My Ls400 1995 Rad Expansion Tank

[Malc]

It's been running up to HOT on the gauge and just checked and the plastic expansion tank is EMPTY

Forever it's run at bang in the middle of the gauge, probably for 25 years but at least the last 9 years of my ownership

Checked what I can of the rad hoses and they seem fine, flexible and seemingly dry .......  from the open bonnet access only

Topped the expansion tank up with water until my indy or someone can tell me something useful about it all !

The waterpump was changed with the cambelt etc about 26k miles / 2 years ago so that should, hopefully be fine

Your thoughts please

Thank you

Malc

[rich1068]

Very odd. Now you've topped it up at least you'll be able to check for leaks!

[The-Acre]

I don't think loosing just an expansion tank of coolant would be enough to run it to hot, I'd be checking the thermostat first. Also check to feel if the top and bottom hoses are hot.

[Malc]

Having topped up the reservoir with plain water, it's difficult to see any water level there.

I ran the car for about 5 miles and topped it up again till I thought it was running out of the overflow pipe

A few hours later and back to the car and the reservoir water is now red coolant colour

My indy was thinking after 25 years it could be an O ring, and he thought there's lots all over the place, or a hose finally giving up after 25 years

Anyway, having moved the car to a dry spot earlier, and no rain yet, I've been running the engine on idle for 25 mins and there's zero signs of water anywhere, from the hoses, O rings ( whatever they are ) nor the radiator itself

I'm thinking, hoping, that with all this incredibly hot weather we have had that it's simply evaporation of the water ( leaving the red coolant concentrate of course ) 

I know i haven't checked under the bonnet these past 3 / 4 months, and having done many trips to the hospital, some 1400 miles in this time ( I've had a cancer scare and intensive radiotherapy treatment )  COULD IT BE  that the general Lexus self-healing process has occurred yet once again !!

I'll keep an eye on it all much better these coming days and weeks and months

Indy has just told me to check as the engine cools down, to see if there's any drips showing

Malc

[Malc]

I'll be doing a local run tomorrow to see if my theory stands up or if it needs more thorough remedial treatment and a good telling-off !

and if the thermostat needs seeing to, too

Malc

[Tinonline]

Leaks can be tricky to detect but you can smell them...damp sweet whiff...

If your reservoir cap old?

I had a very gradual coolant loss that worried and baffled me - I had the original cap. Last ditch was to fit a new OE cap.

All good now. Lots of short journeys hot/cold/hot/cold = pressure loss and evaporation.

Just a thought.

 

[Razor61]

I had a loss of coolant on an Audi A4 recently, I did a post about it (link below). In my case I could see coolant around the front grill and underneath the front of the bonnet but couldn't see where the leak was, even running it up to temp etc. Not exactly the same symptoms as you, as it was a sudden major loss, but still relevant. In the end I bought a coolant pressure tester and that found the leak straight away. I expected to have to look around all over the engine bay for the leak but in my case it was blatantly obvious.

If your coolant loss continues then your indy mechanic will be able to pressure test and find the leak.

 

 

 

[Malc]

Thank you guys

Last night in the dark, and dry, I went out and shone a light absolutely everywhere and not a damp patch to be seen, either on the car, under the bonnet nor on the road surface AND the reservoir hadn't moved a dot

Mentioned the thermostat possibility, maybe it got stuck and freed itself ?

The reservoir cap is a standard metal pressure cap and seems to lock down ok BUT I'll be running her gently for a while now and I know I can replace the cap ok ? and the other issues will be dealt with by my indy as necessary when I can get over to see him, he's an hour away !

 

I remember on my Mk1 that the cap was a simple plastic screw on cap and that split vertically BUT I could replace that at that time from EuroCarParts or whatever it was then for a £5, they had one in stock so maybe it was a generic part for other cars too ...........  maybe 15 years ago tho 

Malc

[Razor61]

18 minutes ago, Malc said:

Mentioned the thermostat possibility, maybe it got stuck and freed itself ?

