Solving Radiator Blockages (Was Re: Overheating)

[MadMaz]

Hi all

Once rust & scale builds up in an engine's cooling system, you've got real
problems. Pieces will keep breaking off, moving around and jamming up the
radiator cooling tubes - even after they've been rodded through and flushed.
Because the real problem now lies with corroded water jacket surfaces of the
cast iron block - and scale deposits sitting in the bottom of the car heater
air heat exchanger.

The best way to avoid the dreaded problem of rust and scale build up, is to
drain your engine coolant every year and refill with distilled water (now
readily available at most supermarkets for drinking purposes) and running anti
freeze at 50/50 for cold climates and a tad less for warmer climates.

Don't use tap water if you can help it, because even with plenty of
anti-freeze, the tap water in some areas is very corrosive - and/or will of
itself deposit scale when heated.

Solving the problem yourself: Scale and rust on the jacket walls and deposited
in the radiator bottom tank and in the heater can be partially dissolved and
dislodged chemically and then flushed out.

Run a chemical radiator flush (such as CRC or Wynns brands ex-Repco etc)
through your cooling system, as per the instructions. (Make sure the heater
is on full hot). I've been advised to do this not just once, but fill, run,
drain & flush at least twice, using another whole bottle each time. The
thermostat needs to be removed for these operations - but there is no
alternative - because you don't want loose scale and grit backing up against
it during the process and it also increases the run flow.

Finally run the engine with just water in the system to dilute any traces of
scale remover chemical. Then drain right out, flush again then replace the
thermostat and refill with distilled water and antifreeze at the recommended
proportion. Caution: Take care against being scalded with hot water during
the whole operation.

Also, check that the rad cooling fins are clear of insects, leaves and
anything else that restricts airflow and that they are not significantly
damaged by corrosion or impacts.

This should work in most cases, costing just two bottles of radiator flush and
some of your own time. You may need to take the radiator out of the car
afterwards, and flush through the drain hole and filler, while alternatively
turning it upside down and then right side up. You can also more effectively
flush the block & head, while the cooling hoses are disconnected.

As an alternative right from the start, (but costs much more), try the
services of someone who can backflush your cooling system with chemicals and
water under high pressure. I know AutoCare in Pukekohe for example provides
this type of service.

Bad cases may need still need the rad rodded through utilising either option.
In every case though, prevention is much better and cheaper than the cure.

Cheers all
Mark