Mi16 engine removal

Citroën BX – The Mi16 Engine Removal

4 min read

While G553 XPO has an interesting back story, it has been largely untouched since 2008. The Mi16 engine that came with the car has a very different story to tell. It does however need a bit of work, and to do that it will best to start with a bit of engine removal.

Where to start on such a big restoration project?

Taking the engine out and rebuilding it as the first stage of restoration seems mad, even to me. But there is a little bit of logic to the madness. The engine that came with the car originated in G-SEG, a well-known car in BX circles. It was one of the few parts saving when the tin worm did for the shell it was being carried in. Previous owners have reported a number of issues with it, so it needs a damn good overhaul.

G-SEG well loved finish on the exterior, not matched underneath
G-SEG well loved finish on the exterior, not matched underneath

The engine was quickly thrown into the shell of XPO to aid in shipping it to me, but it’s not connected and sat on a block of rubber on one side. Under the engine, the steering rack needs new gaiters and new fuel hoses need to go in. The wiring throughout the car is also a bit of a mess and the more access to the engine bay the better. The engine really needs to come out. Its also February and, at the time of writing, the snow is still falling. If I focus on the engine restoration first, I can work on it in the warmth of the garage!

Removing the engine for teardown

Having borrowed a Clarke CFC100 engine crane from a local chap, I could start to remove the engine from the car. Having been here before, my preference on a Citroen BX 16Valve is always to lift the engine out with the gearbox. But this huge mass has a way of hitting expensive stuff on the way out, like the radiator!

G-SEGs engine, sat in the engine bay of XPO
G-SEGs engine, sat in the engine bay of XPO

The radiator and cowl were easily removed, with too few bolts barely holding it down. What little wiring that was still around the engine was removed. And of course, the bonnet was take off and it really gets in the way of the engine cranes jib. With only four M10 nuts to disconnect it from the car, it seems rude not to.

The soul of the Citroen BX 16Valve removed from XPO for a teardown
The soul of the Citroen BX 16Valve removed from XPO for a teardown

The angle of the picture above doesn’t do justice to just how much of an angle is on the engine and gearbox. I’m using a cheap load leveller on the crane, something like this one from SGS. For around £25 it’s a must-have for an engine crane, and not just for getting awkward engines out. I find it helpful for maximising out removal and working at better angles.

Removal of the engine fluids

With the engine back in the modest warmth of the garage, the first task is to drain out the fluids. As the transmission already has the driveshafts out, there isn’t a lot of gear oil in the diff. But what is there is absolutely golden brown, free from debris and stinks as gear oil should. The engine oil however . . .

Removal of the well used engine oil
Removal of the well used engine oil

If I start by telling you it took a brave pill and a 3ft breaker bar to get the oil sump plug out, then the next bit shouldn’t come as a surprise. The oil is absolutely filthy! And I don’t mean in a teenage boy who’s just found out about girls sort of filthy. This oil is long past due a change and is seriously contaminated. But the old magnet under the drip tray trick suggests no metal in the oil which is always good. It’s also thicker than I would expect, perhaps the wrong grade or maybe the garage temperature isn’t helping.

Oil in air intake obvious after throttle removal
Oil in air intake obvious after throttle removal

While waiting for the oils to drain out, I gave them overnight in the end, I started taking some bits off. Starting with the throttle body, I found rather a lot of oil in the intake manifold. Probably a result of many short runs and not bringing the engine up to temperature. I can’t say I’ve ever seen an engine this bad, but then I’ve not pulled that many apart.

What to do with the engine?

While I had hoped for a quick clean, service and throw it back into the car, I think this engine is going to need a little bit more. In fact, the more I look at it, the more I can see years of neglect and some bodgery. Previous pilots of the engine tell me it suffers from a stuck hydraulic tappet too. So I’ll through caution to the wind, tear down the whole thing and rebuild from the bottom up.

M

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