Dressing the Engine (Part 1) - Fitting the Starter Motor, Pressure Regulator and Sensor Wires

With the engine and gearbox reunited just a couple of small but satisfying jobs…

Starter Motor

I had rebuilt the starter back at the beginning of the year. Now it came to fitting it, I cleaned all the paint off the back of the two brackets that bolt to the engine to make sure I had good earth contact.  I tucked the battery positive cable well out of the way low down behind the starter – as far from the exhaust manifold as I could.

Rebuilt Starter Motor

I also (retrospectively) spread a little grease on the teeth of the flywheel – partly to aid engagement when the starter was operated and partly to reduce wear between the pinion and the teeth. With the engine on the stand I had access to the exposed bottom portion of the flywheel and, with the starter handle engaged, could rotate the crank and flywheel as necessary.

The flywheel is visible under the bell housing

This was also a chance to put in place the last of the bolts that serve to hold the gearbox to the engine. Finally I added the heat shield. This had looked quite scrappy and the only way I could tidy it up was to give it a good polish. I don’t think it would have been polished when fitted, but it’s no bad thing, as a highly polished shield will radiate the exhaust manifold heat away from the starter more effectively.

Starter Motor Heat Shield

Pressure Regulator

The bracket and regulator were both refitted. I put them back in their original spot – down below the fuel pump. On the photo I have highlighted the bolt you undo to release system pressure. It only needs about one turn. Don't take it all the way out or you will lose the little ball bearing that sits behind it!

Pressure Regulator mounted underneath the Fuel Pump

I had no serious plans to relocate the regulator – partly because – with the engine out – I couldn’t be sure where I had enough ‘spare’ space to put it. I didn’t want to relocate it then find it got in the way of something when I tried to fit the engine and gearbox. I will fit a recharged accumulator sphere (65bar) and worry about changing it as and when it’s flat.

Many years ago (11 September 2001 to be exact) I bought a regulator hose for a GSA (£8.99). These have a reinforced end to help absorb the pressure pulse in the hose and can also be fitted to Ds. It's not been used: my car was off the road at the time. Perhaps it was part of my plan for when I got it back from the garage? You can still buy the same reinforced hose for about £45 these days....

Regulator hose with reinforced end

Sensor wires – temperature gauge and oil pressure warning

The flying lead for my oil pressure switch was badly corroded and so I made up a new one. While I was at it I made a new leads for the water gauge sender too. At some point that had broken and had had a modern crimp end fitted.

Temperature gauge sender - August 2015

More by luck that judgement it was blue, but I wanted to have a 'proper' Citroen bullet and tag on it. 

New Wires for Warning light senders

Both sender wires have an eyelet connection where they connect to the senders but, for the other ends, and while the water gauge lead needed a ‘standard’ 4mm male bullet connector, the oil pressure switch needed a smaller 3mm bullet. In both cases I re-used the original protective rubber sleeving over the wires to protect against chaffing.

On my car, the water gauge sender is fitted near the bottom of the water pump housing.

Temperature gauge sender - August 2018

Later cars with the three big dash dials can have a water gauge sender, AND a temperature warning sender. The circuit wiring diagrams for these suggest that the latter (the warning sender) was fitted on the water pump, with the optional temperature gauge sender (if fitted) relocated to the cylinder head near the inlet manifold. Be careful if you plan to replace one of these as the two senders do different jobs and are not the same.

An oil pressure warning light was introduced with effect from the end of the 1967 model year – so just in time for the 1968 model year. It bolts on to a modified casting on the oil gallery in the engine block.

Oil pressure switch below the fuel pump - 26 November 2015

Oil Pressure switch - August 2018

To accompany this introduction, the conical battery charge warning light on the (mid period) dash was altered to a dual function indicator - but only for the 1968 model year. 

Pre-1968 battery light (left) and for 1968 only, 
combined battery charge and oil pressure light (right)

The top half glows red if the battery is not charging........

.......and the bottom half glows red if your oil is spread down the road…….

I have always preferred the aesthetic look of the conical light as a dashboard feature and am still in two minds about whether to fit that or the correct 1968 dual light. 

