Replacing internal heater pipes, day 3

Oh my god, this is a baptism of fire and frustration. So far the entire interior has come out, seats, carpet, underlay, console and central console face and rear armrest- which I planned to replace anyway, then found a coolant leak on one of the pipes that run internally from the engine to the heater.
So far the gear lever mech, heater control pod, cross member thingy support behind it, srs unit, a mass of wires that are routed in between various pipes, nooks and crannies. Small floods of coolant that decided to wait until I put my head just where it run anywhere a towel had not been laid. Then finally accessing the pipes in the engine bay, found that the only way to remove the old pipes was to angle them up into the dash, into the heater vent and remove the rubber pipes from the end. Finally the faulty one is out. Dread revering the process, but very grateful for David's how to pipe layout diagram as the carefully marked notes telling me which rubber pipe was fitted to the correct metal pipe was rubbed off during the battle to disengage each other.
Really, were the Rover engineers who designed these cars on drugs?! They really couldn't have made the design more complicated if they tried!

Anyway, deep breath and cup of coffee in hand - question to the sane.... The old pipes contained a load of rust and debris, which is floating around the system. Should I flush the system out, and does anyone recommend a particular flush to use? Any pointers and advice on the procedure would be appreciated.

No harm in flushing, I've only ever had to flush old coolant so have just used a hose and tap water.

Reverse flush if you can, the opposite way to the coolant flow, to release more contaminants.

Wow , what a job you've taken on . Having worked for a vehicle manufacturer it is very different on the production line to having to reverse the process . I think that the previous suggestion of just reverse flushing would be okay . Unless the system has got oil contamination and in that case I would use Forte cooling system flushing additive as that is excellent for that type of job . In the mean time , more power to your elbow ! ! :clap:

John

I'd put a dishwasher tab into the coolant tank and let it run for a while before reverse flushing with clear water

Why does the heating flow and return pipes have to be replaced with steel again?
This is not a job I have had to do yet, but surely there must be something more flexible and resistant to corrosion that would replace existing.
I'm thinking on the lines of silicone hoses, but there will be alternatives.

Maybe because they are close to the exhaust, as with radiator pipes, heat would damage rubber pipes. Not sure how well silicone type pipes would cope with heat.

I know that replacing both the gear cables resulted in me stripping the interior as you have done. I did it as a precaution.The car had done about 55K miles at that stage (it has now done 65K miles, 12 years later).

Frankly, I would replace ALL the rubber hoses whilst you are at (budget permitting) including the valve and heater matrix (only if you can buy new).

In my experience, cars (in fact all manufactured items) are designed to be built quickly and cheaply, not taken to bits. Audi is the same.

It is a job that I never want to do again. Best of luck.

Why does the heating flow and return pipes have to be replaced with steel again?

The original steel pipes lasted 25 years. So another 25 years should be fine? No!

A few coats of heat resistant paint may help in that regard.

I agree the lifespan is good, its just the issue of installing rigid steel pipes inside the car from the engine, not to mention weight. Maybe there is a twin walled plastic alternative such as the pipes used in central heating.
I want to strip out the interior of the F next summer, this could be a job to look at whilst it is stripped.

Browsing my new F/TF Rimmer catalogue I notice they do Stainless underfloor heater pipes , PEP102231SS, £96 inc VAT excl postage.