Fuel Pump Strip Down and Rebuild

My fuel pump looked a mess......

Fuel Pump - 7 June 2015

Even though modern, reproduction fuel pumps are readily available, I was keen to try to retain my original and distinctive 'SEV-Marchal' pump. I had re-plated the top cover back in 2015, but have only just got to the point where I need to be refurbishing and refitting the fuel pump. Instructions for rebuilding can be found at Operation DX. 173-3, which can be found in section 2 of volume 2 of Citroen workshop manual 814.

Orientation of the Two Pump Valves

The upper and lower body were unscrewed. The seal under the domed top cover was very, very carefully prized off the pump body and feed tube using the edge of a stanley knife blade, allowing access to the two valves within the chambers. These are orientated in opposite directions and I took a reference photo. Despite what step five in the Workshop manual suggests, I was able to remove the valves. I planned to use a socket to drift the valves out, but found a socket too chunky for what looked to be quite delicate valves. Searching around I found that the 22mm end of a copper plumbing pipe reducer was a good fit for the diameter of the chambers. The valves were then easily removed. The key is to put your chosen tool in the dished side of the valve, so that the sharp edges of the valves are pulled - rather than pushed - through.

Moving on to the bottom half of the body, the cam that operates the pump was released by carefully removing one of the tiny locking circlips from it's groove in the cams spindle. The cam was then unhooked from the base of the operating rod inside the lower body, allowing it to be pulled out -  freeing the spring within. There were also two spacer washers that fit inside the body on the spindle.

Soldered Bolt on Diaphragm

The bolt holding the diaphragm assembly together is locked with solder. I suspect that this is to set and maintain the correct operating force (pumping force) on the diaphragm spring. With this in mind, I marked the orientation of the bolt to the diaphragm before unsoldering it, and made a note of how many turns it took to separate the bolt from the operating rod.  (Note: In Step 3 of Operation 173-3, the diaphragm and attached rod are removed as one - without removing the soldered bolt).

The small black rubber cup at the cam end of the operating rod was as hard as rock. In fact at first I wasn't even sure it was rubber. It was the workshop manual that confirmed it was. These parts aren't obtainable as spares and so it was make or break. I left the rod and cup soaking in a mixture of wintergreen oil and isopropanol alcohol for a couple of days*.

Wintergreen oil is the smell you get in Deep Heat. It is a very strong smell. People tend to either love it, or loath it. I left my parts soaking in the green house so that I didn't stink up the workshop! Personally I like it - but not in these quantities and strengths. I accidentally getting some of my mixture on my hands: the smell travelled everywhere with me. I poured some in a saucer. Despite washing it thoroughly first, dishwashing the saucer caused the whole dishwasher load to stink!

Miracle of miracles, after a couple of days the rubber cup began to soften with no signs of swelling. I left it a few more days but didn't want to push my luck. The pump diaphragm was showing signs of fatigue. Removing the metal plates that sandwich it, I gave it a bath in my wintergreen mix. Again, this had the effect of softening it.

Components of My SEV-Marchal Fuel Pump - 16 December 2017

With the valves removed and the rubber parts salvaged, the two halves of the body were taken away for vapour blasting - as was the metal spacer plate that fits between pump and engine. All the parts were then carefully cleaned before re-assembly.

The diaphragm sandwich was reassembled and the bolt tightened as per the note made during removal and then re-soldered. Reassembling the cam on the operating lever was fiddly because of the need to also align the spindle spacers in the body. I VERY carefully teased the circlip back on the end of the spindle and, after cleaning the end with alcohol, sealed it on with a small blob of Araldite.  The valves were refitted - again using the copper water pipe reducer - and the body re-assembled. 

Rather nervously I followed the instructions in step 12 of Operation DX.173-3 and tested the pump by emerging it in petrol and putting it under a little pressure to check for leaks. It passed muster. After draining, the spindle and cam were lightly lubricated with clean engine oil and I fitted the pump to the car. The smell of wintergreen oil dissipated (after about a week!).