Engine Rebuild (Part 12) - Joining the Engine and Gearbox

With the clutch and distributor tower fitted, I could reunite the gearbox and engine halves.

The engine had been split before: back in 1999 to deal with gearbox input shaft that sheared as the result of a vicious clutch snatch. That was what took my car off the road for all these years. The solution back then was to fit an alternative gearbox from a low mileage car. As the car was never put back on the road after that surgery, the replacement gearbox never really had a road test and remains an unknown quantity. It probably only ran another 3 or 4 miles after it was put back together again.......before I pulled it all apart again in 2016.

Engine about to be split: 25 September 2016

With this engine build now well underway, I was getting closer to finding out if that gearbox was any good.

The procedure for refitting the gearbox doesn't seem to warrant a mention in manual 814, but is covered (succinctly) in step 18 of Operation DX.100-2 in Manual 518. The thrust bearing refit is covered by step 23 of Operation D.330-3 in section 2 of volume 2 of Manual 814.

I refitted the thrust bearing. my car has the type with the 'eye' that fits over a guide rod. It took me ages to work out that the retaining clips are meant to go through holes in the clutch fork.

Thrust bearing eye mounted on guide rod

Gearbox bolts come in all shapes and sizes. Some hold clips to secure hydraulic pipes – so it’s important that they go back in the right places. This is where earlier reference photos come in handy!

Reference photo - 25 September 2016

Before zinc plating the bolts, I laid them all out, to make sure they were all accounted for and to work out which went where. The 'anti-tamper' bolts had been replaced with normal hex heads.

Gerabox Bolts - All Accounted For

 I also numbered their positions on the bell housing. 

Working out Bolt Positions.....

When I built my engine trolley earlier in the month (see other post), I had taken account of the need to accommodate the gearbox on it as well as the engine: it would become the platform on which the rest of the engine build took place before re-fitting.

Lots of room for the gearbox....

With the engine now on the trolley, and the gearbox innards complete, all I had to do was swing the gearbox back into place. Simple. In fact it was simple, but just tricky for one person to do on their own. Alignment of the two halves was crucial. Strapping the gearbox to the crane to achieve a level lift was fiddly and I used blocks of wood strategically placed to pad out the strapping to give me ’level’. It was frustrating when, thinking everything was lined up, the two halves would not mate. More than once I pulled the halves apart convinced something was blocking the way.

Aligning the gearbox and engine

In reality, it was probably just a slight mis-alignment of the end of the gearbox input shaft to the splines on the clutch plate. After several attempts the gearbox suddenly slid into place. Pinching a corner together with no more than finger and thumb I was able to put one bolt in place by a couple of turns. I didn’t force it as I was concerned about exact alignment and the risk of stripping the threads on the aluminium bell housing.

Bolting the Gearbox to the Engine

Working around the engine I put more bolts in place (with some threadlock) and gradually tightened each a little to pull the gearbox into position (it has two locating lugs). When I was happy I blocked up the gearbox end and l released it from its sling…..

Reunited - August 2018

There are three bolts that hold the starter motor in place – these also serve to hold the engine and gearbox together and I would fit these in due course.

Engine Rebuild (Part 11) - Flywheel and Clutch

With the engine off the stand and now sitting on the trolley I had made  I could, at long last, refit the flywheel and clutch.

The Flywheel
As a 1968 car, my car has the 95 tooth flywheel and uses a starter with a 10 tooth pinion. (From October 1969 - so approximately 1970 model year - the flywheel then had 123 teeth and matched to a starter with a 9 tooth pinion). You can find out more about the change in flywheels in an earlier post HERE.

Back to business. With the retaining circlip removed, I had used a suitably sized socket to drift out the old flywheel bearing. I would fit a replacement later.

Using a socket to drift out the bearing

Anyway, fitting the flywheel was straightforward. The procedure (short and sweet) is covered in step 36 of Operation DX.100-3 and in step 36 of Operation D.100-3 in section 2 of volume 2 of Manual 814.

There is a lug on the flywheel that corresponds to a notch on the end of the crankshaft - so it stops you putting the flywheel on the wrong way round. I used a block of wood and some long bolts in the clutch pressure plate holes to hold the flywheel in place while I prepared to torque up the flywheel bolts.

