Getting to know your engine before you cast off

Before you untie the ropes, spend ten minutes in the engine bay with the handover skipper. Every hire boat is slightly different, even if the basic diesel engine is familiar. Ask where the dipstick is, where the coolant expansion tank sits, how to check the drive belt, and where the fuel shut-off valve and battery isolator are located. Find the weed hatch, too, because a fouled propeller is a common cause of overheating and loss of drive.

Do these checks while the engine is cold and switched off, with the gear lever in neutral. Make sure the boat is securely moored and the key is out. If anything is unclear, ask during the handover. Staff would rather answer a question at the pontoon than rescue you later from a windy towpath.

Oil checks: the simplest job you must not skip

Engine oil lubricates, cools and cleans your diesel. Running low can cause rapid, expensive damage. Pull the dipstick, wipe it clean, push it fully home, then read the level. It should sit between the minimum and maximum marks. If it is near the minimum, top up with the recommended grade, a little at a time. Overfilling is almost as harmful as underfilling.

• Check engine oil with the engine off and the boat level.
• Look for milky oil, which can suggest water contamination.
• Check gearbox oil if it has its own dipstick.
• Inspect the engine bay for fresh drips under the sump, filters and hoses.
• Give the stern gland greaser a turn if fitted.

If you find a significant leak, a sudden drop in level or unusual oil colour, contact the hire base before setting off.

Coolant and cooling system checks

Narrowboat engines are usually cooled by a closed system with a heat exchanger or keel cooling, or by raw water from the canal. Either way, coolant level matters. Check the expansion tank when the engine is completely cold. Never remove a coolant filler cap while the engine is warm; hot coolant can cause serious burns. Top up with the correct pre-mixed coolant, not plain water, unless advised otherwise.

With the engine running, look over the stern for a steady tell-tale of cooling water from the exhaust. If it disappears, stop promptly. Check the raw water strainer if fitted, and clear weed from the weed hatch if the propeller is fouled. Hoses should feel firm, not spongy, and clips tight. Report any unexplained coolant loss immediately.

Belts, hoses and visual inspections

The drive belt turns the alternator and often the water pump. Press it gently midway between pulleys; it should have a small amount of deflection, not feel slack or rock hard. Look for fraying, cracks or glazing. If the belt squeals when the engine starts, it may be loose or contaminated. Do not adjust it unless the hire base has shown you how.

• Hoses for cracks, bulges or chafing.
• Fuel lines and filters for leaks.
• Battery terminals for tightness and corrosion.
• Bilges for water, fuel or coolant; they should be dry.
• Engine mounts, exhaust lagging and ventilation grilles for damage.

Photograph anything that worries you and show it to the hire base. They can often identify a problem before it becomes a breakdown.

Starting up and listening for trouble

Start the engine according to the handover instructions and let it idle in neutral. Watch the oil pressure warning light: it should go out within seconds. Check that the temperature gauge rises slowly and settles in the normal range. Listen for anything out of the ordinary: squealing belts, knocking, rattling, excessive smoke, heavy vibration or a strong diesel smell. Test ahead and astern at low revs while still tied up.

Unusual noises are your engine's way of asking for attention. A new rattle, a rhythmic knock or a sudden change in exhaust note should never be ignored. Switch off, investigate what you safely can, and contact the hire base straight away. Better to delay departure by an hour than break down in a lock cut.

Daily checks and while underway

Make a short routine part of every boating morning. With the engine cold, check oil and coolant, glance at the belt, and confirm the bilges are dry. Clear the weed hatch if you have been through shallow water. Check fuel level before each day's cruise. While underway, watch the temperature gauge, listen for changes, and feel for unusual vibration through the tiller.

Every few hours, or at a convenient mooring, check the stern gland drip rate and give the greaser a quarter turn if fitted. If the temperature climbs, reduce throttle, move to a safe mooring and stop. Do not open the coolant cap. Check the weed hatch and raw water strainer first. If the problem persists, call the hire base and describe what you see, hear and smell.

A little attention before you leave the mooring, and a few minutes each day, will keep your canal holiday relaxed. Clean oil, adequate coolant, sound belts and an attentive ear will reward you with many happy miles.