Fuel Pump Fitted

* CAUTION: there are different compounds of rubber and there is a danger that some may react badly to soaking in wintergreen oil and/ or alcohol. This may take the form of swelling (growing alarmingly in size) or the surface dissolving (black sludge rubbing off on your fingers). If you are tempted to try this but cannot afford to risk ruining a piece, then you would be better off finding another way.

Engine Rebuild (Part 5) - Exhaust Manifold Prep

The exhaust manifold has studs for a protective heat shield and also studs to hold the air cleaner on top. All these studs were quite badly pitted and rusted and the manifold itself looked very rusty. I decided to replace the studs and repaint the manifold.

Stud for Mounting Air Cleaner - 19 November 2017

I'm planning to use a high temperature manifold paint. It should really be cured at a high temperature - higher than the oven in the kitchen can produce. Alternatively you can cure the paint by running the engine. I think that's the way I'll have to go.

Where I'd expected to find studs between the manifold and downpipes, I found a couple of bolts.

Bolts Instead of Studs?

I'd already bought and fitted new studs to bolt the manifold to the cylinder head. In addition  I'd gone ahead and bought replacement manifold to down pipes studs, and studs for fixing the heat shields to the manifold.

New Studs and Nuts for the Refit

One Sunday afternoon in November 2017 I set to work trying to remove from the manifold, the rusty stumps they were going to replace.

Double-nutting did nothing. I just stripped the threads on four nuts. Tackling each stud, I had to use my biggest mole grips set as tight as possible to get any purchase on the studs.  They had to be repositioned copious times to maintain any grip and the threaded studs were  starting to shred.

With an insistent wiggling action I began to sense microscopic movement in a stud and blasted it with some Plus Gas. A little more wiggling, a little more Plus Gas and I could feel definite movement. Persevering in this way - lots of wiggling and Plus Gas - I was gradually able to great greater rotation on each stud and teased them all out this way. Well, most of them. One snapped and had to be drilled out.

Out With The Old, In With The New....

With all the studs removed, I put them back in again! Just loosely. I was sending the manifold off to be blasted and didn't want all the stud holes blocked up or the threads damaged. My workshop guy blasted the manifold and downpipes, then he gave them a squirt of WD40 to stop them rusting. 

I actually wanted them as grease-free as possible to give the high temperature paint I planned to use the best chance of adhering. Never mind. I think I will probably have him blast them again but leave them dry next time.

A Quick Word About..........Cylinder Head Bolts

I knew that the cylinder bolts on the inlet and exhaust sides were different lengths, but I hadn’t appreciated that the lengths of the exhaust side bolts on early DX engines are shorter than those on later DX and subsequent DX2 engines. It’s all about washers.

The cylinder head bolts on early DX engines were fitted without washers and so pressed directly against the cylinder head surface. The exhaust side cylinder head bolts on later DX engines and thereafter were used with a thick washer – presumably to minimise compression damage to the alloy head. The upshot is that the bolt is correspondingly a little longer to compensate for the length taken up by the washer. The parts books give the two lengths as 111.5mm up to July 1967 and 114.5mm thereafter, when a 3mm washer was also used.

Early (top) and Later (bottom) Exhaust side Cylinder Head Bolts

Fitting the 3mm Washer Brings the 'Working' Length Back to 111.5mm

Bolts on the inlet manifold side stayed at 160mm throughout and weren't used with washers. There was no need: they bolt to the head through the inlet rocker rail so the head already had something of a 'cushion' between them and the head.

Anyway, when my engines were stripped, several bolts on the exhaust side snapped on removal – and some of the rest were rusted and pitted. These exhaust side bolts are the ones most likely to fail (not only on removal but also on reassembly) and so are the ones most likely to be replaced.

Failed Exhaust Side Cylinder Head Bolt

For this reason I bought lovely new replacement exhaust side cylinder head bolts. As I have written elsewhere – many of the reproduction parts are geared to DX2 engines – not DX. The replacement bolts I bought are 114.5mm long and so are a little longer than the ones originally fitted to the early DX engines. There is a risk that if I had gone ahead and used  new, 114.5mm bolts on my DX  engine without  washers, the bolts could have ‘bottomed-out’ in the tapped holes of the block before they were sufficiently torqued:

• Leaving them at that point might have meant that the head gasket was not properly sealed - and failed down the line
• Continuing to try to torque the bolts when they had bottomed-out possibly risked the bolts snapping – causing quite a headache or:
• Continuing to try to torque the bolts when they had bottomed-out risked cracking the block – which would be even worse.

