THE FORD SIERRA

SIERRA ENGINES














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Engines

The main beauty of the Sierra (from a technical point of view rather than aesthetically-speaking) was it's mechanical simplicity. In designing the Sierra, Ford intended the car to be easy to maintain and keeping running costs low was one of their stated design objectives.

Initially, the Sierra used engines and gearboxes previously used in the Cortina, which it replaced. These fell into two main types : The Over-Head Cam "Pinto" engine, and the Over-Head Valve "Cologne" V6.

In the mid-to-late Eighties, unable to meet strict new emission laws for the nineties, the phasing out of the Pinto began with the introduction of the American-designed 1.8 CVH (Compound Valve angle, Hemispherical combustion chambers) engine to replace the 1.8, then the Ford Double-OverHead Cam (DOHC) replaced the 2.0. Finally, late in 1991, the 1.6 CVH replaced the aging Pinto entirely.

Ford were not entirely lazy with the V6 either. Both Pinto and Cologne engines had been around for some time, and the V6 was looking distinctly dated compared to some of the Japanese stuff that was rolling up. The 2.8 was "breathed on" to create the 2.9 - the capacity increase and change in cylinder head design was intended to give the unit better low-down torque but some enthisasts felt it made the car sound more coarser under load.

And this is how it stood when the Sierra was replaced altogether at the end of 1992. The incoming Mondeo recieving a completely new engine, the "Zetec" 16-valve DOHC engine for the new decade.

Petrol Engines

OHC ("Pinto") Engine : Very much the 'old faithful' of the Sierra range throughout the years. First introduced to the UK in 1970 in the Mk. 3 Cortina, the Pinto engine was the OHC engine for the masses with it's cheap rubber-belt-driven design. Over the years it has served millions in the UK alone - be it in Escort RS2000's, Cortina's, Sierra's, Granada's or the everyday Ford Transit van.

Initially available in 1.3, 1.6, 1.8 and 2.0 capacities, the Pinto was gradually phased out. Unable to meet the strict new emissions guidlines coming into force over the 1990's, Ford decided the humble Pinto had had enough and replaced it. The 1.3 went first - it wasn't really suited to a car the Sierra's size - followed by the 1.8 in 1986 (replaced with a CVH unit); then the 2.0 with a new engine altogether in 1989 (the 2.0 8-valve DOHC). The 1.6 finally disappeared at the end of 1991 with the introduction of the 1.6 CFi CVH, though it has been known to find the occasional 1.6 Pinto in cars as late as the '93-model year - cars that were built right at the end of the production run were rumoured to be "parts bin specials" and this seems bourne out by the aged interloper where a CVH should have ruled.

The Pinto shares several niggles with the CVH engine (detailed next). Both designs of engine can get noisy with age - both are prone to oil-related problems including accelerated camshaft and tappet wear caused by dirty oil sludging up oilways. The camshaft drive belt can break in use if the service interval has been ignored, or the belt has become contaminated with oil. This can cause extensive engine damage on 1.8 and 2.0 engines. Practical experience has shown it best to ignore the Ford service interval for this belt, and change it every 20 - 25,000 miles or two years. It is recommended to check the condition of the belt every service as a matter of course, even if not replacing it.

CVH Engine : Seen in the Sierra and Sierra Sapphire in 1.6 (late-1991 onwards) and 1.8 (1987 onwards) capacities.

First introduced in the UK in the early Eighties, the CVH first found a home in the front-wheel-drive Fords : it was a mainstay of the Escort range, appearing in 1.3, 1.4 and 1.6L capacities. The Fiesta utilised it too, in 1.3 and 1.6L form initially, but then 1.4 and 1.6L.

The CVH engine is of the OHC design, utilising a cast aluminium-alloy cylinder head on an iron cylinder block. If allowed to overheat, cylinder head gasket problems can be common as the head can easily warp. Like the Pinto, the camshaft is driven by a toothed rubber belt, with hydraulic tappets as opposed to the Pinto's solid lifters.

