Sheared Bolt In The Block

[Obey_R 23]

Whilst changing the alternator, the bolt that holes the adustable bracket onto the block broke off - I've got about 2mm left sticking out of the block

 

What are my options? That is the only bit holding tension on the alternator, so it's not like I can just go without it being there.

 

It's right at the front of the block, behind the radiator so I can't even drill the old bolt out as there's only about 8 inches before the rad.

 

 

Any ideas?

[Obey_R 23]

[Anthony 1,003]

How on earth did you manage to snap it? You don't need to touch it when removing the alternator.

 

If the bolt is stuck in the block, then you'll likely have to remove the radiator to drill it out - you might be able to get a right-angle drill adapter in there, but it's not a particularly difficult/long job to drain the coolant and remove the radiator and I'd personally go down that route. If the bolt is stuck, I'd be very wary of trying an easy-out in there - snap one of those off in the block and you're in a whole world of pain.

 

From memory, it's just an M8 x 1.25 bolt, so it's a very common tap size if needed.

[Obey_R 23]

No I shouldn't have had to remove it, but the bolt in the tensioner/adjusted had also seized, so it wouldn't slide at all. So me being me, thought if I removed the whole assembly I could free up the other bolt when it's off the car - which still isn't free, the casting of the old alternator broke before the bolt has even started to budge!

 

Would it be possible to weld the braket back on?

[smithy 1]

as anthony said rad out and drill it out do not be tempted to use easy outs as they are impossible to remove if they snap in the bolt.

 

get some decent drill bits and gradually work up the sizes you will find when the remains of bolt are really thin a small screwdriver should be able to pick it out,then clean threads with a tap.

[Tom Fenton 1,548]

This is how I would do this.

 

VERY important, do not heat this up. Once you have heated it hot enough you will not be able to drill it. Heat absolute last resort.

 

I have a 90 deg air drill but otherwise remove the rad to make enough room.

 

Next with a grinder very gently tickle the head of the protruding part of the bolt so you have a nice flat surface. Do this slowly and gently as if you get the stud too hot you will draw the carbon to the surface making it pot hard so you cannot drill it.

 

Now with a decent centre punch pop the centre as accurately as you can. Again important to do this well.

 

After that it is just a drilling job, forget any cheapo drills they are s*ite, get hold of some good quality Ti-N coated drills, forget B&Q, find an engineers merchant.

 

Then carefully start with a small size say 3mm, drill a pilot, keep as square to the face as you can. Increase up in size, in stages, up to 6.5mm. This is 0.25mm below M8 root size. If you have drilled reasonably square you should now be able to pick the remains out of the block with a sharp scriber. Try up to 6.8mm if you struggle here.

 

If you still can't get it out then you will need to get a helicoil kit, drill oversize (8.2mm typically for M8 helicoil) and then wind a helicoil insert in.

 

NOTE- if you drill too deep you will break through the water jacket! So go careful on depth.

[Obey_R 23]

Brilliant, just my luck!

[Obey_R 23]

Right, the radiator is off, one of the screws in the slam panel has been rounded off previously so had to drill that out, but that's the last of my worries now.

 

One good thing is now that the radiator is off and drained at least I can get the heater matrix done, which has been waiting a while.

 

Good job I sorted my bike out yesterday, I'll be biking 20miles a day for work now!

[Obey_R 23]

Just a thought, instead of trying to get all of the old bolt out, is it possible to just drill and retap what is left of the old bolt to take an M6, or would that be just as much trouble as trying to get the old one out?

 

Was thinking that would mean it wouldn't need to be perfectly square and have to get every last bit of the old bolt out?

 

Oh and how long is the bolt that is in there? I don't want to drill too deep like Tom says.

Edited March 7, 2011 by Obey_R

[Bigtimmy 1]

Just a thought, instead of trying to get all of the old bolt out, is it possible to just drill and retap what is left of the old bolt to take an M6, or would that be just as much trouble as trying to get the old one out?

 

Seems silly to get 90% of the way to doing a proper job then botching the last 10%.

 

If it's worth doing it's worth doing right!

[welshpug 1,666]

As you drill down the centre of the bolt you will feel a change in the resistance as you hit the bottom of the bolt, stop right there, as you will cut into the alloy below.

 

I dont think this part of the block is near the water jacket at all, as its on the lower half of the block where the bearings sit.

 

I dont think the bolt is particularly long there, have a look at servicebox though, it shows the specs for most fasteners, will be handy for finding a new bolt too

[Obey_R 23]

Well without a centre punch the hole went off centre, so I drilled to about 15mm and have then re-tapped it in M7x1. I'll get a new bolt tomorrow and hope for the best!

 

I know it's not the best way of doing it, but with limited time and tools, it's about all I could do.

 

Whilst the system was drained I had the heater matrix out with the intention of swapping it over, but it doesn't seem to go all the way in? It sits about 1cm out of the heaterbox, no amount of whacking and wiggling can get it in!?

 

Does it matter if it sits out of the bot a little? I guess some hot air will be lost out of the gap, but other than that? Or what's the best way of getting it in? The leading edge seemed to be a very tight fit when first putting it into the heaterbox, so maybe it's just as tight at the other end and doesn't want to go in?

 

What a wonderful day I've had!

[welshpug 1,666]

have you removed the packaging off the bottom end of the matrix? they sometimes have a plastic piece you need to remove.

[Jrod 7]

I hope I never buy a car from you! Bodged bolts, half fitted heaters... I know you want to get it back on the road but it really is worth putting in a bit extra time and sorting jobs properly.

[Obey_R 23]

I hope I never buy a car from you! Bodged bolts, half fitted heaters... I know you want to get it back on the road but it really is worth putting in a bit extra time and sorting jobs properly.

 

 

Just so nobody thinks my car is a complete bodge should they buy it off me. I got the heater matrix fitted properly, replaced the pipes with new seals, bolts etc and refitted the original matrix. The bolt in the block, I removed the radioator, drilled it out, picked the threads clean, retapped it and refitted a new bolt, along with a freshly cleaned adjuster, alternator and drive belt

Edited April 9, 2011 by Obey_R

[petert 601]

An alternative to Tom's advice, is to still drill a pilot hole, but stop at 4mm or so, and hit in a high quality Torx bit. The Torx bit has to bite into enough metal to get a good grip. Then you'll be able to unwind the broken bolt. Don't forget to spray some Penetrene (or similar). If the Torx bit idea fails, just keep going with the bigger drills as per Tom's advice.

Edited April 10, 2011 by petert

[Obey_R 23]

There was no way that bolt was going to move unless it will drilled out. Anyway all sorted, just wanted to say it's not a total bodge!

[omega 82]

There was no way that bolt was going to move unless it will drilled out. Anyway all sorted, just wanted to say it's not a total bodge!

 

well done for fixing it

its alright for people to say only do it a certain way but when you have limited tools and you need the car you have to find a way that works for you.

and i bet there are very few 205s out there without "modifications".

[jeremy 71]

Too late now but the bolt hole depth is between 29mm to 30mm deep.