If ever proof were needed............

Over the past week I decided to replace my two heater hoses, not because there was anything wrong with the old ones, but I knew it was not an easy job, and I did not want them to let me down on my trips to Macon where a good few years ago Dave Miles had one let go in Macon and I remember the trouble it caused him. Since then I have always carried a new spare set of hoses with me ....... amongst a hundred and one other spare parts for the Alp ...... on my Macon adventures.
I eventually got the two hoses replaced with a lot of swearing and blooded knuckles and arms, and as the cooling circuit was as empty as is possible without draining the block, I decided to flush out the radiator as it has not been done since I replaced the radiator at least 15 years ago.
So with all the stories about the amount of sludge deposited in the lower part of the rad as the hose joints are half way up each side of the rad, I thought I would take the rad off and see how much sludge/ silt had collected in the rad. I had also removed the temperature sensor to reduce the level of fluid in the rad.
Having removed the rad without loosing any more coolant, I blocked up the hose pipes on the rad, and replaced the sensor.
I then sloshed the remaining fluid from side to side a couple of dozen times, and removed the "blocks" and poured the remaining coolant into a large light grey bowl.
Expecting to see some sludge/silt ........ imagine my surprise to see how clean it was.

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I then got my garden hose with the trigger nozzle on mains pressure and having removed the sensor again and blocking the rad input just above the sensor fired the nozzle into the sensor fitting, and was again surprised to see just the very slightest browning of the water for about 2 seconds before the flow was clear. I continued to flush the rad every which way I could, and by sloshing the rad from side to side and I never saw anything but clear water exiting from the rad.
I know I have been on and on about Type D coolant as I had noticed that, since using it from 1994, that the coolant seemed to not change colour over time unlike the original Type C which turned to a rusty brown from day one, which was discoloured by rust from the steel coolant pipes.
So to me it is pretty conclusive that Type D coolant is definitely always worth using.
I know some might say that the damage has already been done, but I am sure due to the lack of colour change of Type D, with its inhibitors, the corrosion will slow down if not stop it getting any worse.
In conclusion, I add two pics of how I found the state of the rad with debris having been scooped up over the years ........ which says to me ..... if the bumper is removed, it might be worth removing the scoop to check the state of the rad, if the scoop is not removed, you would need to lay on the floor with a torch in order to see if there is any debris there. If so, then the chances are that a vacuum cleaner will be needed to clear the rad of debris.
Anyway ..... that's my sermon for today, ........ I hope some might find my observations interesting.
John

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You sold me on type-d years ago John. I've got about 10 litres extra stored in the garage from when I replaced the hoses with samco recently.

Interestingly re the rad, I don't know if you're aware but there was a supplementary service book that was in addition to the normal renault service schedule and specific only to the gta. One of the main extra service items was high pressure cleaning of the radiator to get rid of debris and insects that might clog the fins.

One of the main extra service items was high pressure cleaning of the radiator to get rid of debris and insects that might clog the fins.

Hi Darren .......... I was not aware of that, but I did do a wash through of the core from rear to front whilst it was off, but I did not use a pressure washer, I just used the hose under mains pressure. Even then I was very careful because, as you know, the fins are very fragile and I did not want to flatten them which would be very easy to do with a pressure washer. But with my hose, I got all of the debris out but there were still some very small "stones" stuck in the fins but not enough to be too worried about.

Well keep in mind this was from the 80s anyway, so pressure-wash back then meant a squirt from a hose, nothing like what we have now. Plus I think the usual car manufacturer self-importance that their techniques are somehow only known and available to them.

Reality I reckon was a quick squirt with a hose if and when they remembered to do it. Like you say, fins are delicate, plus there's a few connectors behind there for the rad fans.