Eagle-eyed viewers will notice that during the first start in Episode41, there was something missing in the engine bay. A general lack of cooling system and, critically, no radiator. Given that the sole purpose of the Mi16 engine is to turn petrol into heat, a complete cooling system is needed to run the engine for more than a few seconds. Despite the cliffhanger of an empty ramp, the car won’t move under its own steam without some drive shafts. This article will focus on XPO becoming driveable.
The Cooling System
To overcome the engine’s keenness to turn into a fireball, the engine cooling system would need to be in perfect working order before becoming driveable. While the majority of the BakerBM silicone piping had already been installed, there were a few pieces of the cooling system puzzle left to be installed or repaired.
Water Level Sender Bracket
The later Citroen BX cooling system uses a slightly complex system to monitor water levels. While earlier (or simpler) BXs have an integrated radiator header tank and a float switch to turn the low coolant lamp on, the BX16V is a bit different. Like the 8v GTi and a few others, the XU9j4 has a separate coolant reservoir with a continuity switch.
To drive this continuity switch, an amplifier circuit is needed, or “CONTROL UNIT WATER COOLANT LEVEL 97517535”. This little box sits next to the radiator and turns the ‘you’ve lost your coolant’ lamp on in the instrument cluster. XPO did come with the little box, but it was a touch damaged. Given where it the box mounts on the car, it is not uncommon for someone to pull the harness and break the tab off.
Rather annoyingly, when testing the circuit in the box, it actually worked perfectly well. There seemed little point in throwing away a good part for the sake of a little plastic tab. In this case, the solution was to print out the missing part with a little added reinforcement. PETG should be up to the job.
With a repair piece made for the water level sender, applying Loctite Super Glue bonds the two pieces together. Once installed onto XPO, the coolant level warning circuit should be complete and functional. I don’t expect to lose any coolant, but it will be nice to know if I do!
Coolant Pipes
Back in episode 31, I had a large number of the metal parts plated by a grown-up after my failed homegrown attempts. Finally, the remaining pieces could be installed onto the car. The last of the freshly plated parts would complete the coolant system and the hydraulic system.
There is a lot of satisfaction in moving to the ‘rebuild phase’. I finally start to see the benefit of all the cleaning that was completed nearly a year ago.
I wish I had a vapour or CO2 blasting setup to get everything just about perfect. However, I have to make do with the parts wash and heavy degreaser for now. The fleshly plated parts really lift the appearance of the engine bay and spur progress.
Radiator
For a little while, I debated what to do about the radiator. I have a number of usable condition OEM radiators that will keep the freshly built engine cooled for many years to come. However, I also have a supply of brand new aluminium radiators which have no better or worse performance over the originals but are definitely not OEM.
In the end, I opted to use one of the aluminium radiators I already had. I should point out these are not the ‘Winner’ rads off eBay, and cost half the amount. Although not black in colour like the original, they should outlast any of the spares that I have in stock in good condition.
Cooling Fan
After the fun and games I’ve had in recent years, especially FOTU 2021, I am just a little paranoid about the cooling fans. After the cooling fan replacement saga in 2021, I’m left with only one cooling fan motor with very long leads. The motor was already assembled on the right-hand side of the cooling fan cowling, with very long wires.
New connectors are installed on the cooling fan leads, and they are hooked up to the vehicle engine bay harness. By shorting out the cooling fan wires, I can check to make sure the fan circuit is working. Fortunately,, in this case, the fan works at both high and low speeds, which confirms the motor works and the low-speed resistor works!
Cooling Fan Switch
The cooling fan on the Citroen BX should turn on and off automatically in line with the temperature of the coolant that flows over the cooling fan switch. The switch is installed at the end of the radiator and comes in a range of flavours with different temperature trigger points.
One of the many bodges in XPO’s electrics was the removal of the OEM cooling fan switch connectors. Fortunately, the FastOn/FastOff terminals are still available new, and I was able to re-terminate the wires. After a little electrical sleuthing, I identified which wire was for the low and high-speed switch and marked up the cables.
I salvaged the OEM connector shell/housing from one of the many spare engine bay harnesses I have acquired. The cooling circuit was complete with an old cooling fan switch installed into the end of the new radiator. The system was filled with suitable specs of blue antifreeze with a 50:50 ratio with de-ionised water. Finally, we are one step further on XPO’s journey to becoming driveable!
Drive Shafts
If I want XPO to move under its own power, I’ll probably need to connect the wheels to the engine through the clutch, gearbox and, of course, the drive shafts. While XPO was delivered with a single drive shaft, there was of work needed to get them installed onto the car!
