ventilator pump

Is the ventilator pump supposed to let air in or out? Does a broken spring affect the pump from working properly? Any ideas would be appreciated.

The ventlator pump balances the crancase pressure/vacum against the piston movement to keep from causing a problem of oil being pushed out by the down stroke of the pistons. The broken springs will make it blow oil out the eshaust stack.

NOT!! most engines have no pump on older stuff. the purpose of the pump is to keep fresh air moving through the crankcase to prevent buildup of harmful combustion gasses that inevitably sneak by even new engine rings & also keep condensation to a minimum. it creates airflow but no measurable pressure, & certainly not vacuum. it takes air from the aircleaner so its clean. if the vent tube where the gasses are supposed to exit gets stopped up u will have problems.

Which is it?

i'm still not clear on wether the ventilator pump, pumps air in or out of the crankcase. if it pumps it in where is it supposed to exit from?

Well, I am guessing from you handle that you are talking about a Deere 2 cylinder. They used a couple different systems. The explanation I had gotten for how the system works is exactly opposite of how GTX explained it. The crankcase is not a positive ventilated system. The breather vent with the horse hair filter is an intake for fresh air which as it passes thru the crankcase removes all the bad gases and fumes as it is sucked to the ventilation pump. The pump then forces the bad gases thru the little line and into the air filter casting to be run thru the engine again.
That is a different system than the 60 and 70 use with the crankcase vent that come right out of the tappet cover. Part of the reason I don't believe the system works the way GTX explained it is if the pump forced air thru the crankcase and out the upright vent by the pulley, it would not need the filter inside it. The 60 and 70 and all the 1010-5020 just had vent tubes with no filter in them. But because the A, B and G sucked air in thru the vent, it had to go thru the horse hair filter to be cleaned. This works until the engine develops enough wear that the blowby overwelms the sytem and then there is a positive crankcase pressure and gases then comeout the upright breather vent as well as go thru the pump and line into the intake.

Can't speak for all JD's, but on a late B, the pump pumps air out of the crankcase, through the fanshaft tube, through a tube at the fan end of the shaft up into the air filter. The air going into the crankcase is supplied from a tube that connects the elbow (between the filter and the carb) to the valve cover. If a spring is broken, oil will travel up the fanshaft tube and into the breather. That is, unless the tube between the fanshaft tube and the breather is rusted out, then the operator gets an oil bath. Don't ask how I know.