Engineering – Removing Stuck Bolts

This post seeks to record the ways I generally go about removing a stuck bolt using a particular repair I did – Skip further down if you don’t want the background.

I recently agreed to help out a friend with her first car which she had bought for a few hundred pounds and then found out how much a cam belt replacement actually costs when you get a garage to do it!

The car in question was a fairly common 2004 Fiesta 1.4 – this is the Ford Sigma engine which was also used in the Puma and Focus. Having done a few different cam belt changes over the years I figured it would be comparatively simple. Turns out that logic was badly flawed due to a design “feature” included by Ford which makes the job very difficult. This “feature” is a single bolt which can be almost impossible to remove – the crank bolt!

To explain the technical problem you need a bit of background knowledge on how pulleys are normally mounted on shafts. The method normally used is called a Woodruff key, this is a lump of metal which goes into a slot on the shaft. A corresponding slot is machined into the pulley/gear to be driven preventing any rotation. The key can be seen on the bottom left of the shaft in the photo.

RX8 Crank Key

Now the problem caused by Ford on the engine I was dealing with was that to save money (machining that slot adds a manufacturing operation) they did not use a key and instead relied solely on friction. The Ford engine uses the crank bolt to not only hold the pulleys on the crank but actually tighten it sufficiently that the friction between the pulley and the crank prevents rotation. The down side being that the bolt has to be incredibly tight so it can be very difficult to remove and if replaced must be absolutely torqued to specification because if it allows the timing gear to slip the engine would likely be destroyed!

Removing a stuck bolt…

In terms of getting out a bolt start small and build up. In this case there’s no chance a ratchet will do it so I started with a normal short breaker bar and an 18mm deep socket (a slighly unusual size not found in most smaller kits) so I had to buy one) and not terribly surprisingly nothing happened. So I got out my big breaker bar – it’s 800mm long so allows a significant amount of torque to be applied. To get clearance to use this I had to use two long 1/2″ drive extensions so the bar could be positioned outside the wheel arch. Again this didn’t do as much as I’d hoped…

Normally at this point the common next step is to put a bar in place resting against a cross member and then crank the engine. This uses the torque of the starter motor with the mechanical advantage resulting from the starter ring gear to apply a very large torque. Unfortunately you can’t do this with this engine because of the above issue with the crank not having a key. The moment the bolt undoes the engine would lose its relative timing and would probably be badly damaged or destroyed. Unfortunately at the time I wasn’t aware the crank had no key so we tried it anyway. After several goes on the starter and still having no luck I thought we might get more force into it by pushing the car rolling and having the driver let up the clutch like a bump start – using the inertia of the car as the force. Astonishingly even this didn’t get it moving (actually very lucky as it later turned out!).

Having exhausted hand tools I contacted a mate of mine who has an impact gun. It was a fairly basic one but rated at 220Nm should give the bolt a good beating and the percussive action will free up a good many stuck bolts but in this case it just wouldn’t do it!

I started drilling small holes in the bolt head to try to relieve some of the friction between the flange under the bolt head and the pulley. The idea being to remove enough material from the back of the bolt such that it relieves the force by the head flexing a little. After quite a bit of drilling and several goes with the gun it became apparent it just wasn’t going to cut it on this one!

Having accepted I needed a lot more force and having few ideas how to achieve this I decided I would finally splash out on a tool I’d been looking at for ages…

http://products.dewalt.co.uk/powertools/productdetails/catno/DCF899P2/

XR 18V BRUSHLESS 3 Sp High Torque Wrench

This is a Dewalt DCF899. The torque ratings for it are amazing for something of this size at 950 Nm continuous but it is a bit pricey. That said it will undo almost anything I’ve found and the batteries last forever!

So having bought this beast I gave it a go and after a number of goes at full power and some rust falling out the bolt still didn’t move! Careful inspection of the bolt head showed that the impact gun was hitting it so hard now for a comparatively small bolt head (18mm hex) the steel of both the bolt head and the socket we getting damaged. I made the choice to give it one last go and ended up rounding off the bolt head entirely!

Most people at this point would probably give up but I had one last idea I wanted to try! I realised that an M20 nut could be drilled out to a 20mm round hole and then it would fit over the rounded off bolt head. The benefit being an M20 nut is much larger hex than the original 18mm across flats bolt head at 30mm, this would replace the stripped head and resist a huge amount of torque before rounding off. I also needed to drill the nut half way through to 24mm as the m20 nut was much thicker and I needed clearance for the next part of the plan…At this point a mate of mine turned up so we broke out the welder and proceeded to join the combination of nut and bolt with weld. After a couple false starts where the new nut sheared off because we didn’t use enough weld we just filled up the head with weld as a last ditch attempt and once the whole bolt was glowing cherry red we used the big impact gun and out it came!

Fiesta Bolt comparison

Spot the difference! The one on the left is the replacement ready to go in because on this engine the crank bolt should not be re-used.

 

 

Finished Pipe Vice

So I finally finished the pipe vice seen in a previous post after getting distracted by other projects. I actually needed to use it for its intended purpose which is something I never fully expected when I started restoring it. I needed to tap a thread into a section of bar as part of another long term project (involving a Mazda RX8 – soon to be added to this blog).

