An Engine Rebuild Thread for Beginners

Big lumps of metals and spanners. Including servicing and fluids.

Moderators: Moderators, User administrators

User avatar
kevtherev
Posts: 18782
Joined: 23 Oct 2005, 20:13
80-90 Mem No: 2264
Location: Country estate Wolverhampton Actually

Re: An Engine Rebuild Thread for Beginners

Post by kevtherev »

T25Convert wrote:
kevtherev wrote:The "limescale" is rust, Aluminium rust. (Aluminium Oxide)

Worth adding that it comes back too, unless you treat the case in some way.

So consider how shiny you want to make it. I painted mine to get round this, but there is probably little point making it too nice.
Yes
Smoothrite satin silver.
Or just plain satin aluminium paint and engine lacquer
2.1 DJ on pierburg + LPG

User avatar
T25Convert
Posts: 352
Joined: 20 Jun 2009, 09:27
80-90 Mem No: 7819
Location: Chester

Re: An Engine Rebuild Thread for Beginners

Post by T25Convert »

kevtherev wrote:
T25Convert wrote:
kevtherev wrote:The "limescale" is rust, Aluminium rust. (Aluminium Oxide)

Worth adding that it comes back too, unless you treat the case in some way.

So consider how shiny you want to make it. I painted mine to get round this, but there is probably little point making it too nice.
Yes
Smoothrite satin silver.
Or just plain satin aluminium paint and engine lacquer

Or red - everyone knows red is faster!!
RIP - George - 1.9DG '85 AutoSleeper Trident - rusted away

George Second - 1.9DG '89 Caravelle

User avatar
Snowmark
Posts: 216
Joined: 16 Mar 2016, 21:28
80-90 Mem No: 15217
Location: Christchurch, Dorset

Re: An Engine Rebuild Thread for Beginners

Post by Snowmark »

OK, so further investigation yesterday to see if there was an obvious defect in the compression seal as noted above.

Unfortunately not - it must have been a trick of the camera or a build up of paraffin and dust. When I checked yesterday there was no evidence of an obvious flaw

Image

Regarding cleaning the exterior of the heads to remove the Aluminium Oxide - I shall give the oven scourers/ wire wool a go. Don’t really want a ‘shiny’ false finish, just clean. I’ll look into what options I have for maintaining the cleanliness once I’ve worn my fingers down by half.

So, onto the next task - removal of the Compression Seals (I am slowly learning each one as required)
Image

Picture shamelessly stolen off one of Itchy’s links :)

Compression seals are metal rings that sit in the recess of the Heads, two each side, and seal the head against the top of the cylinder liner. On the Heads I removed they are basically only held in by a build up of rubbish but they are very snug fitting in the recess and therefore you risk damaging the sealing face behind them trying to lever them out with a blunt chisel or similar.

Tools Required: Blowtorch, Plastic Trim Remover
Time: 15 Minutes

The plan was to apply direct heat to one area of the thin metal ring that is the compression seal. The theory being that the seals are thin and therefore will expand relatively quickly - as they try to expand in the confined space of the recess then they will buckle allowing me to get the plastic trim remover underneath and pick them out.
Image

Image

It all went rather well - between 1 and 2 minutes heat on one area meant that the seals lifted from the head sufficiently to be able to force the trim remover under and then the seal just popped out. Admittedly there may have been a small bit of melting to the end of the trim remover but it’ll live.....

Image

All four out within 15minutes leaving me with more areas that need carefully cleaning.......


Sent from my iPad using Tapatalk
1986 1.9DG WBX Autosleeper Hi Top

User avatar
Snowmark
Posts: 216
Joined: 16 Mar 2016, 21:28
80-90 Mem No: 15217
Location: Christchurch, Dorset

Re: An Engine Rebuild Thread for Beginners

Post by Snowmark »

Section 3 (Cont.): Cleaning the Heads

Got a little more of the exterior ‘sprucing’ done yesterday. Used a combination of the Filament Wheel in a drill, oven scourers, a small brass bristled brush, paraffin and a large chunk of my sanity...

