017


Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

1 Answer

I have a Yard Machines/ Briggs & Stratton 675 series 190cc lawn mower. It started this morning then stopped. I replaced the spark plug now the pull/start cord won't pull, what could be the problem.

CHECK THE OIL. If oil level gets too low, the engine may seize due to excessive friction. Check the safety interlock cable for proper operation. Check under the mower for anything that may prevent the blade from turning. If the mower hit something hard like a stump, tree root, or a large stone then check the woodruff key where the flywheel slides onto the crankshaft (there is a notch in both the flywheel and the crankshaft where this key fits). If the notches are misaligned, then the key is sheared. If the key is sheared, remove the flywheel, replace the key, reinstall the flywheel.

Apr 23, 2015 | Briggs & Stratton Garden

1 Answer

Hit a stump with lawnmower, now wont start

You may have sheared the flywheel key. This throws the timing off. If the shaft isn't bent replace the key.

Jun 22, 2014 | Poulan Pro 22inch 625 Series Briggs ...

1 Answer

My craftsman lawn mower started fine I pushed it about 100 feet it died won't start has gas and oil got it last summer

Here is one suggestion,that may help. When mowing,did you hit something hard,like a root or maybe a small stump. There is a key to a key way under the fly wheel. The key has to line up with the key way for the motor,to run. This is a way that the motor is timed. This key is made to shear off if the mower hits something solid,this is to protect the motor crank shaft from damage. To get to the key,to check to see if has sheared,you must remove the fly wheel. If the key is sheared you will have to purchase a new key,any lawn mower parts store has them. If you don't have a part number,that okay,just give the model # of the motor and the horse power. The parts department can look up the key. If this is a problem,for you,than take the sheared key to the parts department,and they can match up the key,by actual seeing the key. Remember this,you must have some mechanical knowledge,when doing this repair work. The flywheel usually comes off with little effort,then again,on some fly wheels has to removed with a puller tool. I hope this helps. Sincerely,Brad Locke

May 06, 2014 | Craftsman Garden

1 Answer

Lawnmower blade hit a stump now can't pull starter cord

sheared timing flywheel key replace it check to see if crankshft bent if throw it away or replace motor

Apr 01, 2012 | Briggs & Stratton Briggs Stratton...

1 Answer

I have a 675 series self propelled push mower. i hit a stump in the yard and now it will not start. what happened?

Hi ddjklamar...

You most likely sheared the flywheel key, and that causes the flywheel to turn and not be in time to start.
Remove the flywheel and replace the key, that should solve your problem
Please take time to rate me

Aug 23, 2011 | Briggs & Stratton Garden

1 Answer

After hitting a low bearing tree stump with my troy bilt 6.75 push mower it bent the blade and now refuses to start. How do i fix it?

You will need to replace the key under the flywheel because it probably sheared when you hit the stump and you will need to replace the bent blade before starting the mower again.
I hope this helped
Please Rate Me

May 22, 2010 | Garden

2 Answers

B & S 10D902 lack of compression when starting

may have broke crank newer mowers are not built as they use to be take out plug and place finger over hole to test for compression if none u broke more than likely the crank

May 05, 2010 | Briggs & Stratton Lawn-Boy Insight Series...

1 Answer


I have a 12hp birggs riding mower, hit a stump, damaged shaft key, removed flywheel, replaced sheared key and I still have no compression. What do I do now?

Mar 31, 2010 | Craftsman 17.5 hp 42 in. Deck Lawn Tractor...

1 Answer

Lawn chief 10 horse riding mower wont start. sounds like no compression. Any help? herd a noise and the engine stopped. no oil leaks. starter spins engine faster and sound like there is no compression. Is...

There is a key on the flywheel. This key will shear if the blade(s) come into contact with a fixed object such as a tree stump. Check to see if this key is still intact. If it is, you probably have a broken piston rod. Hope this helps.

Sep 20, 2009 | Garden

1 Answer

Mower hit a big rock and stoped running

If you hit something hard enough to partially shear the key on the blade adapter, you did shear the key on the flywheel, and it will need to be replaced for the engine to run properly.

Apr 11, 2009 | Garden

Not finding what you are looking for?
Garden Logo

Related Topics:

215 people viewed this question

Ask a Question

Usually answered in minutes!

Top Garden Experts

Dennis Key
Dennis Key

Level 3 Expert

2478 Answers


Level 3 Expert

708 Answers

john h

Level 3 Expert

14309 Answers

Are you a Garden Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides