Servicing The Heater Valve

 A nice, simple, one this.....

Heater valve on a mid/ late 1960s car

From the 1969 model year (so about September 1968), the valve to control the heater was mounted on top of the heater matrix and controlled by a lever and cable. Prior to that, the valve was mounted on the bulkhead below the dashboard and operated by a rotating knob.  My car, being a 1968 model year car was one of the last to have the rotating knob.

Pallas-trim on the heater knob

The styling around the knob, and of the knob itself, varied between ID/ DS and pallas spec models, but the function and valve are the same.

DS/ ID variant of the heater knob
(photo copyright Mark Rueneuf) 

As well as looking retro and cool - especially as they were married to the 60s DS and ID 'gris rose' dashboards........

Heater knob in a 1968 DS
(photo copyright French Classics)

........the valves are a lot simpler. The later plastic valves tended to clog up easily and the bases would crack and they would leak. The bulkhead mounted valves were made from brass, had fewer moving parts, and were sturdier. Unfortunately they still clogged up and the valves jammed.

If yours is jammed, think very carefully before you apply brute force as the ends can, and do, snap off. The weak spot is the threaded part at the end.

Broken spindle....
(photo copyright Jonathan Palmer)

If you need to service your valve, the other downside of these ones is that they are far less accessible than the ones on top of the heaters. They are tucked down at the back of the engine.

The valve is down the back behind the engine

I'm reliably informed that you can remove the valve with the engine in situ. The first step to removal is to free-up the valve on the engine bay side. There is very little working room between the engine and bulkhead. Even less if your car has the extra aluminium heat shields. As such, it is virtually impossible to access and loosen hose clips - even more so if they are the original 'Mirex' buckle clips. 

Hose clips on the valve body. Note that my hoses had been leaking!

You might be tempted to cut the hose ends. This is fine: one of the hoses is a specific moulded 'S' shape, but both hoses are available as modern reproduction parts. The quality of the rubber may not be as good - but they will work.

Original hoses (top) and a reproduction (bottom)

The best way to loosen the valve on the engine bay side is to tackle the other ends of its two hoses: one on the feed pipe from the cylinder head (behind the air cleaner) and one on the heater matrix itself.

With the hoses undone, the valve itself is removed by first either removing the rubber cover from the knob (if the car is a DS or ID) or by winkling out the stainless steel disc from the knob if the car has Pallas spec. trim.

Stainless steel capping disc on a Pallas knob

In both cases this reveals a nut to remove the rest of the knob and temperature indicator.

The valve itself is them removed by undoing the two cheese-headed screws from within the cabin. These two screws also serve as the 'stops' for the rotation of the knob between hot and cold.

Screws holding the heater valve in place

The valve spindle is a tight fit through the bulkhead, so needs to be pushed back through all the way before it can be angled and lowered down and out.

In theory, at least, there is another way. If you wanted to remove the valve from the bulkhead with the engine in situ, removing the rubber/ metal plate would leave a bigger hole in the bulkhead and provide more wiggle room. I removed mine, however (as the marks on the rubber in the photo show) that rubber plate sticks to the sound deadening on the bulkhead and was surprisingly hard to remove - even with the engine out. It was stuck so fast that at one point I wasn't even sure it COULD be removed.

Rubber seal and backing plate

I vaguely recall, many years ago - back in the 1990s - that my valve got stuck and stopped turning. I took the opportunity while the engine was out to remove and free it up. I managed to find an 'O' ring that fitted and that was that. The car has since stood idle for decades and rubber doesn't last for ever so, given the passage of time, I felt I needed to go back and re-do that job.

Engine out - circa November 1998

Once I'd committed to removing my car's engine (again) in 2015, I always planned to service the heater valve (again).

I'd already removed the valve and the rubber/ metal back plate it fits to a year or so ago, as part of plans to repaint the engine bay. 

Heater valve and backing plate

The valve was unscrewed from the plate - just as you would do if the plate/ valve assembly was in situ on the bulkhead.

