B7100 question: Is this a broken head bolt?

[Sir Thomas Crapper]

I went out and started my 7100 yesterday Battery tender was hooked up, so hood was up. I saw a small squirt of anti freeze pop up from the head, then noticed a bolt head missing. Consulted my manual, but it doesnt really address head bolt location. Inserted a small screwdriver into the hole, went in about 1 1/4".

Either way, does anyone know what size and whether if its a broken head bolt, can I get it out with a left handed drill bit or extractor rather than pulling the whole head?

 

[GeoHorn]

Sure looks like it. If it is a broken bolt (and not one completely missing) I doubt you’ll get it out without pulling the head unless you’re willing to accept the risk of causing even more damage working thru the casting.

 

[85Hokie]

Im with GeoHorn -

Broken head bolt - and a PITA to get out .....,
You are going to have to remove the head ..... and a new gasket ....and a new bolt!

 

[Lil Foot]

I would agree, if it is a broken head bolt, pull the head, remove the broken bolt, new head gasket, o-ring, and replace all the head bolts.

 

[armylifer]

I agree that it is a head bolt that is either missing or broken. Before you take it apart, you may want to try shining a flashlight into the hole to check if you can see a broken piece of the bolt in the hole. If you cannot see a jagged piece of broken bolt in the hole, try carefully threading a new bolt in the hole by hand only. No tools. If the bolt threads in all the way or most of the way, then you may have gotten lucky and just lost a bolt that came loose for some reason. Just be sure that you are using a replacement bolt that is for that hole. Sometimes head bolts are different sizes and must be the correct bolt for that position on the head.

 

[North Idaho Wolfman]

Ditto on others info.

Really odd to see that!

One other thing to try is a magnetic pick up tool
put it in the hole all the way till it bottoms the spin it counter clockwise and see if you get lucky, I done quite a few like that.

The fact that you are getting antifreeze out of that bolt hole leads me to believe either the head gasket is damaged, or the bolt is completely missing.

 

[Henro]

Ditto on others info.

Really odd to see that!

One other thing to try is a magnetic pick up tool
put it in the hole all the way till it bottoms the spin it counter clockwise and see if you get lucky, I done quite a few like that.

The fact that you are getting antifreeze out of that bolt hole leads me to believe either the head gasket is damaged, or the bolt is completely missing.

Just a question from a no-nothing guy that is interested.

NIWM, do you mean that broken head bolts or missing head bolts are common?

I do not have a clue, but curious...

 

[North Idaho Wolfman]

Just a question from a no-nothing guy that is interested.

NIWM, do you mean that broken head bolts or missing head bolts are common?

I do not have a clue, but curious...

No, I mean missing or broken head bolts on that engine are very Uncommon.
When I said "quite a few like that" I meant spun out broken bolts with a magnet, not those head bolts.

 

[xrocketengineer]

No extensive experience here but if the bolt is broken, I would put some PB Blaster in the hole and let it sit. Then try to mark the center of the bolt wit a narrow center punch and try a set of these:

Left Hand Drill Bit Set, 13 Piece

Amazing deals on this 13Pc Left-Hand Drill Bit Set at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

You might get lucky if you are careful.

 

[dlsmith]

When broken head bolts were common on Cummins NTC truck engines, I was taught a trick by one of the old hands I knew to get them out with a steel rod and welder. I wrapped the rod, 1/4" to 3/8" and a foot long or so, in electrical tape leaving only a couple of inches at the top to attach the stinger, and 1/8" to 1/4" bare at the bottom
Fire up the welder and set it for 100-130 amps, ground the welder on the block, stick the rod in the hole keeping it as centered as possible, touch off on the broken bolt stub, letting it arc for just a second or two, then stick it down on to the stub to stop the arc and stick fast to the stub and pull the stinger off the rod. Let it cool for a few seconds and put a pair of vise grips on the rod and spin the stub out. Never failed to work for me.
I must add that I always did this very soon after the bolt broke, so nothing ran into the hole to rust it fast.

 

[armylifer]

When broken head bolts were common on Cummins NTC truck engines, I was taught a trick by one of the old hands I knew to get them out with a steel rod and welder. I wrapped the rod, 1/4" to 3/8" and a foot long or so, in electrical tape leaving only a couple of inches at the top to attach the stinger, and 1/8" to 1/4" bare at the bottom
Fire up the welder and set it for 100-130 amps, ground the welder on the block, stick the rod in the hole keeping it as centered as possible, touch off on the broken bolt stub, letting it arc for just a second or two, then stick it down on to the stub to stop the arc and stick fast to the stub and pull the stinger off the rod. Let it cool for a few seconds and put a pair of vise grips on the rod and spin the stub out. Never failed to work for me.
I must add that I always did this very soon after the bolt broke, so nothing ran into the hole to rust it fast.

I have seen a variation of that tactic work. It takes a modicum of skill and luck to make it work. It s worth a try if other less powerful methods fail.

My choice would be to just pull the head before I went to the welder stick method though. One wrong move or unsteady hand and you could weld the threads and end up with a much larger job on your hands.

 

[D2Cat]

I have seen a variation of that tactic work. It takes a modicum of skill and luck to make it work. It s worth a try if other less powerful methods fail.

My choice would be to just pull the head before I went to the welder stick method though. One wrong move or unsteady hand and you could weld the threads and end up with a much larger job on your hands.

I agree, remove the head. Much easier to get the bolt out and a new head gasket will asure it's all sealed when you get it back together.

 

[retired farmer]

ThinK i would try to center punch, left hand drill bit, then an ease out. Sometime I have been lucky
and gotten the bolts out. If that didn't work it would be off with the head.

 

[whitetiger]

ThinK i would try to center punch, left hand drill bit, then an ease out. Sometime I have been lucky
and gotten the bolts out. If that didn't work it would be off with the head.

He said it was leaking coolant from the hole, the head needs to be removed anyway to replace the head gasket.

 

[GeoHorn]

EXACTly as whitetiger posted... even if successful extracting the broken stud... the risk of leaking coolant finding another pathway into a cylinder and causing a hydraulic-Lock possibly ruining the engines is simply too great. Do this right. Remove the head, extract the stud, inspect head and block and reinstall with new gaskets.