Coolant Change

[James_N]

Hi Guys

After finally getting my 940 breakdown fixed (Thanks Dave and everyone else that helped!), Next on the list is a coolant flush / change, as due to the leaking coolant hose, i kept filling up with water.

I have some time on sunday so i'm planning on flushing and putting some proper stuff in rather than just water!

Wondered how easy this is to do myself (can't be hard surely) and the best coolant to use (is Eurocarparts stuff generally OK to use, as i have one not far away)

Thanks
Jim

[aardvarkash10]

Hi James - good to hear you are venturing into the dirty realms yet again!

Coolant / Antifreeze is not a highly complex set of chemicals and as long as you are not planning on trans-arctic or saharan trips, you can't go too far wrong with a cheap and cheerful coolant. The majority of the cost is marketing in the more expensive brands.

Follow the dilution ratios described on the product - more antifreeze than water in the coolant actually REDUCES the heat capacity of the coolant, a counter-intuitive that many fall foul of.

[James_N]

Thanks mate is it as simple as removing the bottom radiator hose, flushing and refilling with coolant?

[cheshired5]

Originally Posted by James_N

is it as simple as removing the bottom radiator hose, flushing and refilling with coolant?

It can be as simple and quick as you want but I would recommend spending an extra couple of hours to do the job thoroughly then you won't have to return for some years.
There's a detailed video on my YouTube channel which will be relevant to most cooling systems.

[volvo always]

On my 940 I use a 50/50 mix. If possible have the car facing uphill to enable air to escape from heater matrix. This is a good time to replace and rusty jubilee clips on the cooling system.

Yes undo lower rad hose and empty old antifreeze into container under engine under tray. Antifreeze is poisonous to animals so catch as much as you can/wash it away.

Use a hose to flush out the existing antifreeze, or temporarily re attach rad hose and refill and drain several times until clear water comes out.

Mix antifreeze in bucket or measure each antifreeze/water mix if adding direct to header tank.

Squeeze the rad hoses and when at minimum level start the engine with cap off and heater on full heat and fan on full, checking and topping up the coolant as it goes down. Once level stops dropping put cap back on. Allow the temp gauge to run to the normal mid position.

Check any disturbed jubilee clips for leakage. Your heater vents should be blasting out very hot air once fully up to temp. After it's cooled back down check the water level once cold to see if settled and top up to the minimum level if needed.

Do not use OAT antifreeze. Either use Green or Blue.

James.

[James_N]

presume i need 5 litres of this:

http://www.eurocarparts.com/ecp/c/Vo...f3b7cb9&000397

is that OK?

[volvo always]

Originally Posted by James_N

presume i need 5 litres of this:

http://www.eurocarparts.com/ecp/c/Vo...f3b7cb9&000397

is that OK?

I think so. You want the non ready mixed. Can't read description as chat box can't remove.

My motor factors looked up my 1996 940 LPT and can use either green or blue antifreeze so presume correct. I have blue in now for 4 months, no issues.

James.

[stephend]

If you live in a hard water area, I'd buy ready-mixed for preference, save putting hard tap-water in your cooling system.

[volvo always]

Originally Posted by stephend

If you live in a hard water area, I'd buy ready-mixed for preference, save putting hard tap-water in your cooling system.

Good point, you can't think of everything.

James

[Laird Scooby]

Originally Posted by James_N

presume i need 5 litres of this:

http://www.eurocarparts.com/ecp/c/Vo...f3b7cb9&000397

is that OK?

That will do the job nicely James. You've already had most of the advice i was going to give except after flushing it through with a garden hose until it runs clear (remove top hose from rad, remove thermostat housing and 'stat, refit 'stat housing and top hose and insert garden hose into rad end of top hose), remove the bottom hose to allow the water to drain.
While it's draining the water used for flushing, refit the top hose to the rad, then refit the bottom hose.

Now, instead of adding pre-mixed coolant or mixing it and adding it, just add the 5L of concentrated antifreeze then top up with water.

Run the engine up to temperature and leave to cool, preferably overnight. Check the level, top up with water if needed.

Why am i saying to do it differently to what everyone else has said? It's like this :

When you drain the coolant by removing the bottom hose you never get all the water out of the system, there's always a few litres lurking in various places.
By adding the 5L of concentrated A/F then topping up with water, it mixes with the water that is lurking in those places and you end up with the correct 50/50 mix.

By adding a 50/50 mix after flushing it, that gets diluted by the water that's lurking.

That means you end up with a much lower concentration than you should have!
Doing it this way (add the 5L of A/F then top with water) has worked every time for me for errr.............. a long time now! The one and only time i did it the other way, my engine froze, the cam belt jumped and lunched the engine.

Some people may tell tales that the antifreeze doesn't mix properly in the engine - these days it does. That goes back to times when the water pumps (if they had them) weren't very efficient and the flow rate of coolant through the system was pretty low.