With the valve removed, the spindle (the part with the threaded end) should just pull out of the body - as it's only the rubber 'O' ring that's holding it in place. In my case, it's an 'O' ring I put in about 25 years ago. My spindle shows the battle scars from the mole grips I used to get it rotating back in the 1990s. At least I gripped around the main shaft and managed to avoid snapping the threaded part off. 

Spindle removed from the valve body

It's maybe worth noting at this point, the shape of the valve part of the spindle and in particular the cut out that gives varying levels flow as the knob is rotated. I'm not sure what the thin slot is for? Perhaps to absorb heat expansion? Perhaps to allow a small flow even when the valve is closed?

Note the thin slot

Starting with the valve body, I used some emery cloth to gently clean the bore where the valve spindle sits. It's soft brass, so don't use anything too abrasive. I also used a small wire wheel on a Dremel to go up and down the bore to polish it a little.

With the 'O' ring removed, I lightly cleaned the spindle with wire wool. I used a file to dress the worst of the gnarled edges from the mole grips. I also cleaned up the threads on the screws. Yhese stick through into the bulkhead and their ends tend to rust. I decided to run all the parts though my ultrasonic cleaner. rather than fill the whole thing with cleaner, I just put the parts in a small jar of heated cleaning fluid and filled the rest of the ultrasonic cleaner with hot water.

Parts to go in the ultrasonic cleaner

The ultrasonic cleaner did a fair job of cleaning the parts up, but they still looked tarnished so, after removal and rinsing I gave them a clean with 'Brasso' - followed by another ultrasonic bath. And then it was time for reassembly.

There is no point in dismantling and cleaning the valve if you are not going to fit a new 'O' ring. recently John Titus - another Citroen enthusiast - recommended a 'size 112' 'O' ring for this job. He also recommended one made from 'EDPM' rubber, as opposed to 'nitrile' or 'buna'. Nitrile rubber is used in marine (wet) applications but performs less well in hot conditions. The benefit of EDPM is that it more resistant to heat and can stand temperatures over 100 degrees. It's weakness is that it is not very resistant to petrol, oils and solvents. That isn't going to be a problem in the valve of a cooling system - provided you use the right lubricating grease. It's best to use silicone grease. Don't be tempted to use Vaseline (aka petroleum jelly). The clue is in the name. Plus it has a low melt temperature so is not suited to a hot water valve. 

All ready for reassembly

I sourced a size 112 EDPM 'O' ring from Ebay. It fitted a treat. I also sourced some silicone grease. This particular one has an effective operating temperature range of -40 to +220 degrees centigrade so should have a long life in service.

I greased the groove where the 'O' ring sits and reapplied a little grease after I had located it. While it's the 'O' ring on the spindle that seals in the bore, I also smeared a thin film of grease on the bore and spindle body to help reduce the risk of jamming. I was careful not to clog the thin slot - just in case it hampered heater performance.

New 'O' ring (note old mole grip marks!)

The spindle just pushes into the body. There was a small pocket of trapped air at the end that initially prevented the spindle pushing home, but that soon cleared.The body seems to have a groove in the end of it as though there should be a second seal to cushion it on the backplate. 

Groove for a second seal?

Mine didn't have a second 'O' ring  but I will investigate that further and can always fit one later. So in the meantime I refitted the backing plate to the bulkhead and then the valve to the plate. If you are also refitting the backing plate, note that it's easy to orientate it wrongly. It needs to be fitted so that the holes that hold the valve are at top and bottom (north and south).

Backing plate and valve refitted.

It looks (and works) a lot better than it did

If your engine is still in the car and you are trying to refit the valve, I've read a tip that supposedly make things easier. It's in the "Goddess" book by Charles Vyse. He suggests feeding a piece of string through the hole in the bulkhead where the valve spindle/ knob will fit, and then trailing the string down to the ground on the engine bay side. You then tie the string to the valve and tug it back into it's approximate position from inside the cabin.

It would make sense to be tying the string to the threaded tip. Partly for grip but also because it's a smaller dimension because of the flatted side. Also bear in mind that you will have/ should have two rubber hoses connected to the valve - which may make it heavier and harder to manoeuvre. Lastly, t's also worth noting that the valve assembly needs to be almost perpendicular to pass through the bulkhead hole - so some final fiddling and aligning on both sides of the bulkhead are probably called for. 