Bracing the flywheel to tighten the bolts

BE WARNED that the instructions for tightening differ between Manuals: the earlier Manual  518 (dating from 1966) says to torque the bolts to between 5.9m.kg and 6.5m.kg. The later Manual 814 (from 1974) says that for bolts with a "spherical imprint on the screw head", they should be torqued to 9m.kg - so quite a difference. I judged that my bolts had the later spherical pattern and so went for the higher figure......

Has this got a "spherical imprint"?

With the flywheel fitted, I was able to fit a new flywheel bearing. The gearbox drive shaft will slot through the clutch plate and into this. The bearing is simply held in place with a circlip.

New Flywheel Bearing Fitted

You know that you can insert a pin into a little hole in the bell housing - and when it engages with a slot in the flywheel you can set the timing? Well if you ever wondered what that notch looks like, you can see it in the photo below. On my 1968 car, the notch in the 95 tooth flywheel gives 12 degrees before top dead centre of number one cylinder. The notch continued to give that mark for a while - even after the change to 123 teeth flywheels. However, from July 71 - so approximately the 1972 model year - the notch in 123 tooth flywheels changed to giving TDC - top dead centre. See my post of 1 October 2016 for more information.

Timing Notch in Flywheel

The corresponding hole where you insert the 'timing pin' is on the carburettor side of the engine - tucked away underneath the mounting point for the alternator.

Same view: the hole for the timing pin (centre in this photo) is beneath the alternator

The Clutch
If fitting the flywheel was straightforward, then fitting the clutch more of a head scratcher. I had agonised for weeks beforehand over the clutch disc and pressure plate. Mine is a three fingered clutch and, with the clutch off the car, rough measurement indicated that the three fingers were set at slightly different heights. Precise measurement with the clutch all bolted together on my bench confirmed it.

Even crude measurement showed the clutch fingers were at different heights

The difference was only a millimetre – but that might be crucial. Citroen specify heights for the fingers and the tolerance on these is a millimetre or more – but that does assume that all fingers will be set to the same height. Mindful of the ‘clutch snatch’ problem that led to my car being taken off the road back in 1998, I worried that this difference of finger height might mean that the clutch had not been releasing evenly and smoothly due to finger height? For peace of mind, I needed to sort those fingers out. 

Three problems: firstly Citroen give no correct finger height measurements with the clutch off the car – or more accurately they give no measurements that a home mechanic can make. They rely on the use of special Citroen jigs that mimic the clutch being fitted to the flywheel and operated.

Second problem, my car has an after-market ‘Valeo’ brand clutch that is (apparently) thicker than the Citroen originals - so any Factory set up measurements were not much use anyway. Darrin at Citroen Classics did give me a magic number that he used when checking the fit of Valeo clutches: with the plate clamped between flywheel and pressure plate - 35.2mm from the surface of the flange around the clutch plate centre, to the top edge of the clutch finger. That's pretty precise! At least I could use this measure to make sure all my clutch fingers were a consistent height, right?

Wrong: third problem, I could not release and adjust the nuts holding the fingers together! Not without ruining the bolts and nuts.

before i started hacking at nuts, I contacted a clutch specialised looking for replacements. He couldn't help me and simply advised instead, using very thin shim washers under strategic points of the pressure plate to give consistent finger heights. Trouble is that this would then take the flywheel and pressure plate surfaces out of parallel – something I judged to be just as important as consistent finger height. 

The alternative was to part exchange my clutch for a reconditioned one - but i could do without the expense of that. In the end I resolved to do nothing at that time and wait until the flywheel was fitted and then try it in situ on the car - and that time had now come........

The procedure for fitting the clutch is covered in step 37 of Operation DX.100-3 of Manual 518, and in step 37 of Operation D.100-3 in section 2 of volume 2 of Manual 814.

