25ch Need a little help

Discussion in 'Mechanic and Repair' started by Floridalandcare, Oct 22, 2012.

  1. Floridalandcare

    Floridalandcare LawnSite Senior Member
    from Tampa
    Posts: 314

    Question 1- Have a 25ch Kohler (950hrs) on a Scag that had a blown head gasket . I ordered the gasket set from Kohler ,received it today and they're so many gaskets,seal and O-rings .I dont know where they all go . I know the 2 shaft seals ,intake and exhaust gaskets , breather gasket ,governor seal ,valve cover seals and the carb gasket. Where do all the other ones go or do they ship 1 set for all different models.( It came with 2 rubber tube that I have no idea about.

    Question 2 - The head gaskets have a piece of metal that goes around the gasket , does this face up or down when I put it back together

    Question 3- The inside of the cylinders are like a mirror with no sings of the crosshatch and no signs of any scoring.Should I have it honed or deglazed and if so do I need new rings or over sized rings .As far as I can tell the rings still look fine ,they sprung apart when I pulled the piston.

    Any help would be appreciated
     
  2. piston slapper

    piston slapper LawnSite Platinum Member
    Posts: 4,246

    1....its a universal kit...use what you need
    2...metal side to the head
    3...insert the rings into the bore and measure the ring gaps...
    If they are ok..reuse them and don't deglaze the cylinders...don't mix them up.
    If it needs rings..deglaze the bores and wash the block out really good..
    Posted via Mobile Device
     
  3. BigFish

    BigFish LawnSite Gold Member
    Posts: 3,367

    Man, you need to go to the Kohler website and download a manual!
    Yes, you definitely need to deglaze/ brush hone the cylinder and get new rings.
    To be done right, you really need to accurately measure the bore, and the piston/s. Then you can figure out whether you can use std. rings, or need to bore the cyl. oversize.
    You can get a feel for whats goin' on by squaring up your old ring in the bore and measuring the gap. You can also use a new std ring and do the same thing.

    I'm not a big fan of re-using old rings period! In this case, with no trace of crosshatch left/mirror finish , its a sure bet the rings will be worn........

    The two rubber tubes go inside the air filter to seal the hold down bolts on some models.
     
    Last edited: Oct 22, 2012
  4. Floridalandcare

    Floridalandcare LawnSite Senior Member
    from Tampa
    Posts: 314

    Ok, I took the top ring off the piston and put it in the bore ,flushed it up with the piston and I have a gap I can fit a nickle in .(I dont have a gauge at the house). New rings?
     
  5. piston slapper

    piston slapper LawnSite Platinum Member
    Posts: 4,246

    I keep a few different new top rings in my toolbox..
    It gives me a good read on the bore without having to break out my snap gauges or my bore gauge...
    I merely stated that the rings could be reused if they were in spec...usually the oil wiping rings lose their tension so you have to replace all the rings anyway..

    There is no substitute for experience....
    Building engines is like cooking..one wrong ingredient and you ruin it......
    Posted via Mobile Device
     
  6. piston slapper

    piston slapper LawnSite Platinum Member
    Posts: 4,246

    Max top ring gap is .015 to .020....
    No shortcuts today...
    Posted via Mobile Device
     
  7. ricky86

    ricky86 LawnSite Bronze Member
    Posts: 1,852

    They used two styles of cylinders on that engine. One was plated - not much could be done to recondition it. The other was a sleeve - it should be at least honed. If you're doing a budget job, the sleeve can be roughed up with sand paper (backyard repair style). Ball hone is a better choice. If the tubes you speak of are orange, they are for the a/f assy. They slide down on the stud.
     
  8. Floridalandcare

    Floridalandcare LawnSite Senior Member
    from Tampa
    Posts: 314

    Got new rings from Pro Mower today , standard size and they were about a millimeter from being together when I put them in the cylinder to check the gap.. I cleaned the whole engine with a degreaser and when I put the fly-wheel back on and tightened it up - the crank would not turn by hand (this is with the heads off ,so there's no compression to turn against). Pulled the fly-wheel back off and the magnates were sticking to the stator. They came unglued from the inside of the fly-wheel. Should I use an epoxy to secure them back on and I know regular magnates have poles ,does it matter which way they're facing when I put them back on?
    P.S The stator was undamaged as I was only trying to turn the crank with my hand.
     
  9. piston slapper

    piston slapper LawnSite Platinum Member
    Posts: 4,246

    I covered this in an earlier thread...
    The magnets have 3 poles...NSN and SNS...
    They have to be installed N S N S N S N.........
    Clean everything...use JB Quik weld and glue them back in .
    Use small v shaped pieces of cardboard between the magnets to keep the magnets from migrating while they are drying...spacing is important as improperly spaced magnets will make your flywheel out of balance.
    Done a hundred of them....no problems...
     
  10. piston slapper

    piston slapper LawnSite Platinum Member
    Posts: 4,246

    Ricky...Ricky...Ricky...:dizzy:

    Backyard Repair Style ?????....roughing up the cylinder with sand paper..:hammerhead:
    The crosshatches are important..they hold a thin film of oil to keep the piston and rings from digging into the cylinder....The angle of the crosshatch helps the rings seat ....optimizes compression...and controls oil usage...

    Whats next ??? 9 in bodygrinder to remove gasket material...???:dizzy:
     

Share This Page