I am coming to realise that the majority of hours spent on a rebuild are actually spent washing up - think I’ll buy some rubber gloves today.

Image

Getting to a stage that I’m happy with - I guess I need to accept that, however clean it is when it goes back into the van, it won’t remain that way for long.........and therefore this is a pointless task.
Damn you, OCD.

Image


Sent from my iPad using Tapatalk
1986 1.9DG WBX Autosleeper Hi Top

User avatar
Snowmark
Posts: 216
Joined: 16 Mar 2016, 21:28
80-90 Mem No: 15217
Location: Christchurch, Dorset

An Engine Rebuild Thread for Beginners

Post by Snowmark »

A productive day on the rebuild yesterday, learnt a huge amount and got to have a good look around the inside of my engine.
I finally learnt where the valves live and what they look like (still not absolutely sure what they do but that isn’t my primary concern at the moment.)

Section 4: Removing the Valves from the Heads

Time Taken: 1 Hour
Tools Required: Valve Spring Compressor, Small screwdriver, hammer, socket, Larger Hands

As part of my educational day I learnt that the valves in a WBX engine look like a trumpet (or a hunting horn for the Upper Classes). They are a solid piece of metal and the base of the valves are the 4 circles you can see when you remove the heads.

Image

As the above picture shows, there are 4 valves in each head and there are two different sizes. The smaller diameter ones are Exhaust valves, the larger are Inlet valves. They need to be removed from the head so that where the large, circular ‘trumpet’ of the valves contacts with the head can be cleaned - this is called ‘lapping the valves’ and appears to be one of those terms used to put the general public off attempting this sort of thing so that garages can charge loads.....

Lapping valves is basically using a grinding paste to smooth the contact surfaces between the valve and head to make an air and water tight seal - I will cover this in a separate section as today was all about removing the valves.

If you look at the head from the other side you see four large springs- these, unsurprisingly, are called Valve Springs
Image

These grip the other end of the valve (the valve stem) and provide the tension to pull the valve tight against the head. The valve stems are held in place by a collet.....another one of those terms

From Wikipedia: A collet forms a collar around an object and exerts a strong clamping force on the object.

Image

This is a collet from one of my valves - a two piece, tapered sleeve that sits around the valve stem and, when the spring is in place holds the valve tight.

To remove the valves you have to take the tension off the spring, pick out the two pieces of collet then you can expand the spring and there is no longer anything to grip the valve stem so the valve can slide out. To do this you need one of these

Image

This is a Valve Spring Compressor - basically, a large clamp that allows you to crush the spring and remove the collet.
Now, the springs are really tough and couple that with the fact they work in quite a dirty and hot place, and have probably been there for many years, they aren’t the easiest things to compress. To give myself a chance (and to save the spring compressor......as it wasn’t mine) I hit them with a hammer..
Image

Using a similar diameter socket I gave each spring a sharp tap just to help free them up. Then, grasping the Spring Compressor I got it into position on the first spring

Image

Jaws on the perimeter of the spring cover (this can be adjusted on the tool I was using)

Image

The flat piece dead centre on the valve ‘trumpet’.

It’s then simply a matter of pressing the handle, compressing the spring, the tool locks and holds its position while you remove the collet...........no it’s not, it’s really hard and it hurt my delicate hands. Honestly, I struggled as I have quite feminine hands and found it hard to exert the pressure required to compress the spring. I ended up have to use both hands and then had nothing free to remove the collet or the tool would spring unlocked etc etc.

Image

I managed in the end......above, you can see the spring is compressed and you have access to the collet. I used a small screwdriver to separate the pieces and flick them away from the valve stem. They often appear to be stuck as there are traces of oil that causes suction against the stem so you end up chasing them round in endless circles with your screwdriver.
Sometimes, the tool is in the centre and will pull off to one side with the spring not compressed evenly on both sides. This sometimes means that one piece of the collet is trapped between spring and stem - you can try to rotate round the stem but if it’s stuck fast you have to reset the Compressor.

Image

Image

Collet out, tool removed. There is a disc that sits on top of the spring.....it probably has an official name, I don’t know what it is.

