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Thread: stripped starter bolt hole

  1. #1
    Join Date
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    Default stripped starter bolt hole

    Any problem with drilling, tapping and using a thread insert for a stripped starter bolt hole??
    Mark Chapman DP member #653;
    1983 K2500 6.2 Suburban, 4" lift, 35" tires, ATS turbo, Banks exhaust/intake, pyrometer, tachometer;
    1986 K5 6.2 Blazer, 2" lift, 33" tires, Banks intake, pyrometer, tachometer
    1963 wife, one owner, average mileage for the age but in excellent shape, a keeper
    1992 daughter, low mileage, pretty, limited edition, but requires some money to maintain
    1995 son, sports model, very fast & peppy, time will tell on durability and maintenance costs

    "Grease is good"

  2. #2
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    That will work fine.

    Just be sure to get the thread coil below the area that the knurled shank of the bolt goes into.

    Measure the depth of the shoulder area and place the insert accordingly

    Good luck

    Missy
    (1) 1995 Suburban 2500 4x4
    (1) 1997 Astro
    (1) 2005 Suburban (Papa Smurf)
    THIS IS BOW TIE COUNTRY

  3. #3
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    Will do.

    Always wondered, what is the function of "knurling" on the bolt shank?

    The Helicoil set I have is a standard thread pitch and it doesn't match the factory bolts. I'm guessing they must be metric. So I'm picking up a matching bolt at the store - probably won't have the knurling on it.
    Mark Chapman DP member #653;
    1983 K2500 6.2 Suburban, 4" lift, 35" tires, ATS turbo, Banks exhaust/intake, pyrometer, tachometer;
    1986 K5 6.2 Blazer, 2" lift, 33" tires, Banks intake, pyrometer, tachometer
    1963 wife, one owner, average mileage for the age but in excellent shape, a keeper
    1992 daughter, low mileage, pretty, limited edition, but requires some money to maintain
    1995 son, sports model, very fast & peppy, time will tell on durability and maintenance costs

    "Grease is good"

  4. #4
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    Arrow

    If you use "starter bolts", they'll have the knurling on them. If you use non-starter bolts (smooth shank or all-thread), they'll loosen, and probably cause the starter housing to break, or worse (like break the block). The bolt shank knurling does a better job of keeping it tight than Loc-Tite. The Heli-Coil you need is a deep thread, specifically designed to replace starter mount threads, similar to head bolt repairs. I do not recommend using a hardware store bolt. If you must use SAE bolts, get previous year starter bolts of similar size.
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

  5. #5
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    The knurled shank fits snug in the hole to help take the load off the threads and stabilize the bolt in the hole.

    Yess, the threads on all the bolts in a 6.2/6.5 are metric (except the bell housing bolts are 3/8-16 butttttttt the 96 and later blocks have metric there too

    The Starter bolts are a special dealer item as well, due to the knurled shank.

    This is another portion of the entire package to keep the starters from ripping off the engine.

    With a standard bolt, the bolt can wiggle in the threads some and will eventually wobble out the bolt hole and ultimately break the ear off the block.

    Also, never run without the tail hook attached.

    Missy
    (1) 1995 Suburban 2500 4x4
    (1) 1997 Astro
    (1) 2005 Suburban (Papa Smurf)
    THIS IS BOW TIE COUNTRY

  6. #6
    AKMark is offline Building another 6.2L powered vehicle
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    Napa has always had the starter bolts in their HELP section for a few bucks any time I've walked in there.
    05 2500HD CC LB LLY, 4x4, 3.73s 235/85R16's, webasto cab heater, to keep it warm.
    03 Buick Rendezvous - When you average over 80 miles per day driving around, you need one of these.
    85 K-5, 6.2, SM465, Rockwell T221, 1 tons, 36's. More goodies to be installed as time and money allows.
    82 K20, 6.2, SM465, NP208, stock except for bed rack, snow plow, and glow plugs are on a toggle switch. It works great for plowing!
    72 Postal Jeep - Yet another project

  7. #7
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    Default

    Will hit NAPA on the way home. Did some more internet research and to add to what DMav said, I read that GM used the SAE 3/8 - 16 bolts up to 1981 and switched to 10MM x 1.5 bolts in 1982.

    Thanks for the responses....

  8. #8
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    I'm not a huge fan of heli-coils.... I prefer threaded inserts for a long-lasting repair in high stress applications - like starter bolt threads. Correctly installed with red Loc-Tite, it'll be there for as long as anyone needs it to be.

    Jim

  9. #9
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    Arrow

    Quote Originally Posted by More Power View Post
    I'm not a huge fan of heli-coils.... I prefer threaded inserts for a long-lasting repair in high stress applications - like starter bolt threads. Correctly installed with red Loc-Tite, it'll be there for as long as anyone needs it to be.

