Jump to content

Unofficial Home of Old Simplicity & Allis-Chalmers Garden Tractors

Sign in to follow this  

Briggs crankcase pressure concerns

Recommended Posts

The engine is a freshly rebuilt 12hp cast iron Briggs. The problems I have with it are it is very hard to start and I have oil coming out of the carb. I have not noticed any oil burning, but if I mow with it (about 1 hour) the carb will have oil dripping from around the air cleaner. I'm assumming this is from crankcase pressure, but I not sure why.

Share this post

Link to post
Share on other sites
Questions: 1. is the crankcase over filled? 2. is the Pcv Assy clean and working 3. are the new rings sealing properly or turned in the right directions? Steps: 1A. check the oil level 2A. Clean the PCV (Positive Crankcase Ventalation) assy and check the hose for good unobstructed condition. 3A. perform a leak down test to check the ring seal @ 90 psi set the position of the piston at bottom dead center with both valves closed if air comes comes out either valve its not a good test if valves are closed and air only comes out of PCV then the new rings are not yet sealed properly. of the cylinder holds the 90 psi with no leakage then your induction system is sucking the oil out of the crankcase witch means the PCV assy is bad and needs replaced. Safety Note: The leak down test can be done at top dead center but is not advised because forcing air into the cylinder will cause the piston to move and the flywheel and crankshaft this can cause a pinch situation and can cause damage to fingers.

Share this post

Link to post
Share on other sites
This topic is now closed to further replies.
Sign in to follow this  

  • Who's Online (See full list)

    • MARK (LI)
    • garyosf
    • PhanDad
    • joelk
  • Today's Birthdays

    No users celebrating today
  • Recent Status Updates

    • Paul M.Murphy

      Paul M.Murphy

      Hello glad I got on this site. I hope to upload a couple of photos of my Simplicity Broadmoor 
      Model 707 Tractor. I have replaced all the belts on it and installed a new ignition switch.
      Have a mower deck which was in poor shape , repaced a couple of bushings and welded the
      deck where there was some holes. The tractor and mower deck came from a friend and the 
      mower deck metal was getting pretty thin. Some new metal was put in it and we also undercoated the underside of the deck. This was done by my friend Greg Toulman.
      I have not put the mower deck on the tractor yet, waiting for Greg to come home and give me a hand. Can you please tell me if there is a manual for the mower deck and where I could get one.
      I would also like to get some moon wheel discs as well.
      I will try and down load some photos of the tractor when my wife shows me how to. 
      I really love driving this tractor and also how well it is made compare today's tractors, especially the flexible rear end and the rollers.
      Tell the next time 
      · 8 replies
    • jbrooks

      jbrooks  »  Talntedmrgreen

      folowing  this from a link at the downloads.  I just rescued an AC 920 with the lambodini diesel. I can' t download  yet .  Where did you find the PDF copy you posted. . I would like to figure out how to adjust the injection pump. 
      I assume it's a bosche, correct
      · 0 replies
  • Adverts