And then it went Bang

[Charles P]

Oops!

   

[Martin Prior]

Bloody Hell!!!!

[Dave Wortley]

Charles. What happened here?
Dave.

[Derek Sheldon]

Got to frost or a nuclear explosion.

[Charles P]

I was heading through the Esses at Prescott last week then it all went horrible.
I think that it broke the flange and then the leverage shattered the part by the tappets

[Steve Jones]

Got to frost or a nuclear explosion.

Impressive Charles. Looking at it in the car when it, finally, got back to the paddock it didn't look good but it didn't look that bad! Perhaps if I hadn't had any of that Copper Silicone stuff with me you wouldn't have changed the head gasket so successfully and that wouldn't have happened.

Which way are you thinking of going? Laser welding or cold stitching?

Steve

[Stuart Giles]

Oops!

That is a spectacular, but hideous when it's your motor  failure, could a hydraulic lock have started that?

[Duncan Grimmond]

Incredible! I've never seen anything quite like that. I would be fascinated to know why it happened if you do manage to track down the cause.

[Charles P]

My first thought was hydraulic lock but all bores were dry immediately afterwards and again 3 hours later when I collected the car from where it was parked on the hill. All rods are straight and the piston are carboned as normal.

The rebuild will involve a replacement crankcase - I don't trust the crankcase to be unharmed by the episode, even if there is no visible damage.

[Speedex750]

Hard lines Charles, it's a sickening feeling isn't it? I did mine almost exactly the same a couple of years back pulling the front bit of flange and No1 cylinder off the block and ripping bits of crankcase up with the rearwards block studs, a few of which were snapped. I shut the garage door and didn't look at again for a month. There was a thread running then speculating what causes this; unfortunately you and I aren't the only ones to have experienced this.

With hindsight mine only had about 120 miles on a rebore, it seemed to be going so well up to that point, and I think maybe the solid skirt pistons gripped the bores that maybe were a few thou too tight not reflecting the pistons in them. Also the stickyness of Loctite 515 or 518 came out of the subsequent discussion and the expired engine, again with hindsight, probably didn't have a very good block to crankcase gasket and may have been a bit soggy after juggling the thickness setting the deck height - allowing initial movement.

I now know why you started the thread about extra holding down studs! In addition to what was said on that thread, on the normal 8 studs I use 1/4" thick washers to maximise the grip length, spring washers and Loctite'd nuts with Allen headed bolts front and back in case insitu tightening is needed (hasn't so far).

Commiserations,  Dave