This may sound alarmist, but I found something that suggested i might not be crazy after all....

Thread from the "DS Club Deutschland" Forum

'Pit' had leaks on his DX engine and attributed the problem to head skimming. He was trying to solve the problem with a marginally thicker, hand-made head gasket. As 'HGK' was suggesting, perhaps his bolts were bottoming-out.

It just goes to show what a little bit of research can unearth. In my case, and as I had a DX2 engine in bits as well, I was able to use the 3mm washers from that engine.

114.5mm head bolt........with 3mm washer

Engine Rebuild (Part 4) - Fitting The Valves

By mid September 2017, and after an initial clean up, I had been soaking my DX exhaust valves in Mek pretty much since mid August. This loosened some of the burnt on muck - but not nearly enough. In the end I had to resort to using my wire wheel to clean them up. I was very glad I did as it did a great job. I was very careful to avoid going too far up the shaft of each valve with the wheel as I did not want to introduce scratches.

At the end of September 2017 - while researching cylinder heads and valves -  I was lucky enough to find a set of NOS DX inlet valves for my 1968 car.

New Old Stock Inlet Valves - October 2017

These were the earlier 47mm diameter valves, BUT with the three groove cap and collar. They were only fitted for about 15 months between May 1967 and July 1968. Result! (See my other post on DX valves for more on this).

September and October were spent getting the cylinder head ready - including vapour blasting, skimming, fitting new valve guides and having the valve seats re-cut.

By mid November it was starting to come together: I  had my cylinder head, my valves ready and all other associated parts had been thoroughly cleaned and oiled. I was ready to go.

Underway - 12 November 2017

I spent an afternoon lapping the valves. This process was not nearly as long-winded as I thought it was going to be - possibly because half my valves were new and - more likely - because the all valve seats had been re-cut. The objective is to keep lapping until you have a solid, clean ring showing on valve and seat - meaning the surfaces are flush and a good gas seal. The tone of the grinding note changes as you reach that point. It was really quite satisfying. After lapping I carefully wiped up all traces of grinding paste.

With my new valve spring compressor, I was able to make quick work of re-fitting the valves.

Fitting The Valves - 12 November 2017

Compressing the Springs to Slip the Collars Around the Stem

Working methodically, I was soon done. I was very pleased with the results and finished the day by re-fitting the tappets. I couldn't resist sitting the head on the block and adding the push rods.

Valves and Pushrods - 14 November 2017

A Quick Word About.......DX Valves

One of the main changes between the DX2 (introduced for the 1969 model year in September 1968) and the DX engine that came before it, is different diameter inlet valves. Up until September 1968 they were 47mm. After that, they were 49mm. This change, possibly together with an uprated carburettor, is one of the factors that boosted the 109 bhp of the DX engine to a whopping 115 bhp on the DX2.....

Having pulled the valves from my several cylinder heads, I started to notice a number of other differences and, as a consequence spent long nights trying to get my head around the subtle changes to DX valves circa 1967/ 1968. It was something of a crossover period......

The valves on a 1968 DX engine are different to those used on the 1969 DX2 engine and thereafter. In fact they are also different to the valves used on the DX engine before May 1967. What I'm calling 'early' and 'late' DX. I needed to (wanted to?) get my head around all of this before I could crack on with fitting valves.

From my parts and the various workshop parts books and repair manuals, the first thing I discovered was that up until May 1967, the inlet valves didn't use valve seals as we would know them. Instead, they had a small plastic ring at the top of the stem - up by the cap and collars. The cap and collars were also different: on a late DX, and on DX2 inlet valve, the collars are 'ribbed' and match to grooves around the end of the stem. On an early DX valve, the collars are 'plain'.

Early and Late DX Inlet Valves: Plastic Ring. Different Collars

To accomodate a conventional valve seal, the valve guides on late DX and then DX2 engines have a shoulder - against which the valve seal is seated. As an early DX inlet valve (pre- May 1967) doesn't have a conventional valve seal, the valve guide doesn't have a shoulder.......From May 1967, the valve guide changed to ones with shoulders.

