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no threads in Kohler SV470 engine mount holes

Discussion in 'Mechanic and Repair' started by redeye1964, Aug 17, 2013.

  1. redeye1964

    redeye1964 LawnSite Member
    Messages: 42

    I'm fitting a SV470 into a ride-on, went to screw the bolts into the engine mounting holes - they are unthreaded......is this normal with these engines, do I have to tap threads into them? Seems crazy to me, wondering if it is a casting error?? Please help, I need to get this going, I'm a contractor :confused:


    as you can see, 3 holes are blind, no way to use nut/bolts, except for 1
  2. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,028

    Most equipment makers use self tapping screws when installing engines so no threads is normal, Cut your own with a tap or use the factory equipment bolts...... But....Be careful, I snapped a self tapper off in a brand new aluminum spindle housing ONCE......
  3. BigFish

    BigFish LawnSite Gold Member
    Messages: 3,556

    As was mentioned, you'd be better off to cut new threads using a tap. You can prolly get by with just a " plug tap" which will cut almost to the bottom of the blind holes. If ya don't have a plug tap, you can grind some of the lead/ point off a regular taper tap.
    Use plenty of lube and blow out the chips, shouldn't have any problems.
    Last edited: Aug 17, 2013
  4. dutch1

    dutch1 LawnSite Silver Member
    from Jayhawk
    Messages: 2,235

    This is just another process the manufacturers eliminate to reduce the cost of production. I've never attempted to use self tappers on a new block--I always tap threads since breaking one off while removing an engine. Grade 5 and 242(blue) Loctite works for me.
  5. redeye1964

    redeye1964 LawnSite Member
    Messages: 42

    thanks for the advice, I'll tap threads rather than risk self threaders
  6. redeye1964

    redeye1964 LawnSite Member
    Messages: 42

    finally fitted, was a big job - best part of 3 days, where I usually do an engine swap in a matter of hours - all due to the mounting arrangement......mower is a Cox, made in Oz
  7. gnobles

    gnobles LawnSite Member
    Messages: 4

    I had good success today tapping threads with this technique:




  8. Valk

    Valk LawnSite Silver Member
    Messages: 2,711

    Is the above method preferable to a self tapping screw/bolt? Mechanics??
  9. gnobles

    gnobles LawnSite Member
    Messages: 4

    I should have also mentioned that I inserted the thread cutting tool only 3 to 5 threads deep, then pulled it out, blew it off with air, blew the hole out with air, and then repeated until finished. I also lubricated the hole with WD-40.

    I had never done this before, but found it to be a surprising easy process.
  10. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,028

    As I mentioned above, After snapping one off...... ALL un-threaded holes get tapped......

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