Somewhat appropriately the first time I used it again after putting it back together would have actually been my granddads birthday. Asking around the family by best estimations this vise was purchased for installing pipework when my granddad built his house some 55 years ago. With any luck it will last another few decades!

Anyway, here it is :

Finished Pipe Vise
Finished Pipe Vice

Refurbishing Vises

Another of the things I was given by my granddad was some well used Record branded vises, specifically a type 23 engineers vice, a type 91 pipe vise and a type 52 woodworking vise. All of these had clearly had quite a lot of use in their lives but were still functional. Unfortunately they clearly hadn’t had any attention for a number of years and just needed a bit of tlc before they started their new life.

Yet again I’ve decided to do it properly. The first step was to remove all the grime, there was old grease, loose paint and quite a lot of surface rust so I went to it with a powerdrill fitted with a rotary wire brush.

Vise

This removed the majority of the grime but I needed to use a solvent to degrease the surface prior to painting.

Degreased Vise

It’s probably worth pointing out at this point that due to me wanting to try out the new paint I didn’t clean the entire vise, that’ll have to wait for another day.

The key bit for me of restoring these vises was making them look the part, so while I could have painted them any colour I did quite a bit of research and found the correct factory original colour for them is BS381C-110 Roundel-Blue. I managed to find one place who could supply a this as a very high quality enamel paint – Paragon Enamel Paints it can be bought via Ebay or direct from their website. I’m not going to lie, it’s not exactly cheap but even the smallest 0.5l can goes a surprisingly long way so you can always retouch it if you need to. It’s also worth pointing out at this point that they specify PT8 synthetic thinner as there doesn’t appear to be much that works. I recommend buying this with the paint as it’s probably the best option for cleaning brushes/spills – sadly me being me it hadn’t noticed this and just cleaned the brushes with petrol.

Painting in progress

Now having painted half the first vise I realised that while I was waiting for it to dry I couldn’t clean the other side. I admit that was obvious but I wanted to see what the paint looked like! So I started looking at the next vise:

Type91

This is a type 91 pipe vise is generally used for holding a pipe or tube usually to cut a thread onto the end without crushing it. Such fittings used to be used for water pipes in houses many years ago but that is no longer the case but threaded pipes and rods are still widely used in engineering.

wp_20160831_20_03_29_pro

This time I disassembled the threaded bar to avoid potentially getting paint on it as well as some other moving parts and all three jaws. I then cleaned it in the same way as the other vise – although with the addition of of a toothbrush to get into some of the corners.

wp_20160903_11_30_07_pro

Next up was painting it, this one was a little more fiddly as it wasn’t attached to anything – in retrospect I probably should have just screwed to to a bit of wood but hindsight is a wonderful thing! Also It has a few moving parts which will get stuck if paint gets in them.

Painted Pipe Vise

So I need to finish it off and paint the areas where I was holding it and things but we’re heading in the right direction. The pair if vises now look like this:

23 and 91

Still more work to do to get it all looking spot on but that can wait until part 2 – where I’ll also have a go at the woodworking vise:

Woodworking vise

This gives a better idea of how they all looked before I started cleaning them – not terrible but in need of a clean.

To be continued in part 2…

Cobblers Last (Cobblers Anvil) Refurbishment

So my granddad recently gave me all of his tools as he decided he no longer had a need for them and I decided I would refurbish all of the tools I could and continue using them as long as possible – at the end of the day most hand tools are pretty simple and quite easily serviced given basic equipment and enough time and effort. The last two sadly being things which are in rather short supply at the moment so some of these will take rather longer than they probably should!

Selection of tools

The first item I found in my granddads workshop which I really wanted to clean up and give a new lease of life was a cobblers last, these were quite common in antiques/vintage shops and auctions in recent years but I’m told are starting to get a little hard to find and while it is unlikely to ever be used to repair shoes again they can be used as a good doorstop.

Cobblers last before cleaning

It had been stored in an outbuilding for some considerable number of years and so had suffered as a result. It was covered in lots of rusty scale which would all need removing before I could do much else. Thankfully I recently got an offer I couldn’t refuse on a pillar drill so with the aid of a wire brush that job became much easier!

Last with the scale removed

 

So following heavy use of the wire brush I was left with an altogether cleaner looking last with no loose rust at all.

So the next phase is to mask of any areas you don’t want painted – in this case I wanted to keep the original working faces clean so I masked them out prior to painting. In terms of paint in theory any metal paint could be used but I have found the best thing to use where a tough finish is required is an enamel type paint. In this case I used Hammerite smooth in a spray can. I’ve had some bad experiences using hammerite with it not curing properly but the key is thin layers, lots of thin layers. Turns out reading the instructions is actually a good idea! It does still take a long time to fully dry though…

Painted cobblers last

Leave the whole thing in a dry place for a couple of days to dry fully and it’s ready for the finishing touches. Unfortunately because cobblers lasts are made of cast iron this finishing touch is definitely easier with power tools – I used an angle grinder  with a flap disk but I’m sure there are other options and this was quick and easy! I carefully cleaned the working surfaces until they shined, I didn’t want the last to look completely new – that would detract from the point of the whole project – but I wanted it to look like it was still in use.

The end result

So here’s the end result ready to go back into use as a door stop or house ornament.