    Jim
    I agree. The Heli-Coil (brand) head bolt repair is an insert, not the "spring" thread, typical Heli-Coil. Lock 'n Stitch is another brand I've heard works well. The reason for specifying "head bolt" is that's what the kit is called, but not limited to only head bolts. It'll also help you find them when asking.
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

  10. #10
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    NAPA didn't have the right length SAE starter bolt for me. Think I will follow Jim's advice and go with the metric threaded inserts and use the factory bolts. Never used these before but the look much more stouter. Our local Grainger is suppose to have them, according to their website. I hate non-matching bolts anyway.

    Going on the parts/tool chase again!

    On the down hill side of re-installing my replacement engine. Been a 4 month project. Just haven't had enough free time to work on it plus I've had some roadblocks pop up. Probably have 2 full days of work to get it ready and fire it up. Can't wait.

  11. #11
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    Arrow

    That's what I would recommend.

    Remember when cutting threads, use cutting oil/lube for steel, DRY for cast iron. You can use a non-lubricating tool coolant if needed (brake cleaner works very well). Cut slow, with very frequent turn-backs and back-outs to clear shavings. I usually do no more than about 1/8 turns at a time. Work good, last long time.
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

  12. #12
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    Default spring type helicoil were good for only a few starts.

    I'm planning to put tha Time-sert steel inserts. 10X1.5mm. The kit comes with five 14mm long inserts. That seems to be about the right length. What do you think?

  13. #13
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    I would agree with Jim and Greg EXCEPT

    In this location you don't have the luxury of a lot of material in the block flange where the starter hangs.

    The lower bulkhead is relatively narrow, and removing enough material to screw in a full insert is going to weaken the area a lot.

    The Helicoil will hold all that the original thread will and possibly be a tad better due to the fact that the bolt is tightening into a stainless steel thread, and not iron.

    If the block was twice as wide down there, an insert would be sweet.

    Years ago, I fixed a block for a fellow. The starter flange area had snapped off so we got the block in the mill, cut the area back, raised the flange area 1/4 inch, then added a fabricated and machined piece to replace that which was broken.

    Was a PITA BUTTTTTT, worked sweet.
    Far better than tossing the block, and better than trying to weld it up.

    It's sad that the block was not cast to use a starter with a piloted nose cone and 3 bolts along with the tail support.

    That would have solved a buttload of broken bolt issues.

    Gassers do fine with hanging the starter on the bolts, but the diesels just really stress that plan to the limit.

    Ford has used the piloted starter for years ??????? I wonder why GM decided to cheeze on it ???

    Then again, if the 6.2/6.5 had been set up with a deep full skirt block, and on and on, we likely would not have a lot of the discussions we have here at TDP
    (1) 1995 Suburban 2500 4x4
    (1) 1997 Astro
    (1) 2005 Suburban (Papa Smurf)
    THIS IS BOW TIE COUNTRY

  14. #14
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    Arrow Another tip to everyone

    One thing I can add, for the benefit of everyone, is that loose bolts tend to break the bolt or the block. I put the torque wrench on my starter bolts every time I change oil. No change for a long time, but after replacing the starter, they snugged up a bit at each of the first few oil changes.

    Just an example of a gram of prevention being worth a few kilograms of cure .
    Dr. Lee

    1984 C-10, custom 6.5L SAA, custom 700R4, Gone but NOT FORGOTTEN

  15. #15
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    The big mistakes made on these starters are.

    Leaving the tail support off because its too hard to install (easy if you take the time to do it, especially on the GMT400)

    Using non knurled bolts, is a disaster in the making.

    I still say, that if the block had provisions for a piloted starter, there would be near zero problems.

    A 1/2 to 3/4 inch deep piloted nose cone would fix all the ills of the starter snapping bolts and breaking blocks.

    Hmmmm, the Dmax uses a piloted starter with two bolts, ahhhh, well GM did not do all the engineering ??

    The bean counters were engineering again on the 6.5, instead of those who really understand how to build stuff.

    Well, GM has done it many times.

    Remember the VEGA OMG, What a pos.

    My Dad bought one at a garage sale one time (Sits gagging)

    So many things spark wonder, because so many of us who have engineering backgrounds know better, and just ask HUH, WHAT, ARE YOU KIDDING ME.

    Missy
    Last edited by Robyn; 03-22-2014 at 08:08.
    (1) 1995 Suburban 2500 4x4
    (1) 1997 Astro
    (1) 2005 Suburban (Papa Smurf)
    THIS IS BOW TIE COUNTRY

  16. #16
    AKMark is offline Building another 6.2L powered vehicle
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    I have a buddy with a Vega, it's ugly, but awesome....


    Well, thanks to a 5.7L upgrade, and an overbuilt 700R4.

    Only issue now is it overheats if you idle too long. But moving, it works great. And it moves fast.
    05 2500HD CC LB LLY, 4x4, 3.73s 235/85R16's, webasto cab heater, to keep it warm.
    03 Buick Rendezvous - When you average over 80 miles per day driving around, you need one of these.
    85 K-5, 6.2, SM465, Rockwell T221, 1 tons, 36's. More goodies to be installed as time and money allows.
    82 K20, 6.2, SM465, NP208, stock except for bed rack, snow plow, and glow plugs are on a toggle switch. It works great for plowing!
    72 Postal Jeep - Yet another project

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