Gas leaking into crankcase

ChuckJD50 · Mar 21, 2019

When my JD 50 sits for a while i get gas in the crankcase. I figure the problem is in the carb - maybe float sticking(?). The gas line has an updated auto-shutoff installed by a top 2-banger mechanic (I used to shut the gas off by hand).
All suggestions welcome!
Thanks!

Mike M · Mar 21, 2019

The auto shut off diaphragms could be bad leaking gas into the oil ? But when mine went bad the gas was turning black in the glass bowl while running as the oil pressure leaked through the diaphragms.

old · Mar 21, 2019

Start shutting it off by hand again the auto shut off is not working as it should be

ChuckJD50 · Mar 21, 2019

Problem here is the manual shutoff was removed when the auto shutoff was installed...

Billy Shafer · Mar 21, 2019

I would take a look at the fuel pump. If it is cam driven. Internal leak will put gas straight into the crankcase.

ChuckJD50 · Mar 21, 2019

Interesting! Never noticed black fluid but I'll check that out when I get to the JD (120 miles away just now).
Thanks!

ChuckJD50 · Mar 21, 2019

Was cam-driven pump standard on '53s?
Thanks!

BushogPapa · Mar 21, 2019

NEVER EVER rely on that "Auto shut off..!!

Put a good gate valve in the fuel line...AND...since you have "updated" the "Auto-Shut off", remember, the diaphrams are likely Chinese made..don't trust them...

Your oil in the crankcase is getting there through the oil line that should Open the Auto-Shut off...

I prefer to block the brass fitting and slip a wedge in over the tickler button on top, instead of mess with that trouble maker...

Nothing like getting on a good 630 inside the tool shed, hit the starter and instantly see 1/2 Gallon of Gas heading into the Rafters...

Your choice.......
ONCE was enough for me...Thank God it didn't light up...!

fixerupper · Mar 21, 2019

Replace the diaphragm with a good quality
ethanol resistant one. Roberts carb
repair is a good source if you want to
keep that setup. There are poor quality
diaphragms out there including the
diaphragms from mother Deere. If you
don't feel comfortable with the auto
shutoff a manual valve will give you good
results.

Geo-TH,In · Mar 21, 2019

Chuck, I've installed 12v solenoid shutoffs on all my tractors and some lawn mowers that get gas in
crankcase. Never had first issue with gas in crankcase after I installed solenoids. Two of my tractors
came from factory with in line solenoids. Some mowers have a second solenoid built into carb. That
solenoid doesn't prevent gas in crankcase.

ChuckJD50 · Mar 21, 2019

Thanks for the help, guys! Will check advice out next month when I get back to the tractor.

Mike M · Mar 21, 2019

No fuel pump on a JD 50 they were all gravity feed.

Mark-Ia · Mar 21, 2019

The diaphrams leak and the fuel goes back to the crankcase via the oil lines.

BushogPapa · Mar 21, 2019

Gas can flow back down the oil supply line if a diaphram is leaking..

I Solder the Brass elbow closed..problem Solved..just slip a small wedge between the top "Tickler" abd the tank to open the auto shutoff..but you need a Manual shut off also...

BushogPapa · Mar 21, 2019

Yes, oil could be forced into the sediment bowl by engine oil pressure..

Gas leaking into crankcase

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