The valve has to be turned through almost 90 degrees
 to locate it in the bulkhead

That's about as far as I can go until I put all the carpets back in, but I can show you how it all goes back together. It really just the reverse of removal. The indicator plate is fitted over the carpeting.

The 'stop' is fitted on the spindle......

.....and then the indicator disc is fitted over the stop.

Next comes the knob. At this point, orientate the knob (and spindle) so that the stop only allows it to rotate between the 'hot' and 'cold' positions. When you are happy, refit the grip washer and nut and refit the cover (small disc or rubber knob) according to what model you have.

Refitting The Engine Bay Pipes

 I've been making good progress with replacing the piping and hoses at the front of the car.

Nice to see some progress at last

The job hasn't been particularly hard, it's just complicated and needs a bit of thought applying throughout. 

It all happened on the left side of the car.....

I've written a post before about pipes and pipe seals. You can find that HERE. It's worth repeating some of that earlier post. I can't really explain how I put everything back, as it's a bit of 'journey to discovery' and, if you do this, your journey will be different to mine. I can offer some tips and personal thoughts though.

BEFORE DISMANTLING

Before you even consider taking the pipework apart, ask yourself 'why?' What do you want or need to achieve? Is there another way of getting what you want? Are you trying to replace a particular pipe? Could you just remove that one or will others need to come off. If something goes wrong, how will you salvage the situation. What is 'Plan B'? Will the car be stuck somewhere - a long way from a garage and help?

Take LOTS of reference photos. Photograph all angles. You'll still wish you'd taken more. Clean off any loose muck so that you are clearer about what you are looking at.

Follow pipes and hoses through from the engine bay into the wheel arch and vice versa - taking photos as you go. 

This pipe and hose in the wheel arch........

.....comes out here in the engine bay

Note which pipes sit in front of, or above other pipes. Where are the pipes clipped in place and how. There are several different types of clip and sizes of rubber bushes fitted.

Various clips and brackets

Despite thinking the photos I'd taken would be a good memory jog, I still found myself asking what on earth a lot of them were trying to show and why I'd felt they were relevant.

Me, pointing at something meaningfully......

DISMANTLING

Be clean. Try to remove as much loose muck as you can while all the pipes are in place.  Especially around the flare nuts. 

Mucky pipes

Depending on how big a job you have set yourself, you almost certainly want to avoid grit and road dirt falling into fittings and pipe ends. Also, cleaning the flare nuts up means that you are less likely to damage them when trying to undo them.

Be thoughtful and patient. Think of the job as a puzzle. Don't just dive in. How are the pipes layered and routed? Check the fitting at both ends to decide. Which pipes need to come off first to then allow access to other pipes?  Target them methodically.

Work tactically: target a pipe then remove it

You might find that some of the pipe flare nuts are rusted. This might meant they are harder to undo, but also that their hex heads are weakened - as, potentially, are the pipes they hold in place. Try to avoid rounding a hex head and giving yourself another problem. Also, rounded hex heads often leads to broken pipes. Yet another problem to be dealt with.

Use the right tools. As opposed to an open-ended spanner, a proper flare nut spanner will grip the hex on most sides and is less likely to slip off and start rounding edges. 

A flare nut spanner grips the nut securely

For original Citroen flare nuts, you'll need a 9mm and 12mm spanner. You can even buy ratchet flare nut spanners. They are chunky - so not practical in tight spaces, and fiddly to remove after you've used them. But when in use, they make tightening and loosening much faster as you don't need to lift-off and relocate the spanner ever partial turn.

Flare nut spanners

As the 9mm nuts are prone to rusting, some after market nuts have a 10mm hex head.

9mm and 10mm hex ended flare nuts

For a hex nut to release and undo, it needs to be able to move along the pipe a little. If the pipe is bent close to the flare nut, it won't have scope to move. 

A bent pipe can prevent the flare nut releasing

If you can, gently straighten the last 20mm or so of pipe close to the flare nut - so that the pipe is entering straight into the fixing.

