Briggs & Stratton IC 17.5 HP no power

Chip70 · 09-06-2009, 07:30 PM

Wife cutting the grass, engine gradually lost power and quit. Checked fuel filter (OK), cleaned air cleaner (was OK), reset plug gap (OK), fuel cap checked (OK). Engine runs but does not develop power, can not run mower and move at the same time. All belts okay too. Just an engine that seems to lack any power. Gradual loss does not seem to indicate a timing issue, compression is okay so that does not seem to be an issue either. Oil level is okay too. Help!

Cheers,

Chip

**K-B** · 09-07-2009, 07:12 AM

Does it sputter, smoke or backfire? It could be ignition (more unlikely) or fuel related. Try a new plug. Check valve clearance. Check for water or dirt in carb.

Chip70 · 09-07-2009, 08:00 AM

No, it runs with little power. No smoking, no backfiring or sputtering. Sounds tinny. I thought to about valve clearances but since it has good compression, I kind of ruled that out. But easy enough to check. Next will be to remove the flywheel and see it the woodruff key has failed and the timing is off.

Cheer,

Chip

Chip70 · 09-07-2009, 08:56 AM

Took the valve cover off and the exhaust valve top end of the push rod fell out. It is broken off about an inch into the push rod from the top end. Now to find a replacement.

Cheers,

Chip

**K-B** · 09-08-2009, 04:58 AM

Make sure the valve isn't stuck, or else you'll put a new push rod in and it'll break that one too.

Chip70 · 09-08-2009, 06:44 AM

The valve is not stuck, it actually ran with the broken push rod, it just do not develop power enough to run the mower and move. It would move. So the valve was opening, just not enough. And the reason was the push rod was shortened by the break.

It broke in the swege area where the rod his held and the two ends are press into the hollow rod. The rod wall thickness is very thin, not as thick as you would imagine. I guess they were just trying to save on materials. At any rate the swege area is where the metal is distressed, thus becomes the weakest point. And I betting the swege process introduced a pre-existing flaw, a micro crack or what ever.

Cheers,

Chip

Chip70 · 09-09-2009, 09:44 AM

The new push rod is installed, valves gapped, and engine is running. The new push rod looks like the intake valve push rod, me thinks they are the same. The engine runs great, though the starter is a little weak. It has plenty of power now, like a new engine. I guess resetting the valves after changing the push rod has a lot to do with it.

Cheers,

Chip

09-06-2009, 07:30 PM	#1 (permalink)
Chip70 Registered User Join Date: Sep 2009 Posts: 5 OS: Vista	Briggs & Stratton IC 17.5 HP no power Wife cutting the grass, engine gradually lost power and quit. Checked fuel filter (OK), cleaned air cleaner (was OK), reset plug gap (OK), fuel cap checked (OK). Engine runs but does not develop power, can not run mower and move at the same time. All belts okay too. Just an engine that seems to lack any power. Gradual loss does not seem to indicate a timing issue, compression is okay so that does not seem to be an issue either. Oil level is okay too. Help! Cheers, Chip

09-07-2009, 07:12 AM	#2 (permalink)
K-B Moderator, Linux Join Date: Oct 2005 Location: NY Posts: 2,876 OS: Vista, Ubuntu My System	Re: Briggs & Stratton IC 17.5 HP no power Does it sputter, smoke or backfire? It could be ignition (more unlikely) or fuel related. Try a new plug. Check valve clearance. Check for water or dirt in carb. __________________

09-07-2009, 08:00 AM	#3 (permalink)
Chip70 Registered User Join Date: Sep 2009 Posts: 5 OS: Vista	Re: Briggs & Stratton IC 17.5 HP no power No, it runs with little power. No smoking, no backfiring or sputtering. Sounds tinny. I thought to about valve clearances but since it has good compression, I kind of ruled that out. But easy enough to check. Next will be to remove the flywheel and see it the woodruff key has failed and the timing is off. Cheer, Chip

09-07-2009, 08:56 AM	#4 (permalink)
Chip70 Registered User Join Date: Sep 2009 Posts: 5 OS: Vista	Re: Briggs & Stratton IC 17.5 HP no power Took the valve cover off and the exhaust valve top end of the push rod fell out. It is broken off about an inch into the push rod from the top end. Now to find a replacement. Cheers, Chip

09-08-2009, 04:58 AM	#5 (permalink)
K-B Moderator, Linux Join Date: Oct 2005 Location: NY Posts: 2,876 OS: Vista, Ubuntu My System	Re: Briggs & Stratton IC 17.5 HP no power Make sure the valve isn't stuck, or else you'll put a new push rod in and it'll break that one too. __________________

09-08-2009, 06:44 AM	#6 (permalink)
Chip70 Registered User Join Date: Sep 2009 Posts: 5 OS: Vista	Re: Briggs & Stratton IC 17.5 HP no power The valve is not stuck, it actually ran with the broken push rod, it just do not develop power enough to run the mower and move. It would move. So the valve was opening, just not enough. And the reason was the push rod was shortened by the break. It broke in the swege area where the rod his held and the two ends are press into the hollow rod. The rod wall thickness is very thin, not as thick as you would imagine. I guess they were just trying to save on materials. At any rate the swege area is where the metal is distressed, thus becomes the weakest point. And I betting the swege process introduced a pre-existing flaw, a micro crack or what ever. Cheers, Chip

09-09-2009, 09:44 AM	#7 (permalink)
Chip70 Registered User Join Date: Sep 2009 Posts: 5 OS: Vista	Re: Briggs & Stratton IC 17.5 HP no power The new push rod is installed, valves gapped, and engine is running. The new push rod looks like the intake valve push rod, me thinks they are the same. The engine runs great, though the starter is a little weak. It has plenty of power now, like a new engine. I guess resetting the valves after changing the push rod has a lot to do with it. Cheers, Chip