The area around the base of the valve guide is also different - with the early DX head having a distinctive step. As a consequence, the thrust washers that sit on these - and the inner valve springs - are different to those on a late DX and DX2 head. That's a bit of a minefield with several changes during 1967. Best not to go there......

Early DX Inlet Valve Guide - Double-Stepped base. No Shoulder on Guide

Late DX Inlet Valve Guide: Single Base Step. Guide has a Shoulder for a Seal

Exhaust valves: unlike the inlet valves, both the early and the late DX exhaust valves did have 'ribbed' collars that match to grooves around the end of the stem. In this respect they are similar to the subsequent DX2 exhaust valves. But not the same........A DX exhaust valve is 9mm along the full length - including the collar area. On a DX2 exhaust valve, the stem is 9mm diameter along most of its length, but ribbed collar section reduces to 8mm. That change seems to have happened for September 1968. So a DX2 cap and collar won't fit a DX exhaust valve properly. Remember that if you lose your DX collar and need to buy replacements - they will almost certainly be for a DX2.

DX and DX2 Exhaust Valves: stem end is smaller

Still with me? Okay, nearly finished.

DX exhaust valve guides: Prior to May 1967, the guide had no shoulder and valve seals weren't fitted - at all - not even a plastic collar on the end of the valve stem. Exhaust valves seals seem to have been introduced in May 1967, along with a change on the valve guides - presumably to guides with a shoulder. Seals are described in the relevant parts book but not shown in the parts picture. Because of the stepped base, thrust washers and inner springs before May 1967 are different to those on late cars.

Early DX Exhaust Valve Guide - Base is Double-Stepped

Late DX Exhaust Valve Guide - Flat Base. Shoulder for a Seal.

I'd already bought a set of replacement valve guides from Citroen Classics back in summer 2015 without even considering they might not be standard for all engines. With the vast majority of reproduction parts geared to DX2 engines, my conclusions over the implications for my 1968 DS21 were as follows:

DX2 valve guides - good thing
DX2 valve seals - good thing.
DX2 valves - bad thing.

I could replace the valve guides and fit new valve seals, but I should really try to press my valves back into service.

Technical details about replacing valve guides can be found in Operation D.112-3 in Section 2 of Volume 2 of manual 814, however it's a specialised job if done right.

Lautrette Air Cleaner Refurb

I would say that when you lift the bonnet on a later DS (anything post 1965), two of the most defining features that strike you other than pipes snaking here and there are (1) the large LHM reservoir - especially if it is painted AC502 'vert' - and (2) the flat, circular, 'gris rose' coloured  air cleaner with it's long elegant trumpet intake.

Miofiltre Air Cleaner and Label

So if you're doing a restoration, you paint the air cleaner gris rose - right? Well you can if you want to of course, but if you want period accuracy, then it's not that straightforward. Not all cars had the LHM reservoir painted green and not all had the 'gris rose' air cleaner. 

Just as they did with electrical components (Ducellier and Paris-Rhone) Citroen also had two suppliers of air cleaners: Miofiltre - suppliers of the 'gris rose' version -  but also a second company called 'Lautrette'. The air filters from both companies have very similar designs and do the same job.......except, most noticeably, the Lautrette air cleaner is painted black. Instead of the cleaning instructions being a gold label on the trumpet, they were written around the circular top face of the air cleaner lid, in several languages, and in bright yellow.

Tatty Air Cleaner - 2000

My car has one of these black 'Lautrette' air cleaners. It was already looking a bit rough when I got the car - with rusting chip marks and a few letters and words knocked off here and there. The fact is that, when you're working under the bonnet, the flat, dished tops of these air cleaners - both the Miofiltre and Lautrette -  are just so handy for popping loose nuts and bolts into. In this way they are scratched and chipped. The main culprits are the spark plugs with their crisp hex heads and sharp edges.

Deteriorated - 12 November 2014

When I went to recover my DS from the barn in 2014, I was shocked at how much more my air cleaner had deteriorated. I wasn't simply going to be able to wipe this over with an oily rag. Though I did try that first......

