What the owner brought it in for
The owner booked the BMW 5 Series in for a service. It included an engine oil change, a gearbox oil and oil pan change, and a check of the coolant.
This BMW 5 Series came in for a gearbox oil and oil pan change, and the owner asked us to check the coolant. Our technician found a top up coolant warning caused by the expansion tank, and some coolant hoses close to cracking. We sorted both jobs in one visit.
Job completed: September 2026
| Car | BMW 5 Series |
|---|---|
| Symptom | Top up coolant warning. The owner also asked for a gearbox oil and oil pan change |
| Fault found | Top up coolant warning caused by a problem with the coolant expansion tank. Some coolant hoses close to cracking |
| Repair done | Replaced the expansion tank with cap and the coolant hoses, serviced the automatic gearbox with a new pan, integrated filter and fresh ATF |
| Parts | Quality replacement parts throughout |
| Time taken | Timeline confirmed after inspection |
| Cost | Quoted item by item after inspection |
| Warranty | No workmanship warranty on gearbox service or routine maintenance |
The owner booked the BMW 5 Series in for a service. It included an engine oil change, a gearbox oil and oil pan change, and a check of the coolant.
The BMW 5 Series is BMW's executive car. This example is fitted with the colour-accented grille, identifiable by the M-colour stripes on the kidney grille. Coolant hoses and plastic connectors become brittle with age, and the automatic gearbox needs periodic fluid and filter changes to keep shifting smoothly and protect its internal parts.
On an older car, neglecting the gearbox service allows the old ATF to degrade, and the filter to become restricted. Replacing coolant hoses before they crack avoids overheating damage.
Our team checked the car through. The top up coolant warning came from a problem with the coolant expansion tank. Our technician also found some coolant hoses that were close to cracking. We quoted the tank, its cap and the hoses item by item, and the owner approved the work.
For the gearbox, the owner had asked for the gearbox oil and the oil pan to be changed. We offered an original or an OEM pan, and the owner chose OEM.
Coolant hoses are rubber and the expansion tank is plastic. Both age with heat and time. Hoses harden and crack, and an ageing tank or cap can stop holding coolant properly, which brings up a low coolant warning.
Left alone, a cracked hose can fail suddenly. A sudden loss of coolant can overheat the engine and cause serious engine damage. On this car the hoses were replaced before they cracked, so the fix stayed a straightforward tank and hose job rather than an engine repair.
We completed both jobs in one workshop visit.
Coolant system:
Automatic gearbox service:
We also performed a battery health check at the same time.
From our team's record of this job. Number plates are pixelated.
The cost depends on the extent of the coolant hose replacement needed and the specific gearbox service package. We inspect the car first, identify exactly what is required, and give you a clear quote before any work begins.
We do not guess from outside the car. Lift the car, check underneath, quote item by item.
Check the coolant level in the expansion tank regularly. If a top up coolant warning comes up, have the tank and hoses checked instead of just topping up. If the level keeps dropping without an obvious external leak, it is worth having the hoses and connections inspected. White mineral deposits around a hose connector or at the expansion tank cap are a clear sign of a slow weep.
For the automatic gearbox, the ATF does degrade over time. If the car has not had a gearbox service within the last several years, it is worth having it done, especially on an older car.
This BMW 5 Series (Coolant hose replacement, expansion tank replacement, automatic gearbox service) was handled at 1 Car Service, an independent workshop in Sin Ming AutoCity, Singapore. For BMW, we use dealer-level ISTA diagnostics. We hold a 4.9★ rating from 1,836+ Google reviews.
WhatsApp us your BMW model and what you are noticing. We will inspect the coolant system and check the gearbox, and tell you exactly what needs doing before any work begins. We use BMW ISTA diagnostic tools to read the car properly.
It depends on how many hoses need replacing and whether the expansion tank needs changing too. We inspect the cooling system first and give you a clear quote before any work begins.
Common signs are a dropping coolant level in the expansion tank, a sweet smell from the engine bay after driving, or dried residue around a hose connector. On this BMW the sign was a top up coolant warning, which came from a problem with the expansion tank.
The ATF does degrade over time. On a high-mileage or older 5 Series that has not had a gearbox service, it is a good idea to have the pan, filter and fluid changed.
Yes. A small hose weep stays manageable if caught early, but if coolant loss continues and the engine overheats, it can cause head gasket failure or more serious engine damage. On this car we replaced the ageing hoses before they cracked, so it stayed a simple tank and hose job.
Yes. We use BMW ISTA diagnostic tools to read the car's systems, check for stored faults, and confirm the repair is complete.
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