How can I tell if there is coolant in the oil of my JD 420?

Also, if the oil has got anti-freeze in it, you'll know it's coolant... If the water is clear and you've got anti-freeze in the coolant, it may be rain water or something like that getting into the crankcase...

Also, if you've been running the engine and there was water in the oil, the oil will be anywhere from a white creamy color to a grayish color (depending on what your coolant was like). It definitely won't be the clear, clean brown or black of good oil...

Why are you suspecting a problem??

HTH,
Howard H.

I would pull the drain plug and watch it as it drains out. if it's water or coolant, there's no mistaking it. It might be gasoline from a stuck float (not completely familiar with the 420 carb, so if this is not possible, excuse me now).

If it's gas, you can track it down, If it's water, probably more serious, unless there's an easy way for coolant (or even rain water ?!?) to enter (like a water pump seal on some designs).

Again, I'm speaking generically, but I'd drain it into a clean container and evaluate. Don't be hasty and cause a worse problem.

Frank-in-Tallahassee
70D // 855