My 518H dies after running for 20 min

[bmsgaffer 2,052]

Guys,

 

let's give Jess some breathing room here.

 

Maybe too many cooks in the kitchen at this point?

 

He ran into a firehouse and yelled "fire"... its bound to happen...

[Save Old Iron 1,571]

Since the fireman aren't going to show up at Jess's house to put out his fire, don't you think they should assume some responsibility for making certain the instructions being given are understood thoroughly?

 

You understand your instructions, I understand your intentions,  but have we assured a self admitted "non-techy" understands the how and why?

 

I always view confusion as a failure on my part, not due to the person I am trying to help.

Edited November 10, 2014 by Save Old Iron

[Jess 29]

How many hours on this engine?

  still around 1,300

[Jess 29]

Guys,

 

let's give Jess some breathing room here.

 

Maybe too many cooks in the kitchen at this point?

Well I had some time tonight to run My tractor . It is a 518H I purchased new around 1986 . For the first time it started doing something different. It always starts right up and runs like a champ for the first 20 to 30 minutes. Well tonight when It started to break up like it has been doing just before it dies , I gave it full throttle and it ran lousy and sputter and ran slow for 10 to 15 minuets but never died as has been the case. It sputtered some puffs of white smoke here and there also. It would have died if I lowered the throttle . I let it run this way to see what it was going to do? After running like S -T it started to smooth out . It didn’t run great like in the first 20 min but it did smooth out quite a bit. I shut it off and it actually restarted , still not running smooth but it ran again. These are still the original spark plug wires , I did change the plugs several years ago. Would this be a cause for when it heats up ?

Just asking.

I want to thank you all for your input and hopefully some day I can get this tractor straightened out.

Respectively  Jesse

Edited November 11, 2014 by Jess

[Save Old Iron 1,571]

Jess, when you saw white puffs of smoke, did the exhaust smell like raw gas?

[Jess 29]

Jess, when you saw white puffs of smoke, did the exhaust smell like raw gas?

It stunk like old stale gas! and ran like a hit and miss engine before it started to smooth out ? but like I said the first 20 min or so it always runs great

Edited November 11, 2014 by Jess

[Save Old Iron 1,571]

Next question would be if the "white fog" hung in the air like oil smoke or did it dissipate fairly quick like gasoline vapor.

 

I have worked on cars that you would swear had a bad head gasket because of the amount of white smoke coming from the tailpipe. It turns out the car had a fuel injector stuck open and no spark in that cylinder from a wet plug. The gas was not being ignited or incompletely burned (black smoke) but instead the cylinder was just pushing raw gas thru the engine and the gas was vaporizing in the exhaust.

 

Now why is gas not burning?

 

If this was a damp cold morning, the spark for one cylinder may have been diverted from the plug and started jumping from a bad ignition coil wire directly to ground. This would stop one cylinder from firing and raw gas pumps thru the one cylinder. You can test for this theory by spritzing water over the ignition coil, wires, an spark plug boots for both cylinders while the engine runs. Doing this after sunset in the darkness can reveal a spark leaving the wiring and jumping to ground.

 

Try this when you can and get back to us. There are other considerations such as a stuck float in the carb dumping excess gas into the engine but that usually shows as black smoke if the ignition system is working. Let's work the easy ignition spritz angle first.

[Jess 29]

Next question would be if the "white fog" hung in the air like oil smoke or did it dissipate fairly quick like gasoline vapor.

 

I have worked on cars that you would swear had a bad head gasket because of the amount of white smoke coming from the tailpipe. It turns out the car had a fuel injector stuck open and no spark in that cylinder from a wet plug. The gas was not being ignited or incompletely burned (black smoke) but instead the cylinder was just pushing raw gas thru the engine and the gas was vaporizing in the exhaust.

 

Now why is gas not burning?

 

If this was a damp cold morning, the spark for one cylinder may have been diverted from the plug and started jumping from a bad ignition coil wire directly to ground. This would stop one cylinder from firing and raw gas pumps thru the one cylinder. You can test for this theory by spritzing water over the ignition coil, wires, an spark plug boots for both cylinders while the engine runs. Doing this after sunset in the darkness can reveal a spark leaving the wiring and jumping to ground.

 

Try this when you can and get back to us. There are other considerations such as a stuck float in the carb dumping excess gas into the engine but that usually shows as black smoke if the ignition system is working. Let's work the easy ignition spritz angle first.

It dissipated fairly quickly like a gas vapor . I will try the water thing when I can some time tomorrow. When this mess started before I started replacing parts and the machine died I pulled a plug and had no spark to the plug . At least it starts and runs now .

  Thank you for your reply

 Jesse

[Save Old Iron 1,571]

 

 I pulled a plug and had no spark to the plug .

 

 

I don't think we ever asked .........

 

how do the plugs look? 

 

Do they both look the same color ?

 

nice tan color ?

 

black / sooty ?

 

wet with gas ?

 

any carbon tracks down the side of the white insulator ?

[Jess 29]

I don't think we ever asked .........

 

how do the plugs look? 

 

Do they both look the same color ?

 

nice tan color ?

 

black / sooty ?

 

wet with gas ?

 

any carbon tracks down the side of the white insulator ?

 I pulled the plugs and wires off today , the plugs were black / sooty!  They didnt seem burnt , but I think from the way it was running in the end it must have been loading them up.

 I will replace them and the wires. The wires are the original . Do they do things like fail when heated ?

 Thank you for your time .