Need some guidance and ideas

[Gsnod]

I have a Toro model 20444 that I can't get to start. Here's what's happening to this B&S engine, model # 127802, Type 0640-01. Even when I pull the recoil, I can not get it to fire, other than an occasional/rare pop. I have spark, and know gas is getting to the plug. The pop indicated that I might have a timing issue, so I took off the top and found the key sheared. Replaced the key and put it back together. Also removed the carb and soaked it and rebuilt, as it was quite dirty with old gas.

Still no fire....so I grabbed a coil that I know is good and put it on, just in case the coil was going out. Put the coil from this mower onto another, and that mower works...so the coil is not the issue. Still nothing. Looking into the plug hole and can see both valves opening and closing. Pulled the muffler and can see movement of a valve shaft.

I've got spark, fuel, and air....I've tried three different plugs, including a plug that worked on a different mower.

I need some more ideas from the group please!

 

[Gsnod]

Poop. Put this in the wrong forum.

I have a Toro model 20444 that I can't get to start. Here's what's happening to this B&S engine, model # 127802, Type 0640-01. Even when I pull the recoil, I can not get it to fire, other than an occasional/rare pop. I have spark, and know gas is getting to the plug. The pop indicated that I might have a timing issue, so I took off the top and found the key sheared. Replaced the key and put it back together. Also removed the carb and soaked it and rebuilt, as it was quite dirty with old gas.

Still no fire....so I grabbed a coil that I know is good and put it on, just in case the coil was going out. Put the coil from this mower onto another, and that mower works...so the coil is not the issue. Still nothing. Looking into the plug hole and can see both valves opening and closing. Pulled the muffler and can see movement of a valve shaft.

I've got spark, fuel, and air....I've tried three different plugs, including a plug that worked on a different mower.

I need some more ideas from the group please!

 

[motoman]

Well, I was totally baffled years ago and discovered (what was then) a strange thing. With valve covers off the Intek V 24 I watched valve movement as I turned over the engine. Eureka, the #1 exhaust valve was barely moving. Both cyls had identical compression. Reason: the exh guide had pushed up into the head over time (2 years) , inhibiting full valve opening as the rocked touched the guide. The "stack up" of the valve train caused the softer cam lobe to yield to the pressure of the lifter. When the engine would finally not run on cyl#1 there was apparently not engough intake charge to fire. Pulled down, the #1 exh cam lobe was almost perfectly round. Take a look.

 

[Gsnod]

Thanks motoman -- I guess the next thing to do is pull the head to check the valves.

If the key is in the crankshaft slot, that is the main way to assure correct timing, right? Since the key was sheared, I assume that the owner hit something....is there any other way this motor could have gotten out of time (and stayed out of time) even after I put in a new key?

Well, I was totally baffled years ago and discovered (what was then) a strange thing. With valve covers off the Intek V 24 I watched valve movement as I turned over the engine. Eureka, the #1 exhaust valve was barely moving. Both cyls had identical compression. Reason: the exh guide had pushed up into the head over time (2 years) , inhibiting full valve opening as the rocked touched the guide. The "stack up" of the valve train caused the softer cam lobe to yield to the pressure of the lifter. When the engine would finally not run on cyl#1 there was apparently not engough intake charge to fire. Pulled down, the #1 exh cam lobe was almost perfectly round. Take a look.

 

[motoman]

If you are curious about the pushed guide YOU DO NOT HAVE TO PULL THE HEAD, Just pop the valve covers and watch the valves go up and down. If something is not quite right (especially exhaust valves) look through the springs on the exhaust valves at the guide height in comparison with the intake guide height.

I have had my flywheel off once . It is not very difficult to align the key, but who knows . Is it possible to drop the key and not know it? Maybe if the keyway and key are off it is possible to crush home the mangled key with 100 ft lbs. There are many people on this forum who can help you and I hope they see this. The only other thing I can think of short of surgery is MAYBE you could hook up an auto timing light if you can mark off TDC from the piston position through the plug hole. Then turn the flywheel while observing the light . I once tried a timing light on my tractor Intek 24.The "flash" is not a flash , but a faint red glow so you will probably want to turn the lights down or shut the garage door. :anyone:

 

[Gsnod]

Motoman -- thank you! Sadly, this engine (B&S 127802, Type 0640) is an L head engine,so it does not have a valve cover. It's from1995, so no OHV cover. By the look of the schematics, if I pull the head, I'll be looking directly at the piston head, and immediately to the right of the head are the two valves....I guess I've got nothing to lose by pulling the head and making sure the valves are opening & closing fully.

If you are curious about the pushed guide YOU DO NOT HAVE TO PULL THE HEAD, Just pop the valve covers and watch the valves go up and down. If something is not quite right (especially exhaust valves) look through the springs on the exhaust valves at the guide height in comparison with the intake guide height.

I have had my flywheel off once . It is not very difficult to align the key, but who knows . Is it possible to drop the key and not know it? Maybe if the keyway and key are off it is possible to crush home the mangled key with 100 ft lbs. There are many people on this forum who can help you and I hope they see this. The only other thing I can think of short of surgery is MAYBE you could hook up an auto timing light if you can mark off TDC from the piston position through the plug hole. Then turn the flywheel while observing the light . I once tried a timing light on my tractor Intek 24.The "flash" is not a flash , but a faint red glow so you will probably want to turn the lights down or shut the garage door. :anyone:

 

[motoman]

gsnod, Sorry. shows my lack of knowledge. That said your flat head may have guides machined right into the head material so no guide movement is possible.

 

[Gsnod]

Absolutely no problem motoman -- Over the weekend....once this darn heat breaks, I'm going to pull the head to make sure that all the parts that should be moving are doing so....then we'll go from there!

gsnod, Sorry. shows my lack of knowledge. That said your flat head may have guides machined right into the head material so no guide movement is possible.