Radiator cleaning - economically of course!

[Speedex750]

Hi,

Despite searching the Forum I can't find anything on cleaning out a radiator. I have a functional non-leaking radiator but have noticed the running temperature has gradually increased over recent years that has no engine related explanations. I can see a skin of brown scale through the cap.

So: what potions can I flush out the core with, preferably something proprietary and economical - and with a residue that I can safely dispose with a clear conscience! I know about citric acid but wonder what experience others have had with it? What about kettle etc descalers? And maybe not relevant, I've heard that Milton fluid is great for taking that brown tea stain out of stainless vacuum flasks - that's the sort of idea I'm looking for - but would it work in a radiator?

I know I'll take a risk of springing a leak but what's worked for you?

Thanks, Dave

[Simon Scott]

Just back flushing it will shift a lot of crud, maybe worth trying first.

[Hedd_Jones]

Viakal or similar will shift all the shit. But be carefull if you have a steel core it might make it leak. Whatever you use will have a high chance of springing leaks in all honesty.

[Charles P]

Fernox DS3 central heating descaler works well if applied hot

Charles

[Nigel Ricardo]

I keep Screwfix version of Fernox in mine all the time, it cleans and also is an antifreeze

[Robert Leigh]

Hi,

Despite searching the Forum I can't find anything on cleaning out a radiator. I have a functional non-leaking radiator but have noticed the running temperature has gradually increased over recent years that has no engine related explanations. I can see a skin of brown scale through the cap.

So: what potions can I flush out the core with, preferably something proprietary and economical - and with a residue that I can safely dispose with a clear conscience! I know about citric acid but wonder what experience others have had with it? What about kettle etc descalers? And maybe not relevant, I've heard that Milton fluid is great for taking that brown tea stain out of stainless vacuum flasks - that's the sort of idea I'm looking for - but would it work in a radiator?

I know I'll take a risk of springing a leak but what's worked for you?

Thanks, Dave

Some of the problem could be sediment and rust in the block. While you are sorting it out I suggest removing the hoses and using a pressure hose on each engine water connection in turn.

[Chris KC]

Holts Radflush / Speedflush. Seriously, just go to Halfords. And read the label...

Do please listen to Robert though - if your hoses and manifolds are not already blocked they will most likely be after you use a chemical flush. I used radflush just before I stripped my engine and despite copious flushing through with a garden hose in both directions, I found the side manifold almost completely blocked with scale and debris when it came apart.

In the course of my rebuild I poked out everything I could from inside the block, likewise the head, new top and side water manifolds, had some custom hoses made, flushed the radiator some more and finally filled up with Penrite classic car coolant. She now runs cool as a cucumber.

[Charles P]

I keep Screwfix version of Fernox in mine all the time, it cleans and also is an antifreeze

Fernox makes many useful chemicals for water systems.

DS3 (descaler) or DS40 (a more acidic version) are short term cleaning chemicals. You can't run with them in the system long term. 

Fernox F1 is a corrosion inhibitor that you can leave in. It doesn't have antifreeze properties but is better if you do speed events because any overflow onto the track isn't slippery like a normal anti-freeze. You will not be popular if you leak slippery coolant on the start line. It also doesn't lower the boiling point as normal car anti freeze does.
Fernox Alphi 11 is a combined corrosion inhibitor and anti-freeze. Many use it but I haven't. 

To clean my block/head in situ I took the approach in the picture


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I filled the tank and system with a solution of Fernox DS3 and ran the engine up to temperature a few times. The debris left at the bottom of the plastic tank was instructive and none of the loose crud got caught in my freshly rebuilt radiator.

Charles

[DavidL]

I like that rig...and thank you for the reviews.

[Hedd_Jones]

I assume you have a water pump Charles?.