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Citroën BX – XPO – Engine Bay Preparation – Eps37a

7 min read

The day is getting closer when XPO might finally have an engine again after nearly 16 years. However, before throwing the engine in, the empty engine bay is looking, well, a little rough. Now would be the obvious time for some titilation. So, for once, I’ll seize the opportunity rather than looking back in anger. Before that Xu9J4 lump goes back in, lets do some engine bay preparation.

Nearside wing preparation

The left-hand inner wing has several blisters in the paintwork which made me concerned that corrosion may have gotten in. This is a very common area for failuer on the BX. The root cause is the wheel arch liner which rubs on the thin metal causing the painted surface to break. Then the line compounds the issue by trapping dirt.

January 2023 - Are these paint blisters cause for concern?
January 2023 – Are these paint blisters cause for concern?

The two parallel stripes running towards the harness guides/zip-tie are a giveaway that heavy corrosion was not the case here. From the underside, there is no obvious corrosion through the panel joins. I could esily trat a little bit of paint fatigue.

Rubbing back for engine bay preparation.
Rubbing back for engine bay preparation.

Stripping back a little with the finger sander, I quickly found solid metal. As I continued to strip the paint back in preparation for paint and the corrosion really was limited to the areas the harness ducting had been running. Phew!

June 2023 - Engine bay preparation is well underway.
June 2023 – Engine bay preparation is well underway.

Once the concern areas were stripped back and the general area rubbed back, a corrosion-inhibiting primer was applied. Once rubbed back the first of two coats of 2k top coat where applied. I’m not generally a fan of patch painting like this, I prefer to cover whole panels so I don’t have to work the overlaps. But down here, under the air filter, it will be hard to see the joins. So thats one side of the engine bay preparation complete.

Offside Preparation

The right hand side of the engine bay was a little more ‘involved’. Similar small areas of blistering on the inner wing join where not cause by something rubbing on the paint. In this case the corrosion was between the panels.

Feb 2023 - Drivers side inner weheel arche needs treating.
Feb 2023 – Drivers side inner weheel arche needs treating.

The solution here was to work the joint from both sides. I tackled the underside of the joint during the A-pillar and wheel arch repairs. From the top, I removed the seam sealer and cleaned the joint between the panels as best as possible. A heavy dose of corrosion converter (RC900) was applied to the join. I then primed and painted the area, seam sealed, and painted again. Building up layers like this is excessive and only preventative. However, the treatment should last a good few years until the inevitable replacement of the wheel arch is required.

Jun 2023 - Some new paint really tidies up the engine bay.
Jun 2023 – Some new paint really tidies up the engine bay.

Another area of paintwork that I tackled simultaneously was the engine mount area and chassis leg. These areas were riddled with deep scratches where the engine had been in and out a few times. This cosmetic improvement hides someone’s shame for dragging the engine against the body. That someone was me!

Airbox mounts

Back to the passenger side of the engine bay, the engine looms are run through their fixings to allow the airbox to go back in. This is more about preparation to make sure the harness and brackets are in the right places. I would not think it was wise to fit the engine with the plastic airbox in place!

The recently treated airbox bracket looks great.
The recently treated airbox bracket looks great.

With the rubbers cleaned, and new bolts, I could offer the recently refinished bottom bracket to the body. On the first fit, the wiring conduit was definitely in the way, and also twisted. But a few minutes later and the airbox mount is looking almost factory condition.

I had to wait for the wife to go out so I could use the sink!
I had to wait for the wife to go out so I could use the sink!

Perhaps a little early in preparation, I took the airbox to the kitchen for cleaning. Cleaning the two airbox halves is straightforward with the airflow meter off the plastic housing. There was a surprising buildup of filth in the bottom of the airbox, which took more than one scrub with the fairy washing-up liquid to shift!

Clutch Cable

Changing the clutch cable on a BX is easy when the engine is out. When the engine is back in, changing the cable becomes a battle of mental strength. So, changing the snapped cable during the engine bay preparation makes a LOT of sense.

June 2023 - Clutch cable replacement is easy with no engine.
June 2023 – Clutch cable replacement is easy with no engine.

There we have it, no engine means the 8mm head screws are easy to get out to release the cover and run the cable through the support bracket. I’ve never done this job on a 16Valve engined BX, only a 19RD. There is plenty of space between an XUD9 normally aspirated engine, and this job is still a pig. From this experience, I would recommend that taking the engine out to get to the cable is less stressful!

Clutch pedal return spring was found snapped.
Clutch pedal return spring was found snapped.

While working on the cabin electrics, I noticed that the clutch pedal was decidedly floppy. This is not normally the case, as the pedal should be tensioned by a return spring. The fault was immediately identified after removing the clutch spring from the pedal box. The retaining hook seems to have fallen off!

Clutch pedal spring has been replaced with a spare.
Clutch pedal spring has been replaced with a spare.

A replacement spring was sourced from a spare pedal box, and I replaced the broken one so that full tension returned! That should help clutch feel and get the adjustment on the clutch release arm. I can’t begin to explain how much of a pig this thing was to get back onto the pedal box. Upside down under a steering wheel is not my favourite place to be.

A small but important part of engine bay preparation.
A small but important part of engine bay preparation.

From within the engine bay, this preparation step is very subtle, but oh so incredibly important to do now. I can’t imagine having the replace it again if, for example, it was a little bit too short for some reason :O

Gear Leavers

At some point in XPO’s life, someone has deliberately removed the main gear lever pivot. Since this is not required for engine removal, perhaps it was borrowed as a spare for another car.

Brand new gear linkage pivot.
Brand new gear linkage pivot.

Frustratingly, I had no spare in my vast cavern of treasures. For an eye-watering sum of money, I managed to purchase a new old stock part with shiny new pivot balls, which is lovely but didn’t solve a major problem. The securing arrangement is unique to the BX and has a number of special parts. Unfortunately, there is more than just a big bolt and washer securing the pivot arm to the steering rack.

XPO rescued by the'Doc' once again!
XPO rescued by the ‘Doc’ once again!

Once again, the ‘Doc’ from Adventures In Rust fame came to my aid and posted a replacement pivot arm with all the nuts and bolts. I don’t think XPO would ever get on the road without his immense generosity (and warehouse of donor BXs). At some point I need to confess that a lot of missing parts where in a box I misplaced and wouldn’t find for another year!

Amazon supplied parts that aren't much use.
Amazon supplied parts that aren’t much use.

While I was at it, I decided to set the lengths of the all-new linkages that I had bought as a kit from Amazon. The only problem was that the cups were all the wrong size for the balls on the linkages. Fortunately, I had enough spares to make up a complete set. Again, I will install them after the engine goes in, but it will be much easier to prepare them now, with the engine out.

Engine bay preparation complete?

So is that enverything in the engine bay prepared for the motor and gearbox to go back in? No, no it is not. Before G-SEGs rebuilt engine goes back into XPO, I need to change the fuel lines. Unfortuantely, that is quite a lengthy and technical (exciting?) discussion, so I’ve split the topic.

See you in Episode 37b!
M


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