Broken bolt while replacing Thermostat housing

[Jonnsa]

Vauxhall Corsa
2011
110,000 miles
1.4 engine

Attempt made to replace Thermostat housing (that was leaking) on the side of the engine block, one rusted bolt has broken in the process of removing the old part. attempt made to drill out the broken bolt but two drill bits have broken in the process. Have new part ready for install, looking for advice on removing the bolt.

Thanks
Jon

 

[Burnerman]

Really bad luck jon, you have our sympathy!
Best give us a pic if you can, but you'll need a very sharp centre punch and some quality HSS drills......say 3mm to start with.
John

 

[Jonnsa]

Really bad luck jon, you have our sympathy!
Best give us a pic if you can, but you'll need a very sharp centre punch and some quality HSS drills......say 3mm to start with.
John

Thank you, I appreciate the sympathy.

You can see the start of a hole with a 2mm bit, but I guess a 3mm bit is going to be stronger.


It is in a really awkward spot ... I have tried to avoid disassembling the parts around it but may have to remove more to make the repair.

 

[Harry Bloomfield]

Attempt made to replace Thermostat housing (that was leaking) on the side of the engine block, one rusted bolt has broken in the process of removing the old part. attempt made to drill out the broken bolt but two drill bits have broken in the process. Have new part ready for install, looking for advice on removing the bolt.

Either place a nut over the stub, and weld inside the bore of the nut, to the stub, or look around for someone with spark erosion.

For a long time, I ran a car, where a threaded stud and broken on the exhaust flange. To replace the missing fixing, I fitted a G-clamp.

 

[Deluks]

Smear some grease or vaseline on a piece of paper or card, make a hole in the middle and put in around the area to be drilled, it helps catch the swarf, although may not be critical in this location.

These bits are great off the shelf, get a reverse thread bolt extractor set too.

https://www.screwfix.com/p/dewalt-extreme-straight-shank-metal-drill-bits-3mm-x-61mm-2-pack/8924V?tc=VT5&gad_source=1&gclid=Cj0KCQjw4v6-BhDuARIsALprm31cFQS5WvR1GfLaNPCfr5EK95Aw9auFSu00sVBTJPEKxAhZfRu-_RsaAr9vEALw_wcB&gclsrc=aw.ds

 

[Jonnsa]

Either place a nut over the stub, and weld inside the bore of the nut, to the stub, or look around for someone with spark erosion.

For a long time, I ran a car, where a threaded stud and broken on the exhaust flange. To replace the missing fixing, I fitted a G-clamp.

Nice, once I have the plastic housing of the old part off the stub that might be a good option. Thank you for your reply!

 

[Burnerman]

Hmmm bloody hell.
Can you remove the remains of the thermostat housing, so we can see any stub of bolt remaining?
I'd centre punch the middle of the stub, and use a 3mm HSS bit at high speed to see if any impression can be made.
2mm is a bit small, the slightest bend and bang it shears off. Access is your great friend here, if there is any!
John

 

[thomp1983]

If the old thermostat housing is plastic I'd use a sharp chisel to break it up and get it out the way and then see what your left with

 

[Jonnsa]

Smear some grease or vaseline on a piece of paper or card, make a hole in the middle and put in around the area to be drilled, it helps catch the swarf, although may not be critical in this location.

These bits are great off the shelf, get a reverse thread bolt extractor set too.

https://www.screwfix.com/p/dewalt-extreme-straight-shank-metal-drill-bits-3mm-x-61mm-2-pack/8924V?tc=VT5&gad_source=1&gclid=Cj0KCQjw4v6-BhDuARIsALprm31cFQS5WvR1GfLaNPCfr5EK95Aw9auFSu00sVBTJPEKxAhZfRu-_RsaAr9vEALw_wcB&gclsrc=aw.ds

Nice, thanks for the link!

 

[Jonnsa]

Hmmm bloody hell.
Can you remove the remains of the thermostat housing, so we can see any stub of bolt remaining?
I'd centre punch the middle of the stub, and use a 3mm HSS bit at high speed to see if any impression can be made.
2mm is a bit small, the slightest bend and bang it shears off. Access is your great friend here, if there is any!
John

Yeah that is a good shout with the centre punch.

 

[Jonnsa]

If the old thermostat housing is plastic I'd use a sharp chisel to break it up and get it out the way and then see what your left with

Yeah getting the housing off is definitely going to be the next step! I have some chisels, how sharp they are is questionable!

 

[Burnerman]

If there is a trace of a stub visible, then Harry's advice on post #4 is well worth considering.......someone good with a MIG could weld a nut on, and the intense heat produced would be a great help too on getting the thing undone.
Of course, you have to get the damn car there somehow.......
Be lucky!
John