Fitting new heater hose

[StevehS3]

I need to change the heater hose (although I don’t have a heater) on my K series car. Will I manage to do it without draining down the coolant? Many thanks, Steve

[Jonathan Kay]

No need to drain but you might lose a bit, so I'd have some ready to top-up.

Do you have a filling and bleeding method that works for your Seven?

Jonathan

[StevehS3]

Many thanks Jonathan. I’ve drained before and have a method that works for my setup thank you (it seems I’ve got one that is easy to bleed!).

[revilla]

the heater hose (although I don’t have a heater)

Do you mean you need to change the full bypass hose round from the water rail above the exhaust round to the thermostat housing? 

If  so, you will need to drain it. And beware, the hose is 15/16mm at the water rail end, something like 19mm at the thermostat housing. They often use two pieces of hose with a joiner in the middle.

[StevehS3]

Hi Andrew, yes it is that hose. I was hoping I would manage it without draining, accepting I would lose a bit. Interesting with regard to the sizing, my existing one has a joining piece which I assumed was for connection to the heater, if fitted. My replacement is a one-piece silicone hose from Classic Silicone Hoses. I now wonder if it will fit.

[Jonathan Kay]

Sorry. Well spotted, Andrew.

Jonathan

[revilla]

The one piece silicone hose should be made to fit, so should be the correct diameter at both ends. That seems to be a lot easier to manufacture in a single piece in silicone than in rubber, so no joiner needed. But you will need to drain it. The thermostat is low down in the cooling system, as soon as you remove the bypass hose it will gush out everywhere. And access is awkward so you won't be able to slip the old hose off and the new one on quickly.

[StevehS3]

Thanks again. I will measure the IDs of the new hose before draining down. It is made for this so as you say, it should fit.

[StevehS3]

Just for info. the I.D. of the hose is approx 16mm at the water rail end and 20mm at the thermostat end with the 90 degree bend. So, all good and a neat solution avoiding the joiner in the middle.