radiator/cooling system flush......is it worth it??

[benyimin]

I'm in the process of draining my cooling system (and refilling!) to see if this will help my car run at a slightly lower temperature. Before I started I noticed you can get a radiator flush to put through the system but thought I wouldn't bother.....however I've put 3 lots of clean water through it and I'm still getting it come out the other end with the old coolant in and bits of rust and dirt. Will a radiator flush get rid of this and arew there any downsides to using it?

[Busa_Rush]

Not really. I'd take the radiator off and tip it up to get the crud out, that's where most of the sediment usually is.

Usually helps to take the thermostat out as well when flushing. Just keep at it with a hose pipe.

When you refil the system use a small amount of water wetter. Some people claim it does nothing but I have found that when the system is marginal or under load it can help. It won't fix a faulty system though.

[Steve_D]

A really well clogged rad may benefit from a flush product but for most a good clear water flush will do fine.
As said getting the rad out and both back flushing and inverting will help.

Back to getting it to run cooler, what are you trying to achieve and what thermostat have you got fitted at present. Also is it new as they do get lazy when old.

Steve

[lenientism]

Perhaps flushing radiator coolant while engine is running, like flushing automatic transmission fluid, is very ideal for the best result. I think it is still better to change radiator coolant periodically, than not at all. Drain out the old coolant, let plain water with some pressure running into the radiator tank, wait a moment, and fill it up with new coolant.
Besides its function to keep engine working at proper temperature, the right coolant inhibits corrosion.

I just wanted to drain radiator of Volvo. Trying to look for where the outlet plug lies, usually it lies at the bottom of the tank, strange it didn't have that plug. I think I have to put the hose pipe off to drain the old coolant out. I see some corrosion in the plastic tank, so flushing should be in immediate effect.

[Busa_Rush]

Gavin,

Is there any benefit in using an acid flushing agent on a relatively new engine, say 2003/2004 with just 12,000 miles ? Thinking about motorbikes in particular, have had regular coolant changes but spend half the year in the garage.

What should I look for in a coolant ? I've always changed them every 2 years with a water flush but have a couple of engines now which I'll be keeping for a lot longer. They all state they have corrosion inhibitors but are there any worth paying a bit extra for ?

[lenientism]

GavinPearson said:

If the coolant hasn't used up it's inhibitor pack then what you say might be valid. But by the time the coolant is old enough to warrant changing you need to remove the pips & pits in the castings, get all the contaminants out so you need to follow the method I listed.

Yeah, your method is much preferable...

[flat16]

Gavin,

Would you be kind enough to let me know of a source for this Phosphoric acid-based cleaner you use? I have a car that's been off the road for 9 (!!) years and its cooling system is full of white crud. Surprise, surprise, it's overheating. A standard flush hasn't achieved anything.

One thing I've thought of trying is a pressurised radiator cleaner, like this one on Ebay: http://cgi.ebay.co.uk/Limited-Stock!--Britool-UK-R...

One side goes to the tap, the other to an air compressor. Various people seem to think I'll need a new rad... However, I need a custom rad which will take ages to get, not to mention cost.

Thanks!

Edited by flat16 on Friday 10th July 21:33

[paintman]

Or this http://www.forteuk.co.uk/Cooling_system_flush.htm

[Busa_Rush]

Thanks, explains why 10 mins with Holts rad flush doesn't achieve anything

Will try somehting different for a bit longer next time.

[PJ S]

Used the BG Products one recently, just in case the OE factory-filled coolant was beyond its useful life.
Filled with 35-40% Motul coolant using deionised water from Halfords - £3 for 5L iirc.

[flat16]

I bought 500ml of Forte yesterday (spares shop only had one bottle left). Put it in the car and drove / revved it for over 40 minutes. I didn't believe this would do the job, so to be sure I also bought 2 x 250ml bottles of Holts 'Speed Flush' (was all spares shop had in stock). I drained the Forte and put both bottles of Holts in. I've driven car for around an hour with this in it, and intend to drain and replace with coolant mixture later today (I figured it wouldn't hurt leaving it in overnight - I'll make sure to fully warm up car before I drain).

Anyway, I'm not overly optimistic. The car's 9 year sabbatical wasn't planned, and fluids were not drained (I don't need reminding of how stupid this was). The mechanic who re-commissioned the car swore he flushed it twice, and I only flushed it again as it had done some miles since he flushed it, and the Forte cleaner supposedly contains acid.

I suspect that the only hope here, bar a new rad, will be to try a pressure washer, as mentioned before. If this overheating issue is purely down to crud in the cooling system, it's very stubborn crud.

Thanks to all of you for the advice - much appreciated.

[flat16]

Here's an example of a home-made pressure flusher I found via Google: http://smg.photobucket.com/albums/v653/peterhowell...

Maybe what you want is a pressure washer, being fed with some noxious acid?

[Pumaracing]

A good way of getting water which isn't full of dissolved crap for use in your cooling system is from a dehumidifier if you have one or know someone who uses one. I bought one many years ago to keep my workshop damp free to stop the tools and machinery from going rusty. For a few pence a day in electricity it chucks out a litre or more of clean, contaminant free water which you can bottle and use for topping up batteries or refilling the rad. When you have water as hard as we have where I live everything scales up in no time flat. Kettles, immersion heaters etc and it does neither your car battery or cooling system any good at all.

The price they charge for deionised water in the shops is beyond a joke given how easy it is to make.

[lenientism]

On engine without outlet plug on the bottom of radiator, we need to disconnect hose pipe from engine. Preferably to disconnect pipe from radiator but since it was not easy then I prefer the first.

Consequently the hot water come into contact with pulley and belt of the fan. How can I get rid of chirping noise of the pulley and belt, if this flushing has caused the pulley and belt damaged this raises new problem.

[lenientism]

I gave light oil on the pulley and rag for belt dressing. Problem fixed now.

[Conrad990]

I suggest cheap diet cola as flush, it contains phosphoric acid which chemically slows rust by forming iron phosphate in place of oxide. Can work as rust inhibitor with a stiff wire brushing too. The co2 will make it mildly acidic, and it may be bad for aluminium parts eg modern radiators. I think the fizz dies fast when warmed. Use diet stuff as sugar is sticky when cooked on😕
Backwards flushing helps for really bad cases, garden hose in at the bottom rad hose and flow out the top.
Also, better to use soft soap on squeaky rubber aux power belts than oil. Rub it on whatever you can reach, it spreads out fast.
Keep it simple...

[sospan]

The Pepsi is also good for cleaning cast iron manifolds. Scrub them with a Scotchpad soaked in it, dry...voila.
Brings back a greyish cast finish and removes light rust. Phosphate coating too from the phosphoric acid in the Pepsi.