Image

The next surprise is that there is actually two springs per valve - who knew?

Image

Remove these pieces and you get a clear view of the end of the valve stem with the recesses that the collet sits into. If you give the valve stem a push this is what should happen on the other side of the head

Image

Now, this bit is important I’ve been told - you need to keep all the pieces from each valve separate and label them accordingly. I stole of box of freezer bags from my kitchen for this very purpose.

Each cylinder will have an exhaust and an inlet valve as mentioned above and each one will be bagged separately- 8 freezer bags for both heads. Contents of each bag: 1 Valve, 2 Collet pieces, 2 springs, 1 Disc

Image





Sent from my iPad using Tapatalk
Last edited by Snowmark on 20 Jul 2019, 20:41, edited 1 time in total.
1986 1.9DG WBX Autosleeper Hi Top

User avatar
Snowmark
Posts: 216
Joined: 16 Mar 2016, 21:28
80-90 Mem No: 15217
Location: Christchurch, Dorset

Re: An Engine Rebuild Thread for Beginners

Post by Snowmark »

Section 4 (Cont): Removing the Valves from the Heads.

On each head the valves are Exhaust, Inlet, Inlet, Exhaust in that order (or Small, bigger, Bigger, Small if you like).
Make sure you have each cylinder correctly numbered and keep the pieces for each valve together.

Within the head there is a brass sleeve that the valve stem sits in - I think they are called valve stem guides. These can wear due to the movement of the valves and you are meant to measure the amount that the valve can move within this sleeve to see if the guides need replacing.

The problem that this causes is that replacing the valve guides ain’t easy........so, I applied a ‘token effort’. I measured the displacement for the valve which felt like it had the largest amount of movement. My theory being, if this was within spec then I could forget about it and never mention it again.
I fully understand that this isn’t the best advice I can give.....therefore I fully recommend you check every single valve and replace whatever needs replacing. I’m just not going to do that.

The way to measure is set a constant position - I achieved this by bolting a piece of wood (very precise) to the top of the head. The valve is then pushed by the stem until the end of the stem is level with the end of the valve guide sleeve and held there. The trumpet is then wiggled (technical term) up and down and the distance it travels is measured using a dial gauge.

Image

Haynes Manual Section 2B.2: Maximum Lateral Rock in Guide: 1.2mm

The one I measured felt like it moved about 4 inches.....when measured it was actually 0.48mm so well within spec and certainly good enough for this amateur.

. Image

And when your hands are hurting....a lot, and all your 8 bags are filled and labelled, you are left with two heads that no longer have valves in them

Image

Section complete......next exciting instalment Piston Removal


Sent from my iPad using Tapatalk
1986 1.9DG WBX Autosleeper Hi Top

User avatar
Snowmark
Posts: 216
Joined: 16 Mar 2016, 21:28
80-90 Mem No: 15217
Location: Christchurch, Dorset

Re: An Engine Rebuild Thread for Beginners

Post by Snowmark »

Section 3 (Revisited): Cleaning up the Heads

One thing I forgot to mention in this section was that I took this chance to replace the hex bolts that are in the drain holes of the head.

Image

I have read in the Haynes when doing coolant changes that there are drain holes between the pushrods. I had, until this week, never found them as they are usually hidden by both the push rod covers and then hidden behind the push rod tubes......a ridiculous place to put a drain hole as it’s much easier just to disconnect a pipe.

Anyway, with the head on the bench you can clearly see the hex head bolts.

Image1

Remove the bolt with a 6mm hex bit - the bolts are surprisingly short (12mm thread) and M8 width. Replacements are available on Brickwerks for the huge cost of 29p each - Socket Head Cap Screw M8x1.25/12mm.

Image

Each bolt has a copper washer to seal against the head - these are included in the gasket set that I have bought for the rest of the rebuild.....details in a (much) later section when I start putting things back together.

Image

I actually used a stainless steel replacement - a 25mm one cut down to 12mm using a cutting wheel in a dremel.




