mk1 focus coolant level drops randomly

[steveo3002]

got a mk1 focus , i check the levels regularly and have noticed the coolant drops down to min

ive topped it up and we did a 400 odd mile motorway trip , no loss all good

then over a few weeks of local trips maybe 250 a week or so it drops back to min ..top it up and same again over about a month

no visible signs of leaks /residue , spark plugs all good and no misfires

what do you think ? just keep topping it up or what

[Mr2Mike]

Could be a number of things, but simplest would be to check that the seal on the expansion bottle cap is in good condition. If they leak then you will suffer from a slow loss of coolant.

The other common problem on older cars is leaking water pumps. These can leak at a slow enough rate that the coolant evaporates on the hot engine block so you don't get to a see a puddle under the car, but it usually leaves some evidence on the pump itself.

[steveo3002]

its had a recent water pump when the cambelt was done

wouldnt you expect to see a powdery mark if theres a small leak somewhere?

[Athlon]

Thermostat housing are plastic and are common to leak as the grooved area that holds the 'O' ring fail, look for pink stains on the gearbox.

[j666eds]

Athlon said:

Thermostat housing are plastic and are common to leak as the grooved area that holds the 'O' ring fail, look for pink stains on the gearbox.

WHS. When i used to have my focus, this failed twice. Coolant would be fine then randomly drop.