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Discussion Starter · #1 ·
Just wanted to share my experience with you, in case anyone else finds it useful.

Symptoms: idle revs hunting, initially just a little up and down, a few days/weeks later the engine cuts out after a few up and down cycles, for example when approaching a busy junction and depressing the clutch.

The main symptom was coupled with high oil consumption (1l per 1000km or thereabouts).

Interim diagnosis: black crud on throttle flap reducing the cross-section of the opening when the flap is at warm idle position - ECU compensates by opening throttle, revs go up, ECU shuts flap, and so on. Once there is enough crud on the flap, the engine is eventually starved and cuts out.

Interim solution: with engine and ignition off, remove rubber air hose between filter and throttle housing (two 7mm jubilee clip bolts - or use a screwdriver), carefully push open throttle flap and clean it with a clean wipe with some alcohol or other suitable solvent - especially the bottom edge.

Final diagnosis and permanent solution: I got a big clue driving down a mountain - blue clouds on acceleration after prolonged periods at high revs with vacuum in the intake manifold (low gear, throttle flap closed, coasting downhill).

Sudden blasts of burning oil like this are a good indicator of worn valve stem seals - worn rings tend to produce continuous smoke, or smoke at startup, neither of which were present.

I've now replaced the valve stem seals, and the smoke has vanished, as has the oil consumption and the unstable idle.

I tried to do the valve stem seals with minimum effort but had two issues which led to near-maximum effort: couldn't undo the blanking plug to release the timing chain tensioner, so the whole cover had to come off, and also managed to drop a valve into the engine despite using compressed air (I think that because of the angle on the exhaust side, I couldn't see and accidentally pushed the valve down while inserting the seal pliers). It would have been fine on cylinder 1 or 4, which were at TDC, but of course it was on cylinder 3 so the head had to come off.

Don't forget that the crankshaft pulley bolt and the cylinder head bolts on this engine are TTY (torque to yield) and should not be reused. If you are doing the valve stem seals anyway, I would buy these bolts and the cylinder head gasket and rocker cover gasket, as well as the sealant for the chain cover, in advance, just in case.

Also, the cylinder head bolts are recessed in the head casting, so that a "normal" 1/2" T55 driver won't reach them - you need to get an extended T55 driver, in which case for a few pounds extra you may as well get the whole set of different drivers, e.g. 6Pc 1/2" Drive T55 T60 T70 T80 T90 T100 Star Torx Socket Bit Set Ratchet Torque | eBay

Happy Fording!
 
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