Complete coolant drain/flush without touching thermostat?

[akiller]

Hi all,

I'm sure this has been asked several times but despite searching for a good while I can't seem to find a answer. I've recently bought a 182 Trophy and I'm working through servicing it - just got coolant and brake fluid left to do. It's currently got red coolant in of unknown origin (I believe it was done at a Renault garage). I've bought the proper Renault Type D stuff to replace it and want to flush out all the old stuff to be on the safe side.

Ideally I don't want to take the thermostat out if I can help it as it's working fine and I don't have a new gasket on hand. The last time I replaced a thermostat it was a complete pain getting the housing itsself to seal up again.

Will removing the lower rad hose drain the block or is there a separate drain for that anywhere? I'm guessing the other option is to drain through the lower rad hose, fill up with water and run it up to temp (opening the thermostat and mixing it all up), letting it cool and draining again until it runs clear. Though how much water does the block hold? Don't want to dilute it too much if I can help it as I'm using pre-mixed.

Cheers.

 

[chris blue]

Did this work?

 

[akiller]

Yep. It was ~10,000 miles ago so clearly I didn't ruin the engine!

What I did was keep filling the coolant reservoir up with water from a hosepipe and opened the bleed screw by the thermostat up to flush the old coolant out into a large jug. It probably took half an hour and several jugs of drained water before the old pink coolant finally ran clear enough that I was happy it wasn't going to cause any problems.

Definitely happy I didn't have to remove the thermostat

 

[Mr Plums]

The stat takes about 90 seconds to remove and seals fine ime.

 

[DrR]

If you've filled it with water, how did you get the water out before filling up with new coolant?

 

[akiller]

The stat takes about 90 seconds to remove and seals fine ime.

Ah fair enough. On my last car I had a nightmare sealing it again - though that was probably because I bought a generic EuroCarParts one, had to resort to using some Blue Hylomar I had (awesome stuff).

Also seem to remember it unleashed coolant absolutely everywhere which took ages to clean up so no cats could drink it.

 

[akiller]

If you've filled it with water, how did you get the water out before filling up with new coolant?

I started this thread a year ago so I've mostly forgot to be honest with you! Pretty sure the majority of it just drained out from the header tank via the bleed screw; it would have been a little more diluted I guess but hasn't seemed to have caused any issues.

 

[Martin.]

I did a full drain on mine the other month with my mate

You can bend and unbend the coolant hose from the block to create a vacuum which sucks out all of the coolant. No need to touch the stat then, apart from bleeding it.

 

[akiller]

Ah handy, will remember that for next time around.

My next job is to get the peeling clear-coat repaired on my door/wing, but that's for another thread I think and not one I can really do. Not going to be cheap

 

[Gus]

Hardest part with the coolant change is getting the lower hose clip off the bottom of the rad. Id recommend anyone looking to do this buys this or similar:
https://www.amazon.co.uk/dp/B00Z73T9RK/?tag=cliospnet01-21
makes the job a breeze.

 

[akiller]

heh I remember at the time thinking I wish I'd bought some of them. Struggled for ages with mole grips and pliers!

Jubilee clips. So much easier to work with.