94 Ford Escort extracting broken Bolt

MWALDEN89

MEMBER
1994 FORD ESCORT

So my van had an intake issue with the radiator we knew nothing about till on a road trip and it ultimately waited to throw on the tempature warning a good 30 seconds before it caused my engine to blow. This I know however my husband has a 94 ford escort he’s been trying to repair for some time. As he was removing the bolts one busted. He was still able to replace the thermostat but as we know it’s not a good idea to just jb weld the seal and go about our day. So he has tried a bolt extractor and it worked on one of the broken bolts but one the threading is broke right on the edge of the housing block. He tried searching for help but all we get are people advising we heat up the block and extract it and being that it’s an aluminum block in the middle of winter I don’t have to explain why that is a very bad idea. So he purchased a tap and die set but no matter what he’s tried he says he needs a high powered drill to extract it and isn’t sure what type of bolt to replace it with and when taking it to the local automotive places no one can give him an answer (odd in my opinion) I’m disabled and been having to walk just about everywhere despite this and am ready to go out while he’s at work and just try and do it myself since he clearly can’t while at work. This is something I’ve never done because on my caravan it was much easier because bolts never busted on me. Any help on what can successfully get this car up and running for the sake of my feet and my children would be immensely appreciated!

Wednesday, January 23rd, 2019 AT 5:29 AM

1 Reply

STEVE W.

MECHANIC
15,233 POSTS

Welcome to 2CarPros.
Broken bolts can be very frustrating, being in the rust belt I get to deal with them a lot. The reason folks are suggesting using heat from a torch around the hole is because the aluminum will expand faster than the steel bolt. That effectively makes the hole larger. This is needed because the reason the bolt is stuck is due to galvanic corrosion. The steel bolt and aluminum corrode into each other and it effectively welds them together. The heat breaks the bond enough that you can get some type of lube into the threads. Then you can proceed with removal.
My first thing after heating is to use a punch just smaller than the bolt. Place it so it's in the center and give it a couple good hits with a hammer. This helps to break the corrosion free as well. Next depends on what tools you have. I generally will weld a nut to the broken bolt if it is flush or barely sticking up from the casting. However for that you need a welder like a MIG or TIG.
If it is below the surface I center punch the bolt very carefully, then use a left hand drill bit to drill a small pilot hole through the center of the fastener. Then I increase the size of the drill bit until it is just inside the bolt threads. Usually I will also heat the casting between drilling attempts. Once drilled to the threads I will use a sharp pick to remove the thread coil from the casting. Then run a tap into the hole to chase the threads clean.

If the above doesn't work the other option is to drill the entire bolt out then install a Heli-Coil or another style of thread insert. That allows the use of the original size and style of fastener which can be important in some places. With these you buy the kit in the correct size and follow the directions. When finished yo have nice new threads.

I try to avoid drilling and tapping to an oversize because most parts barely have the material for the original size used and depending on the hole it can be easy to drill off center and damage parts.

For a few videos showing various methods go to you tube and find South Main Auto Repair then search for broken bolt. Eric shows a few options and how they work.

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Wednesday, January 23rd, 2019 AT 9:30 AM