A straight end makes things easier

Know your enemy. Some pipes are 'simple': they have a flare and flare nut at each end. If they are damaged and need to be replaced, it's very easy to make a replacement up - or to get someone with the right tools to do it. In the UK, 'cuprinol' (aka cupro-nickel  tubing) is used for this purpose. It's nearly as strong as the original pipe (perfectly fine for Citroen high pressure hydraulics) but is more malleable and easier to shape.  

Others pipes on a DS are more complex: Some ends are silver-soldered into special fittings.

Pipes with a fitting plate attached

If these pipes get damaged, they are much harder to repair as the fittings need to be heated red hot for repairs and cuprous-nickel pipe becomes soft and unstable at such temperatures. Be warned and take extra care of such fittings. Some/ many are available as replacement parts but are costly and may not fit your car: D plumbing varied over the years and across models/ specification. 

Be gentle. You should not have to bend any of the pipes to remove them. With a little care and thought, they can be manipulated out. You will need to loosen or remove brackets, and you may need to loosen components. 

Pipe clamps

You may need to 'flex' a pipe, but avoid bending and re-shaping. You risk weakening the pipes and, if the shape is changed, may also lose track of where it was meant to go.

Be thorough. If you are only removing some pipes, or removing pipes from components, be aware that there will be little probably be shards of the old pipe seal left in the fitting or component. You will need to hook those (and any stray pipes seals) out before you put things back together.

Removing pipe seals leaves slivers of rubber

Be organised. Try to label up the pipe ends in some way for easier identification. Come up with a system that works for you. My system worked for me. 

You can't have enough labels....(red means 'engine bay side')

Well, the system worked most of the time anyway.....I still lost track of what my 'code' meant. 

It's easy to get confused.....

After I'd removed the pipes I separated them and catalogued them - taking even more reference photos. It pays to have a system.

More cataloguing (green tag means 'wheel arch side')

Dealing with rubber hoses. Some pipes have hoses fitted to the end. If you car has been tampered with before, these may be held on with jubilee clips. Easy to undo. If they are original, they will have a steel belt and 'Mirex buckles on them.

Mirex buckles on hoses

These have been tightened with a key - a bit like a split pin. Removing them means loosening the pin (by unwinding a little) and then carefully dismantling the strap. 

Removing a Mirex buckle and strap from a hose end.
(Note the protective collar)

If you are lucky, you will reach a point where the key - the split pin can be pulled out. Sometimes it's easier to remove a pipe with a hose still attached, and deal with it on the bench. 

The rubber hoses on Ds all have part numbers: they are of a size and length needed to do a particular job. length aside, in terms of internal and external diameters, they, by and large, conform to a few standard sizes. However there are a few hoses that are particularly special.  Don't be tempted to cut the hose off and then deal with the stump end in due course. Firstly, you will possibly end up with a hose that is too short to do it's job. Secondly, not all the hoses are of a standard dimensions. How do I know? You can read all about that in my previous post......

CLEANING

Not a lot to say really. I thought about getting the parts vapour-blasted but my local workshop guy said it would be a long process to get all surfaces and angles covered and time meant money. Expensive. It also introduces gritty sand to hydraulic pipes. Probably not a good idea. Instead I gave all my parts a wash in Jizer and stippled them with a tooth brush and paint brush. I rinsed and dried them. I also put a wire brush over them all to clean off loose rust. At this point you need to take care not to bend or damage the pipes through rough handling.

I examined all the ends with flare nuts and carefully straightened any that were bent and prevented the flare nuts from moving a little along the pipe. I used emery cloth to gently de-burr ends to aid refitting. Similarly, I used a wire wheel to clean up the threads and hex ends of flare nuts. 

I also rubbed over the pipes with wire wool. There were all washed again and I blew them through with compressed air. be aware that compressed air can have moisture in it and this can condense when you blow the wire through a cold pipe: cleaning the pipe can also introduce moisture. For this reason, I didn't seal the ends up completely after blowing them through.

