Engine backfires but won't start.

[Fish]

Looking at the top of the flywheel, it is evident that the fanwheel is held on by the two bolts. The service tech telling you that your installing/removing the flywheel would not affect the warranty is "bogus", you need to step up and "prove" that one.......

As far as you having a good running engine that all of the sudden had totally "reversed" timing marks, that is impossible to believe as well....

For us to consider this thread any farther, you might need to tell the "whole" story, if any of this tale has any credence........

Otherwise, we have better things to do.

If you fess up and are talking about an engine that you bought from someone else, and the info you provided is secondhand, well.......

 

[Limfe]

That took a really hard blow to split the flywheel or flywheel shaft (top of crankshaft?) like that. Could be over-tightening as aluminum won't stand up to it. Impact air gun would do it. I've seen tops of crankshafts mushroomed from hammering on them, even broken in two, but never split! On the other hand I've seen go cart racers tighten flywheels without the shear pin keys in them to advance time and they didn't crack them! Just have to get a lock washer to keep the wheel from turning. But in that case, if it did turn, what difference would it make since there is no flywheel key in it? Just re-set the timing position and try it again. I've never tried that but have friends who did.

The Sears tech said that he believed that the flywheel was defective. The top of the flywheel itself cracked on the top. It was visible as soon as I pulled the cooling fan off.

 

[Limfe]

Looking at the top of the flywheel, it is evident that the fanwheel is held on by the two bolts. The service tech telling you that your installing/removing the flywheel would not affect the warranty is "bogus", you need to step up and "prove" that one.......

As far as you having a good running engine that all of the sudden had totally "reversed" timing marks, that is impossible to believe as well....

For us to consider this thread any farther, you might need to tell the "whole" story, if any of this tale has any credence........

Otherwise, we have better things to do.

If you fess up and are talking about an engine that you bought from someone else, and the info you provided is secondhand, well.......

I bought the tractor in June of 2012 from The Sears outlet store in Rome NY. It came with the factory warranty. As far as you not believing what happened, there is nothing I can do about that. The tractor was running fine, stalled, would not start up again and only backfired. The first thing I checked was the flywheel key and that was when I noticed the top of the flywheel itslef being cracked at the very top. I noticed the crack as soon as I removed the bolt. After replacing the flywheel and key, which I torqued down to the 100 lb-in per the factory specs.

 

[Fish]

I bought the tractor in June of 2012 from The Sears outlet store in Rome NY. It came with the factory warranty. As far as you not believing what happened, there is nothing I can do about that. The tractor was running fine, stalled, would not start up again and only backfired. The first thing I checked was the flywheel key and that was when I noticed the top of the flywheel itslef being cracked at the very top. I noticed the crack as soon as I removed the bolt. After replacing the flywheel and key, which I torqued down to the 100 lb-in per the factory specs.

Nah, sorry. I am not buying any of it.

They wouldn't have allowed you to install the new flywheel, and have it covered, unless they are total morons.

And your finding the engine 180 degrees out of time.... Bogus too....... If it was running great before.........


Nah, give it up........


Fish

 

[Limfe]

Nah, sorry. I am not buying any of it.

They wouldn't have allowed you to install the new flywheel, and have it covered, unless they are total morons.

And your finding the engine 180 degrees out of time.... Bogus too....... If it was running great before.........


Nah, give it up........


Fish

Then I would suggest that you stop reading the thread. I came here for advice and help about my tractor not to be ridiculed by someone acting like they are on facebook

 

[GetTechnicalWithJd]

The engine model number is 33187/0869 G5/111220ZA. The service tech stated to me that having me install the flywheel would not affect the warranty. Obviously the cooling fins were easily seen just by looking at it and I did not imply that any of the other issues had anything to do with it. The timing marks on the cam gear and the main gear were completely on opposite sides of each other. How or why this would happen, I have no idea. That would be why I asked on here.

The timing marks will only line up once in FOUR revolutions not on every revolution. Unless you knew this you would not have gotten them to line up.

I'm with Fish on this one. not possible for timing gears to jump one tooth let alone multiple.

 

[Limfe]

If the marks only line up every four revolutions then I am going to guess that the timing wasn't off and it was the exhaust valve seat causing the issue. If that was preventing the valve from closing properly would that have caused enough stress on the engine and flywheel to cause the damage? What is the correct way to set the timing using the marks on the two gears?

 

[GetTechnicalWithJd]

I suspect that a piece of the seat got on top of the piston resulting in a massive impact. When this occurs the crankshaft either slows down as it absorbs the impact or stops all together. All the while the flywheel wants to keep rotating as it is storing all the kinetic energy of the engine.

This usually results in the little aluminium flywheel key sheering and very rarely, if ever, results in the flywheel or crankshaft cracking.

As a matter of interest, was it the exhaust valve seat that dropped out?


With regards to setting the valve timing, download the workshop manual for full instructions.

http://www.powerproducts.co.za/technical/briggs_276781.pdf

 

[Fish]

Not trying to fight, but when someone posts something that is highly improbable, I ask more questions, to try and get the full story.

When someone posts 3 or more highly improbable, if not, impossible things, I throw a flag.

I think that what is real likely is that you have been doing a whole lot of beating and pounding on this poor engine that you are not telling us about, and trying to roll all of your troubles into one nice scenario that makes it Brigg's fault.

You came here for advice/help, it is hard enough to do online when we have all of the facts {correct}, it is almost impossible if we have to devine
what info given is true or fabricated.

We offer free advice for free, so full disclosure of what really happened would be nice to have. We cannot possibly help if you don't give us the
whole story.

Fish

 

[Limfe]

Not trying to fight, but when someone posts something that is highly improbable, I ask more questions, to try and get the full story.

When someone posts 3 or more highly improbable, if not, impossible things, I throw a flag.

I think that what is real likely is that you have been doing a whole lot of beating and pounding on this poor engine that you are not telling us about, and trying to roll all of your troubles into one nice scenario that makes it Brigg's fault.

You came here for advice/help, it is hard enough to do online when we have all of the facts {correct}, it is almost impossible if we have to devine
what info given is true or fabricated.

We offer free advice for free, so full disclosure of what really happened would be nice to have. We cannot possibly help if you don't give us the
whole story.

Fish

That is the whole story. This tractor hasn't been "beat" or neglected. I have taken very good care of it. I change the oil every 50 hours and it is kept clean and greased. The only thing that I may have screwed up on it was moving the cam gear due to my misunderstandin of how the timing marks are supposed to align. When the tractor quit I was mowing in the middle of an open 1.5 acre patch of lawn with absolutely NOTHING to come in contact with the blades or any other part of the tractor what so ever. I am not pushing blame on anyone or anything. I just asked if the broken valve seat could have caused this and if so what would have caused the valve seat to become pushed out enough to prevent the exhaust valve from retracting fully enough to close properly.