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whynot

how to repair a broken bolt hole in the aluminum block

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Need a picture. There’s a lot of options and variations for each option dependent on the specific application needs. Need to see it to decide.

 

“Broken bolt hole” - I am assuming you mean a chunk of metal came out of the block? Or do you mean it cracked or a sheared bolt is left in the block or just threads are mangled?

 

Also we should know what engine and what happened? Broke while removing or dropped the engine or an accident....any other collateral damage?

 

Also - verify it’s the block.

 

If it’s the timing tensioner bolt that is just a bracket and not the bolt. It deceives people who think it’s the block but it’s just a bracket. Remove a couple bolts and swap in another bracket. Used or $25 from Subaru.

 

Also if it’s the head and not the block then you can always swap heads as a last resort or take the head to a good machine shop and they’ll fix it for $150 or less.

 

If a chunk came out of the block you or a machine shop can essentially make a plug that threads into the block.

 

Drill and tap the block to accept a large diameter thread. The outside of the plug will have that same thread and then thread into the block. Then the plug has threads to match the original bolt threads.

 

Or leave the inside hole unthreaded and timesert it after the fact.

 

Welding and pinning and fastener changes can play a role as well in superseding or working in conjunction with a “plug”. As can other methods depending which bolt, what size, how much, and more.

 

Again we need pictures for specific help unless you’re Resourced enough to run with what I’ve given you so far.

Edited by idosubaru
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Try a heli coil, i did one on a spark plug, so they can be used for just about anything.

Head bolt might be shaky, but they do it to old jaguars

What are you trying to fix?

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wow, what a failed post.

This is a 99 outback that I am moving the engine into a non wrecked car. It has been hit in the front, and pushed the power steering pump back and broke the bolts out of the block. 

Thanks 

 

post-62661-0-65959800-1521172277_thumb.jpg

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Take the block to a machine shop or cylinder head shop that is familiar with welding cast aluminium. It will be SOFT when they are done and you MUST heli-coil the holes.

 

Either that or spend about $4k - $8k on a TIG setup and expect a big learning curve. Learn on old water pumps.

 

GD

Edited by GeneralDisorder

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So this is where I am on this car. 

I changed the head gaskets, and it did not last. So I was going to use this engine. The car was hit high by a 4x4 and it mostly curled the hood back and the impact from the tire that made the car look like it hit a tree (from the tire of the truck)

So if I get this cleaned off, and find no other cracks, can I be sure it is ok? or do I do head gaskets on the other car again? 

If taking in for a repair, would I use a welder, or a machine shop?

 

 

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S**t I would just delete the power steering.

My old 92 legacy felt pretty good p/s delete. I understand looping the lines and modding the rack is pretty easy, but i never went that far.

Of course an outback is a bit heavier than a first gen leggo, you didn't mention what car you are installing this engine into.

Oh yeah an old ford escort fan belt will drive the alternator. I deleted my ac as well unfortunately, so no idea on that.

My first subaru hg attempt was a 2.5 dohc and i just slapped it together cast iron style (the only other one i did at that point was a 70 250 inline six for my camaro)

And she blew a hg weeks later because I didn't even use sandpaper on the heads, but the strait edge looked good haha! Then I did it properly and she was good for years.

I'm certainly not suggesting that you unwittingly half assed it like me, but why did your other engine blow the hg?

Why not do both so you can have a spare engine?

Edited by sparkyboy

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So this is where I am on this car. 

I changed the head gaskets, and it did not last. So I was going to use this engine. The car was hit high by a 4x4 and it mostly curled the hood back and the impact from the tire that made the car look like it hit a tree (from the tire of the truck)

So if I get this cleaned off, and find no other cracks, can I be sure it is ok? or do I do head gaskets on the other car again? 

If taking in for a repair, would I use a welder, or a machine shop?

 

Clean all the surfaces, smear The Right Stuff (or something else adhesive) all over the contact points underneath and bolt it down with the remaining bolt up top.  Just leave those two out.  I've seen tons of EJ power steering pumps and A/C brackets not have all their bolts in them, it's almost normal.  Granted I would want two fixed points, but meh if it was my car i'd give it a go as-is as a thought experiment. Check and make sure the existing bolt hole/bolt isn't fatigued from the original failure and if not there's no way it's going to shear just from a pump spinning. 

 

"welder or machine shop"....whichever one has extensive automotive experience with aluminum.  you can always stop in and show them pictures and ask. 

 

a machine shop that works on mining equipment nor a welder that does no automotive work would necessarily win my immediate attention. 

Edited by idosubaru

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Cylinder head shops are usually quite adept at cast aluminium welding. I have had that exact scenario fixed before. My cost was $100.

 

GD

Edited by GeneralDisorder

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Cylinder head shops are usually quite adept at cast aluminium welding. I have had that exact scenario fixed before. My cost was $100.

 

GD

same here.  blocks, heads, timing chain covers, this will be an easy one for them. 

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Well $100 is not bad. GD who did you use, I am not too far  north of Portland. I will check with the one place in battle ground and see wha they say.

I have the missing pieces and was hopping to just JBweld them back on and have it work. I will have to clean the engine really well to make sure that nothing else is broken. it has not ran since the wreck. 

 

 

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That’s some easy welding so any competent shop can do that, about as easy as it gets.

 

I personally wouldn’t bother with JB weld. I realize people swear by it but I find it’s generally a poor substitute or anecdotal celebration. It has its uses ocassionaly but in any kind of real world need with loads and vibrations it’s not often helpful and other situations are easily resolved another way. I see it as pointless here, weld it or use one bolt and call it good.

 

I’ve seen JB welded timing pulley bolt holes fall apart in short order, doesn’t last under real loads and stressful conditions which don’t describe a power steering pump bracket.

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That’s some easy welding so any competent shop can do that, about as easy as it gets.

 

 

 

Not really.  Those bolt holes, especially the "left" one as pictured, are basically ontop of the main oil feed gallery to the entire engine.  Welder could blow through, or melt closed without knowing.  I've actually seen a ruined block from someone drilling through to helicoil a stripped one of those mounts. 

 

Possible that a really good TIG welding expert could do it, but I would make absolutely sure to inform them that just Milimeters behind that hole is the main artery of the entire engine.

 

Personally, for my own car or a mechanically inclined owner, I would use JB weld and the one bolt on top and watch it closely........Or I would find another block.

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I have had those exact two bosses welded due to the same collision damage. Steven of Inferno Fabrications had no trouble at all. But he is VERY good with TIG in general. He has welded cracked AVLS pressure switch bosses IN THE CAR with perfect results. The man is an artist. Given his skills I have no problem handing him that block.

 

GD

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Use oven cleaner (it has lye, so double-check can for "lye"). Can usually get it for around $2-4 a can. Go with generic to save money. It's caustic, but tolerable. Can dull polished aluminum, but stuff like this engine, etc. won't matter. Works better than any degreaser imho. Shake can, spray on, let it foam up for 5 minutes, spray off with garden hose water. Repeat for excessive built up or scrap thick stuff 1st, then apply. Works excellent on cast iron, steel, and fugly aluminum. Price per performance is better than anything else out there. Any kind of oil, grease, etc. it strips to factory fresh castings. Works great on oil pans (inside and out) too, as well as pick up tubes, metal screens, etc.

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