Hillman imp Buyers Guide

THE HILLMAN Imp is a compact four-seater that handles brilliantly, is economical, rides serenely and is ultra-cheap to both buy and run. The Imp was one of the few cars that could truly be considered a rival to the Mini. Not only was the Rootes car great fun to drive but it was also eminently practical. Where the Mini featured a small hoot, the Imp’s top-hinged rear window allowed it to carry far more than a car of its size could realistically be expected to.

Handling was kart-like thanks to a low centre of gravity achieved by canting the lightweight all-alloy powerplant over at 45°. A mixture of swing axles at the front and semi-trailing arms at the rear ensures a smooth ride and 45mpg is easy to achieve even when the car is driven with zest.

To increase the Imp's desirability as much as possible there was a choice of bodystyles, including a saloon, a coupé, the Hillman Husky estate and the Commer van. Today the Husky and Commer are quite hard to track down, but not as difficult as the Imp-based sportsters such as the Ginetta G15, Clan Crusader and Davrian.

Despite all these selling points, by the time production ended after 13 years just 440,000 Imps had been made. While the bad news is that just a tiny fraction of those survive, the good news is that there’s an enthusiastic band of Imp owners out there keen to keep the remaining cars going. Even better, you could join them for a lot less than you’d think.

BODYWORK

The Imp’s bodyshell was never particularly well rustproofed, which is one of the reasons why the attrition rate has been so high over the years. Having said that, it takes quite severe corrosion to weaken the car’s structure as the bodyshell is strong. Although pretty much any part of the car can rust, there are certain key areas to that you must always check. The first area to inspect is the leading edge of the bonnet. Once corrosion gets a hold here the whole panel will quickly dissolve to the point where it’s too tricky to properly repair it. The problen is that there’s a double skin, with moisture getting trapped inside.

Next have a look at the bottom of each door, which is probably showing signs of corrosion. If it isn’t see if it’s full of filler by holding a magnet to it and seeing if it sticks. The problem is usually caused by blocked drainage holes allowing the door to fill up with water. At the back of the car take a look at the seam at the base of the rear pillar. When the bodyshell flexes the paint cracks and allows water to get in. It’s just a matter of time before rust starts to develop, so check for evidence of rot or poor repair.

Rear wheelarches are also rot-prone so look inside and feel all the way round. While the front wheelarches don’t tend to rust as badly as the rears it’s also worth looking down their trailing edges as mud can get lodged at the base of the inner wheelarch, leading to corrosion where the front wing meets the sill.

The sills themselves also need careful inspection as they give the car much of its strength so look out for poor patch-repairs in this area. The spare wheel well, located in the luggage compartment, has a tendency to fill up with water, then rot out. And because the spare is rarely lifted out, the well can rot unseen for years. Because no new panels are available it’s a question of patching it up — which is fine as long as the suspension mount beneath is not affected. If this has rotted it means making up a tricky compound curve repair piece — a job often best left to an expert.

Get underneath the car and have a good look at the entire floorpan, which will probably be looking a bit tatty in places. More critically, inspect the rear suspension very closely as corrosion can set in and cause big problems. First look at the suspension pans where the coil springs are located. These corrode to allow the spring to go straight through. The spring mounting points also rust badly, allowing the spring to crash through the bodywork.

At the front things are potentially as serious with the box-section swing axles prone to corroding very badly. Although the metal used is pretty thick once corrosion takes a hold it soon weakens the suspension. New parts are no longer available, and as the suspension can’t be welded, you’ll have to replace the corroded parts with decent used ones which cost about £20.

 ENGINES

Although the all-aluminium engine has a reputation for being fragile the reality is that if properly cared for it’ll just keep going. The key is to maintain the right concentration of antifreeze within the cooling system. Experts recommend a 50 per cent solution so take along an antifreeze tester to check. Once the mixture gets too weak corrosion will set in. As the alloy breaks up, bits of it will float into the radiator, consequently blocking its core and reducing its efficiency. Make sure the head gasket of the Imp you’re inspecting is in fine fettle by checking for emulsion on the oil filler cap. Also see how low the coolant level is — if it’s allowed to drop below the base of the header tank the engine will overheat. Once that happens the head gasket is pretty much guaranteed to fail — leading to the powerplant cooking.

If an Imp’s engine is allowed to overheat, it’s not necessarily just the cylinder head that warps — the block can too. While both can be skimmed, there’s only so much metal that can be removed before either unit is scrap.

On the test drive, as you accelerate through the gears, listen out for pinking. While it could be that the ignition hasn’t been set up correctly it’s more likely that it’s a consequence of the cylinder head having been skimmed several times because of overheating. The only fix is to find a replacement head that is OK, for which you can expect to pay about £30 if it’s a standard car. if it’s a Sport unit you’re after the cost is three times that. Engines built after 1966 had a stronger block, which is much less prone to deformation if the temperatures get a bit too high.

If you’re looking at a pre-1966 car see if the top of the cylinder block has a straight edge, or one that follows the outline of the cylinder walls. The straight-edged block is the stronger of the two. Make sure that you get the chance to start the engine from cold. When you first fire it up check for blue exhaust smoke which signals that the inlet valve seals have gone. Replacements cost £5 each (while valves are £6 apiece), but obviously the engine has to be dismantled to replace them.

if you’re looking at a Sport, there are no valve seals, in which case it’ll be the valve guides that have worn out — but those are also cheap enough to replace at just £55 for a set of eight. If the smoke appears continuously, the piston rings or cylinder bores have worn, which means the engine is due for a rebuild. Rebuilding an Imp engine isn’t an especially difficult DIY job. A professional rebuild costs in the region of £500 - £700.

