Rx400h coolant

welland · February 18, 2019

I've just noticed that my engine coolant bottle is empty. Although I check it regularly, I had been misreading it: the shelf inside creates a shadow on the side of the bottle which i had mistakenly thought to be the fluid level. I'm pretty sure that the coolant level is not seriously low because there has been no trouble with high engine temperatures, and I can detect warm water inside the radiator top hose.

So, now I'm wondering which coolant to add: and I have no idea what is in the engine already. I can see the hybid coolant is the pink/ orange one and I have both blue and pink in stock in my garage. I know it's not a great idea to mix the two colours.

What would you do? I suppose I could detach the top radiator hose and see what colour comes out.

Herbie · February 18, 2019

I would bin both of those (or keep for a different car if you have more than one in the household) and use whatever is recommended in the manual, which may possibly be Toyota Super Long Life Pink (which is what our RX300 had).

I have no qualms about buying things such as batteries, wipers, exhausts, tyres etc., etc., from other sources but with any fluids I always stick to the recommended one because you just cannot be sure of the exact chemical component blends. Any system that carries fluids will also have rubber (or other material) seals and just one wrong chemical could attack these seals, causing leaks and untold damage further down the line.

In my opinion it's just not worth it to save a few quid.

welland · February 18, 2019

ok Herbie, point taken.

Anyway, I have just discovered the radiator cap beneath the cover on the left hand side of the vehicle. I didn't look under there earlier, as I thought that was all hybrid inverter stuff.

In the top of the radiator, I can see the fluid is red (which from my research seems to be the colour of the Toyota SLLC). But, I'm now confused about why I can see fluid in the top of the radiator , when this is higher than the level in the expansion bottle (which I think is empty), and also higher than the fluid level in the radiator top hose (which I noticed to be hot on the bottom and cool on top, and seems to contain air when I squeeze it).

I will be topping up as a short term solution, and plan a full drain and refill in the near future.

PCM · February 19, 2019

Levels sometimes seem to have a mind of their own!

However, I agree, use the recommended Toyota Red stuff.

welland · February 19, 2019

It took about 400ml to fill the radiator. Then about 50ml to bring a visible fluid level in the expansion bottle. Then a further 150ml to bring the level approximately half way between LOW and HIGH.

The handbook says that it holds 10.3l, so it wasn't dangerously low, but I will keep a closer eye on it in future. I can't say I've noticed any fluid leaks.

Gliderpilot · February 20, 2019

I'd keep a very careful eye on it as I've had my 400h for 5 years now and it hasn't lost a cm from either the rad or inverter. I don'y know your cars history but it could be weeping out from the water pump.

welland · August 3, 2019

Finally tackling my coolant issue today. I have new coolant and a bottle of rad seal. Will give that a go before changing the radiator.

Anyway, I've opened the drain ***** on the radiator, and was surprised that not much coolant has drained. The slow flow has now stopped, and my bucket is less than half full. I'd be surprised if even 5l has drained - but the handbook says capacity is 10.3l.

The radiater was full before I started, so coolant was not dangerously low.

Is it not possible to completely drain the system - or is there another drain ***** that I've not yet found?

welland · August 3, 2019

That's funny, the system has automatically masked my appropriate use of a word deemed to be rude! 🤣

To keep it clean, consider that ***** = tap!

welland · August 3, 2019

My drive has a slight gradient and the front of the car is down hill. Is that in any way stopping the system from emptying of coolant?

Wondering if I should momentarily start the engine to get it circulating and help it to completely drain?

welland · August 3, 2019

I noticed that the service schedule for coolant change is 10 years initially, then every 5 years. I was wondering why new coolant does not last as long as that put in when the car is new. Perhaps this is because at coolant change, the change does not actually change all of the coolant - and some (half?) of the old coolant remains?

Herbie · August 3, 2019

Never, ever use Rad Seal or other sealants. Yes, it may block up a leak, which is good, but some of the waterways around the engine can be very small bore and the sealant also does a good job of sealing those too, which is very bad.

You need to do things like this on level ground, doing it on a slope is only going to give you headaches.

I think there's also a drain plug on the engine block somewhere but can't look at the workshop manual for you until later this afternoon.

welland · August 3, 2019

OK Herbie. I've now determined that 3.6l drained, and I'm now in the process of refilling with the old coolant to ensure that it really was full (to save wastage of new coolant).

Initially, I couldn't find the relevant section in the workshop manual, but I now have, so no need for you to look it up. There are two drains on the block, apparently.

welland · August 3, 2019

It all looks so easy on the workshop manual: two nice little plugs protruding from the front side of the block. What they don't tell you is what else needs to be removed in order to see these taps / plugs. I can't see anything remotely like those shown in the diagram. What I have spotted is a round metal cover close to the oil filter - slightly higher and to one side - held on with two nuts. What is behind this cover - it does not look in the right place to be related to these drain plugs.