Short Side drive shaft
First, I tackled the short drive shaft that came with the car. While complete, there were many issues that needed to be addressed. The first issue was the very heavy coating of built-up dirt and grease. While I’m not a spinning metal bar expert, I suspect a significant weight build-up around a rotating member probably isn’t a good thing. Scraping, degreaser, and brushing later,work could continue.
Once cleaned, I was happy that the short drive shaft was usable. However, the zip ties on the drive shaft cover/gaiter/CV boot were a little concerning. Zip ties are great for a short-term solution, but they don’t tend to age well. Over time, the plastic will stretch, and the CV boot will fail or worse, moisture will get in a destroy the constant velocity joint.
Surprisingly, the zip ties were still reasonably tight. However, the CV boot could not be saved as it already had a perforation that was letting grease out. Unfortunately, this CV boot was past its best and would need replacing.
The CV boot appeared to be completely original at the other end of the shaft. A testament to OEM parts, at some thirty years old, the rubber was still holding together. However, the cracking around the bend shows how the VOCs have leaked from the rubber, making it hard and brittle.
Driveshaft Rebuild
There was no other solution. Both CV boots would need to be removed. Surprisingly, the inner CV gave up its hold on the drive shaft remarkably easily. This aided a fairly rapid change of the rubber gaiters. Unfortunately, it has been a long time since I last changed the drive shaft covers on any car. However, the rebuild process went surprisingly smoothly.
Once again, I am incredibly grateful to Luke. Not only did he tell me the part numbers for replacement CV boots, but he also posted a box full of drive shaft parts. But for a few amazing people, I might have given up on XPO a long time ago. However, I’m very grateful to all those who have raided their spares and got me back on track!
Long Side Drive Shaft
The drive shafts are different lengths because the Citroen BX gearbox is offset. The long side has a really long inner CV output shaft. The shaft is so long it has to be supported by a bearing in the rear engine mount housing. Unfortunately, XPO didn’t arrive with a long shaft. However, that seemed like a minor issue, as after-market parts can still be bought.
And buy an aftermarket shaft I did. The inexpensive part arrived relatively quickly and I had kept it to one side for this moment. However, the supplied shaft must be used on another vehicle. Although the shaft is the right length and fits perfectly, the ABS ring is clearly from another model. In the picture above, I have a BX rear ABS ring along side the new drive shaft ring. You don’t need to count the teeth to find the difference.
After some hunting, I managed to source the correct ring from Latvia! Although an inexpensive part, the emotional cost of fitting the ABS ring was significant. The wrong ring was quickly cut off, but the CV boot had to come off to press the new ring on. The new ring was heated with a blow torch in an old break disc, to achieve even softness. The red hot sensor ring was then pressed onto the shaft with a ten-tonne press. Very stressful, but I got there in the end!
Finally, with both drive shafts installed and the intermediary bearing secured, the gearbox could be filled. Only the best Total fluid for XPO; after all, who spends years building a car only to replace the fluids with cheap, out-of-spec oil?
Becoming drievable?
So, after all this work, was the car driveable? Well, yes and no. With the coolant system completed, the engine could be run for a longer period. After topping up with a hydraulic reservoir and a lot of bleeding, the suspension was finally alive. However, with the hydraulic system not pressurised, the LHM leaks started.
With the driveshafts in, the car could, in theory, move under its own steam, but there was a slight issue. No matter what I did with the cable, I could not get it to fit into the clutch release arm. I did manage to coax the car off the ramp by running the engine to raise the suspension and then restarting the car with the gearbox already in gear. Finally, the car drove out of the garage, but something was wrong with the geometry, so I couldn’t go backwards, even pushing!
Definitely not driveable at this stage, with just a few things to sort;
- An exhaust needs to be installed
- The front wheels need to point roughly in the right direction
- The clutch pedal/cable/lever needs connecting together
- And finally, there are a couple of leaks that need sorting!
Some might suggest I’ve just listed the final articles until the XPO project reaches it’s conclusion, and they would be right!
Until next time.
M
Great progress as usual. Without the drive shafts fitted was there a tube in place to keep the gearbox internals in place? I’ve just done the gaiters on the short side on DKK and the manual said to use a suitable tube to keep the planet gears where they should be – or is that just on an auto?
Hi Panky, the requirement for the sun gear retainer is only on some of the early BE1 gearboxes. While documented in the Haynes, I’ve never actually needed to retain the sun gear on a Mk2, BE1 or BE3 gearboxes. Mk1 might be a different story, but I’ve never done much mechnicing on them.
Hope that helps
M