Sent from my iPad using Tapatalk
1986 1.9DG WBX Autosleeper Hi Top

User avatar
Snowmark
Posts: 216
Joined: 16 Mar 2016, 21:28
80-90 Mem No: 15217
Location: Christchurch, Dorset

An Engine Rebuild Thread for Beginners

Post by Snowmark »

Section 5: Removing the Pistons

A standard WBX engine has 4 Pistons. They live in the 4 cylinders/Barrels/Piston liners that can be seen when the Heads are removed. The movement of the pistons causes the compression of the fuel and air mixture that is then ignited by the spark plugs. As the starter motor turns the flywheel then this rotates the crank shaft. The crank shaft has 4 Con Rods (connecting rods) attached to it - these covert the rotational movement of the crank shaft into lateral (or backwards and forwards) motion of the pistons.
The pistons are attached to the con rods by something called a Gudgeon Pin (also known as Piston pins)..........I have no idea why they are called this as I thought a gudgeon was a fish.

Turns out it is a fish, but not linked.....

Why do they have to be removed? Well, the cylinder liners are where the various seals in a WBX are attached to, so, to replace the seals you need to get at the liners.
There is an argument that I could leave the pistons in the liners and not disturb the various seals (piston rings) that make them a snug fit in the cylinder liner.......however, I’m working along the line that as I’ve come this far, I might as well change the piston rings and hone (description in a later section) the cylinders so that the engine goes back in in as good a state as I could achieve.
They are various measurements to take to check whether the pistons and liners are still within VW Spec - this will largely determine what gets replace......at a later date.

Anyway, to remove the pistons you will require a Gudgeon Pin Removal Tool......VW made an Official tool for this very purpose but it is no longer available. Therefore, I blatantly stole this from another thread and made my own.

Required: 50cm of M8 Studding, 60 or 70 M8 Washers, 3 x M8 nuts, 2 x M8 Large Washers, 1 x M8 Rawlbolt and a Large Socket

Cost: Studding £1.17 for a metre, Washers 70p for 70, Large Washers 10p each, Rawlbolt About £1 each
Total: Approx £2.50

Image

I cut my metre of studding in half using a dremel. I had screwed a nut onto it so that, once cut, I could unscrew the nut to clean up the cut thread.

Image

Add one nut and screw on about 15cm. Then thread on your Washers - ideally you want to form a spacer of approximately 65mm.

Image

Once your Washers are on, add your rawlbolt

Image

This now means that if you tighten the M8 nut it will pull the studding back and therefore the tapered end of the Rawlbolt and cause it to expand

Image

At the other end, add a large socket,that will be used as a hammer against the two large washers, followed by the large washers, then finally two more nuts, locked together to allow you to put a spanner on to stop the whole thing rotating.

Image

And that’s it, you’ve made yourself an essential tool for removing the pins that hold the pistons to the connecting rods......all for a couple of quid.
Last edited by Snowmark on 23 Jul 2019, 22:20, edited 1 time in total.
1986 1.9DG WBX Autosleeper Hi Top

User avatar
937carrera
Posts: 3429
Joined: 05 Apr 2015, 19:29
80-90 Mem No: 16333
Location: N Yorks.

Re: An Engine Rebuild Thread for Beginners

Post by 937carrera »

Snowmark wrote: The crank shaft has 4 Con Rods (connecting rods) attached to it - these covert the rotational movement of the crank shaft into lateral (or backwards and forwards) motion of the pistons.
The pistons are attached to the con rods by something called a Gudgeon Pin (also known as Piston pins)..........I have no idea why they are called this as I thought a gudgeon was a fish.

I'm mainly just reading this thread and letting you continue with your contribution, but a couple of comments on the above. It's more correct to think of the crankshaft converting the up/down movement of the pistons in the bores (or any other longitudinal movement) into rotational movement. Just like on your pushbike.

