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Sump bolts
After removing the sump and cleaning out about a inch of gunge I'm refitting the sump with a silicon gasket , I've got all the bolts in bar 2 and they won't tighten they just spin,    what can I use that'd help ?
Some Helicoils or oversize bolts.

What size would you recommend R ? 
I think the bolts look standard !
This has everything you will need to do the job: [Only registered and activated users can see the links Click here to register]

Thanks R, I'm new to that type of thing does it create a new thread or helps with the existing bolts ?
It repairs the thread back to what it should be.


I used the V Coil 1/4 BSW kit to do my sump bolts. The kit comes with the right drill, tap and the helicoils, and the tools to insert them and break off the tangs. They work very well!
Hi Morrisminor 

I’ve repaired several crankcase threads using Helicoil or Vcoil kits.  It’s a good idea to “glue” the insert into the hole with some thread locker (Loctite).

It is a fairly easy, satisfying job.

You drill out the old threads, using the drill bit provided.   Don't forget to put it back in the box with the coils, it is an odd size.

Tap out the hole with the tap provided, you really should invest in a proper holder for the tap.

When tapping it is good practice to take a (say) half turn, then turn the tap back a little to cut the swarf so it doesn't build up and mess up the thread you are cutting.

Maybe remove the tap after a couple of turns and blow out the bits if you can, then carry on.

Screw the helicoil in until it is just below the surface of the casting, using the tool provided.   Then if you turn the tool backwards, the tang at the bottom breaks off, you turn the job upside

down to get the little wiry bit out, and the job is done.

What can go wrong?

You can drill too deep, you can tap too deep.   Doesn't matter with through holes, but can do do damage if in a blind hole.   The sump has both.

You can drill at an angle.   Not usually a problem, the thing is usually self guided by the old hole, and not particularly a problem with sump bolts.   Not

so good where I have just managed to do it, though.

You can drill/tap too shallow.   You discover this when the Helicoil sticks out of the hole.   The coil will NOT wind out, don't try unless an important bolt.

The projecting coil can be cut off flush or nearly so with a sharp pair of side cutters and dressed back to the surface with a careful file.  If you have really cocked it up,

you may need to shorten the bolt.   Those that know these things say you only need a couple of turns on a bolt to get the design strength of the joint.

The tang at the bottom of the coil doesn't break off - this happens with my current batch of coils.   A problem if the bit breaks off later and goes round in the engine with the oil flow.

No easy answer with that one, you have to fiddle a way to extract it if need be.

If you can, do a practice hole in a spare bit of aluminium before starting on the car.

Hope this helps, you did say you hadn't done it before.

I have done the odd one whilst the engine has been in the chassis by working from underneath in a similar way to what Simon ( Slack Alice) suggests. The only difference is I put a clean piece of rag above the stud hole to catch any pieces is swarf and the broken off tang. I finalise by washining the area with petrol from a clean pump style oil can filled with petrol. Because the sump bolt holes are are at the lowest part of the engine and the rag prevents metal swarf going upwards I consider this method safe.

John Mason.
Would you believe it "Her who must be obeyed" refers to my Ruby as the toy.


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