Primary cover damaged screw heads

[Mickygee]

Primary cover screw removal problem.....

My A65 still has the original Phillips head screws fitted from new. Was going to remove the case to check the chain tensioner. All the screws came loose except the drain and level screws at the bottom which are pretty chewed up and I can't get a purchase with a screwdriver. Tried an impact drive but the heads are too far gone.

Any top tip for removing them ?

[DAVE BRADY]

Hi,

You could try using a drill to remove the remains of the head so the case can slide over but it will be difficult to keep the drill central and the case could end up damaged.  I recently used a rotary file in a Dremel to reduce a damaged screw in a similar situation.  Use one smaller than the head of the screw to, in effect, bore in until the head comes loose.

Dave.

[Ian C]

I take it you have removed the primary cover as you don't need to remove the drain and level screws for this. If it were me, I'd apply some gentle heat in the vicinity of the screws then gently tap the heads of the screws. Then I'd take a small sharp chisel and make a groove in the heads to then give you purchase to knock the heads anti-clockwise. Obviously be careful you don't gouge the aluminium!!  You could also apply some freeing agent spray like WD40 to the rear of the screw threads. HTH

[DAVE BRADY]

Hi,

It must be an early case with the level and drain facilitated by the two lower screws. 

Dave.

[Ian C]

D'oh on my part!! Cheers for that Dave.

[DAVE BRADY]

Hi,

Thinking a bit more, the idea of a freeing agent is worth trying.  Perhaps 'plusgas' if WD40 does not work.  Another thing to try is candle wax.
If you can lean the bike over, apply gentle heat and melt a bit of candle wax on to the screw.  When warm, the wax is very thin and can penetrate and release the corrosion that is more than likely causing the problem.
I would put the other screws back if applying heat as a precaution against any distortion but not that much should be applied.

Dave.

[Allan G]

The original filter head screws would have had a screw driver cut more
Like a Frearson drive, as opposed to a Philips or a pozi. However, if it's mashed up then it doesn't really matter what you're using.

Use a carbide tip like Dave showed above, aim at the centre of the screw, or use a 6mm drill bit (case screws are 1/4" = 6.35mm. Once you start drilling the centre the head will spin off and up the drill bit. Once you've removed all the troubled ones, remove the case then remove the screw remaining studs with a set of mole grips or pliers afterwards.

[V500]

That's what I'd do, if I was convinced that heat and a good impact driver wasn't going to work.
With respect to the posts above, WD40 is more a lubricant than release agent so is actually pretty useless on "stuck screws" and Plusgas is more akin to white spirit than it was back when it used to actually work as intended.
Given that the screws won't remove because a) some gorilla tightened them up too much, and b) the heads are chewed, I would suggest that "heat and hammer" would work better than fluids designed for corroded parts, which these almost certainly aren't.

[DAVE BRADY]

Hi,

I suppose that as these screws have the potential to leak a bit it is possible that a PO has used a sealant on the threads exacerbating the issue of over tightening.

Dave.

[Ian C]

WD40 is more a lubricant than release agent

WD40 is a brand title for various products such as a penetrating oil.

https://www.wd40.com/products/penetrating-oil/

[DAVE BRADY]

Hi,

Thanks for the link Ian.  At an age when my sagacity should be at its peak I had not realised that WD-40 embraced such a useful range of products.

Dave.

[V500]

WD40 is more a lubricant than release agent

WD40 is a brand title for various products such as a penetrating oil.

https://www.wd40.com/products/penetrating-oil/

True, but that's not the typical general purpose WD40 that the average person (or shop) has.

[Allan G]

We used to use Wd40 as a preference when I worked as a car mechanic. Out of all the maintenance sprays we used, WD40 was the best for penetrating rusty nuts and bolts, track rod ends
Etc etc.

Since the screw is buggered anyway, using the drill as I mentioned above is the quickest and the least likely solution to damage anything if done
Properly.

[iansoady]

I have some left handed drills which in theory will tend to wind the screw out. I have to say I haven't had a lot of success with them however. What I have used on a very hard and reluctant seized screw are cobalt drills - a set is available from toolstation for under a tenner. These went through the screw in seconds. I was amazed.

I also use a slocombe type centre drill to start proceedings as it's easier to get centred with one of those.

[cornishbob]

sowing machine oil. can be got easily. the best freeing agent you can get. i didnt believe it but now i'm a be paidup member

or drip coca cola (not pepsi) on the area including the backside and leave a few hours returning now and again to dip a few more drips

then an impact driver with an appropriately sized flat head bit. gentle persuasion with a bl**dy big hammer (not really) with maybe a modicum of heat.

the left hand treaded extracters are good too