I call them gudgeon pins, because I'm a Brit. Over the pond they tend to call them wrist pins, or at least that's what I have to order when buying from there. I have not come across piston pin so much, it's perhaps a non regional description.
1981 RHD 2.0 Aircooled Leisuredrive project, CU engine
1990 RHD 1.9 Auto Sleeper with DF/DG engine

User avatar
T25Convert
Posts: 352
Joined: 20 Jun 2009, 09:27
80-90 Mem No: 7819
Location: Chester

Re: An Engine Rebuild Thread for Beginners

Post by T25Convert »

Gudgeon is a anglicisation of goujon, which apparently is either French for crispy fried strips of fish or chicken, or also dowel or pin. This is what the internet has to say on the matter, so it must be true. Why we have decided to use a French word for dowel only for those that hold pistons to con rods is anyone’s guess.

You may find the circlips that hold the pins in have created a bit of a burr on the piston edge that will prevent your slide hammer from gently easing out the pin.

If this is the case, you can modify your slide hammer into a handy puller - just insert into pin, slide the socket so it rests against the case and wind the nut down into the socket. Two tools in one - bargain.
RIP - George - 1.9DG '85 AutoSleeper Trident - rusted away

George Second - 1.9DG '89 Caravelle

User avatar
Snowmark
Posts: 216
Joined: 16 Mar 2016, 21:28
80-90 Mem No: 15217
Location: Christchurch, Dorset

Re: An Engine Rebuild Thread for Beginners

Post by Snowmark »

It's more correct to think of the crankshaft converting the up/down movement of the pistons in the bores (or any other longitudinal movement) into rotational movement. Just like on your pushbike.

That makes much more sense.....now you’ve explained it and I’ve thought about it!
As I may have alluded to, I am basically learning as I go - I’m hoping that by the end of all this I’ll have an engine that works AND a very vague understanding of how it works.

At the moment my brain is full from learning the practical stuff so thanks for your input, I’ll try and piece together the logic when driving around listening to the lovely noise of a rebuilt engine.......
It seems a terribly long time away



Sent from my iPhone using Tapatalk
1986 1.9DG WBX Autosleeper Hi Top

User avatar
Snowmark
Posts: 216
Joined: 16 Mar 2016, 21:28
80-90 Mem No: 15217
Location: Christchurch, Dorset

Re: An Engine Rebuild Thread for Beginners

Post by Snowmark »

Now that we have a tool to remove the Gudgeon (Piston/Wrist delete as appropriate) Pins then I suppose I’d better get on with it.

Tools Required: Circlip Pliers - both straight and angled end ones, Gudgeon Pin Removal tool, 2 x 13mm Spanners, Rags lots of rags, Length of studding or long thin screwdriver

Last time we saw the engine block it looked like this

Image

Removed the wooden supports and then will start on the left hand side - Pistons 4 and 3. As mentioned, the pistons live in the cylinder liners and are attached to the con rods by the Gudgeon Pins. The Gudgeon pins are held in the centre of the piston by 2 circlips - only one for each piston needs to be removed. Access to these circlips is limited but the left hand ones are found through the hole left by removing the water pump.

Image

The circlips are naturally springy and have a tendency to want to jump off the end of the pliers and disappear into the lower engine to be chewed up by cranks and cams and other unknowns - this is not a desirable outcome, therefore I stuffed rags wherever I could to minimise the risk of losing a clip.

The idea is to gently pull the cylinder liner out.....very slowly, just enough to get a clear view or the circlip but not too far that the piston emerges from the cylinder. The cylinder is an excellent support for the piston to stop it clanging against head studs or the case as you try and remove the pin.
Image

It may be necessary to rotate the flywheel to position the piston in the ideal place ONLY ROTATE CLOCKWISE - otherwise you run the risk of the distributor drive jumping out (I don’t really know what this means but I believe the man who told me so have followed his advice).

Ideally you get a nice clear view of the Gudgeon Pin without pulling the cylinder to far to release the various piston rings. It’s not the end of the world if you do go too far but the piston will have less support as you withdraw the pin.

