Broken head bolt...Dammit!

Maverick2518 · Apr 16, 2018

Good evening to all.

I’m in a bit of a jam and I was hoping for some advice/info.

Started stripping my series LR and one of the head bolts has snapped in the block... couple of questions...
What are my options? Is it repairable?

A friend mentioned heli coiling it, but it’s my it something like 7/16 UNC whitworth...what are my chances of finding that! Haha

Maybe someone’s had the same issues and can help? Bar replacing the block ofcourse! Haha

Mav

The Mad Hat Man · Apr 16, 2018

is there any bolt protruding?

pics needed

Turboman · Apr 16, 2018

Maverick2518 said:
Good evening to all.

I’m in a bit of a jam and I was hoping for some advice/info.

Started stripping my series LR and one of the head bolts has snapped in the block... couple of questions...
What are my options? Is it repairable?

A friend mentioned heli coiling it, but it’s my it something like 7/16 UNC whitworth...what are my chances of finding that! Haha

Maybe someone’s had the same issues and can help? Bar replacing the block ofcourse! Haha

Mav

If it is below the level of the block, have you tried drilling it out?
Should be possible to remove it without damaging the block, if you are careful.
Drill it out with cobalt bits, increasing in size, until you can pick out the threads with a sharp point.
Might be worth trying an easy out when you have drilled a decent size hole in it.

Helicoil inserts should be available if you get it wrong.

jamesmartin · Apr 16, 2018

is it a v8 ,it wont be unc whitworth if its a v8 it will be unc,helicoil or similar type is a good fix for spoilt block thread make sure you get the right length

Maverick2518 · Apr 16, 2018

Cheers for the info guys.

I probably should’ve said it’s a ‘71 3.5 Rover V8.

Just been on the phone to a thread removal guy and he didn’t seem to convince me it was going to be a breeze

I’m tempted to try the LH drill bits but now I’ve spoke to the guy, I don’t want to try, cock it up, and then call him anyway! Haha

Turboman · Apr 16, 2018

Maverick2518 said:
Cheers for the info guys.

I probably should’ve said it’s a ‘71 3.5 Rover V8.

Just been on the phone to a thread removal guy and he didn’t seem to convince me it was going to be a breeze

I’m tempted to try the LH drill bits but now I’ve spoke to the guy, I don’t want to try, cock it up, and then call him anyway! Haha

It isn't easy, but it is quite possible for someone with reasonable mechanical skills, and good tools.

Remember that the thread removal guys living depends on people not doing it themselves.

Maverick2518 · Apr 16, 2018

[GALLERY=]

Here’s a few pics of the lil bugger

freelance · Apr 16, 2018

As they say “ fortune favours the brave”!

jamesmartin · Apr 16, 2018

drill it out ,small the increase size gradually, once near use one of these ,drills are good quality and are the best type for stud removal, the tubes help you center the drill bits

The Mad Hat Man · Apr 17, 2018

@jamesmartin
Linky reqd

freelance · Apr 17, 2018

Stahwile make those, I have a set, they are very good

Turboman · Apr 17, 2018

Maverick2518 said:
[GALLERY=]View attachment 147028 View attachment 147029 Here’s a few pics of the lil bugger

Try using a good quality point ended punch to make a small ding in it as dead centre as you can, and proceed as suggested^^^^^.

freelance · Apr 17, 2018

jamesmartin · Apr 17, 2018

The Mad Hat Man said:
@jamesmartin
Linky reqd

google blue point e-1020 stud extractor set there are other brands

MattMatt · Apr 17, 2018

I drilled the stud out on my Jag engine quite successfully but the threads were poo so I had to use a good quality helicoil kit. it would have been much easier if I had a good big drill press or mill as getting it straight was difficult freehand. When it happened to my mate, his local machine shop took 1 hour to set it up in the press, 30 seconds to back it out using a LH drill. I'd go that way if it happened again

Maverick2518 · Apr 18, 2018

So bit of a sit rep... LH still bits have turned up, just waiting for the courage to commit to do the same! Haha.
Found a 7/16 unc helicoil style kit which isn’t badly priced too. However... for anyone that’s done this previously...are the inserts in these kits long enough to take the head bolts? ‍

jamesmartin · Apr 18, 2018

Maverick2518 said:
So bit of a sit rep... LH still bits have turned up, just waiting for the courage to commit to do the same! Haha.
Found a 7/16 unc helicoil style kit which isn’t badly priced too. However... for anyone that’s done this previously...are the inserts in these kits long enough to take the head bolts? ‍

try recoil kits and you can get different lengths

Ratae · Apr 18, 2018

Maverick2518 said:
Cheers for the info guys.

I probably should’ve said it’s a ‘71 3.5 Rover V8.

Just been on the phone to a thread removal guy and he didn’t seem to convince me it was going to be a breeze

I’m tempted to try the LH drill bits but now I’ve spoke to the guy, I don’t want to try, cock it up, and then call him anyway! Haha

The main risk is breaking a drill in the remains & if that happens & it's stuck then you really do have a problem as you've now got hardened steel to deal with & spark erosion may be the only solution.

During head removal I snapped an inlet manifold bolt in one of the heads on mine (RRC V8), lots of rust & corrosion visible around the remains.
I did consider diy, but not wanting to risk making a mess I took it to a local engine reconditioners I've used from time to time over the years & left it with them.
They used a similar type of tool to the one that jamesmartin pictures & got it out without issue.
I still have the remains of the bolt with a hole dead centre as a souvenir.

Appreciate you may be unlikely to be able get the block to an engineer so are relying on a mobile guy but if he's established he's going to have the kit AND the experience to do it.

ETA. As jamesmartin says, you can get various lengths of helicoil & if you already have a set with the correct drill & tap you can find them at engineering stockists or ebay & I've had them from both.

eightinavee · Apr 18, 2018

I once had a Rover v8 in my workshop that had 5 snapped studs. I removed all of them by mig welding a blob on the top of them then used a stud extractor made by Klinn,looks like this;
Amazon product
Most of them required more than one go,but the heat of the weld helps to release the remaining bolt or stud.The good thing is that you don't run the risk of snapping a drill or extractor in the block,or that it might go off centre.

purplemk · Apr 20, 2018

Looking at the photos I would definitely second welding a washer then nut to that and I'm sure it would back out without damaging the threads, I've done lots like that. Drilling it out is very difficult to do properly with a hand held drill, you will almost inevitably be slightly off center or off square and damage the original thread and then the only option is a heli, I'm sure for some they have worked fine but to me thats a bit of a bodge repair and I would not want to use one on my car if I could avoid it, original threads are always going to be a stronger safer bet in my view.

Broken head bolt...Dammit!

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