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Discussion Starter #1
Well, my Aveo developed a nasty misfire a few weeks ago, so I swapped out all of the ignition components, and checked the sensors, all to no avail.
Pulled it from use, and finally got round to doing compression tests this morning, 125/125/80/125 so it would seem to have either a stuck or burnt valve. Oddly when it was in use, the misfire would sometimes suddenly stop, then start again, which was why I went through all the ignition stuff first.
Workshop info for the B12D engine seems a bit elusive, so if anyone has any links or experience of a stripdown of this engine it would be gratefully received.
Mileage is now 95k, thankfully gaskets and valves do seem to be available.
 

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So, some progress here, but no proper answers yet. Apologies if this is boring, but thought I would post this as a "resource" in case someone in the future contemplates a major stripdown of this engine.

I would have preferred to lift the engine out to do this work, but continuing lockdown and travel restrictions mean that my friend with the engine crane cannot come over to assist, so I looked at ways to remove the cylinder head in-situ, this would normally be easy, however this is a chain cam engine which causes certain complications.

Drain water and oil first.

Then I removed the manifold heat shield, 2 x 5mm bolts, both sheared off as expected so will need to be drilled out later.

Then I undid the exhaust manifold nuts. However one of these at the Nr1 (timing) end of the engine is fully obscured by the complex bracket that holds the PAS and A/C pump in place. Both of the pumps need to be removed to access the bolts holding the bracket on. My A/C was depressurised, however it is possible to dismount both of these pumps without disconnecting them, and hang them up nearby so the area is clear.

With the bracket off, the last exhaust manifold nut can be undone. In this case, the manifold would not release, despite careful application of blows from a soft hammer. So I undid the three catalyst top nuts instead (this allows the exhaust to hang down as well, required later on). One of the bolts sheared, so the cat will have to be removed later from the bottom, to allow a drill out and replacement on the bench.

Then the engine/ transmission was locked, and the crankshaft pulley nut loosened, Important to do this now, as later on the engine is "loose" and it is more difficult.

Next to come off is the alternator, having first released the tensioner and removed the belt. Access is quite poor, but it is do-able, and there is space to shove it out of the way without disconnecting it. The alternator has to come off to allow access to the bolts that hold the bracket that braces the plastic inlet manifold.

Next the engine was propped from below, as the timing cover also serves as the engine mount connection. Engine mount is then removed.

I then worked my way around the timing cover removing the numerous bolts holding it on ( I had already released the cam cover at this point). One of them is fully obscured by the water pump, so this had to come off too. One of the three bolts sheared whilst doing this so will need to be drilled out and replaced later. I then took out the two studs from the bottom of the timing cover, that secure it to the sump.

With the last of the bolts out, the timing cover is "free", however it has a very strong (RTV?) seal instead of a gasket, so needs quite a lot of persuasion. Foolishly, I expected to be able to lift the cover off at this point, However this is not possible with the engine in place, This is because the cover is also home to the crank driven oil pump, and the pickup pipe is so shaped that that the cover cannot be removed.

At this point however, the engine is propped up on the sump. I thus fashioned a bracket that could be bolted to an exposed thread on the front of the engine, allowing this to be used to hold the engine up, such that the sump could be removed.

The next move was to remove all of the sump bolts (the last 3 need the small flywheel cover plate to be removed), having the exhaust hanging low makes this much easier. Once again, the sump is held on with some very strong sealant. Prodding with an old screwdriver, it was clear that this would just cause damage to the sump and trouble later, so I cut through the sealant along the front of the sump with an old stanley knife and a nylon hammer, until enough was cut to allow the sump to hang from the flywheel end.

This exposes the 2 bolts that hold the oil pickup to the casing/pump, which can then be removed, after which the timing cover can be easily removed.

The engine was then rotated to TDC and the positions of the three coloured links on the chain checked and photographed to avoid any confusion at re-assembly. Bottom marker link is 180 degrees from the crank TDC mark, top two point to markers on the cam sprockets.

The engine was then rotated to "pistons level" position (equal length sticks down the spark plug holes), prior to removal of the chain.

Two bolts then remove the conventional tensioner, and three more remove the chain guides, at which point the chain was removed and stored.

Cams were then removed and stored, the bearing caps are laser marked with position and orientation, which is handy.

No wear was visible at all, and the hydraulic tappets all spin freely in the remaining oil.

I had previously determined that access is so poor with the engine in place, it will be easier to remove the inlet manifold complete with the head, so have removed the egr, pipework, cables etc with this in mind.

I have stopped at this point as I didn't have the metric spline required to remove the cylinder head bolts, it should arrive on Thursday so work permitting, the head should be off soon and we will know exactly what has gone wrong.

If anyone is interested, I will post pictures of the stripdown sequence.
 

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Discussion Starter #3
Timing details for the B12D are available in this excellent video from an Indian chap, covering the rebuild of a B12D from a Chevy Beat (Spark).

 

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Metro , very enlightening. This highlights just what our professional mechanics have to face - and we wonder why our repair per hour costs are high!

Well done buddy. It is these old shearing bolts which add unnecessary aggravation.
 
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