How to have several hours of fun with starter bolts

Who knows what this is?

Freaking snapped off starter bolt on GM engine

NDT said:

Freaking snapped off starter bolt on GM engine

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GM and their one use bolt (if it makes it through one use).

At least you have both pieces in one spot.

Tinstar said:

At least you have both pieces in one spot.

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After spending several hours of work with tweezers and a pick to make this reunion possible. (I didn't have my drill and left handed bits with me).
At least now I know why GM sells the starter bolts in boxes of 5.

As to why the bolt broke: the stud AND nut holding the starter bracket and gear reductions starter were gone.
Now I'm not sure if the starter used metric or standard bolt.
Usually a US made starter would be standard , but if it's made in china, then it's gonna be metric.

Update: So the starter is not made in China.

Been there, done that. The knurling on the shank gives it away. Great job getting it out!

Ive done it so many times and it still irritates the heck out of me.

Put plenty of anti-size on the new bolt

M543A2 said:

Put plenty of anti-size on the new bolt

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i replaced both bolts and used plenty of copper grease. And red locktite on the two bolts of the support bracket.

Just get some good "grade 8" bolts and use anti-seize on the threads. After I switched I never had another bolt break again.

Grade 8 will still fail, especially if the support bracket is missing.

rustystud said:

Just get some good "grade 8" bolts and use anti-seize on the threads. After I switched I never had another bolt break again.

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Ive seen grade 8 bolts shear off. Besides I rather have a bolt break, than the bolt rip out the threads of the starter bolt hole.

Leroy Diesel sells an arp starter bolt set,supposed to be an upgrade.

I guess I have been fortunate.

In ten years of daily driving the M1028A2 I have had no bolt problems.

Can only think of one instance of bolt failure in 30+ years of owning and driving
GM 6.2 Diesel powered trucks.

You must keep the rear starter bracket in place and Don't fiddle with the IP Timing.
The IP must be correctly timed and any attempts to advance it results in starter
Kickback and broken crankshafts.


I have seen plenty of military cucv's with the pump improperly advanced trying to
Get more power.
Kind of surprising really when you think the motor pool mechanic's
Would not have done such a dangerous trick.
Of course I guess engines are plentiful so to them it's business as usual.
Tom

I also have been fortunate and never had any bolts break on my CUCV starters. I use them starter bolts once and toss them. I go as far as smashing the threads on the anvil. Same as glow plugs. I break the spades off bad ones. I have however bought a few CUCV's that had starter bolts broken off. Worst case senario was an M1028A1 I bougt in Flint, Michigan off of Ebay back in 2005. A beautiful 23K truck in excellent condition. I paid $2K for it because it had both starter bolts broken off in the block. It had a half dozen drill bits in the one inner bolt all broken off and an easy out broken off in the other outer bolt with a drill bit also. The outer bolt with the easy out I spent 8+ hours messing with. I used a torch and very little patience. I was successful. The inside one was a real treat. I ended up pulling the engine and putting it on a engine stand inverted and getting the broken bits and bolt out that way. If not for 2 1/8" bits broken close to the outer edge it would have came out easily. It also had a bolt broken off in the support hole of the block. The starter was hanging by the cables with the support bracket. The man I bought the truck from said they came from the fire service sale and they did not want to spend the time and money getting it fixed. Good deal because my Son ended up with the truck and he thrashed it for 13 years until he sold it last summer. That truck went from home to Camp Lejeune many times. That truck eventually became Mr. Crusty and was sold last year. I am glad he sold it. I was tired of working on it and seeing it regress backwards. Have a Great Day. Keep your starter bolts torqued and your support bracket tight and in place.

doghead said:

Grade 8 will still fail, especially if the support bracket is missing.

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True, the reason the bolts fail is fatigue. Not from excessive force. Grade 8 have higher yield stress yet lower cyclic fatigue strength than grade 5. This is why removal success rates are quite high as the threads are not stretched. And usually coated with oil.