The Jack's Small Engines Forum - Join Our Online Community
Jacks Small Engines Lawn Mower & Power Equipment Forums
Community Stats
1 day 7 days 30 days Max. View More
Top Posters
  1. SRTsFZ6
    (97 Recent Posts)
  2. doug2500
    (12 Recent Posts)
  3. Jchaps20
    (10 Recent Posts)
Most Active Threads
  1. Briggs 21 HP Single Cylinder. Bad rings?
    (22 Replies)
  2. The mounting bolts shrank- Briggs mower carburetor reinstallment
    (21 Replies)
  3. Compression Release on FS111R Trimmer not working
    (17 Replies)
Top Rated Posts
    There is no record available at this moment
Birthdays
7/9/2025
Roberto N. Underwood
Current active users
There are 1 member and 144 guests.
SRTsFZ6
Moderator Moderator
2019/09/21 10:24:43
soulsnipes40

Mower spins but won’t turn over

I have a Craftsman YT3000 that suddenly stopped working. I noticed the intake pushrod was bent but the valve seat didn’t move. I replaced the head gasket that looked blown and replaced pushrods. When I attempt to start it, it spins but won’t turn over. Also, it was backfiring a few times as well. Is it something with fuel or possible camshaft?
22 comments Leave a comment
AVB
The engine should not turn over if it is bolted down. <LOL> But I know what you mean as it will not start and run.
 
Then the question is did the valve guide move? Another question about the backfiring as I know most says backing even when it is out the exhaust. Is out the exhaust or intake? Also I had one 310000 series that was what I call sneezing out the intake which was an intake air leak but was when the engine was running.
 
Depending on the engine model, type, and date code as I assume it is a single cylinder Briggs. It can be a sheared flywheel key on top of the valve problem. Especially if  it is older 280000, 310000, or 330000 series.
 
As to if it a camshaft problem depends if the valve lift is correct or not. I have yet to see a cam lobe to rotate on the camshaft.
2019/09/21 11:38:44
kshansen
As some terms are being being used in a confusing way can you confirm if when rotating the crankshaft the rocker arms are opening and closing the valves? Also did you adjust the valve clearances with crank shaft in the correct position?
2019/09/22 08:58:04
AVB
Was it what I posted that need clarification of?
2019/09/22 09:14:27
kshansen
AVB
Was it what I posted that need clarification of?


No, I was referring to the original posters use of terms. I see this on many different forums. One I have seen often is someone saying their engine "will turn over but not crank!" The "crank" turns out to mean it will not start and run. Can be very confusing at times. Samething about the term "Back Firing" to me that term would say it is firing out the intake or carb and not going out the muffler.
 
If you want to have some real fun try troubleshooting something with someone from England or Australia! Hard to believe we share a common language at times!
2019/09/22 09:26:35
soulsnipes40
Trust me I understand the lingo can be confusing. What I meant is the flywheel is spinning but engine won’t crank over/start. The valve guide looked to be seated correctly and didn’t move. I took off the air filter and sprayed a little stater fluid and then it would “backfire” out air intake. I made sure the valves were set at the right specs and the valves are opening and closing.
2019/09/22 10:10:11
AVB
Okay. Have you check for a sheared flywheel key and it sounds like an ignition timing problem?
 
The engine model and Type/Spec numbers plus date code/serial number would be helpful in determining a know service bulletin needs applying. As I said if a Briggs the 28, 31, and 330000 series did have some improvement made due to flywheel/crankshaft problems shearing keys on early models.
2019/09/22 11:03:03
soulsnipes40
I checked initially at the flywheel key and it looked ok but I’m going to take another look to make sure I didn’t overlook something. Model 917.289210 engine # 331877. Appreciate it!
2019/09/22 11:33:42
soulsnipes40
So I checked the flywheel key and it was sheared in half. I put in a new flywheel key but same thing is happening, it’s not starting. Also my brand new battery is draining under 12 volts when attempting to start it a few times
2019/09/22 14:53:57
AVB
This is why I asked for the engine's date code so you would be using the correct key and torque specs. First if it has a date code before 120701xxxxxxx the key needs to changed to a steel key and the flywheel torqued to 110 ft-lbs. After 120630xxxxxxx the key will be the longer 1" key and the flywheel torqued at 110 ft-lbs. Plus during at time in 2016 some flywheels were under torqued from the factory [160501ZDxxxxx THROUGH 160922ZDxxxxx].