A key requirement is to fit the clutch disc centrally in the flywheel/ pressure plate sandwich, so that when engine and gearbox are reunited, the gearbox shaft can pass through the clutch disc and into the flywheel bearing. Citroen workshops use a special mandrel to get this alignment. The alternative (and since it's the gearbox shaft that needs to pass through the clutch) is to use a spare gearbox input shaft......Fate, as it often does, took a hand: reading of his gearbox rebuilding exploits, I contacted Badabec who very kindly lent me his worn and surplus gearbox input shaft to use as a clutch alignment tool. 

A spare input shaft can be used to align the clutch disc

I thoroughly cleaned the surface of the flywheel and clutch pressure plate using 'Mek' and did the same to both sides of the clutch disc.

With the engine off the stand and the flywheel fitted, I used the old input shaft as a mandrel to align the clutch disc to the flywheel.

Using  the input shaft to centre the clutch disc on the flywheel

With the clutch disc held centrally, I slipped the clutch pressure plate over the mandrel and orientated the pressure plate to line up the marks made when it was removed.

Chalk marks highlight the alignment of the two parts. Mandrel still in place

It was time to bolt up. The later Manual 814 updates on Manual 518 by advising you to replace the old-type clutch pressure plate bolts used on pre December 1969 cars with a later type (and presumably specification) of bolt. The distinction being the pattern on the heads.

Different Specs of Flywheel Bolts

My pressure plate bolts most definitely had chevron heads (like 'type 1'), and I didn’t have any of the updated bolts to use - so swapping up was not an option. I re-used my bolts (with serrated washers) and tightened to 2.9m.kg as per Manual 518 (not the torque in the later Manual 814). As I tightened, I checked to make sure that the clutch disc was still central and that mandrel was free to slide in and out of the bearing and splines of the clutch disc.

I Fitted the older 'type 1' clutch bolts..........

Taking a measurement of the finger heights again, I was surprised to find they all came up very close! Not the magic 35.2mm figure that Darrin had given to me, but all were about 34.8mm. While I didn’t know whether 34.8mm was a good or bad number, it was at least consistent for all three fingers - which had been my objective!


In the absence of any other information to the contrary, I resigned that there would be some clutch adjustment i could make to 'fine tune' the clutch once the car was running and decided my clutch was going to have to do - so left it at that.

Engine Rebuild (Part 10) - Fitting the Distributor Tower: Aligning the Slotted Head

Refitting the distributor tower is only a small job in the overall engine reassembly, but the steady flow of questions raised on forums shows that it's very easy to get this wrong......

Distributor Tower

It helps to understand how the bits and pieces relate. 

The spindle in the distributor tower rotates the distributor arm which causes a spark to occur at the spark plug of each cylinder in turn. The spindle in the distributor tower has a pinion at the base that is driven by the camshaft. 

The pinion inside this bit.........

.......Needs To Be Correctly Engaged With This Bit.

The camshaft also determines when the engine valves open and close. The camshaft is in turn driven by crankshaft - which controls the movement of the pistons. Through the distributor tower spindle, the camshaft is seeking to manage the correct point for the distributor to make a spark for each cylinder - meaning the spindle needs to rotate the distributor arm to the right position at the right time for the firing sequence in the correct cylinder.

To help ensure this happens, the drive socket on top of the distributor tower spindle has a slot in the top: the slot determines how the distributor is fitted to the spindle in the tower and so influences the point (relative to piston and valve movement and spindle rotation) at which a spark is produced....... 

Drive Socket in the Distributor Tower.
Note that the slot does NOT pass centrally through the axis

The slot in the drive socket seems to be the cause of much confusion and error as the slot does not pass the centre point of the drive head - it is very slightly offset  - giving a 'big half' and a 'small half' - thus when fitting the tower, the alignment of this head socket is crucial for correct ignition timing. 

From background reading, having fitted the distributor tower, any problems typically seem to fall into three scenarios:

1.  The distributor tower has been refitted with the drive socket of the spindle aligned - but the wrong way round (180 degrees out of alignment)

1. Looks okay - but 180 degrees out....

2.  The distributor tower has been refitted without the drive socket of the spindle being orientated in any particular way at all (anything up to 360 degrees out of alignment)

2. No Chance.....

3.  The distributor tower has been refitted with an attempt to align the drive socket, but the drive socket itself is not correctly orientated to the pinion wheel on the other end of the spindle and so will not rest in line with the camshaft. (can be anything up to about 15 degrees out alignment).

