Distributor Tower - Strip Down and Overhaul

One of the steps in an engine rebuild is replacement of the camshaft seal. As the camshaft drives the distributor, it passes through an eye at the base of the distributor drive tower, and that is where the camshaft oil seal is. All this hidden away behind the bell housing. 

Distributor on the drive tower - August 2015

I planned to vapour blast the drive tower. To do that, I would need to dismantle it - so this was also a good time to change the distributor spindle oil seal. 

When I ordered a load of new seals from Citroen Classics, I'd very rashly also ordered a replacement seal for the distributor drive tower spindle, as well as the cam shaft seal and oil pump seals. Money changed hands and I started to put the phone down. "Good luck with the distributor drive tower seal" were Matt's parting words. Whatever did he mean?

I soon found out. You won't find it in manual 814, but instructions for dismantling the drive tower are covered in Operation DX.211-6 of Manual 518. The oil seal is located near the top of the drive spindle, just underneath the slotted head. 

And that is where the difficulty lies..... The technique for removal involves pressing the spindle and its cam down and through the slotted distributor drive socket, in the course of which it also pushes out the sealing cup (a hefty core plug) at the bottom.....That's a lot of pushing, and the ledge on which the drive socket sits would take all the pressure.

I was worried about the force on the cast alloy underneath the drive socket - and so was my local engineer. He welded a threaded bolt to the cup at the base and used a nut to pull the cup out. He left me to remove the spindle.  

The manuals make no mention of the need to align the distributor drive socket with the teeth of the cam on the spindle - to preserve ignition timing settings, but I would strongly advise you do mark the relative alignment, as there is no way to check or adjust this once the distributor tower is rebuilt. 

With the cup removed by my local engineer, there was less resistance to the spindle and, with the alignment marked, I carefully drifted it out from the drive socket. The oil seal was then easily removed - as was the camshaft seal. The spindle seal was lubricated and fitted back into place.

Something You Don't See Every Day: The Oil Seal in the Distributor Tower 

While the body was vapour blasted I zinc-plated the distributor clamp and cleaned up the drive socket and spindle. Reassembly was pretty straightforward. My engineer gave me a replacement core plug for the bottom but it was not as hefty as the proper Citroen one - which I decided to re-use.

Drive Tower Stripped - 16 December 2017

With the spindle and oil seal lubricated with engine oil, The spindle was orientated on the drive socket using the marks made earlier, and the spindle was then pressed back on from the bottom of the tower.

With the spindle pressed back through the drive socket, as per Operation DX.211-6, I checked the freeplay at the base (0.15mm to 0.30mm) to make sure the spindle was free to rotate. Once happy, and leaving the feeler gauge in place, I used a long socket of the appropriate diameter to press the cup back into place until it just touched the end of the spindle. (The feeler gauge prevented me from pinching the spindle too tightly in the tower body). The gauge was removed and, with a bit of judicious wiggling, so was the welded bolt on the cup. 

The camshaft seal was lubricated and pressed into place using a socket. On my first go I pushed it all the way to it's base - only to find that it snagged on the pinion of the distributor drive spindle.  Luckily it could be pushed out a little from the other side.

All back together and ready to go back on the car

I'm still deciding on whether or not to buy 123 electronic ignition, or to rebuild my distributor. However, since my distributor is not the right one for the car, I'll probably go for the 123. If so, I'm hoping to be able to fit a new Ducellier distributor cap.