B&S 16 HP hard turning over

[scott181]

16 HP model 313707 hard to turn over. Starter pulled and spins fine under no load.
Removed spark plug and no difference. New battery, fully charged. Even with spark
plug removed can only turn engine by hand about 1/4 to half a turn. No belts connected
either. Drained oil and replaced, making sure not to over fill. Pulled valve cover, they were
wet, but no standing oil. Every now and then it will crank for a few spins and if choke
and throttle are correctly set it fires up, but very very seldom can I get it to turn over
with the starter more then 1/2 to quarter of a turn.
Any help or thoughts would be greatly appreciated.

 

[bertsmobile1]

Sounds very much like you have overheated the engine and a valve guide has shifted causing coil bind on one of the springs.
Take the rocker cover off and look at the valves.
They should both be at equal heights and move the same amount when the engine s turned over.

 

[Tinkerer200]

"and a valve guide has shifted causing coil bind on one of the springs."
??

The valve guide should extend 1/8" above the head casting. Much more than this may cause trouble. The valve spring keeper may be hitting a slipped valve guide.

I can send you a Service Manual for your engine IF you like. Address below, put in proper format and remind me engine model number and what you want. I have several fixes for slipped valve guides also.

Walt Conner
wconner5 at frontier dot com

 

[scott181]

Here are a couple of pics I took after removing the rocker cover.
Does this help or do you need a different angle???

 

[Tinkerer200]

I can't tell anything for sure from your pictures, perhaps others can. Does not appear the valve guides are excessively high. I think you are going to have to do the investigating yourself.

Any possibility engine was run low on oil or other wise over heated and metal transfer on the crankshaft is causing difficulty rotating?

Walt Conner

 

[bertsmobile1]

Watch the rockers move as you turn the engine.
Note exactly what is happening when the engine gets hard to turn.
there are several things that can cause the engine to bind.
if it happens every second revolution at the same place then it is valve or cam related.
if it happens in the same place every revolution then it is crank or fly wheel related.

If the latter then remove the flywheel and check for damage to the stator or debris stuck between the magnets.
If not then it is open heart surgury time.

 

[Tinkerer200]

"Starter pulled and spins fine under no load."

"Even with spark removed can only turn engine by hand about 1/4 to half a turn"

" Every now and then it will crank for a few spins and if choke and throttle are correctly set it fires up,"

Some confusing statements here. Loose magnet under flywheel is a possibility BUT hard to fit it into these statements.

Walt Conner

 

[scott181]

Sorry if it got confusing, I'll try to answer each one fully on it's own.

"Starter pulled and spins fine under no load."
I removed the starter and connected it to the battery with jumper cables. It spins just
fine. No hesitation and a good high speed.

"Even with spark removed can only turn engine by hand about 1/4 to half a turn"
reinstalled starter, removed spark plug so as not to have any compression. can get a turn or so
out of it using starter. when it binds up can not manually rotate the engine.

" Every now and then it will crank for a few spins and if choke and throttle are correctly set it fires up,"
Before it got to this point it was acting like a low battery, spin a couple times kinda slow, but if all
was set correct it would fire up and run. Once running it drove ran fine, just don't shut it off until you
were completely done with the job.

Some confusing statements here. Loose magnet under flywheel is a possibility BUT hard to fit it into these statements.

Walt Conner

I was asked earlier if it had over heated or ran low on oil. No to both of those questions. Oil was always checked
before starting, and being a riding mower it is only used for a double city lot, not a big acreage type area. I'm starting
to think that open heart surgery will be my only option. Thank you to all for suggestions and comments.

 

[scott181]

Watch the rockers move as you turn the engine.
Note exactly what is happening when the engine gets hard to turn.
there are several things that can cause the engine to bind.
if it happens every second revolution at the same place then it is valve or cam related.
if it happens in the same place every revolution then it is crank or fly wheel related.

If the latter then remove the flywheel and check for damage to the stator or debris stuck between the magnets.
If not then it is open heart surgury time.

It is happening about every revolution. Valves seem to operate fine. I'm gonna
pull the flywheel and take a look. I can actually hear some rubbing type noises
when I turn it by hand around the flywheel. Not a grinding or loud rubbing
noise, but it is there.

 

[scott181]

Here is the update and the problem found. Took the flywheel off, talk about a
pain in the ***. Here is what I found........... Thank you to everyone for all
of your help and suggestions, and I hope this thread will help someone in
the future if they have a similar problem.