Like the Pinto, serious engine damage can result from camshaft drive belt breakage in use - this is more likely to apply to all CVH engines, not just those of hgher capacities (as in the Pinto's case) due to the finer tolerances in manufacture and the engine's more compact design. The CVH also shares the Pinto's appetite for fresh oil - not only can the top end become noisy should old oil sludge up and block oilways but the valve-stem oil seals are known to come adrift leading to a cloud of blue smoke on startup. This does not appear to be confined to particularly high-mileage units either, and several Ford magazines have often observed in the past that the ideal interval for a CVH top-end overhaul is around 80,000 miles.

DOHC Engine : Saw service in Sierra and Sierra Sapphire 2.0 models from 1989 onwards as a replacement for the Pinto. Initially available in both carburettored and injection format, the DOHC is often overlooked by tuners - yet it is a capable engine. Economical around town but still flexible enough to provide the pull when necessary. This is more than confirmed by Carl Davis, who describes his experiences with the unit in his 92-model Sierra GLX :

"Personally I'm very fond of it - it's perhaps a little harsh and makes that sort of slight pinking sound that all Sierras seem to make when hot and on load sometimes, but it's very reliable, satisfyingly responsive and respectably economical. I get around 36mpg round town and recently managed 42.3mpg on a run. My Dad has a 2 litre Mondeo and I definitely wouldn't swap! The 16 valves may give it 11bhp more than mine and I'm sure it could just about outperform it in 0-60 trials - but it just won't pull from low revs where you actually need it. The Sierra responds immediately, the Mondeo doesn't really wake up until you've passed 4000rpm, by which time you don't need it anymore. It's thirstier too - I can't do much better than 35mpg with the Mondeo.

You mentioned oil consumption - I change it every 6000 miles and there's no noticeable consumption during that period. As you say though, some of the seals do weep a bit, especially around the cam cover and crankshaft pulley, but it doesn't drip. I think the crankshaft isn't as well balanced on my specimen as it could be though - there are lots of drillings in the pulley for this purpose but there's a slight resonance at 4000rpm which I've not noticed on other 2.0i DOHC engines I've driven. Perhaps this has some role in the oil leak at the pulley.

My mechanic says they're pretty solid engines - one guy who drives a Granada with the same engine has reportedly covered 250000 miles without any rebuilding! The tappets rattle a bit on a cold start, so I think low mileage cars suffer with this more than motorway high- milers because of the more frequent cold starts. Having said that, I don't see this as being any worse than any other engine I've had anything to do with.

The most common fault I'm aware of with the DOHC is the same as the 2.9 - erratic idling caused by the idle-speed control valve gunking up, although I've not had this yet. The only non-routine thing I've had to do is rewire the plug to the temperature gauge sender as it had an dodgy connection.


The dual camshaft arrangement is driven by a chain which is designed (according to Ford) to last the service life of the engine, whatever that might mean as surely this is variable depending on circumstance. However, it would seem sensible to assume that if the chain is worn and needs replacement, chances are there are more pressing wear-related problems elsewhere although there are service items available from Ford and they are reasonably priced. Although not specified in any available Ford literature, the website author has knowledge of engines that have experienced snapped timing chains between 100,000 and 150,000 miles. Such breakages can be terminal and result in a wrecked engine and the author recommends that the chain is replaced at least every 100,000 miles but advice should be taken from your local dealer or a specialist to establish a more suitable interval beyond this.

One other point that has come to light through conversation with other owners is that the engine suffers through it's cylinderhead, which is prone to cracking if allowed to overheat. It also warps and can have quite an appetite for cylinder head gaskets as a result which can cost upto £600 to replace depending on circumstance. A bubbling noise through the heater is a reported usual first sign (though this could also be an airlock if the system has been drained down for flushing or maintannance) - the expansion bottle should be examined for signs of the system pressurising and water consumption which would indicate possible head or gasket trouble. Although the Haynes manual says it shouldn't be skimmed, Ford have reportedly since advised that this is OK providing a thicker head gasket is subsequently fitted to keep the compression ratio approximately the same. As before, take advice from a specialist company as appropriate on this score.

Despite these characteristic niggles, there are plenty of units on the road and running perfectly reliably. It is a very responsive unit with dozens of positive tesimonies to bolster the feeling that it is one of the better engines ever made by Ford for the European market.

V6 ("Cologne") Engine : The Cologne saw service in 2.3L guise in the earliest Sierra's then later as the 2.8L XR4x4 models. Re-worked in the late Eighties to give it better low-down torque, it gained a capacity increase to 2.9L

 

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