Removing broken sump bolts

[GM6VXB]

Still waiting for the dynamo which is udergoing a full rebuild. Otherwise car is ready for some road testing.

Meanwhile decided to take the sump off to check how clean it was and also
clean the filter and sump pan. Suprisingly clean inside but
found two snapped bolts, one is the centre rear (flywheel end) and the other on the offside
second from the rear.
Both do not have enough metal to do anything with, so my only alternatives are:
1. Remove the engine and get someone with the right gear to drill both out.
2. Try welding a nut onto the top of the bolt and see if I can get them out that way.

Was hoping to be on the road when the dynamo comes back, so wondering how
safe it would be to try welding a nut onto broken bit, knowing the block is aluminium.

Do have access to both a 'stick' and MIG welders but have to admit I am not the best
of welders.

Any hints or tips before I make an attempt ?.

Martin

[Chris KC]

(1) At least on the centre rear, is there any thread sticking out on the other side which you could grip? (it breaks out into the flywheel housing).
(2) Warm the case with a blow torch and then try carefully "unscrewing" the broken bolts (i.e. drifting at the circumference in an anti-clockwise direction) with a sharp punch and a ball-pein hammer.

[Ruairidh Dunford]

There are many ways to try, a left handed drill bit can catch the remains and wind it out, if you are lucky.

[GM6VXB]

Spent a few hours looking to see if I can get any perchase on the remains of the sump bolts.
I suspect the one nearest the flywheel has been cross threaded. Did manage to file a slot into it
but even with lots of pressure the slot was not strong enough to get any movement.
The second bolt is just below the surface of the bottom of the block so have not attempted
to do anything with it.
Tomorrow I will be in Fraserburgh and will chat with a couple of engineering shops to see if they
have any other suggestions but suspect they will only do any work wiith the block in front of them.

So it looks like the tourer will not be on the road before May now as we will be away from mid April
'motorhoming'.


Martin.

[Steve Jones]

Spark Erosion will sort it as a last resort but you'll need to find somewhere with the kit and they'll need the component.

Steve

[Robert Leigh]

When I had the head come off a little end bolt I put a lump of mig weld on it, and got a purchase on the lump with a miniature Mole grip. It came out without difficulty. I think the same technique has a good chance, particularly as you are not in danger of welding to the surrounding metal (aluminium).

[Nick Lettington]

I had success removing a broken tap from a sump bolt hole (left in by a previous owner), first blobbing a few mig weld spots on top of each other to build the centre up above the surface of the crank case, then welding a nut on to it. Heat from the welds was not so excessive as to cause any issues to the aluminium and the resulting expansion freed the broken section when I wound it out with a spanner.


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[Colin Morgan]

I second Ruairidh's suggestion of trying left-handed drill bits to attempt to drill the bolt out. Start small and increase the diameter of the drill - and with luck it will come unstuck and out.

[AustinWood]

Some sump bolt holes are 'blind', ie do not go into the sump. Which ones varies with the year of manufacture. If there is crud in these holes the sump bolts bottom early and snap very easily. It's a good idea to make sure they are clear.
If the sump wasn't leaking with the 2 broken bolts it may well be OK anyway.

[David Stepney]

I have had success with carefully tapping the remains of the broken bolt round with a small centre punch. I have managed to extract both broken sump bolts and a broken filter gauze bolt with this method.