My pipes were left clean, but mottled and patchy. At this point I considered getting them all zinc-plated. I've found a good local plater and this was affordable so not out of the question.  However the plating process involves the use of acid and I was concerned it might weaken old pipes. There was also the risk that the plater bend a few pipes along the way. I've also seen cheap, re-plated, pipes on sale in Holland. In many cases the flare nut has moved along the pipe during plating. When it's move to the end for fitting, it leaves a bald spot. I also noticed that plating accentuates old pox-marks on pipes and they never really come out looking 'new' - just 'odd'.

If your pockets are deep, you can buy newly re-made pipes with fittings brazed to the ends. These certainly pass the 'shiny' test, but beware that they may not fit your car and it's not until it's in your hand and you compare it to the part you removed, that you realise it's a bit different.....

New pipes. From 'Der Franzose' in this case

The original Citroen pipes with fittings on the end have a different appearance to the 'simple' pipes. I wonder if they are made of a different material, or are perhaps copper plated to help the silver-solder joint process?? I've brought brand new old stock original Citroen pipes and they are that way from new. 

A 'new old stock' pipe with a copper finish

 

Another original 'new old stock' pipe (photo credit Citrotech)

 

And it's modern, reproduction, equivalent (photo credit: Citrotech)

 

 So it looked as though they weren't originally shiny zinc anyway?

Lastly I thought about my use of the car. I plan to take care of it and keep an eye on it. In the end I just decided to rub my pipes and flare nuts over with an oily rag to give them some resistance to moisture and rust.

Hoses were washed in Jizer and inspected for cracks, cuts or rub marks. They all passed the test. They had lost some flexibility and had become a little stiff but were perfectly serviceable - especially as they are for the low pressure return circuit.

REFITTING.....

.......Is the reverse of removal. In many ways it is. You need to be organised, thoughtful, careful, gentle etc. Above all you need to be methodical and study your photos. Consider starting with the pipes that seem to be buried deepest. Which ones would then go on top of them? Some trial and error is involved.

Pipe seals and 'O' rings'. You will need plenty of pipe seals....and it's always good to have spares in case you need to disassemble a pipe to shift things around a bit. You will need a lot of the ones for 4.5mm pipe, and at least three or four seals for 6.35mm pipe. For these 6.35mm pipe seals, most will need to have an outer diameter of 10mm, but if your car has a brake accumulator sphere, the seal at that end of the pipe needs to have a 12mm outer diameter.

A selection of seals

The original small 'o' rings that sit inside plate seals were painted white on one side. The painted side was meant to face towards the direction of fluid flow. Perhaps the rings were 'o' shaped at all and had a different profile? 

White marks on 'O' rings

Anyway, the modern replacements aren't marked in this way, so it seems they have no right or wrong side. That makes it easy.

Fitting pipes. The correct way to refit a pipe with a flared end is to wipe the pipe and seal with a little hydraulic fluid and then to push the pipe seal onto the pipe leaving 1mm or 2mm of pipe exposed at the end. 

Fitting hydraulic pipes with seals

In some cases the pipe seals sold by different suppliers are different lengths.

Not all pipe seals are made the same

It's not a lot, but if they are too long, when you try to expose 2mm of pipe at the end, the seal rides up over the flare in the pipe. As you push the pipe in, the seal rides up further. This then prevents you from engaging the flare nut thread in the fitting - increasing the risk of you cross-threading the flare nut. For this reason, the slightly shorter seals are perhaps better as they allow you to have a millimetre or so of pipe end exposed.

The seal should fit over the pipe end leaving about 2mm exposed

Fit the pipe with seal onto the receiving end

The pipe is then pushed squarely into the fitting so that the pipe end engages centrally.

The pipe end should fit in squarely

You should then be able to turn the flare nut a couple of turns by hand before you tighten it.

When you are re-assembling your pipes, there is quite a lot of spring and flex in them: you push the pipe end home in the fitting and it springs out...You need to keep the pipe ends pressed in as you begin to do up the flare nut. 

Rubber collars for pipe brackets and hoses. You will need these too. To stop vibration and rubbing some pipes have brackets with rubber liners/ collars to cushion the pipes. These rubber collars are often squashed and distorted.  For some reason, you can buy the 'cotton reel' type ones (that are only used in a couple of places) but not the 'plain' ones? I reused a lot of the old ones and cut the rims of a couple of cotton reel ones. 

