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Drilled through stuck intake bolt... and head bolt.


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Well kids, let this be a lesson to you. Don't indulge your insomnia by performing critical repairs at 3am, you might forget something small, like resetting your depth marker for drilling out your intake bolts.

 

So, I had the rear intake bolt on each side of an EA82 snap off during careful removal. The stubs are completely chem-welded into the block, and multiple days of point blank heat gun, penetrating oil, left hand drill bits, cold chisel, etc failed. I cut the first one off flat , and noticed that the smaller drill hole was not center enough to keep drilling it out and Time Sert it. I used transfer punches in the manifold and checked their center locations against a factory gasket, and made a drill jig out of a 1 inch block of cold rolled steel on my mill. I bolted it up and it looked perfect. Thats when I failed to remark the depth stop, and plunged through the bottom of the intake bolt.

 

If you are working on the head on a bench, this doesnt matter, because you will drop into air when you hit the passage for the headbolt. On the car however, you can cross drill a 1/4' hole allllllllll the way through the headbolt itself. Then you get to feel very smart.

 

So, my inclination is to pull the engine, pop off the cam carrier, and replace that one damaged headbolt. Anyone with more engine experience see a reason this wont work? Or a reason why I shouldn't have to?

Edited by Corvid
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Show us the damage & we might be able to work out what the next move is ... ;)

 

Add : It'll depend on how far you drilled through it - Bolts can be replaced, but If you drilled through any water passages ... :/

Ciao, Bantum ...

Edited by Bantum
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I'm not sure about what to do with the head bolt as far as remove and replace. But if yo decide to try to remove it, get the block up to near normal operating temperature with heaters and a heat gun. Meat thermometer or something to monitor. I have removed many very stuck bolts intact with that method. It has not failed. Once a bolt is snapped, my next trick is weld a nut or washer to the stub, then unscrew. This I learned before the heating the block trick, but it works once the damage has been done. I mention these also to possibly save others trouble if they read this before snapping a bolt...

 

The drilled through headbold may fail where it was drilled, so you may be removing the head....

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The drilled through headbolt may fail where it was drilled, so you may be removing the head....

 

Oh, I know. This was supposed to be a Weber Swap, and its ending up more like the beach scene in Saving Private Ryan.

 

It's not my first rodeo, but some jobs just have the curse.

 

I'd love someone to explain to me why I haven't compromised the holding strength of the headbolt, and that I should leave it there.

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For anyone that missed it in the first post, I drilled all the way thru the headbolt. There isn't a coolant passage that I am aware of in jeopardy.

 

What's even better, is that the intake bolt hole is slightly offset to the headbolt through-passage, which means I didn't cross drill the headbolt in the middle, but just barely wiped out one edge of it. What are the odds getting THAT out without snapping it off?

 

If I hadn't ruined the headbolt, this would be a triumphant day. By making a drilling jig to core out the center of the broken intake bolts with a 1/4" drill, I was able to leave just the bolt threads hanging out in the block threads. I twisted a few coils out with a pick and needle nose pliers, and than carefully ran a M8x1.25 BOTTOM tap down the holes. If you do this, use thread cutting fluid and a real High Speed Steel tap, not some grey carbon-steel trash from Ace Hardware.

 

Saved both the holes, pretty as a daisy, no Time Serts.

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  • 1 year later...

I was putting the heads back on my EJ22 and snapped head bolt #3. I got brand new fel pro bolts and gaskets. My manual said to torque to 22, 51, back out 180˚, back out 180˚, then torque the middle 2 to 25, then start on 3,4,5,6 to 132 for non-turbo. I can't seem to figure out where I went. Thoughts, suggestions?

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Welcome to USMB. 

 

EJ is a newer generation engine.  You will likely get more replies for this question in that sub forum. 

Do you have a factory service manual?  There are links on a lot of new gen forum threads to online ones.

 

Probably best to start a new thread, rather than adding to a year old one.

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I'd use used Subaru head bolts before aftermarket head bolts.

 

You're saying one head bolt broke right?

 

1. Chase the threads first with a tap before installing the head bolts. Pay particular attention to the bolt hole that snapped.

 

2. Carefully oil the threads - not so much that it pushes out and runs everywhere.

 

3. Thread the bolt by hand without the head first so it's not under any tension and see how easily it installs.

 

4. Verify your torque procedure

 

5. Verify the units you're using - are you converting or how does your torque wrench read?

 

6. Test or calibrate your torque wrench. How old is it?

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I'd love someone to explain to me why I haven't compromised the holding strength of the headbolt, and that I should leave it there.

Wish I had seen this last year. No way I'd worry about or touch it. That headbolt isn't going anywhere nor going to "give up" any tension or cause any issues. I mean look at your intake bolts - they're screaming at you that there's no chance those bolts are giving any ground without specific focused applied forces.

 

I'd love to hear what you ended up doing.

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