Note also that the flywheel and crankshaft key ways were change at the same the new longer key was issued.
2019/09/22 16:54:11
soulsnipes40
Ok gotcha, the date code was 080709. Do you believe this is the only reason that the mower won’t start due to timing being off?
2019/09/22 18:13:29
soulsnipes40
I checked the part number for the flywheel key and I am using the correct steel key #222698s
2019/09/22 18:48:24
AVB
Actually PN 222698S is an aluminum key and the correct updated steel key is PN 796335. Being aluminum or steel does change the timing just keeps it from shearing easily due to flywheel / crankshaft key way design.
 
Once the sheared key was replaced it should have at least started on raw fuel introduction into the cylinder or intake provided nothing else out of order.
2019/09/22 19:17:19
soulsnipes40
Definitely appreciate the information, I’ll grab the steel version. I’m sort of at a loss to figure why it won’t turn over then. Pretty much checked everything else, besides possibly being a carburetor problem? I’ll continue to see if I can find out the culprit.
2019/09/22 19:28:15
soulsnipes40
So everything is still the same. Flywheel is spinning but not cranking over. Also I have to jump the battery because if not battery goes under 12 volts after a few spins. Also I noticed a lot of oil coming out of the exhaust valve where it connects to muffler
2019/09/24 13:11:17
Roy
If the flywheel is spining it is cranking over, just not starting. Recheck the push rod, it may be bent again indicatinng a loose valve guide. Did you properly torque the flywheel nut? If not it may be sheared again.
2019/09/24 13:24:52
soulsnipes40
Yeah not starting, I’ll check the pushrod again and I torqued it to 110
2019/09/24 13:30:11
AVB
soulsnipes40
So everything is still the same. Flywheel is spinning but not cranking over. Also I have to jump the battery because if not battery goes under 12 volts after a few spins. Also I noticed a lot of oil coming out of the exhaust valve where it connects to muffler

Something definitely not right as there shouldn't be a lot oil coming out the exhaust at any time. Is the crankcase overfilled? If so then it is likely the carburetor is leaking and has flooded the cylinder and polluted the oil with fuel.
 
A flooded engine will not start.
2019/09/24 14:31:02
soulsnipes40
Is it best to install a manual shut off valve to stop gas flow in the case the carb solenoid or carb doesn’t stop gas flow?
2019/09/25 10:10:12
soulsnipes40
AVB thanks so much for all your help. I emptied the crank case and installed a shut off valve. I cranked it over and after a few seconds it finally started. There was white smoke coming from the exhaust and the muffler was getting very very hot. Reasons for this?
2019/09/25 11:41:54
soulsnipes40
Also I restarted and it’s not blowing smoke but it runs and then shuts off. Can’t keep it staying running? Valve clearance issue?
2019/09/25 11:50:02
AVB
A couple comments are in order here.
 
First the fuel solenoid is not intended to be a fuel flow control other blocking the main carburetor jet(s) during to prevent raw fuel from entering the exhaust which results in a loud report. It has nothing to how fuel flows from the fuel tank. This is the job of the float needle valve and seat. This is a misunderstanding many DYIers have about the purpose of the solenoid.
 
Second the white smoke was most likely just oil burning off in the muffler due oil overflow from the crankcase due to fuel polluted oil. Usually take 5 to 10 minutes burn off once the muffler is hot enough.
 
Now if the crankcase was overfilled then you most likely have a leaking needle valve/seat problem and it would still flood out the engine. If you have a Nikki carburetor the fuel bowl gasket can also cause fuel overflow in the carburetor as the part of the gasket or separate o-ring depending which version was use can leak. As the fuel overflows in the carburetor it work its way through the intake system into the cylinder which then leaks pass the rings, polluting the oil
2019/09/25 13:47:49
soulsnipes40
Ok great information, do you believe it’s best to rebuild the carburetor then?
2019/09/25 16:01:24

Comments are closed.

Copyright © 1994 - 2016 Jacks Small Engine & Generator Service, LLC
© 2025 APG vNext Trial Version 5.5