Engine spins very slow

[DavidO]

New here so I hope I can get some help.

I have an Ariens mower that is a couple of years old and has been running great with no problems until two days ago. Engine won't spin fast enough to start , just lugs.
had the same problem with an older mower and it was the valve adjustment so I thought that was the problem. The motor is a 310000 model and the spec call for intake valve to be .003-.005 and the exhaust to be .005-.007. So I set the intake (bottom) valve at .003 and the exhaust (top) at .005, spun the engine several times by hand and rechecking the clearances each time. They were at the correct setting.

Thought it may be the battery even though my son put one in this year, battery read 13.1 volts at the terminals but when i checked the voltage at the starter it read 7.6 volts. i used some jumper cables and hooked the mower to the car and it lugged for about 1/8 turn of the flywheel and then started spinning and fired right up. I am now leaning more toward a weak battery and wondered if anybody else had experienced a similar problem.

Thanks in advance for any input.

 

[KrashnKraka]

New here so I hope I can get some help.

I have an Ariens mower that is a couple of years old and has been running great with no problems until two days ago. Engine won't spin fast enough to start , just lugs.
had the same problem with an older mower and it was the valve adjustment so I thought that was the problem. The motor is a 310000 model and the spec call for intake valve to be .003-.005 and the exhaust to be .005-.007. So I set the intake (bottom) valve at .003 and the exhaust (top) at .005, spun the engine several times by hand and rechecking the clearances each time. They were at the correct setting.

Thought it may be the battery even though my son put one in this year, battery read 13.1 volts at the terminals but when i checked the voltage at the starter it read 7.6 volts. i used some jumper cables and hooked the mower to the car and it lugged for about 1/8 turn of the flywheel and then started spinning and fired right up. I am now leaning more toward a weak battery and wondered if anybody else had experienced a similar problem.

Thanks in advance for any input.

Welcome...trust yer mystery gets some air (time).

Assuming the wiring to starter motor has been throughly
inspected/tested for continuity remove the starter motor and
check bendix is free and brushes on motor are serviceable.
There will be a starter solenoid between battery and starter motor.
You could check those internals by disconnecting starter motor
and verify the voltage is close to battey voltage and above the 7.6
you report. Where starter motor and solenoid are a joined component
the whole assembly will need to be benched and tested/dissembled.

Trust that helps some.

 

[Rivets]

The first thing I would check are all connections, sounds like you are loosing your grounds. Make sure you check the one from the ground cable to the chassis.

 

[SeniorCitizen]

New here so I hope I can get some help.

I have an Ariens mower that is a couple of years old and has been running great with no problems until two days ago. Engine won't spin fast enough to start , just lugs.
had the same problem with an older mower and it was the valve adjustment so I thought that was the problem. The motor is a 310000 model and the spec call for intake valve to be .003-.005 and the exhaust to be .005-.007. So I set the intake (bottom) valve at .003 and the exhaust (top) at .005, spun the engine several times by hand and rechecking the clearances each time. They were at the correct setting.

Thought it may be the battery even though my son put one in this year, battery read 13.1 volts at the terminals but when i checked the voltage at the starter it read 7.6 volts. i used some jumper cables and hooked the mower to the car and it lugged for about 1/8 turn of the flywheel and then started spinning and fired right up. I am now leaning more toward a weak battery and wondered if anybody else had experienced a similar problem.

Thanks in advance for any input.

The 7.6 V at starter when cranking is too low. With the battery having a full charge have it load tested for free at most any auto supply.
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QUOTE: i used some jumper cables and hooked the mower to the car and it lugged for about 1/8 turn of the flywheel and then started spinning and fired right up.
****************************************************************************
Typical of a loose and or dirty connection of a high amp. cable. Heat is created and when enough heat it finally makes a good enough connection to crank.

 

[logan01]

Are you testing voltage at the starter during cranking, only with key on/off, other?

 

[bertsmobile1]

Run a jumper from the mowers battery to a good earth point ( engine drain plug is good )
Next run a + jumper from the battery and touch it to the + on the starter motor. Starter turns OK = bad, dirty, broken, corroded connections

 

[DavidO]

Thanks for everyone's input, hopefully I will get done with work early enough tomorrow to try some of your suggestions and let you know the results.

 

[DavidO]

Had a little time this evening to run some more test and this is what I came up with.

Hooked up jumper cables from battery directly to starter, using the oil drain plug to hook up the negative from the battery as the ground and touched the starter with the positive from the battery. There was no change I assume doing this bypasses all the starter wiring.

Next I took some voltage readings here is what I got:
Key off
Battery 13.1 volts
Starter Sel. battery side using oil drain plug for ground 13.1 volts
Starter Sel. starter side 0 volts

Key in start position using oil drain plug for ground
Starter Sel. Battery side 12.9 volts
Starter Sel. starter side 6.4 volts
Starter wire connected to starter 6.4 volts
Starter wire disconnected from starter 12.9 volts

Could this mean that the starter is shorting out and needs a rebuild or could it be another problem. Is there a way to check the decompression system to see if it is operating properly?

Like I stated earlier with the spark plug out of the engine the starter spins the engine fine but with the plug in and compression doesn't allow the engine to spin.
Thanks

 

[KrashnKraka]

Had a little time this evening to run some more test and this is what I came up with.

Hooked up jumper cables from battery directly to starter, using the oil drain plug to hook up the negative from the battery as the ground and touched the starter with the positive from the battery. There was no change I assume doing this bypasses all the starter wiring.

Yeuppp...and no need to go further.
Shot duck 'starter'.
Technically the starter is "taking down" the circuit.
Why could be a number of possible faults in the starter.
If you want to have a go, post a pix of the removed starter
and someone here will have worked on one.

Thanks for that work, huge help for yourself.

 

[Mikel1]

The 7.6 V at starter when cranking is too low. With the battery having a full charge have it load tested for free at most any auto supply.

Yep, I would load test battery to be sure.