Had one of my 450s idleing and loosening the dipstick as soon as I pulled it out of the motor it sprayed oil everywhere like it had in a lot of pressure behind it is that normal ???

 

On most machines pulling the dip stick would get you sprayed even if the crank case vent was clear and open. Had one guy learned the hard way not to remove a dipstick while running on one of the first 850s that we got in. Pressure forced to dip stick to fly out at an angle,sprayed him and broke most of it off leaving just the plug end.
Tried every way possible to remove it but couldn't. Gave him the choice of hoping that the large piece of plastic wouldn't screw up the engine or split the engine to remove it. We ended splitting the engine. On remote oil tanks such as what the 500 engines used, usually no problem pulling dipsticks out.

 

In your engine, on each revolution of the crankshaft 450ccs of air is pulled into the sump as the piston rises, and out as it goes down again. On parallel twins and four cylinder engines, this doesn't happen, as one piston sucking in while one is blowing out, balances the breathing.

 

Yes you would think pressure would be balanced,but apparently this has happened before on the Polaris 850 which is a parallel twin also.They were already noted for having fragile dip sticks to begin with plus they had to be inserted correctly through a slot in the case hole.This is from another forum.

06-23-2015, 11:05 AM
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Polaris ATV Junkie!

Join Date: Oct 2014
Location: Northeast PA
Posts: 1,479

"i made the mistake of pulling my dipstick while it was running once, knowing ahead of time that it could easily be snapped off due to a friend doing it on his. i hate how tight this setup is. he tore it down to retrieve the parts. i would most likely do the same if it were to happen to me. leaving it in there is just asking for trouble."

Just not a good idea on any engine,single or twin cylinder, to pull a dipstick while the thing is running.Exceptions being dry sump engines with their remote oil tanks such as the Polaris Sportsman or Predator 500s. I had no problems in removing these as the tank vent was right there.