3. Nearly - but not parallel.......

Of the above, scenario 1 seems to be the most common and the most likely. It tends to reveal itself only when people come to refit the distributor and set up the timing - by which time the gearbox and clutch housing will have been bolted over the distributor tower - making it impossible to remove and correct properly without stripping the engine down.....However there is a workaround and a fix. The workaround: scenario 1 affects the firing order of the cylinders: rotating the distributor 180 degrees and refitting it restores the correct firing order. The solution also necessitates swapping the long and shot HT leads around a bit. BUT, one issue you might have with a "stacked" (side entry) distributor cap is the matching notches in the distributor and cap: if the distributor is 180 degrees around, then the plug leads will be facing the nose of the car rather than the back! Solution? Fit a 'top exit' distributor cap! The fix: remove the distributor, remove the roll pin holding the drive head on the bottom. Rotate the drive head 180 degrees on the shaft and refit the pin. Firing order will be restored and your plug leads will still point towards the back of the car.

The fix for scenario 1: remove and rotate the drive head of the distributor

The other scenarios should be obvious as soon as you fit the tower, but if you're not paying attention, problems will only come to light when you try to start the car.....

Scenario 3 only really come about if you have stripped the distributor drive tower to replace the oil seal and messed up the reassembly. If you have stripped the distributor drive tower to replace the oil seal, then you will have removed the slotted drive head from the spindle. When reassembling, it is vital that this is correctly oriented on the spindle - to preserve the relationship between the line of the slot and the teeth of the spindle that engage with the camshaft. Mark the drive head and the spindle so that these can be matched up on reassembly.

All three scenarios can come about if you fail to follow the Manuals and check your work.....The correct procedure for refitting the distributor tower correctly is covered by step 35 of Operation DX.100-3 of Manual 518. However the photograph there is not at all helpful and you are better off looking at the equivalent, but updated, photo in Operation D.100-3 of Manual 814 - as it is much clearer and easier to understand the process: it more clearly shows the offset of the drive socket. In BOTH manuals the photos can be misleading as they show the tower bolted home, but also illustrate the two ('before' and 'after') positions of the drive socket.

'a' is orientation before bolting the tower on. 'b' is after it is fitted

STEP ONE

Identifying The Compression Stroke. The first stage of refitting is to find the compression stroke of number one cylinder:  the stroke on which its compressing the air/ fuel mix in the cylinder. Number one cylinder is the one nearest to the gearbox. I used a short length of polythene tubing threaded tightly into the spark plug hole and and a balloon on the end as a 'tell' to show when the piston was compressing: it inflated the balloon.

Tool for Identifying the Compression Stroke. It works with any colour of balloon.

With four of the flywheel bolts loosely fitted to the end of the crankshaft I used a bar to rotate the crank until the balloon inflated. 

Rotating The Crankshaft

Turning the crank a  little more I waited until the balloon was at the point of deflating. In this way I found an approximate position for TDC. 

Compression stroke identified

STEP TWO
Finding TDC (top dead centre). Removing the tube and balloon, I inserted a length of dowel through number one spark plug hole, making a reference mark level with the top of the spark plug 'funnel'. I popped a plastic bottle top with a hole drilled in it over the funnel. This centred the dowel (held it vertical) and accentuated the movement of the dowel and my reference mark.

Using a Dowel to Confirm TDC

Slowly turning the crank back and forth again I was able to find the highest point for the dowel - TDC for that cylinder.

STEP THREE

Aligning and Fitting The Tower. I had rebuilt my distributor tower (see related post from January 2018). Although I had re-orientated the slotted drive socket to the pinion when I refitted it to the spindle, this was a little rough and ready and I wasn't sure it was properly aligned. With TDC of the compression stroke found and set, I did a few dry fits of the distributor tower to check alignment. 

The following instructions assume you are standing on the inlet manifold side of the engine - with the camshaft end sticking out to your left.