I knew straightaway that the big problem in stripping and repainting would be losing the lettering on the top. It was what gave the air cleaner it's soul. The Lautrette may not have the under-bonnet appeal of it's deadly rival - the Miofiltre, but it's what my car had - so that's what I was aiming to restore.....I just needed to think about how. 

I studied the air cleaner carefully. In some cases the letters had flaked off, leaving black underneath. The lettering wasn't an adhesive label as there was no obvious edge to the lettering. It was very delicate and hardly seemed to be raised above the surface of the black at all.

Spring 2015 and I had a production line going, stripping parts and prep-ing them for repainting. This was going to include the air cleaner, so the paint and lettering was going to have to come off. At about this time I found that the parts suppliers were selling replacement clear 'donut' labels for Lautrettes! 

Reproduction Adhesive Label for a Lautrette L1459

Unfortunately these were marked 'L1459' and were for the later style of Lautrette air cleaner with the square trumpet (and summer/ winter lever). Mine was marked 'L1165'. There was another problem. At the Citromobile meeting in May 2015 I saw a DS with one of these repro stickers and, well, it looked like a sticker: it was made of quite thick plastic so had a very obvious lip edge. Although printed on clear plastic, once applied to a black surface, the adhesive on the reverse made the black paint underneath look grey. As a last resort it was one step above simply painting it black, but I really wanted to try to do better than that.

Scanned - 22 March 2015

I had the makings of a plan: remembering my days making Airfix model kits, I reasoned that the lettering was possibly some form of waterslide transfer and I resolved to get one printed - or maybe make my own. Using the flatbed scanner at home, I took a digital scan of the wording on the top. Even if I couldn't find a way to restore it to my satisfaction, at least I'd have a record of what it used to look like.... 

I'm no graphic designer but, using Adobe Photoshop (and latterly 'Gimp'), I managed to 'extract' the yellow lettering from my scan and place it on a transparent background. Using this as a bottom layer template, I then replicated the lettering in another layer on top - using the template to check spelling, font spacing and alignment. 

I went back to this job on and off through 2015. Research was showing that printing at home on an inkjet printer was not going to work as the colours would run. Overspraying the print to protect and fix it was self-defeating as I needed the paper to get wet! Printing on a laser printer was the way to go: the printer would heat-bond the ink to the transfer paper - so no ink runs. Luckily I could run a few sheets off on the big laser printer at work. 

By October  2015 I had a satisfactory template. I did some test prints of my new transfer onto clear film and then laid this over my air cleaner to check for size and general look. I would have to make it in two halves because of the constraints of A4 printing, but I didn't see that as an issue.

Experimenting - November 2015

Things were going to plan and I duly sourced some transparent waterslide paper that was suitable for a laser printer. But by February 2016 my plan hit another snag.....

Printers tend to rely on the fact that the majority of printing is done on white paper, or seen against, a white background. The ink technology relies on this. I came to realise that since I planned to apply my transfer to a black background, the colours needed to be strong and thick if they were to show up. To get the effect I was seeing on my computer screen, my yellow lettering needed a white background - a pre-print in white perhaps? Unfortunately, unlike print shop printing, office printers do not generally have a white toner cartridge. I might be able to make and apply a transfer, but the lettering would be very faint and not have the intended impact. I needed to do some more head-scratching.

While I was thinking about a printing solution I removed the aluminium pins from the hinges of the air filter body so that they could be re-zinc-ed and would not get oversprayed when the body was eventually painted black. As I'd not managed to find a machine shop near me, one of the engineers at a local model railway society very kindly made me a few replacements up.

Sizing Up The Hinge Pins - April 2016

In May 2016,  reading an old thread about a restoration project on 'Aussiefrogs' and searching for inspiration, a message about repro factory marks on parts caught my eye. It read:

The Chausson 4A on the header tank is a computer cut spray mask (paint header tank, then using the mask spray white), very nice correct detail - these would have been stamped originally interested?


This guy clearly knew what he was on about. I joined Aussiefrogs and contacted the author Chris (aka 'Greenblood') for advice. Chris offered to look at creating a screen printed waterslide transfer for me, however he suspected that originally the text would have been printed directly onto the black body. Chris said this might also be a possible way to go but it was unlikely I would find a company that could/ would do this for me. Chris worked on tidying my design and putting it into a file format that a local printer here in the UK might be able to deal with.

