Radiator flush

owains

owains

owains

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16 Jan 2004
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231
About 6 months ago I decided my expansion tank was looking real mucky so I gave the whole cooling system a proper clean out. I removed and cleaned the expansion tank and radiator and gave the pipework a good flush with the garden hose. I didn't think to use a proper radiator flush.

I have noticed the expansion tank is slowly getting more and more dirty... the water turning yellow with an oily layer on the surface and brown deposits. Perhaps the system wasn't cleaned thoroughly enough... I doubt that cold water is particularly effective at picking years of oily grime buildup.

I'm now thinking of giving the system another good clean. Someone said that they used a bit of clothes detergent or dishwashing liquid to clean out their system... adding some to the coolant, running idle for a good while to get things circulating and properly heated, then flushing everything out. I'm a little dubious! Does the detergent contain nasty chemicals etc that will eventually cause further corrosion or damage to the radiator and pipework? Or will it be OK so long as the stuff is thoroughly flushed out?

I've been considering using a proper radiator flush product such as Holts Radflush 2 Step. Does anyone have any experience with these products? Would they be any better than the clothes detergent or dishwashing liquid?

Finally, I'm wondering if perhaps there is a more serious issue... I mean there must be a reason why the oil got into the system in the first place, right?! I can understand a reasonable amount of rust... but is it normal to have an amount of oily gunk in the expansion tank? It's a rather old car which has probably seen a fair amount of abuse!

My first thought is a blown head gasket. However, there's no white goo under the oil filler cap, no smoke from the exhaust, both oil and coolant levels seem constant, and I haven't noticed any performance issues. Is it possible that there is a minor failure which is just allowing oil ingress into the cooling system, but no contamination of the oil? Is there anything else I should be considering or checking? Or, is it likely that the grime is just old residue which wasn't cleared out properly?

Any thoughts or advice welcome!

Thanks!
 
Yes it is possible that there is a HG failure allowing a bit of oil into the coolant and not vice versa.

What car is it? It's also possible that a minor oil leak elsewhere is getting into a coolant pipe somewhere.
 
Clean it out properly, if it comes back after then its time to investigate. if it was HG failure or such it'd be in a right mess


edit - holts radflush is pretty decent, wouldnt suggest using clothes detergent as it can foam a little, especially at near boiling temps. As for dishwasher stuff, not sure some of the seals in the cooling system will appreciate caustic :o
 
Lumeycom said:
Clean it out properly, if it comes back after then its time to investigate. if it was HG failure or such it'd be in a right mess


edit - holts radflush is pretty decent, wouldnt suggest using clothes detergent as it can foam a little, especially at near boiling temps. As for dishwasher stuff, not sure some of the seals in the cooling system will appreciate caustic :o
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In the name of experimentation I decided that when I needed to flush my coolant out that I was going to flush it out with only water until i got no more bits out of the system, then run the system with holts rad flush in it and water for the recommended time on the back then see how much the holts radflush shifted. It looked like I hadn't moved all the gunk out that I had, the water was thick with grime.

Really is good stuff for getting the gunk out :D
 
Bat said:
Yes it is possible that there is a HG failure allowing a bit of oil into the coolant and not vice versa.
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Thanks, I'll bear that in mind If it turns out that there's a serious problem.

Lumeycom said:
Clean it out properly, if it comes back after then its time to investigate. if it was HG failure or such it'd be in a right mess
Click to expand...

Yup I think I'll do that!

Bat said:
What car is it? It's also possible that a minor oil leak elsewhere is getting into a coolant pipe somewhere.
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It's a 1995 Renault 5 Campus, which is particularly susceptible to head gasket failure. I'm not sure if there's any other possibilities for oil ingress... I haven't noticed any at least

miniyazz said:
Any chance it could be antifreeze giving an oily appearance?
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The antifreeze seems to mix pretty well with the water, so I don't think that's the cause of the oiliness. Here's a couple of photos to show what I'm dealing with...




5abr3 said:
In the name of experimentation I decided that when I needed to flush my coolant out that I was going to flush it out with only water until i got no more bits out of the system, then run the system with holts rad flush in it and water for the recommended time on the back then see how much the holts radflush shifted. It looked like I hadn't moved all the gunk out that I had, the water was thick with grime.

Really is good stuff for getting the gunk out :D
Click to expand...

I think I'll give this stuff a go instead of the detergent option. I thought I'd first give it a water flush, and run it for a while (maybe a week's worth of driving) with some clean water in the system. Obviously there's no chance of freezing at the moment, but there's a good chance the water will get properly hot and start boiling (at a lower temperature without the antifreeze). Is it OK to run the system with no antifreeze for a just a short while?
 
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I've seen worse on a poorly maintained engine tbh...

Also, dont bother running it on plain water - drop the coolant, reverse flush the rad if you can, dump the radflush in and follow instructions.

Running plain water = corrosion etc, antifreeze is not just antifreeze its a corrosion inhibitor aswell as a summer coolant.
 
Lumeycom said:
I've seen worse on a poorly maintained engine tbh...

Also, dont bother running it on plain water - drop the coolant, reverse flush the rad if you can, dump the radflush in and follow instructions.

Running plain water = corrosion etc, antifreeze is not just antifreeze its a corrosion inhibitor aswell as a summer coolant.
Click to expand...

Right, I hadn't thought about that. I guess I'll just drain, give the system a quick blast with the hose, then go straight to using the Radflush. Thanks for the advice!
 
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