Sheared engine mounting bolts in VX car

[Scotland North AR]

Hi to all, had a great run out over the weekend driving in shirt sleeves in Scotland!

Weekend marred by mysterious shearing of driver's side engine mounting bolts on my pal's car.

Could have worked loose over time leading to more engine movement leading to weight on the bolts leading to them shearing. Maybe hit a bump. Result all the same.

The car is currently being recovered home to have a closer look. The bolts are snapped off a couple of mm inside the engine block casting i.e. nothing sticking out to get a grip on. The recovery garage has tried to tap them around with a punch we think but without success.

Obviously want to avoid taking the engine out to get at the bolts with a drill and "easy-outs" but may have to buy a right angled drill and do the same thing with the engine in place.

The car is a 1997 S3 Vauxhall Red Top with 20,000 miles on it built by my pal and current owner.......and fellow Lotus 7 Club member.

Any pearls of wisdom much appreciated.

PS car in Aberdeen area.

[blueyedbiker]

Be VERY VERY careful using an Easyout, if it should break off it's more than likely good bye block.  If possible a drill out plus Helicoil is a better solution but again, be careful drilling in case the drill snaps.

Good luck!

[Paul Deslandes]

I can't imagine why that might have happened unless they were overtightened.  Either that or some or all were loose allowing them to fatigue.

To get them out I would remove the inlet carbs and manifold/injection system and the steering column so that you can get at the holes.  You really need a good clear view of what you're looking at so, if drilling, you can go in straight and perpendicular.

Ideally you'd want to spot weld something to the end of the broken bolt that can be used to unscrew the broken remains. I've never had much success with stud extractors but the original bolts are M10 so there might be enough meat on them to risk drilling and using a large stud extractor.

Whatever you do, take your time.

Best of luck

Paul

[Nick T]

A technique I have used in the past on a xflow engine mount bolt, is to drill a small hole 3-4mm-ish into the offending bolt/stud and gently tap a torx bit into it. This, if you are lucky will allow you to unscrew the broken bit.

The advantages of this is that it tends not to spread out the stub as an easy-out does and you still have the option of drilling a bigger hole and using a bigger torx bit.

Cheers

Nick  

[SPA]

Finally logged in!  Big thanks to Nigel for posting this before I had chance.  And a thanks for the feedback also.

Car should hopefully be delivered tomorrow and I can get first proper look at what we're up against.  Cause is a strange one - Bolts have been in there 20 years - and they weren't over torqued.  Coming loose and the resulting play leading to failure seems more plausible....?

For sure I won't be rushing into it!

[ECR]

Not heard of this happening before on a VX so its a bit of a mystery. If I were you, I'd invest in a left hand drill suitable for drilling hard materials. I have a set of three from ebay. The heat produced by drilling plus the left hand rotation of the drill is often (but not always) enough to pull the broken stud out. You can still then use the other methods suggested above if the drilling doesn't remove it

[7 wonders of the world]

Had to deal with many a sheared stud over the years.......

Spend a good 15-20 mins just tapping a centre punch in the centre with a toffee hammer, the vibration will help free the stud from its surroundings, many time you will find it starts to move with this alone

if its flush I've had great success using a size smaller nut, so assuming these were M10 use an M8 nut and carefully tack this in place with a MIG, squirting the weld thro the nut onto the broken stud , the smaller nut reduces the chance of catching the block, the heat will also help to free things off,

Obviously if its sheared off some depth in this is no the best option.

As to cause, maybe overtightened, though usually they work loose and the mount then rocks and with the leverage pops the head off.

New bolts or capheads with Schnorr lock washers....

[Ed White]

The above is as good a description of how to remove broken studs as i've seen. I've done a fair few over the years in allsorts and would tackle it in a similar way. 

ps remember if using left hand drills you need to rotate them that way, easy on a modern good cordless. I'd use lube to protect the drill bit though which might prevent the heat transfer into the stud.

[blueyedbiker]

I'm not familiar with a VX block but I had a similar problem years ago with alternator bracket on a X Flow, it would even ping the heads off cap heads.  It was eventually traced to  the boss cast into the block which had a small piece missing.  The solution was to grind the boss face flat again and pack out with washers, there was still enough thread left inside the boss for more than adequate torque on the set crew.  No problems after that.

[alan c]

I had the same issue with my car several years ago, car was with James Whiting to sort out the carbs and one of the problems was a broken engine mounting bolt. It had sheared just inside the block, engine the moved slightly letting air into the inlet system.

i cannot recall the precise explanation but it was related to vibration even though the bolt appeared to have been installed correctly.

luckily for me James was able to use a small punch a tap it round and out, no idea how he did it but he did say if that failed it was probably an engine out job.

Above may not help much but your fault is not unique.

Alan

[SM25T]

Hopefully if they worked loose to cause the failure, they will unscrew more easily .... so the small hole and TorX bit sounds a good starting point. PlusGas on the thread the day before will help with any corrosion that may be holding it.

[randybugger]

Just checked mine (on my xflow) after reading this and two bolts had come loose. Just goes to show that reading reading blatchat gets you off your bum and under the bonnet just in time.

[SM25T]

Good save Tony !

[7 wonders of the world]

   I'd be spending a couple of quid on schnorr lock washers for piece of mind there

[randybugger]

Not seen those washers before,just ordered  some cheers

[Wrightpayne]

7WOW,

When you say toffee hammer do you mean an actual hammer you get with a block of toffee or is it an engineering reference to a very small hammer? I have what dad called a pin hammer, for knocking panel pins into wood - small and light, which I expect will do the job.

I have a challenging bolt removal task coming up (x12) and I’d never heard the term so thought I’d clarify.

Cheers

Ian