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!

NOS Heater Hose

You are probably used to seeing Ds with the white plastic, cable operated heater valve on top of the heater matrix. Things weren't always that way.......

Prior to the 1969 model year (before September 1968), the heater control valve was operated by a rotating knob on the bulkhead below the dashboard. 

Pallas Heater Control - pre 1969

In fact the knob IS the valve: the valve part is in the engine compartment and buried way down at the back of the engine where the timing chain is.

The Heater Valve is on the Engine Bulkhead

The valves get silted up, or the knob goes stiff - or both. It is just about possible to service the heater valve with the engine in, but it's not much fun. (Don't ask me how I know). 

Because the valve is on the bulkhead, the metal pipe that runs from the cylinder head, along and over the exhaust manifold,  has a downwards curve at the end - so that the rubber pipe that connects to it dips down behind the timing chain cover to the valve - rather than running horizontally across and round to a valve on the heater matrix.

While my engine is out I'm planning to overhaul the valve and change the seals. I also needed to get one of the metal pipes with the curve at the end, as mine was silted up and the curved end had completely rusted off! I found one - but it was considerably more expensive than the straight ones found on late cars.

Heater Feed Pipe - 1965 to 1968

I also wanted to replace the rubber pipes that connect to either end of the heater valve - as they are hard to get to once the engine is back in the car.  The one on my car that runs between the valve and matrix in the 'snail' blower looks to be original as it has a grey outer shroud on it. It looks to be in okay condition. However the 'S' shaped one between the metal pipe from the cylinder head and the valve had seen better days and is perished. I bought a reproduction one at Citromobile in Holland in 2016. 

More recently I got lucky and found a NOS (new old stock) one. Same price as the repro one! I couldn't resist.

Reproduction parts sometimes get a bad press for their shape, colour fit or quality, Sometimes all three! Out of curiosity I've compared my heater pipes:

• Starting from the bottom we have the new old stock part. It has a distinctive 'S' bend shape to it and an outer protective grey sleeve.
• Above that is the reproduction part I bought in Holland. It's pretty close in shape to the original. The curves seem sharper, and it hasn't got quite the right profile, though it's sufficiently close to be bent to the right shape. The end are longer - but it's easier to make something shorter that it is to grow it by a few inches - so that's not a problem. It lacks the grey outer plastic covering.
• Above that is the 'S' shaped hose that came from my car. It's clear that it's just a piece of hose of approximately the right shape that someone has put on at some point.
• The metal pipe with the curved end is at the top. The only difference from the one fitted to later cars is that small kick on the left hand end - but they are nearly double the price of the straight-ended ones.

When I get to that particular job, I will fit the NOS heater pipe. Maybe I should keep a look out for a NOS pipe for the other side?