Things went quiet until January 2017 when Chris got back in touch: his daughter, Charlotte,  was London-based and was going back to Oz for a break in April that year. Charlotte could take my air cleaner with her. He would have a go at printing directly onto the black painted surface  as a one-off. A proof of concept. What a fantastic and generous offer! I nearly fell over backwards. This really was an example of the worldwide Citroen community in action. With the air cleaner already stripped, all I had to do over the next 10 weeks was to get it painted black and get it down to London........

I mulled over what paint to use. I didn't want it to be high, modern two-pack black. I didn't want it to be matt black. I didn't want it to be satin black. I wanted it to be, well, original......Time seemed to get away from me. I went to the cupboard to find my 'go-to' paint for this job: Eastwood's 'Underhood Black' only to find I'd run out! The supplier, Frosts, were also out of stock. With April fast approaching I dug out the cheap air gun I'd bought the year before and bought some 60% black from a local supplier. In late March 2017 I set to. The results were adequate, rather than spectacular, but would have to do.

Ready for the journey - 8 April 2017

Charlotte was flying out of London in mid April and, with just a few days to spare, I arranged to drop the part of at her flat in South London. To beat the traffic I left ridiculously early in the morning, but really enjoyed the drive through the dozing city. Charlotte and her partner were lovely and very tolerant of yet another mad Citroen person. I thanked then profusely and left my air cleaner to its fate. 

A choice of air cleaner labels - Holland, May 2017

Charlotte and the part arrived safely, but Chris contacted me to say that he, too, was having ink supply problems. Charlotte would be coming home without the air cleaner and he would be back in touch.

In mid May there was one of those strange twists of fate: at the 2017 Citromobile meeting in Holland, someone was selling two different types of clear Lautrette sticky labels - some marked "L1459" as before, but now also others marked "L1165" - the type I needed. Unsure of how successful Chris would be, I bought one - just in case....

Arriving back in England, I compared the sticker to the transparent mock-ups I had made from my original. As well as having the problems with the adhesive backing showing through it was, at best, a passing copy of an original. If push came to shove however, it just might have to do.

Chris In Action - early August 2017

10 August 2017 and Chris was back in touch. Mission accomplished! He had printed on my air cleaner! Although a little self-critical of his own work, the photo of the results looked better than I could ever have hoped. But how to get it home? 

Fate stepped in again: another Aussiefrogger - John Albanis - was travelling to Europe shortly and would be in London at the end of the month. John offered to bring my air cleaner back. How lucky was I!

John's stop over in the UK coincided with my wedding anniversary, my daughters birthday (same day) and an associated theatre trip. Although that was down in London, our location and itinerary didn't give me the chance to slip away to meet up with John. Once again, Charlotte - Chris' daughter - came to the rescue, meeting with John on my behalf and it wasn't until mid October that I could make that early morning dash down to London to collect my air cleaner. If i'd been pleased with the photo Chris sent me, the results in the flesh were even more stunning than I expected.

Home from the journey. Restored - 13 October 2017

To recap: my air cleaner has literally been to the other side of the world and back. Had I know how good the results would be, I'd have paid the freight costs without blinking. As it turns out, I have a result better than I could ever have dreamed of AND it has cost me next to nothing thanks to the generosity of others. This is surely a testament to the worldwide community of Citroen and I am genuinely humbled by it. Chris, Charlotte and John - you are treasures.

Cylinder Head Woes...

I'd bought an old DX engine particularly so that I could use the cylinder head on my DS in place of the DX2 head that was fitted.

By mid August 2017, and with the bottom of the engine rebuilt, I turned my attention to the DX cylinder head. The rocker assembly had been removed when the engine and cylinder head were separated. 

One of the long tubes that the spark plugs sits within was missing. on closer inspection it had rusted away at the level it joins the cylinder head. I would have to find a way to fix that......I started removing the spark plugs, the fourth one  - where the 'funnel' was missing - completely disintegrated. All it left leaving a knobbly, rusty stump. I would have to find a way to fix that too.....

