Avensis Change Coolant

[spike22]

Hi I've got a Avensis 1.8 petrol manual, going to change the coolant, is there any special method to avoid air locks or can i just drop off the bottom hose flush the system and re fill from the expansion tank. Many Thanks.

[nezerr]

not sure but i think you release the fluid from a bolt on bottom of radiator just like an oil chage from the sump??

[spike22]

Cheers

[gazza1286]

There's also a 14mm bolt on the engine block to remove. This releases the majority of the coolant. Its facing the radiator. Be very careful - you must undo it when the engine is hot (i.e slacken it - wait until the engine cools to fully undo it!!). The bolt is made of soft metal and will round over if you aren't careful.

[spike22]

Thankyou

[CircularSaw]

Or how about you just drop the bottom hose, like you said, flush it, then refill through the expansion tank? Don't go heating up the engine and taking bolts off the block just to drain coolant...for gawd sake!!! Keep it simple...no point risking a damaged engine for that!!

[Black Knight]

Well except there's a bolt specifically designed for draining the coolant out the engine! Using that to drain the engine won't damage the engine

[spike22]

Thanks for the advice

Thanks for the help i was more concerned if there was a specific was to refill rather than draining the system.

[gazza1286]

Just to clarify

If you don't empty the coolant from the engine and MERELY flush it, you will be left with NEAT water in the block.

You will then be faced with refilling with NEAT coolant to get any sort of frost protection!!!

If possible drain the block as well. The ONLY reason that you need to loosen this bolt when hot is that it WILL round over if attempted from cold. Obviously be very careful of hot coolant and hot exhaust manifold etc. The drain on the radiator is a plastic tap (which might be tight)

You refill through the radiator cap.

To refill does not require any particular technique. Over the years I have done several refills. HOWEVER, you will need to do a couple of heatup/cool down cycles in the days that follow to fully clear air from the system. SO keep an eye on the expansion tank and make sure ther is plenty in so that when it cools it will draw coolant into the system and not air!! It will be fully clear after 5-6 days and you can then correctly fill the expansion tank to the 'full' level when cold.

[CircularSaw]

When you empty the coolant from the bottom hose, flush it and refill via the expansion...you'll find you'll have to add approx 5 litres of coolant. Right? The total amount it will hold is from 5.5 to 6. So...just compensate by adding 1 more part per water. What do you mean by "neat"? You mean it'll be more diluted...it will mix eventually, you know? So just compensate...put a bit more in. There is no "right mixture" for the coolant, it depends on how cold you expect the winters where you live will be.

I find it absurd all this over complication just for a simple job of changing coolant. Why turn a 15 minute job into a 2 hour one? Leave the bolt alone...who cares aout rounding it, what about if you damage the thread? What then? Not worth the risk or hassle...think mechanics take the bolt out? LOL

[gazza1286]

What are you on about??

(i) You cannot drain the coolant in the block by undoing the bottom hose!

(ii) You cannot re-fill by putting coolant in the expansion tank!

(iii) If the coolant already in a vehicle is weak - the amount retained in the block is considerable (almost 50% of the total volume) - Toyotas are supposed to have coolant which should not be diluted by more than 1:1 (Giving FULL protection) - THEREFORE even Putting NEAT coolant into the amount drained from the radiator will NOT Necessarily provide a 1:1 for the total capacity.

(iv) How can you damage the engine by removing the Coolant drain bolt on the block?? (Yes I do think mechanics remove these bolts)

[garethed]

Hi,

Is it the same procedure for the 1.6 engine?

[gazza1286]

yes