Flushing a Rusty Radiator

[Jack]

Hello people!

I’m reading about maintenance of the cooling system (just moved to the tropics 3 months ago) and still quite uncertain what the verdict is concerning the [flushing of] radiator.

See, I have gotten myself a used car and I noticed the rust at the cap area, the tubing leading into the reserve tank and the tank itself. Now I’ve not experienced any overheating problems, yet, but I’ll be traveling long distance in the coming weeks so I need to make sure I don’t break down in the middle of nowhere.

Things I’ve come across are:

1. Flushing it radiator with a garden hose until the flow is clear
2. Adding chemicals, soap powders, acids and even soda!
3. Drain the radiator but never use an anti-freeze (or ‘coolant’, as it’s known in this part of the world). The reason is that it will worsen the condition of the already rusted parts of the radiator.

Elsewhere in the forum, a thread I read states that flushing could actually be bad. So I hope someone could sort of clear this up for me, please :dry:

Thank you!

Topic

[dave]

Here are some fun facts to consider:

• having identified rust in your cooling system might indicate that the containment properties of the system may be compromised. perform a pressure test to identify any leaks. a cooling system leak anywhere will result in overheating.
• the most overlooked and prone part to fail is the radiator cap. it is an integral part of the system and controls pressure and overflow.
• the coolant in your system (specifically the antifreeze) has vital lubrication properties that your water pump, heater core valve, and thermostat depend on. extended life coolant should be changed every 5 years. conventional green antifreeze should be changed every 3 years.
• a flush machine will indicate if your cooling system can hold pressure. if the cooling system passes the pressure test, then the technician can proceed with the flush.
• stop leak will subject your entire cooling system to a gooey metallic coating; your cooling system will never be the same.
• a brand new radiator at autzone will cost you around $150. the cap will cost you $8.
• If your GM vehicle requires DexCool, you can only use DexCool or “universal.”
• never mix green and orange antifreeze. it will form a gelatinous residue and gum up your system. the only excpetion: “universal” antifreeze is green and can be used with conventional green,orange antifreeze and DexCool safely.
• do not run all water in your cooling system, even if it’s really hot outside. the extra water will over pressurize the system and cause a leak. additionally, water does not have lubrication of antifreeze and your water pump impellers will wear down.

[Jack]

Thank you Wrench Turner

[Charles]

None of the radiator parts rust. Its usually made of alunimum, copper and/or plastic. The rust if any comes from the iron parts of the engine or contaminants introduced by the owner. The water pump bearing is permanently sealed and is not lubed by antifreeze. The bearing is not ever touching antifreeze unless the shaft seal fails. The use of antifreeze in your engine in addition to lowering the freezing point also increases the boiling point of the water as does the pressure cap. Flushing the radiator/engine may not help but won’t hurt your engine.

Old school cars had radiators that could be taken apart and cleaned but the new ones made of plastic will need to be replaced.

If you can let your car idle for 30 min. and drive under load for a similar time without overheating you should be OK as long as you are not loosing coolant.

[Jordan]

Are you sure its rust. I have seen in alot of GM cars that use the orange Dexcool they leave a residue that looks alot like rust.

[Venturi]

I agree with the above. This may look like rust, but is not.

[Jack]

Thanks so much for the replies guys. Am pretty sure the deposits (on the body, reserve tank, and the tube running into the reserve tank) were rust. Smells like it too. Anyway, I got it cleaned out at the shop and replaced the worn radiator cap.

While we’re at it, should I be thinking about replacing the hoses too?

Hope it runs fine when I travel up north this weekend :cheer:

[EricTheCarGuy]

As for hoses I’d just do the upper radiator hose for now. That’s the one that takes the most abuse. The lower hose carries the cooled water back to the engine and usually doesn’t have issues.

As for the ‘rust’. My guess is that the system probably was topped off with water. I’ve heard of people in the tropics doing this because there is the perception that antifreeze is not required. This is not true. The antifreeze also helps lubricate the system and prevent rust as well as help with the boiling point of the mixture.

Keep us posted.

[Author]

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