Overheating

[m4rkw]

I was queuing in traffic earlier and noticed the AC wasn't blowing as cold as it normally does, so I turned it down a couple of degrees and then noticed that the engine temp gauge was one notch away from the upper limit. 

Immediately turned off the AC and left the queue, after I've driven for a minute it came straight back down. 

Obviously I will have it looked at but is that likely to have caused any damage? I checked the fans when I got home and both were spinning hard with the AC on.

Thanks,
Mark

[NemesisUK]

Did you get any warning symbols or messages in the cluster? If not then nothing to worry about

[m4rkw]

4 minutes ago, NemesisUK said:

Did you get any warning symbols or messages in the cluster? If not then nothing to worry about

None. But I don't see any coolant in the reservoir so guessing that's probably bad.

[NemesisUK]

I would have thought you'd have got a warning if the coolant was low?

Does the RX have a separate expansion/overflow tank?

[m4rkw]

Ok so I may be wrong, it looked empty but it may not be. I remember now when they did the last coolant change they said the expansion tank had discoloured such that you can't see the level. I tried opening the lid and I can poke a stick into but it just runs into hard plastic that is above where the FULL line is, so I can't actually see if there's coolant in there or not. But given that it cooled down quickly after I drove it and I have no warnings, I'm going to hope it's not losing coolant.

Will see if I still have techstream, that might tell me something.

[m4rkw]

Meh, Techstream doesn’t want to connect, I’ll try again later.

Does anyone know for sure if a 2006 RX would definitely throw a CEL if the coolant was low? I’d have thought it would but I don’t know. Nothing in the owners manual about it that I could see.

 

[ColinBarber]

41 minutes ago, m4rkw said:

Does anyone know for sure if a 2006 RX would definitely throw a CEL if the coolant was low?

No it wouldn't. There is no coolant level sensor on the RX400h, or any other Lexus that I can think of in the last 20 years. If you have a coolant issue that results in a dangerous engine temperature you will get the engine temp warning light come on.

Try shining a touch through the expansion tank to see the level.

[m4rkw]

Thanks Colin, seems like good news that I’ve apparently caught it before dangerous temperatures were hit. Will try your suggestion later. Just praying I don’t have a blown head gasket.

 

[NemesisUK]

10 minutes ago, ColinBarber said:

No it wouldn't. There is no coolant level sensor on the RX400h, or any other Lexus that I can think of in the last 20 years. If you have a coolant issue that results in a dangerous engine temperature you will get the engine temp warning light come on.

Try shining a touch through the expansion tank to see the level.

I'm really surprised there is no coolant low warning!

The only message on my RC relating to this is

 “Engine Coolant Temp High Stop in a Safe Place See Owner's Manual”

A bit like shutting the stable door once the horse has bolted? Surely a level sensor to warn of low coolant could preclude an over heat situation?

[ColinBarber]

You can also check the level from the radiator cap but not sure if you need to remove some of the plastic covers to get to it - it's located at the other end of the radiator to the expansion bottle.

Worth looking at the radiator fins to see if they are blocked with dirt or large areas bent over. You will lose efficiency over time which means it may not be able to hope when the weather is very hot.

[m4rkw]

Impossible to tell if there's anything in this with a light.

 

[ColinBarber]

5 minutes ago, NemesisUK said:

A bit like shutting the stable door once the horse has bolted? Surely a level sensor to warn of low coolant could preclude an over heat situation?

Maybe but a simple coolant temp sensor covers low coolant, thermostat issues, radiator blockage etc. etc.

A level on the coolant expansion bottle would just give you pre-warning on one issue, and the level within the actual pressurised coolant system may be fine. The sensor also becomes a potential leak point on the system.

 

Toyota engines rarely have oil level sensors as well - just rely on the owner to do periodic checks.

[m4rkw]

This looks like the radiator cap? No water in it, just a tiny bit at the bottom. It’s connected to the top of the radiator by the expansion tank.

[ColinBarber]

1 minute ago, m4rkw said:

This looks like the radiator cap?

Yes. Depending on how cold the coolant is you may not see much. If you squeeze the top radiator hose you should see coolant come up to the top.

You can also try adding some coolant, you won't get much in there if the system is full.

[m4rkw]

I assume you mean the large hose that goes to the top of the engine?

Squeezed it quite a bit, no visible water in the cap. I don’t have any coolant to add but I guess I’ll have to get some before I take it in to the garage.

Will Halfords coolant do or does it need to be the toyota stuff?

[m4rkw]

The lower hose has water in it, I can feel it. The upper one is empty though.

[m4rkw]

So does seem like it’s lost a fair bit of coolant. No visible leaks on the ground. This isn’t looking good 😕

[NemesisUK]

15 minutes ago, ColinBarber said:

Toyota engines rarely have oil level sensors as well - just rely on the owner to do periodic checks.

Something drivers of a certain age 🙄 do instinctively 😉😊 (if only because the cars of our youth would leak and burn fluids quite religiously!!)

It's the youngsters that seem to expect everything to be flagged up for them..

[m4rkw]

2 minutes ago, NemesisUK said:

Something drivers of a certain age 🙄 do instinctively 😉😊 (if only because the cars of our youth would leak and burn fluids quite religiously!!)

It's the youngsters that seem to expect everything to be flagged up for them..

I check my oil quite regularly but always assumed the car would tell me if the coolant was low. I guess in a way it has 😄

[ColinBarber]

12 minutes ago, m4rkw said:

So does seem like it’s lost a fair bit of coolant. No visible leaks on the ground. This isn’t looking good 😕

I wouldn't assume it has suddenly dumped all its coolant, you could have a leaking water pump for example and you have been slowly loosing coolant that hasn't been a problem until you are stuck in traffic on a very hot day.

Ready mixed Toyota SLLC is recommended (pink coolant), a compatible ready-mixed alternative in Halfords is an option, distilled water at a push and tap water in an emergency. Fill it up and see how long it takes to go - if it is head gasket you will get it pushed out the overflow expansion vent and/or white smoke from the exhaust.

Look at the engine for any signs of pink stains where coolant may have been leaking.

[m4rkw]

Had a good look around the engine bay, I can't see any signs of red or pink anywhere but I did notice there's another plastic tank underneath the Battery on the right and underneath that I can see a lot of what looks like white corrosion on the metal floor underneath.

Possibly a sign of a leak down there?

Not had any smoke at all from it and the oil filler cap and dipstick both look good.

 

[m4rkw]

Also there's a circular clip shown on those photos in the same vicinity that looks vaguely red-ish, but it could just be dirt and rainwater.

[ColinBarber]

It's very difficult to see if the water pump is leaking on the RX as it is on the side of the engine (drivers side) and mainly covered over.

The other coolant tank by the Battery is for the hybrid inverter - its an independent system so I wouldn't worry about that, although the coolant level on that needs to be between min and max.

[m4rkw]

Hybrid inverter? It’s not a hybrid lol

 

[rich1068]

2 hours ago, ColinBarber said:

Try shining a touch through the expansion tank to see the level.

 

1 hour ago, m4rkw said:

Impossible to tell if there's anything in this with a light.

 

Put the torch hard up to one side of the tank and look through the tank from the other side. Nudge the car as you're doing it and ideally you should see the pink coolant moving.