An engine that runs too hot can do itself expensive damage in a matter of minutes, and a heater that won't warm up makes winter driving miserable and demisting slow. NRH Autoworks repairs engine cooling and cabin heating systems at our garage on Windsor Road in Bray, serving Maidenhead and the surrounding area.
Enter your registration on the enquiry form and tell us what you've seen: a climbing temperature gauge, coolant on the drive, a level that keeps dropping, or a heater blowing cold. A photo of any leak helps. We'll get back to you by phone or email to arrange a look.
What we can help with
- Cooling system pressure testing and leak tracing
- Radiator replacement
- Water pumps, expansion tanks and hoses
- Thermostat replacement
- Heater matrix faults
- Coolant and antifreeze changes
Signs of a cooling or heating problem
- The temperature gauge climbing above its normal position
- Steam from under the bonnet
- Coolant level dropping, or a coolant warning on the dashboard
- Pink, green or blue fluid under the front of the car
- The heater blowing cold, or only warm when you rev the engine
- A sweet smell in the cabin or a greasy mist on the windscreen
- The engine taking far longer than usual to warm up
If the temperature gauge climbs
If the gauge heads towards the red or a temperature warning comes on, pull over when it's safe and switch off. Carrying on is how a leaking hose turns into a warped cylinder head or a failed head gasket. Don't open the expansion tank or radiator cap while the engine is hot: the system is pressurised and the coolant can scald. Let it cool fully before checking the level. If it has lost coolant, topping up may get you somewhere safe, but the leak still needs finding.
Leaks, radiators, water pumps and hoses
Coolant is pumped round the engine by the water pump, gives up its heat in the radiator and returns. Radiators corrode, get damaged by stones and crack along their plastic end tanks. Water pumps leak from their seals or develop noisy bearings. Expansion tanks split along their seams with age, and rubber hoses perish, soften and swell until one lets go. We pressure test the system to find where coolant is escaping, because leaks often only show when it's hot.
Coolant itself matters too. It's a mix of water and antifreeze with corrosion inhibitors that protect the engine, radiator and water pump from the inside, and those inhibitors are used up over time. Different engines need different types, and mixing them can cause trouble. We change coolant using the correct type for your car; check your handbook for the recommended interval.
Thermostats
The thermostat is a simple valve that stays shut while the engine is cold and opens to send coolant through the radiator once it's warm. When one sticks open, the engine takes an age to warm up, the heater stays lukewarm and fuel economy suffers, often with an engine management light. When one sticks shut, the engine overheats quickly. Either way the fix is a new thermostat, but we check that's really the cause, since a faulty temperature sensor or low coolant can give similar symptoms.
Heater matrix faults
The cabin heater is a small radiator behind the dashboard, called the heater matrix, fed with hot coolant from the engine. If it becomes blocked with sludge, the heater blows cold or barely warm. If it leaks, you get a sweet smell, a greasy mist on the inside of the windscreen and eventually damp carpets in the front footwells. A blocked matrix can sometimes be flushed; a leaking one needs replacing, which on some cars means removing part of the dashboard. We'll explain what's involved.
Cooling & Heating: common questions
Why is my car overheating?
The usual causes are low coolant from a leak, a thermostat stuck shut, a failed water pump, a blocked radiator or a cooling fan that isn't cutting in. Less often it's a head gasket. They need telling apart by testing rather than guesswork, so describe when it happens, in traffic, on the motorway, on hills, in your enquiry.
Can I just keep topping up the coolant?
As a short-term measure to get by, yes, but coolant doesn't get used up, so a falling level means it's going somewhere. Topping up with plain water also dilutes the antifreeze and corrosion protection. It's better to find the leak while it's small than after the engine has overheated.
Why is my heater blowing cold air?
Low coolant is the first thing to rule out, because the heater is often the first thing to suffer when the level drops. After that, a thermostat stuck open, a blocked heater matrix or a fault with the flaps that direct the air are the common causes. We'll work through them in that order.
Do you re-gas or repair air conditioning?
No. We don't carry out air conditioning work of any kind, including re-gassing and repairs. This page covers the engine's cooling system and the cabin heater, which work separately from the air conditioning. If your problem is with the air conditioning, you'll need a specialist who handles refrigerant.
Is a coolant leak serious?
It can become serious quickly. A small weep may go on for months, but if the level drops far enough the engine overheats, and that is when real damage is done. If you're seeing drips under the car or topping up regularly, send us an enquiry with your registration and we'll arrange to pressure test it.