Stuck Engine Mounting Bolt

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Skeomorph
Posts: 28
Joined: Wed Apr 28, 2021 3:25 pm
Location: Reading, Berkshire

Stuck Engine Mounting Bolt

Post by Skeomorph » Thu Aug 04, 2022 10:04 pm

Hi,
I'm hoping someone might have a solution to my current problem; the front engine mount bolt from the donor Cali is well and truly struck fast! I resorted to chopping the frame away to extract the engine from the donor but now have to find a way of removing it... All the 'release' sprays I've use have made no impact at all. Heat from a mapp gas torch has failed too. I think I have three options left:
- drill the bolt out - but would this work considering it's corroded at both ends?
- take the casting off the engine and put it in the oven for an hour or two and then get physical
- admit defeat and get it spark eroded out

Do any of these stand a chance of success? Or does anyone have a suggestion that I haven't thought of?

Any and all thoughts/suggestions very welcome!

Andy.

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frederick
Posts: 78
Joined: Mon Oct 01, 2018 8:05 pm
Location: san jose

Re: Stuck Engine Mounting Bolt

Post by frederick » Fri Aug 05, 2022 5:24 am

If you have room use reverse drill (counterclockwise) drill bits starting small and working up almost until you get to the threads. Soak with penetrating oil and pick the leftover bits out with a dentil type pick. Finish with the correct sized tap. Your mileage may vary.

Richard and Pat
Posts: 669
Joined: Wed Sep 26, 2018 2:44 pm
Location: Biggleswade

Re: Stuck Engine Mounting Bolt

Post by Richard and Pat » Fri Aug 05, 2022 9:12 am

Can you weld a crossbar on the end of the engine bolt? The heat would help and the crossbar would give some purchase. This has been used by Frank the editor of a Classic magazine to good effect: https://www.soudal.co.uk/pro/products/c ... degrip-all

iant-s
Posts: 28
Joined: Sun Nov 29, 2020 8:31 am
Location: Staffordshire

Re: Stuck Engine Mounting Bolt

Post by iant-s » Tue Aug 09, 2022 7:02 pm

I had the same problem when stripping my EV Cali. The bolt is being physically gripped by aluminium oxide from the engine and zinc oxide from the bolt. The two white powders really like each other and fill all the space on an almost molecular level leading to an enormously strong hold, as you will already know.
Because my bike was still in one piece what I did was set a long spanner on the bolt head then, using wooden blocks, rig the entire weight of the bike so it was pushing on the spanner. Left it like that and soaked it with diesel for a couple of days with no effect at all.
Then did more research and found the only way to move the bolt was heat. You need to expand the aluminium casting to make room around the bolt shank. Two blowlamps and my Son leaning on the bike to increase the rotational force. Don't use MAPP gas - the flame is hot enough to melt aluminium. You want to get heat into the casting lugs without worrying about melting the aluminium. I had to be pretty bold but after some vigorous heating for 20 minutes the bike front wheel suddenly hit the floor as the bolt rotated. As soon as it had let go the white powder piled out when we maintained the heat level and continued to strongly wiggle the (by now very hot) spanner.
Do not hammer the end of the bolt, you will just burr it over and/or break the lug off the casting.
Your engine being out of the bike means it might be difficult to hold it still whilst you are wrestling and mauling the job. 2 propane blowlamps, big gloves and a bold attitude. Hope this helps.

Skeomorph
Posts: 28
Joined: Wed Apr 28, 2021 3:25 pm
Location: Reading, Berkshire

Re: Stuck Engine Mounting Bolt

Post by Skeomorph » Tue Aug 09, 2022 7:30 pm

Hi Ian,

Thanks for sharing your experience, I've come to the same conclusion as you did. Unfortunately my bolt doesn't have a head on it now - a combination of a rattle gun and my son getting a bit too physical with a breaker bar! I guess I'll need to weld a suitable nut onto the shaft.

I'm contemplating taking the ali casting off the engine and putting it in the kitchen oven for a couple of hours to get it heated through. I'm not sure though if this is a good idea as the casting will not be supported when trying to work the bolt free. At a guess, how hot do you think you got the casting when it released?

Thanks,
Andy.

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