Flushing out cooling system help Seat Leon

[h4mza]

Need advice on flushing out cooling system as I have tried it myself 4 times and nothings getting better. Watched a few YouTube videos on how to do it but it's not going well for me. Am I doing it wrong or using crap products? I have a 2007 Seat Leon with a new oil cooler as old one failed so cooling system is contaminated with oily sludge.

Here's what I do...

1. Drain everything from lower radiator hose.
2. Put hose back on and add water to expansion tank
3. Start car up and put more water until max level then I add whole bottle of 300ml carlube radiator flush
4. Now heres something I don't quite understand, I need to leave car running for 30 mins with heaters on max until temp reaches full (not literally full but halfway at 90) but I don't know whether to leave cap off for air to escape or put it back for, I usually leave it off
5. 30 mins and temp need struggles to reach 90 so I put cap back on and take car for a short 10 mins trip
6. Once car is cooled down, the coolant again is contaminated

I can only get the car to temp on harsh acceleration, on motorways the temp needle fluctuates so I'm guessing there is air in system

I have done this step by step process 4 times and think I'm doing something wrong. Can someone enlighten me please thanks.

[GreenV8S]

Have you flushed the system through with running water? You didn't mention that.

[colin_p]

Washing powder. It is a long accepted and established method of cleaning out a cooling system, google shows lots of results.

Add a cup to the system and run it for a week / few days / day (depends how much you use it), drain down, flush with a hose pipe, you may have to do this a few times. Once you are happy any all all residual oil and sludge is gone, fully drain down and flush with a hose. Refill with just water at this stage, you may have to drain down a flush a few times to get rid of the Persil and you don't want to waste any antifreeze.

I've done this a few times with good results. Be prepared to do both parts of the process a few times.

And obviously get it sorted before winter sets in and any risk of freezing occurs.

[mickrick]

When you back flush with a hose, take the thermostat out.

[227bhp]

Radflush probably doesn't have the ingredients to dissolve oil, as per above washing powder does, a dishwasher tab would do it too. Other things worthy of note:
It doesn't have to be totally clean, it'll work just fine as it is.
Gauges often don't tell the truth, they have flat spots and are geared to give a rough indication as to not worry the driver with what is actually going on.

[Arnold Cunningham]

I've not tried washing powder, but certainly a few dishwasher tablets has done wonders when I've needed it.

[stevieturbo]

Flushing with water alone will do almost nothing. Damage like this can be a nightmare to clean out/

If the contamination has been really bad I would nearly say replace at least the radiator, and very carefully inspect all the hoses as the oil will have damaged/softened them. It maybe impractical to change the heater core, but it would be worth isolating it and flushing it with a good strong detergent several times in both directions.

Do as much independent cleaning as you can before then flushing the entire system with detergent. Whether that's a proper degreaser, washing powder or whatever is up to you.

but it is a messy situation to be in.

[Coilspring]

mickrick said:

When you back flush with a hose, take the thermostat out.

This.

Once the thermostat closes you will not get the full flow so cannot flush it out.

[stevieturbo]

Coilspring said:

This.

Once the thermostat closes you will not get the full flow so cannot flush it out.

It would need to come out for inspection and to enable a thorough cleaning prior to also trying to flush.

[227bhp]

Thermostats are usually in and part of housings with multiple pipes on them so would be difficult.