1978 Triumph Dolomite
Browse our directory of 1978 Triumph Dolomite vehicles. Access instant MOT history reports, tax status, and reliability insights for any registration listed below.
Registration Directory
Showing registrations 1–40 of 68 for the 1978 Triumph Dolomite. Select any plate for an instant vehicle history check.
Common Problems & Reliability
The 1978 Triumph Dolomite has 4 known issues. 2 of these are classified as serious faults that could be expensive to repair. 2 are moderate concerns worth inspecting before purchase.
Slant-four alloy cylinder head warping and head gasket failure
SeriousThe 16-valve Sprint and 8-valve 1850 slant-four engines utilise an aluminium cylinder head mounted atop an inclined cast-iron block. The diagonal angled head studs and high thermal stresses make the engine exceptionally vulnerable to overheating. A lack of high-specification corrosion-inhibited antifreeze allows electrolytic corrosion of the aluminium castings, silting up the radiator and blowing the head gasket.
Symptoms: Coolant temperature gauge needle creeping toward the red zone under load or at idle, Combustion pressure causing coolant expulsion from the radiator filler cap or expansion bottle...
Est. repair cost: £800–£2,500
Bulkhead and windscreen pillar junction corrosion
SeriousThe monocoque shell of the Dolomite suffers from severe structural corrosion in the hidden junction where the windscreen A-pillar meets the bulkhead and inner wing. Water draining through deteriorated windscreen rubbers and blocked scuttle vents collects in this structural joint, rusting through multiple panels into the driver footwells and weakening the passenger safety cell.
Symptoms: Water pooling in front footwells and damp, mouldy front cabin carpets, Bubbling paint, rust blistering, and flaking metal visible around the lower windscreen corners...
Est. repair cost: £1,000–£3,500
Deteriorated rubber carburettor mounts causing lean running
ModerateOn Dolomite Sprint models, the twin 1.75-inch SU HS6 carburettors are isolated from engine vibration by rubber-to-metal sandwich mounting blocks. Over time, heat soak and fuel vapours cause the rubber to perish, split and delaminate. This admits unmetered air into the intake manifold, creating a dangerous lean fuel-air mixture that causes erratic idling, hesitation, and burnt exhaust valves.
Symptoms: Lumpy, erratic engine idle speed that fluctuates or fails to settle when warm, Engine hesitation, flat spots, or spitting back through carburettors under initial throttle opening...
Est. repair cost: £120–£350
Rear suspension trailing-arm and locating bush deterioration
ModerateThe Dolomite relies on a live rear axle located by four trailing links and an anti-roll bar with multiple rubber bushes. Decades of oil contamination, weathering and mileage soften and perish these rubber bushes. Worn bushes permit excessive lateral axle float and axle steer under power, causing the rear end to twitch, squirm under acceleration, and knock loudly over uneven road surfaces.
Symptoms: Rear-end steering sensation and wandering instability when changing lanes or applying throttle, Dull metallic clunking from underneath the rear seats when pulling away or braking...
Est. repair cost: £250–£650
Buying Tips for the 1978 Triumph Dolomite
- On Sprint and 1850 slant-four engines, insist on a thorough cooling check: verify that fresh corrosion-inhibited antifreeze is present, as neglected coolant causes head gasket failure and seizes cylinder head studs.
- Inspect the bulkhead where the windscreen pillar meets the inner wing and scuttle drain under the bonnet; rust here is structurally critical and extremely labour-intensive to repair.
- Check crankshaft end float on iron-block 1300 and 1500 models by having an assistant press the clutch pedal while you check for front crank pulley movement.
- Examine the rubber carburettor mounting flanges on Dolomite Sprints; perished rubber causes unmetered air leaks, lean running, rough idling and burned valves.
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