Remnants of a Spark Plug.......

Using a valve spring compressor I set about removing the valves. The technique is to start with the valve compressor lever closed and the arm would back. Keeping the compressor closed, locate the ends on the valve and spring. Then wind in the arm until the spring is sufficiently compressed to enable you to reach the collars under the cap. To release the spring, use the lever arm on the compressor - don't wind back the arm. in this way, the degree of compression is 'set' so that to remove the next valve, you only need to operate the lever to compress the spring to the right degree. Well, that's the theory.....Initially I didn't find this easy as my choice of compressor had been the wrong one. A 'Laser' brand 0287 model. 

Although it had adjustable width jaws - useful for maximising the space needed to remove the cap and collars from the valve stem, it barely had the 'reach' around the cylinder head to clamp over the valve head. With some careful placement, it worked at first with, as ever, all the thrust washers, caps and collars associated with each valves going in to labelled pots. However after a couple of valves the adjustable end of the compressor buckled and gave way.

Looking for something else to do, I gave the cylinder head a shake a ton of grit and hard core fell out! I was amazed at how much there was!

I removed the remnants of an exhaust gasket and noticed - for the first time - some significant pitting around one of the (exhaust) ports. Worse was to come: on closer examination of the port I found that I could see the back of the valve seat exposed. The area around the seat was badly corroded. I'd had the engine the best part of a year. Why had I not noticed this before!

Exhaust Port Damage

Valve Seat Eroded and Exposed

I had a sleepless couple of nights. Even if the rotten spark plug stump could be removed, could this be repaired? If so, how and by who? Could I trust the repair to hold out? If I left it alone, and reassembled the engine, would I risk the valve seat collapsing into the cylinder - causing significant damage? This was the last straw. I decided I couldn't take the chance and would need to find another DX cylinder head.....

I rang around. Addie had a head but had already invested significant time and money in it: it was out of my price range. Jamie at DSWorld had a look but drew a blank. Darrin at Citroen Classics thought he had one and would have a look around. After an anxious wait for a call back, he came up trumps! AND it was very reasonably priced. 

On 1 September 2017 I made an early morning dash down and around the M25 to Citroen Classics in Staines. My first visit! I collected the head and a few other bits and pieces and was heading back home before 9am - getting back miraculously by just after 10am. I still don't know how I managed that. So now I had three heads..........

DX2 +2(DX) = ?

While this was going on, I went big and bought myself a Sykes-Pickavant 03950000 valve spring compressor. No messing. This is more of a closed 'C' shape design and, although it has fixed sized adaptors, made easy work of removing the remaining valves on  the  heads.

In mid September 2017 I found a local machine shop and got the DX cylinder head skimmed and vapour blasted. Boy did it look good. Stunning in fact!

Shiny..........

Then I noticed a problem...... There was a tiny, tiny, pin-prick hole eaten away through the water way to the outside of the block. The vapour blasting hadn't caused it, but had revealed it. Perhaps no bad thing. I was however gutted....

The hole was right on a corner at the water pump end, with the erosion perhaps caused by the flow of coolant through the head. I compared the DX head to the later DX2 head and found that the casting had been changed on the DX2 to include a large, prominent extra lump of casting at that corner. Perhaps it was a known weak spot?

Other DX Head: Eroded Valve Seat But No Pin Hole in Water Sleeve.....

DX2 Head: Extra Casting Lump in the Corner

I gave it to Barry - my machine shop guy  - to assess and he concluded that to repair it he would have to cut away quite a bit of the  corner of the block.  I trusted his opinion, but didn't fancy the sound of that, so looked for another solution. I used a two part, Loctite filler product used for pump repairs and similar. It's aluminium based and resistant to high temperatures. 

With the eroded area already having been cleaned by the vapour blasting, I degreased it all down with alcohol before filling the hole - making sure the Loctite oozed out of the pin-prick hole. Following the example of the DX2 head, I built up an additional level of filler to provide added protection. The repair looked good and was invisible from outside the cylinder head.

Now nearly mid October 2017, two months had gone by since I completed the bottom of the engine. Perhaps at last I had a decent cylinder head and could get on with the rebuild!