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Tractor spark plug hole seems to be stripped

Post in 'DIY and General non-hearth advice' started by PapaDave, May 31, 2013.

  1. PapaDave

    PapaDave Minister of Fire

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    So, my sis-in-law got herself an older Simplicity that she thought was in good shape, but one of the spark plugs will not thread into the cylinder.
    Would a helicoil work for this, and can it be done without pulling the head?
    I'll be checking youtube, but thought I'd ask here.
    Thanks for any help.
    ScotO likes this.

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  2. heat seeker

    heat seeker Minister of Fire

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    They do make threading kits for just such a purpose, and it can be done with the head on. It would be better to remove the head, but not necessary if you're careful. An auto parts store could get the item for you.
  3. ScotO

    ScotO Guest

    Will the head come off without much work PD? If so, that'd be the route I'd go. That way, you aren't getting metal shavings and slivers in the cylinder bore, which would find their way into the rings and cylinder walls right quick.....

    I've helicoiled many small engine spark plug holes over the years, and never had one fail.......if you aren't comfortable doing the job yourself, I'm sure a local small engine shop (or machine shop) would do if for you for a small price..
    Dune likes this.
  4. PapaDave

    PapaDave Minister of Fire

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    I haven't looked that close yet, Scotty. All the tires are flat, so it's not easy to move around to work on it. I'd need a manual for the torque sequence and values.
    I couldn't figure out why the thing wouldn't start. When I pulled that plug, it was almost falling out.:eek:
  5. ScotO

    ScotO Guest

    That'd be hell on the compression in that one cylinder.....>>

    yeah, that'd do it for sure!::-)
    PapaDave likes this.
  6. Jags

    Jags Moderate Moderator Staff Member

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    If at all possible, pull the head. The new coil will cut threads on the way in, and it would be almost impossible for some of those small chips to not get into the cylinder.
    PapaDave likes this.
  7. Hogwildz

    Hogwildz Minister of Fire

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    What model is it? I have one I use here. Maybe same manual depending on model number.
  8. PapaDave

    PapaDave Minister of Fire

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    Hang on Hog.
    Pretty sure it's a 5212.5H, 12 or 12.5 HP twin B&S motor.
    I was able to find a manual that I think is correct. I'll have to look in there to see if they have torque #'s, etc.
    Nope.
    Need repair manual.
  9. PapaDave

    PapaDave Minister of Fire

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    Looks like I'll need to find the B&S repair manual for this motor.
  10. MasterMech

    MasterMech Guest

    Sav-a-thread spark plug inserts. Better than a Heli-coil in this app.
    ScotO likes this.
  11. MasterMech

    MasterMech Guest

    That requires a whole lotta thought, skill, and not to mention some pricey equipment. There are metallurgical issues to consider in many cases as well. The sav-a-thread kits are every bit as strong, relatively inexpensive, and well within the abilities of the average DIY guy.
    ScotO and Dune like this.
  12. Dune

    Dune Minister of Fire

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    Tourque specs are based on bolt diameter, not engine model, and sequence is just common sense. 12 -6-9-3 -11-5-1-7-2-8 using a clock face as an example and progressing in three stages (10 foot pounds, 30 foot pound, 55 foot pounds for example. The point is simply to not warp the head during the tourquing process.
    charly and ScotO like this.
  13. PapaDave

    PapaDave Minister of Fire

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    Thanks Dune, and I'm aware of that, but it's also based on grade...isn't it? I don't always see markings on bolt heads. Maybe I need to look more closely.
    I'd rather use a manufacturer's diagram than my common sense.>>
    Might be ok, but might not.
    5 bolt star pattern is easy.:cool:
  14. basod

    basod Minister of Fire

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    Dave it can be tapped with the head on.
    apply grease to the reliefs on the helicoil/insert tap with piston just past TDC. It'll help catch the chips.
    When done compressed air and a small hose duct taped to a shopvac to most remaining chips out
  15. MasterMech

    MasterMech Guest

    More and more of these small engines are using Torque To Yield fasteners that require stretching the bolt a measured amount while torquing the head. (If the specs say "20ft lbs then turn 90 degrees" or similar, then you have T2Y fateners. Which NEVER should be reused BTW.) While Dune is absolutely right concerning the ability to torque components down using "common sense" and generic torque settings, there are variables such as the material the fasteners are threaded into and torque-to-yield fasteners that make having the manufacturer's specs more than just a good idea. ;)
    Dune and charly like this.
  16. Hogwildz

    Hogwildz Minister of Fire

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    Here is the Simplicity owner's manual & parts list, & the Briggs owner's manual & parts list.

    Attached Files:

  17. fbelec

    fbelec Minister of Fire

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    i just did a helicoil on my 01 grand marquis. the spark plug on these 4.6's are about 4 to 5 inches in which made it hard to use the tool that the kit i bought at autozone includes. but what i did was insert the tool run through the treads and on it's way to the larger size threads for the helicoil i used a ratchet and it cut the hole through to the next size which is on the same tool. threaded the hole and unscrewed it out. gave the cylinder a 3 or 4 blows with the blow gun off the compressor and then turned over the motor a few times without the plug installed to get any additional shavings if there was any. then put in the helicoil. oh ya you do want to put a big glob of grease on the tap it works well. the kit gives you 3 different size (length) for different size plugs. the difference with this spark plug kit vs. a regular helicoil is that there is no tang of metal to break off like regular helicoils. just thread in use the other tool provided to peen over the top part of the insert so that it never gets screwed into the cylinder and thats it. it work so well. the kit cost 40 dollars. saved me from pulling the head on that overhead cam motor.
  18. PapaDave

    PapaDave Minister of Fire

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    Thanks for those, Hog.
    The 2 for the Simplicity look to be the same as what I found. I hadn't seen the B&S, though.
    I need to get my hands on a repair manual too.....sis-in-law may just have to fork over a few bucks for one of those.
  19. charly

    charly Guest

    When I was a tech for the local Harley dealer,, when taking an Evolution motor head off,, you had to even back the bolts off in small increments or you could fail the threaded studs that the cylinders slide over and upon assembly and the motor heating up, the expansion stud or studs could fail.. lots to know.. Harley service school was interesting... There's one way to do things,, simple but the right way.. I too would remove a head to do any tapping of a hole. Residue, oily carbon build up,, your never going to blow out all the metal chips,, grease is better then nothing but..... depends on how much you care about what's left behind in the cylinder... I was a bug,, so the head would come off...do it for you like it would be done for me was always my mechanical ethics..no come backs! That's how the Evo motor head bolts were, 90 degree turn at the end after 2 torque values were applied..
  20. homebrewz

    homebrewz Minister of Fire

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    An alternative to a heli-coil is a brand called "Time-Sert". Its a solid insert rather than a coil.
  21. tekguy

    tekguy Feeling the Heat

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    sometimes you can finf used cylinder heads cheap.... probably about the same cost of a coil kit with tool
  22. PapaDave

    PapaDave Minister of Fire

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    Lots of options here.
    I'm not sure I want to tear into yet another project for someone else when I have so many of my own to do.
    Her son that said he'd do the helicoil should find this info. helpful and it will be passed along.
    She also has a chipper/shredder in need of blade sharpening/replacement.
    Gonna pull the housing off soon to check that out. Should be simple...right?:cool:

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