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Overheating (not a Land cruiser) - how to flush?


Staff member
Feb 24, 2010
Country Flag

I am driving my sister in laws Pug while my LC is having its shoes polished.
First off, this pug has the bear minimum in servicing. It does have it's oil changed every, oh I dunno, 25k miles :shock:
It also ran without water for a while (expansion bottle empty, wet with moisture so there was some), was topped up with about 2L of anti-frees and about 1L of water. The current coolant resembles runny rust :shock:

I noticed that when I stop in traffic or even at a red light, the radiator fan kicks in almost instantly and the temp climbs 1 notch past half way, just below 3/4 full scale. If waiting long enough, say 20-30 minutes, it continues to climb. At one point, before I noticed all this, it was touching on the red.

As soon as you drive off it drops slightly below the halfway mark for a few minutes and return to the halfway mark. Stop, off it goes again.

I can understand the overheating part because the lack of "real" coolant, likely semi blocked radiator core etc. What had me confused was the dropping below the halfway mark once moving. The only thing I can think is that when it is getting hot, the thermostat is opening wider than normal, lots of now cooler water being pushed around for a few minutes and then back to "Normal" service while there is lots of wind.

Anyway, real question is: How to flush a cooling system?
- Remove bottom hose from radiator and drain what is in there
- remove top hose and force water bottom up
- Replace, fill with water and start engine - bleed all air out
- repeat as above.
- fill with coolant.

Being a small car, I don't want to remove the rad. I suspect the door mirrors would have to come off to allow that. Would the above be ok? Is there anything else I should, non-vehicle specific of course, watch out for?

Crispin said:

I am driving my sister in laws Pug while my LC is having its shoes polished.CP
Does this mean WHITEWALL TYRES? :o :o
It could well just be in desperate need of a service Cris. Blocked fuel filter/bad oil/blocked air filter can all be contributing factors to an overheating engine.
The method you stated for changing the coolant should be more than enough though.
Yes, what you say is about right. It runs cooler when you drive as the water pump is running much faster and can therefore shift more water. Sounds very much like it is well bunged and just about the minimum in water is flowing through it. I remember having a Renault Chamade many years ago ( :oops: :oops: ) and as the rad was an aluminium alloy type thing the flushing instructions were quite complex and it needed a particular coolant too. This was to prevent internal 'corrosion' of the alloy furring up the water ways. Might be worth checking out before you do anything too rash.
Half a cup of Daz or similar in header tank, drive round for water to heat & circulate, then drain and flush rad as in your first post, warning do not spin vehicle lol. if that Fails replace rad.
Thanks fellas,

I'll do the cooling and then move onto the other bits.

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