Rubber hoses also have collars to stop the tightened Mirex strap or jubilee clip cutting into the hose. You can also buy collars for at least two of the three standard sized hoses. I just re-used all of mine.

Test Fit. I loosely assembled my pipes in their fittings and brackets as I went along. This means you have some 'flex' in the rats nest of pipes as you increasing want to add more. If a pipe won't fit, avoid the temptation to bend or force it. In one case, when I came to thread in a later pipe, I discovered I needed to take a few steps back and undo and remove a pipe I had previously fitted. as it was in the way.

Don't rely on the parts manuals to help you decide which return hose is which. They are for illustration only. In some cases hoses shown as short in the diagram are some of the longest hoses.

Rubbing and Stress. When fitted the pipes should not touch. Gentle rubbing from vibration will soon wear a thin pipe away. And, given Citron hydraulic pressures, it will soon burst. If, when you are fitting your pipes, they touch or are tangled, go back and check your photos. Have you routed the pipe correctly? If it has one, is it held properly in it's bracket?

Refitting hoses. I assembled most of the hoses off the car. I was re-using original pipes which had hardened slightly. To fit them to their couplings, I softened the ends briefly in a cup of boiling water. I have Ligarex strapping and Mirex buckles so used those.

Reassembling pipes. Note use of computer and reference photos!

All I needed to do then, was to re-fit the 'spider' in the middle the cluster to the chassis.....

The 'spider'. This was my nemesis.......The 'spider' may have three or four legs depending on your car model. It's held to the chassis by a rubber plug that tightens in place with a nut and bolt that causes it to expand.

The spider. Lurking.......It nearly had my thumb off.

It's comes off and comes apart easily enough.

The 'spider' and rubber bung. Spigot '2' has a fluted end?

But it's a tight fit to put back on and, several times, tightening it caused it to pop straight back out. It wasn't helped by the fact that the hoses got in the way. In the end I carefully hammered the bung and screw into place using a socket, then carefully added the plastic spider and attached hoses before tightening.

Three ends on the spider have a bulbous end. The fourth has a fluted end for some reason?  Not sure why? I don't think it's anything to do with the direction of flow? 

The 'spider'.
(photo copyright to Citrotech)

The sharp edge made it very difficult to push the hose on and there was a risk that the spider might snap or crack. It's the hose that comes from a fitting connected to the height corrector in the wheel arch. Having been caught out once before by pipes that have different sized ends (and having cut this particular hose!), I even check the parts book to see if it too, was a special hose. Nope. same size both ends as far as I could tell. Eventually it shoved on.

Final fit. As more pipes and hoses are added, the puzzle got simpler. Once I'd got to a point I was happy with, I went round and methodically tightened all the flare nuts and brackets. This meant giving each pipe end a good shove into it's fitting before I tightened the flare nuts up. I tightened up brackets and checked pipes weren't rubbing.

A 'before' shot and..........

.....the gratuitous 'after' shot

To 'yellow' or not to 'yellow'? There are a lot of fittings to tighten and I was still leaving some loose until the suspension and engine were added. This being so (and despite telling myself I wouldn't) I marked all those I'd tightened with a blob of yellow paint..... I can see why Citroen did it. Someone has suggested that it was the quality control team at the factory that that did this, but it's always the same parts with marks. I'd have though it was up to the assembly line workers to do these up right in the first place?

A splash of yellow

And a splash more

I'd also started doing this on all the main nuts and bolts I'd tightened elsewhere - again following Citroen's lead.

Making Sense Of It All. There is an inevitable motorway of pipes and hoses making their way toward where the reservoir would be on the left side of the car.

Motorway

I haven't finished fitting everything yet, but I have done several trial fits to make sure that everything is accounted for and that nothing is twisted, snagged or pinched. 

I'm going to rebuild the 'gear brain' and so will have some pipes to fit when that goes back on.  I will probably fit the reservoir and connect everything to the bottom before the engine goes back in. There are also a couple more brake pipes to fit across the gearbox after the engine is fitted.