Image

For cylinder 4 you need the straight pliers. The circlip can be spun round in its groove to position it in the ideal place. Then, applying pressure against the side of the pin, compress the circlip out of its groove and withdraw in one single movement. I also used a piece of studding, held in the middle of the clip, so that if it did decide to make a bid for freedom then I had half a chance of catching it around the stud (like a miniature game of hoopla)

Image

Image

With the circlip out then there is nothing holding the pin in place.....in theory. They can develop a lip or burr in the recess in which they live and hence the tool I made has a slide hammer incorporated in case any force is needed to overcome this lip.

Insert the Rawlbolt fully into the pin and tighten the lower nut which, in turn, expands the Rawlbolt so it grips the inside of the pin.

Image

As it tightens you made need another 13mm spanner on the two nuts locked at the other end of the studding to stop the whole tool rotating.

When the bolt is fully expanded then use the large socket as a hammer against the large washers.

Image

To minimise movement of the piston and liner use some wooden packing strips down the side - this will mean all Force is applied to the pin.

Image

Try not to trap the thin piece of skin between your thumb and first finger between the socket and washer because it hurts...





Sent from my iPad using Tapatalk
1986 1.9DG WBX Autosleeper Hi Top

User avatar
Snowmark
Posts: 216
Joined: 16 Mar 2016, 21:28
80-90 Mem No: 15217
Location: Christchurch, Dorset

Re: An Engine Rebuild Thread for Beginners

Post by Snowmark »

After a bit of effort and some increasing amount of force, the first Gudgeon Pin is out

Image

Unscrew the lower nut on the tool to contract the Rawlbolt and remove the pin - ensure that you clearly mark which way round the pin sat in the piston (mark the face that came out first). White correction fluid (or Tippex......other brands are available) is useful for this.

You can then carefully withdraw the cylinder with the piston held snuggly inside.

Image

Image

Keep the Gudgeon Pin with the corresponding cylinder/piston and circlip. Clearly mark the cylinder number using a marker pen.

Image

This is what it looks like when the cylinder is removed. You can see the little end of the con rods that the Gudgeon Pin sat through. (The ‘Big End’ of the con rod attaches to the crank shaft). Stuff more rags in and around the con rod as there are large gaps down to the bottom end of the engine.

To do the next cylinder there is more access but you will need the circlip pliers with an angled head to allow a clear grip on the circlip.

Image

Image

It is recommended that you have as much illumination as possible as this will help getting a good sight, and therefore good grip on the circlips. The same process was used and you end up with half the case without cylinders....

Image

Cylinder 3, when removed, had the lower O ring visible. This seals the bottom of the cylinder to the engine case and will be replaced as part of the rebuild.

Image

Cylinder marked up clearly and the end of The Gudgeon pin marked with Tippex.

Once the cylinders and pistons are removed it allows you to have a thorough check of the head studs to check for rust and pitting.

I was absolutely delighted to find that mine were in unbelievably good condition - a sign that the correct coolant has been used throughout its life. No idea why I was so scared undoing the head nuts:)

Image

Image




Sent from my iPad using Tapatalk
1986 1.9DG WBX Autosleeper Hi Top

User avatar
T25Convert
Posts: 352
Joined: 20 Jun 2009, 09:27
80-90 Mem No: 7819
Location: Chester

Re: An Engine Rebuild Thread for Beginners

Post by T25Convert »

Good work!

Have you decided if you are stopping at pistons removal, or are you going inside the case?!

The circlip removal (and later replacement) is the hardest bit I reckon!
RIP - George - 1.9DG '85 AutoSleeper Trident - rusted away

George Second - 1.9DG '89 Caravelle

User avatar
Snowmark
Posts: 216
Joined: 16 Mar 2016, 21:28
80-90 Mem No: 15217
Location: Christchurch, Dorset

Re: An Engine Rebuild Thread for Beginners

Post by Snowmark »

I think I’ll just do the top end on this one - the oil pressure was good when checked before removal, so, as a first attempt I think I’ll do the piston rings, all seals then put it back together.

The DG that is currently in the van has low oil pressure so I’m already thinking about an ‘Engine Rebuild for Intermediates’ where I split the case....


Sent from my iPhone using Tapatalk
1986 1.9DG WBX Autosleeper Hi Top

Post Reply