While you’re taking the car on a test drive keep an eye on that all-important temperature gauge. The gauge needle should settle at the one-third to half-way mark as the car is cruising. If it doesn’t even register a third of the way across the dial, the chances are that the thermostat has been removed — probably to mask a more serious cooling problem. Ask when the water pump was last changed — if it hasn’t been done within the last 25,000 miles it’ll need a new one at £100, or £65 for a reconditioned one. if the car hasn’t been used regularly the water pump will need replacing even sooner as the bearings have a tendency to fail. Once that happens the engine loses most of its cooling.

Oil leaks arc a common problem with Imps, because of the all-alloy engines and gearbox casings. Aluminium expands and contracts more in use than an equivalent cast iron unit, making life difficult for the seals and gaskets. As a result you need to check underneath both for signs of oil escaping. Things aren’t helped by the fact that there’s no rear crank seal fitted so you should expect slight seepage — but if it’s more than just a weep there may be a problem with gaskets that need replacing.

 TRANSMISSION

A four-speed manual gearbox was fitted to all Imps and it should be a joy to use. Changes ought to he slick and precise; if they’re not it’s because the nylon bushes at the base of the gearstick have worn and need to be replaced. It’s cheap and easy to do, with a new kit costing just £8. Synchromesh was fitted to all four forward ratios but on the lower two gears it’s notoriously weak. Try to change up through the gears quickly as you accelerate the car. If there’s crunching when you beat the synchromesh it’s because the gearbox is due for a rebuild. Your best bet is to swap the unit for a rebuilt item off a specialist’s shelf, for which you can expect to pay about £400.

The clutch pedal should be light — if it isn’t it’s probably because the slave cylinder is faulty, or the hydraulic hose has collapsed internally. They’re both easy and cheap enough to fix, but more serious is a bite point at the end of the pedal’s travel. That indicates the clutch is going to need renewing soon, which means taking the engine out. If you’re doing the work yourself (it’s easy enough) that’s not too had, but it adds to the bill if you decide to get it done professionally.

The driveshafts incorporate rotoflex couplings, or ‘rubber doughnuts’ to transmit the power. As with any rubber part, these perish over time and if the car has been driven enthusiastically there’s a good chance they’ll have started to break up. There aren’t any symptoms as such, but a careful visual check will show if the rubber has perished, or even split. Have a close look at each side, because if one breaks it can cause damage to the radiator, exhaust and the dampers. New heavy duty dampers cost £45 but don’t be tempted to fit cheap, or old stock items, as it’ll be a false economy.

 STEERING AND SUSPENSION

The Imp’s rack and pinion steering is a delight to use. It’s light and precise as long as it’s in good condition, It’s also extremely manoeuvrable, with a turning circle tighter than the Triumph Herald’s. If there’s any heaviness or play in the steering it’s because the kingpins and their respective bushes have worn.

Although you can feel if anything is amiss on the test drive, to be certain, just jack up each front corner then you can hold the top and bottom of each wheel and rock it to see if there’s any play. If there’s any discernible movement it’s time to replace the kingpins and bushes. Buying a kit of parts to do the work yourself will cost you about £40. That’s enough to do both sides, and the work is easy enough to do at home. Another potential source of movement when you rock the front wheels are worn wheelbearings. These are a taper fit so it may be possible to adjust out the play. If adjustment isn’t possible because it’s all too worn, a new set of wheelbearings will set you back just £15 per side.

WHEELS AND BRAKES

Steel wheels were fitted to all Imps but aftermarket alloys are a popular litment. If the car you are looking at has alloys make sure the offsets are correct by looking for evidence of rubbing against the bodywork. While clearance at the rear isn’t normally an issue at the front when the wheels are on full lock there’s usually some contact with the wheelarch lips.

All Imp derivatives featured drum brakes all round, which are all that’s needed. Imp Sports and Sunbeam Stilettos were fitted with a larger master cylinder and a servo for easier use. Some owners have upgraded their Imps to Sport specification by fitting the larger units and these are a simple swap, so there’s nothing to worry about in terms of common bodges if the improvements have already been done.

See if the brakes are binding by trying to push the car on a level surface. If it quickly stops it’s because the wheel cylinders aren’t returning properly, which is usually caused by the ventilation hole in the brake master cylinder reservoir cap becoming blocked. The judicious use of a pin is all that’s required to fix the problem.

 TRIM

Interior trim has all but disappeared for the Imp, although some used parts are still available from within the club. ‘l’he seats of Mk III cars (post-1968) are not easy to repair because they’re moulded. The trim in cars built before 1968 is easier to repair because of its simple leathercloth construction. Exterior trim is equally hard to find, with new items all but extinct. Badges are Mazak, so hard to repair, while the rest is either anodised aluminium or stainless steel. Everything is available on a used basis though.

 ELECTRICS

The Imp’s loom is straightforward, with the main problems likely to stem from previous owners who have suffered from more enthusiasm than skill. ‘I’here isn’t anything that’s especially problem-prone, so just check that all the instruments and switchgear works. Pre-1968 switchgear is hard to find now, hut other than that it’s easy enough to track down replacement parts, whether it’s exterior lighting or instruments.

CONCLUSION

Because Imps are worth so little you have to make sure the car has been run by an enthusiast and not as ultra-cheap transport by a penny-pinching owner. There’s a lot of tat out there but there are also some cracking examples, that are probably in better condition than they were when new. While a test drive is essential when buying any used car, with an Imp it’s critical. Make sure you cover at least ten miles over a variety of types of road to see if the engine overheats.

PRACTICAL CLASSIC?

Absolutely — cheap to buy and run, easy to maintain and a hoot to drive