Before fitting the spindle in the drive tower, the spindle was rotated so that the slotted head was at an angle of about 45 degrees (bottom left to top right - position 'a' in the photo in manual 814), with the 'small half' of the slotted head (segment 'b' in the photo in Manual 814) closest to the water pump. 

That Diagram Again

Drive Socket Rotated Before Fitting

Keeping the tower in the position it would be when bolted on, I introduced the drive tower 'eye' over the camshaft - stopping short before the pinion on the drive tower spindle engaged the teeth on the camshaft. I loosely fitted the tower bolts to act as alignment guides for subsequent fitting.

Bolts used to Guide the Tower Into Position

The drive tower was then slowly pushed home along the 'guide bolts' - at which point the slotted head rotated clockwise by about 45 degrees as the pinion engaged with the camshaft - leaving it (1) 'horizontal' or in line with the camshaft (back of engine to front of engine) and (2) with the 'small half' of the drive head (segment 'b' in the photo in manual 814) closest to the water pump housing. With the number one cylinder at TDC of it's compression stroke, this is the correct position for the slotted drive head.

With The Tower Pushed Home, The Slotted Head Aligns To The Camshaft

Satisfied with the test fits, I did it for real: I gave a last squirt of oil to the pinion at the bottom of the drive tower and similarly oiled the surface of the camshaft and lubricated the large camshaft oil seal. I fitted a new paper gasket to the back of the drive tower (it came in the Glaser engine gasket set). I reset the spindle so that the slotted head was at 45 degrees and fitted the assembly over the camshaft - stopping short of engaging the pinion. 

I loosely fitted the bolts (smeared with threadlock) and then tightened the bolts up - as you would the wheel nuts of a car. As the pinion engaged the camshaft the slotted head rotated........ ending up in line with the camshaft and 'small half' nearest the water pump.

Job done!

A Quick Word About..........Building an Engine Trolley

I'd done just about as much as I could with my engine on its stand. 

With the time approaching when I would need to re-join the engine and gearbox, I needed to decide what to do. Many people simply stand the engine on it's sump and block it with pieces of wood to stop it falling over.

My engine: split and grounded - 1998

I wasn't keen on that - partly in case it damaged the plate covering the oil filter, partly because I wanted to keep it off the dusty floor, partly because i wanted it at a height i could still work on it and partly because I needed to be able to manoeuvre the engine around a little and from workshop to garage.

A proper Citroen stand ("stand 3083-T") is shown on several photos in the Manuals.......

Citroen engine stand

.........and you can also make a sledge on wheels to mate the gearbox to the engine (tool MR.630-42/13).

I made enquiries through the DS Yahoo group to see if anyone had tried to make anything similar for engine and gearbox and got lucky: someone replied to say his brother had built a stand. I pressed them for details and he provided a couple of photos. It looked great! Just what I had in mind! They dug around a little more and even came up with a build plan for it - including all the crucial measurements!  

I'm not a welder and so adapted the plans to enable me to build something from wood - 75cm x 75cm fence posts to be exact. I'd already built a basic trolley using a small pallet and some castor wheels. I used that as my base. I used the sturdy fence posts to make the supports under the engine mounts and screwed them to two long 'rails'. It came out looking like this.....

One foot pad has an overhang to leave room for the exhaust downpipes

As ever with these things - copy at your own risk, and put safety first.

I was conscious that the two upright arms may fold in (or out!) under the weight of the engine - so needed to brace them. As well as the main, long, hex headed screws going up through the rails and into the arms, I added some short straps to the outer joins, and used some metal tubing (metal channelling used to protect electrical cabling) to join the two rails - with the bonus that the stand's width could then be adjusted.

Wood was convenient to work with, but a lot chunkier than the steel used in the original design I was shown. I knew at some point I would want to fit the exhaust downpipe, so topped my upright arms with some offcuts of sturdy angle to create a short overhang - just enough to leave me some space on the exhaust side.

Strapping the engine onto the crane to take the weight, I gingerly released it from the stand....

Freed from the engine stand

.....and slowly lowered it onto its new home. And here's what the stand looks like with the engine perched on it.....

Now where did I put that gearbox?