comedo

I decided to remove the PAIR valve cover on the front cylinder. It's held on by two little 5 mm. dia. bolts. The first one came out OK but with some resistance. I sheared off the head of the second bolt. Time for science.

I applied ample amounts of penetrating oil and left it overnight. It received a few decent blows when I made a dimple in the top of the broken bolt with a centre punch and hammer. Drilled it on a drill press, dead centre. Things were looking good.

The screw extractor went in and I applied moderate force. No joy.

I put the cylinder head cover in the oven at 250 degrees F, took it out after 10 minutes, put in the screw extractor and applied moderate force. The bolt didn't move. I applied more moderate force which resulted in me being able to remove half the screw extractor. The other half was nice and safe and dead centre in the stuck bolt.

Lessons learned:
If I remove a bolt, put some anti-seize on it before it goes back in.
If one bolt on something I want to remove offers resistance, think hard about going after the other bolts holding the thing on.
Price the part first if you think there might be trouble.
Be a good friend of a good machinist.

Thanks for letting me share.

Gregw

I’ve had too much grief from extractors that I won’t use them anymore. If penetrating oil doesn’t solve the problem, I’ll drill the bolt out using progressively larger drill bits until I can tear the thing apart with a small screwdriver.

comedo

Great advice, Gregw.

E.Marquez

Left hand drill bits are your friend.
Second,, Next time try heating on the area around the stuck fastener.... By heating the whole cover, you allowed the fastener to expand also.. Net gain,, None.
Also,, try freezing the whole part.. Then use a tight pin point flame to quickly heat the area around the fastener.. It should expand with the heat, but the much cooler fastener will not.. then quickly..
Left hand drill bits are your friend.. Most time the heat, vibration and friction will remove the fastener as your drilling it, at worst, you now have a nice clean hole for your extractor (still must use heat, and great technique to make these work)

comedo

Thanks for the suggestions. I might call around for left hand drill bits tomorrow. I can drill down about 1/4" before I hit the broken extractor.

E.Marquez

One of the problems with extractors is that it can and often does make a bad situation worse.. by expanding the broken fastener in the hole, causing even more friction. If the fastener broke because it was bottomed out or cross threaded, extractor work pretty well. When the fastener is corroded and that caused the failure, the extractor by itself will fail almost every time, normally leaving you with a bit of hardened broken extractor AND the remnants of the broken fastener stuck in the hole.
You have to address the cause of the broken fastener if you want the extractor to work. Penetrating fluid and heat are the best bets.


Good luck

Stumpy

Heat the area around the bolt. then take a rag with ice in it and put it on the bolt. Then take it out. you want the rag to soak up the water so that it will not get on stuff around the bolt and take heat away from there.

Stumpy