Hi

I was wondering if you could help please.

I have a ford fiesta 1.8di on a 2000 plate. The car has done 120,000 miles and carries full service history.

I have had the heater control valve replaced (as it had been bypassed when I bought it for unknown reasons), new thermostat, new injector leak off pipes, new cabin filter and a new battery.

The car has had the coolant system flushed, but the heaters still wont work properly. I am now getting heat out of the heaters (as opposed to previously only getting cold air) but only when it feels like it. I can sometimes turn the heater to cold and it will struggle to get back warm again. Some days it wont even get warm from starting.

What could this be?

Also, on top of the rocker cover, to the far right of the oil filler cap is a circle design that sits flush with the rocker cover. This is leaking ever so slightly.

Does this circle thing carry a purpose? Or is it just a design?

Can it be fixed? Or does it mean a new rocker cover?

Also, how many miles should I be getting out of a full tank (40 litres)?

Many Thanks in advance for your help.

James.