Cleaning out a rad.

[Dave Plowman (News)]

A car one, that is - not central heating.

I've a feeling the one on the old Rover may be a bit blocked. The main rad has been replaced - but not the heater one. And it's not easy to remove. What would be a suitable chemical to clear it? Likely just the scale from hard tap water, as it's had 'aluminium' anti-freeze/inhibitor in it all its life and the engine water jacket is perfect. It's made of copper with possibly steel pipes feeding it.

I'd rather not fill the whole system with a de-scaler, but just the heater rad after disconnecting the hoses feeding it. So something that works cold would be best.

[Luke]

Hi, I would have thought any blockage in the heater matrix must be caused by either a) Years of running with no antifreeze in whatsoever leading to terrible sludging up (not possible in your case) or b) Repeated draining/refilling with hard water from the tap.

It's not going to get scaled up from just a few litres of hard water, as there's only a very small amount of scale in that amount of water, regardless of how long said water has been in your cooling system. I would have said it is far more likely, especially if it's a K-Series Rover, that the lack of heating through the heater matrix is caused by a different cooling system malfunction, either an airlock or a circulation problem. If it has just started happening I would investigate ASAP.

Removing the heater matrix in ANY car is a total ballache IME, so I would avoid this if at all possible!

Luke

[Andy Dingley]

Angle grinder, then new core.

You've got brass headers, I assume, so it's practical to do this. Given the age and parentage, it's not a great radiator core to begin with.

[Caecilius]

Have you tried reverse flushing it with cold water from a hozepipe? That's the first thing I'd try - I've done this on main car radiators before with some success, so I'd expect it may work on the heat exchanger core as well.

[Spamlet]

Dave Plowman

First thing to make doubly sure of is that the connector stubs *are* metal. I once had the B* of a job having to change the heater rad on a Micra, just because I waggled the hose in trying to disconnect it. The modern plastic connector stubs are incredibly brittle. Frankly, if heat comes out of your rad I would leave it alone. Ripping out dashboards is no fun at all.

S

[Dave Plowman (News)]

They are metal. Could be some form of plated copper or brass, but not plastic. The car's too old for this.

[Dave Plowman (News)]

You missed the part about it being a b***er to remove? The dash has to be stripped out.

You'd be very wrong there. The only reason the main rad was replaced was I punched a hole through it when doing something else. Plenty of modern cars with ally/plastic rads won't last anything like as long.

[js.b1]

Heater cores generally do not block.

Heater cores leak (sweet smell of anti-freeze). Thermostates stick, bypass thermostats must be accurately matched as some cars can be fussy. Hoses can deteriorate.

Some thermostats are designed to prioritise the engine "engine gets hot first, then the heater core". This can be amusing (not) in cold climates stopped at traffic lights where the heater core suddenly blows cold air.

Brass heater cores are more likely to leak than aluminium, but the former are cheaper & easier to repair. Aluminium heater cores last longer, but can cost ridiculous amounts of money if no pattern part is available (and usually it is).

Some cars have an oil-filter oil-to-coolant heater/cooler, these are quite reliable if robustly made - but the hoses can often get fried by nearby exhaust piping etc. That can result in leaks which otherwise go undetected.

Low coolant level can result in poor heater performance, usual trick is go around a roundabout - if the heat drops out you may have low coolant level due to airlock (or general level).

[Cicero]

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A domestic kettle descaler might do the job, possibly an 'eco descaler'. A couple of bottles of 'Viakal' would probably fill a heater matrix but you would need to check suitability for use on copper.

For the sake of safety (avoiding blow back) you could extend both hoses and feed in whatever you use through a small plastic funnel.

Cic.

[Dave Plowman (News)]

You've never owned a P6 Rover. They were notorious for this. The only cure was to remove the end caps and clean them out physically - a bit like cleaning a boiler. Both inlet and outlet pipes could be roasting hot - but the heater core itself stone cold.

Mine is a different design, though.

[Dave Plowman (News)]

That's what I was hoping someone would know.

Yes - I have plenty hose of the correct diameter.

[Cicero]

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Viakal cleans copper instantly. This is the immediate result of pouring a few drops on to a piece of used copper pipe and a 2p coin:

were left in contact with the Viakal for over two hours without any signs of etching, pitting or any other signs of corrosion.

It might be a bit risky but I would suggest getting plenty into your radiator (preferably dry) as quickly as possible and out again fairly quickly to see if there are any obvious signs of it clearing lime scale.

If it's as heavily scaled as you suspect it won't have time to risk damage to the copper core and it might shift the scale.

Cic.

[Fredxx]

I have no idea what Viakal has in it, but kettle descaler used to be formic acid, and if I want to descale a kettle I'd use cheap "simple" variety of vinegar.

For a car system I'd use a couple of litres of vinegar and get the engine hot enough for all the rad to get hot, and leave running for 15 minutes before giving it a very good flush with clean water.

[Dave Plowman (News)]

I don't want to get it into the engine or radiator - just the heat exchanger.

[Chris K]

If you can lay your hands on an old central heating pump that that could probably be adapted to reverse circulate hot descaler and could be left running for a while.

Necessity being the mother of invention with old cars.

Chris K