Cooling system flush

[Dazco]

Is there a correct method of flushing the cooling system (1.9 early DG)

[mark]

I did mine in 3 parts rad, front to back pipes and engine. with a hose pipe, get in quick before the ban wash it through ten mins each way.
be careful with the waste coolant as its sweet taste will kill cats and dogs and any children who come across it.

mark

[itchyfeet]

WHS^^^

Also best to remove thermostat to flush properly ( assuming yours is servicable)
At the rad remove both hoses and flush both ways. If you still have plastic pipes It's easier to remove rad hoses at the plastic pipe joint but more risky as they can break so I'd say Radiator is better.

I'd just flush until it runs clean.

Rag around the hosepipe help seal then hand over the exit point to build up some pressure then release shifts more.

Beware you may end up with more leaks after a flush as the dirt and crap is often helping seal it up Radweld style so you may want to just do a quick flush.

[Dazco]

Will be doing thermostat at the same time ( heard lots of up beat comments about this job). Thanks for the advice

[max and caddy]

Wet vac it out, then flush with clean water...then wet vac the water out..and replenish.

[300CE]

Good advice from the chaps above Dazco - I flushed mine out with a hose when I had the engine out and the amount of manky rusty water that came through was unbelievable, even once it looks like it has run clean, stop & re-flush. The bleed rail was also blocked in a couple of areas, so removed and flushed this also.

[Dazco]

Another reason I'm doing it is so that I can check that a couple of the smaller pipes aren't blocked and also check the bleed valve ( early system ) . Then ill be investigating the reason for the small loss of coolant and pressurising of the coolant . I know pressure increases when it gets hot hence the darlek (brickwerks) but mine is holding pressure for days. I'm fearing the worst, cracked head allowing gas through when hot. Ill start with basics and go from there.

[ghost123uk]

Aye, check the bleed ring and the pipes that come off it as you and others above say.

A blockage there can prevent the flow of water round the head(s) and this in turn causes the static coolant to boil, pressurising the system and showing similar symptoms to a combustion gas leak into the coolant. Ask me me how I know (twas a few years ago now - mine was blocked at the l/h rear "T" piece).

You say yours is holding pressure for days. Whilst this would be unusual, as there are nearly always places where pressure can vent away, it is not bad news. It simply means that you do not have any leaks at all in your system
I reckon it also means you are very unlikely to have a cracked head, as if you had, I imagine the pressure would vent away through the crack.

Does your top up tank (behind the flap) retain it's half full state, or do you have to top it up - I ask because one I had had a leak that made me think there was a fault in the main cooling system.

[Dazco]

Hi ghost , level in top up is always as it should be , I'm a bit puzzled . Like I said I'm going to go through the whole system and ill take pics etc as I go and make a thread out of it I think.

[pandp38]

Eyup Daz
Did you ever check tightness of cylinder head bolts? When I had high coolant pressure which lasted for a few days ,chap at Engine Shop suggested I check head bolt torque. Found one a little loose and after tightening up ,was ok. Worth trying if only to eliminate

[Dazco]

That will be on the to do list , in fact you can do it for me of you like

[Mocki]

Aye, check the bleed ring and the pipes that come off it as you and others above say.

A blockage there can prevent the flow of water round the head(s) and this in turn causes the static coolant to boil, pressurising the system and showing similar symptoms to a combustion gas leak into the coolant. Ask me me how I know (twas a few years ago now - mine was blocked at the l/h rear "T" piece).

Early sys has no bleed ring....

[ghost123uk]

Aye, check the bleed ring and the pipes that come off it as you and others above say.

Early sys has no bleed ring....

Ah, (I was going by the year, but even then an 86 can be early, as here)

Take care tightening head bolts, snap one and you won't be happy

[Dazco]

Oops my fault ghost , it's an 84 I've got the year mixed up with summet else , my appogies. what a plonker