Too much compression. adjusted the valves and it got worse

[cary09]

FWIW, I found this answer out in left field... Had similar compression/starting issues. Also, needed an oil change. As luck would have it, a nice shiny 1/4" piece (the pivot pin from the ACR) dripped out in the oil. Question solved.

 

[groundsman1]

Hi. Is it a Briggs & Stratton

17.5hp IC
model 31C707-0154-E1

I bought this engine used and used it 3 seasons now. last year it became hard to start. turning the motor by hand past the compression stroke was difficult and thats where it would hang up when I tried top start it.
of the 5 times I started it this season it would only start 2 times on the first try. If I put my battery charger on it I can get it to start. Battery is testing at 12.8 volts and is charging close to 16 when its running.

I went to adjust the valves today. There was more oil then I expected in the valve cover. Maybe 1/2 a cup. The valves were very tight. No gap at all at top dead center. I re-gapped them. guy on you-tube working on the same engine said 6 thousandths on the top and 10 thousandths on the bottom. That's what I did. When I put it back together it did not start, it hung up in the same place as before in the compression stroke.

The motor was even harder to turn then before. almost impossible to turn it by hand.

What do I need to look at next?

 

[groundsman1]

17.5hp IC
model 31C707-0154-E1

I bought this engine used and used it 3 seasons now. last year it became hard to start. turning the motor by hand past the compression stroke was difficult and thats where it would hang up when I tried top start it.
of the 5 times I started it this season it would only start 2 times on the first try. If I put my battery charger on it I can get it to start. Battery is testing at 12.8 volts and is charging close to 16 when its running.

I went to adjust the valves today. There was more oil then I expected in the valve cover. Maybe 1/2 a cup. The valves were very tight. No gap at all at top dead center. I re-gapped them. guy on you-tube working on the same engine said 6 thousandths on the top and 10 thousandths on the bottom. That's what I did. When I put it back together it did not start, it hung up in the same place as before in the compression stroke.

The motor was even harder to turn then before. almost impossible to turn it by hand.

What do I need to look at next?

Hi . If it is a Briggs & Stratton INTEK engine you will most probably find that the decompression mechanism fitted to the camshaft has broken. They are prone to this. What this mechanism does is it lifts the exhaust valve very slightly to reduce the compression on starting. When the engine starts the mechanism drops out and the engine runs normal. If this device fails there is too much compression for the starter to turn it over. I hope this helps
Eddie.

 

[smallenginesmd]

17.5hp IC
model 31C707-0154-E1

I bought this engine used and used it 3 seasons now. last year it became hard to start. turning the motor by hand past the compression stroke was difficult and thats where it would hang up when I tried top start it.
of the 5 times I started it this season it would only start 2 times on the first try. If I put my battery charger on it I can get it to start. Battery is testing at 12.8 volts and is charging close to 16 when its running.

I went to adjust the valves today. There was more oil then I expected in the valve cover. Maybe 1/2 a cup. The valves were very tight. No gap at all at top dead center. I re-gapped them. guy on you-tube working on the same engine said 6 thousandths on the top and 10 thousandths on the bottom. That's what I did. When I put it back together it did not start, it hung up in the same place as before in the compression stroke.

The motor was even harder to turn then before. almost impossible to turn it by hand.

What do I need to look at next?

Most likely the compression release on the cam is broken. If engine turns over easy with the plug out then it's the CR. Common on OHV single cyl B&S. To verify turn the engine over(with the plug in) by hand past the compression stroke and then attempt to key start. If it starts or spins freely to the next compression stroke you know it's the CR. Remove the engine, remove the oil sump pan & remove the cam. The release spring will be broken. New cam comes with the release assembly. Don't attempt to repair the spring. It can be a bit expensive with the new cam, gasket(s), oil etc. Might be cheaper to look for another motor.
MD Small Engines (retired) Ontario , Canada

 

[Forest#2]

Breaking news:

On page 2 post #14 he indicates that the proper valve adjustment fixed his engine.

 

[Earthquake Landscaping]

But... But... But.. It was so much more fun to continue on as if he hadn't...



Ain't that just ( . ) ( . )

 

[powermax]

Does no one have a B&S shop manual?
Manual says remove plug bring piston to TDC. Insert screw driver, turn PAST tdc 1/4 inch then adjust.
Solved my starting problem.

 

[2ball]

Good Stuff.
I have had 3 unassisted starts since properly adjusting the valves and I am going to call it fixed.

I may have a ACR issue, but maybe this worn old engine can start with full compression when everything else is perfect( valves and battery etc).
I may have a battery issue. I let my battery drain all the way down 2 years ago when it was brand new when I forgot to turn the key off and it sat like that for a week, and I tipped it over once and and a tea spoon or so of the acid spilled out.

So for now, I'm calling it fixed. It runs and cuts grass.

 

[Alton R]

You

17.5hp IC
model 31C707-0154-E1

I bought this engine used and used it 3 seasons now. last year it became hard to start. turning the motor by hand past the compression stroke was difficult and thats where it would hang up when I tried top start it.
of the 5 times I started it this season it would only start 2 times on the first try. If I put my battery charger on it I can get it to start. Battery is testing at 12.8 volts and is charging close to 16 when its running.

I went to adjust the valves today. There was more oil then I expected in the valve cover. Maybe 1/2 a cup. The valves were very tight. No gap at all at top dead center. I re-gapped them. guy on you-tube working on the same engine said 6 thousandths on the top and 10 thousandths on the bottom. That's what I did. When I put it back together it did not start, it hung up in the same place as before in the compression stroke.

The motor was even harder to turn then before. almost impossible to turn it by hand.

What do I need to look at next?

Sure that it's compression or is something broken in the engine.
I know some of these engines can have a broken camshaft pressure release. But in that case it's hard to turn over but you can find still turn the engine over with a socket rinch.
Are you sure something is not in the cylinder. You need to remove the spark plugs and see if it will turn over. If it won't turn over with out plugs in it you have a mech

17.5hp IC
model 31C707-0154-E1

I bought this engine used and used it 3 seasons now. last year it became hard to start. turning the motor by hand past the compression stroke was difficult and thats where it would hang up when I tried top start it.
of the 5 times I started it this season it would only start 2 times on the first try. If I put my battery charger on it I can get it to start. Battery is testing at 12.8 volts and is charging close to 16 when its running.

I went to adjust the valves today. There was more oil then I expected in the valve cover. Maybe 1/2 a cup. The valves were very tight. No gap at all at top dead center. I re-gapped them. guy on you-tube working on the same engine said 6 thousandths on the top and 10 thousandths on the bottom. That's what I did. When I put it back together it did not start, it hung up in the same place as before in the compression stroke.

The motor was even harder to turn then before. almost impossible to turn it by hand.

What do I need to look at next?

Sounds like you have a mechanical problem to me. Remove the plugs then see if it's still hard to turn over.

 

[mpqualdie]

If it's a Briggs and Stratton the camshaft most likely broke. I have a 21hp and a 17hp the same thing happened to, it's a common issue with them. There's a nub on the cam that opens the intake valve a little to relieve the compression so the starter can spin the motor. Once it starts the centrifugal force will fold the nub out of the way. If your mechanically inclined, it's an easy fix. Remove the motor, drain oil, flip it over and remove the bottom cover. Replace camshaft, put it back together (new seal too) adjust valves. Also, make sure you meticulously clean all of the debris out of the inside of the motor before re assembling.