Could be the thermostat, stuck closed - coolant temp/pressure goes high and then escapes through the pressure release - then frees itself. Pretty straightforward to replace as well (unlike the Audi A4 I have which is behind the timing belt and has to be removed) so maybe a good place to start if it's not been replaced before.

[Malc]

thank you

Malc

[runsgrateasanut]

The worst scenario comes to mind that its leaking into the Gearbox.  Don't think your Car had the Valeo Rad that caused so many Cars to  leak into the Trannie fluid.  

Other thing is to smell the exhaust after a short run, just in case its a head gasket leak.  Can smell water when its up to temp this way. Happened on an MR2 I owned but not read about any LS with such a problem. 

I did once have an unexplainable  low water level in the LS's expansions tank Half a cup.  Always fill with the red stuff or Distilled water, never tap water. Don't know why it happened and yet to test the Car for the higher speed issue that I had before changing the Lambda sensors.  Don't know when I'll be able to retrieve the car from France and be sure it had nothing to do with water in the Trannie. Certainly didn't cause any problems at normal speeds. 

[brendangeorge]

On 10/7/2020 at 10:09 AM, Malc said:

It's been running up to HOT on the gauge and just checked and the plastic expansion tank is EMPTY

Forever it's run at bang in the middle of the gauge, probably for 25 years but at least the last 9 years of my ownership

Checked what I can of the rad hoses and they seem fine, flexible and seemingly dry .......  from the open bonnet access only

Topped the expansion tank up with water until my indy or someone can tell me something useful about it all !

The waterpump was changed with the cambelt etc about 26k miles / 2 years ago so that should, hopefully be fine

Your thoughts please

Thank you

Malc

Hi Malc

I have not run a Lexus V8 for a while now - I mutated into a RX450h driver - but remember having fun with the coolant system.  To cut to the chase you probably had or have an airlock in the system. First bit of advice is don't put water in the system only use the correct coolant.  The expansion tank is not for filling the system - it is used while the thermostat is closed when the engine is cold so the waterpump has somewhere to put the coolant.  You mention you had the waterpump changed two years ago (which makes my comment about a airlock a bit iffy becuase you will have had it for two tears) - also my last V8 was a 430 which did not have a rad cap so the engine is filled through a port in the top - I think the 400 is the same.  Anyway here is a URL for how to drain and fill the system if you have not found it http://www.lexls.com/tutorials/cooling/coolant.html

The system should not lose any coollant - don't keep looking at the expansion tank it will drive you mad :).  I messed with this for two weeks until I found the answer that it is not a measure of the status of the coolant level.

My V8's temp gagues were rock solid, as you mentioned, they only moved a small ammount in traffic jams in very hot weather - until the airlock caused during the cam belt change.

Don't trust anybody (including me) - the Lexus dealer in Mega City One serviced my hybrid and left both coolant systems low, over filled the brake fluid and changed the front instead of the read brake disks.  They wanted a £1000 for a new headlight when the AFS cable only needed reattaching :).  I don't use them anymore.

Good luck - off to help my neighbour who's RX450h won't start.  He must have left something on and depleted the traction Battery.

Bren

[royoftherovers]

Do you mean 12v auxiliary Battery, rather than traction Battery Bren ?

[Razor61]

 

28 minutes ago, brendangeorge said:

The expansion tank is not for filling the system

That is true according to the manual for a complete refill. Re fill system at the inlet housing and the radiator reservoir/expansion tank is then used to top up the rest and then to top us as required after running the engine and bleeding.

[brendangeorge]

6 hours ago, royoftherovers said:

Do you mean 12v auxiliary battery, rather than traction battery Bren ?

Hi John
He called the dealer for help so I did not need to help so I am not sure what the problem is - I will let you know if I need some advice John.

We are both isolating because of pending hospital treatment or I would have popped round and helped Bill out.

The manual alludes to being able to start the ICE using the connection under the bonnet if the car won't start but I am not sure if that is only if the 12V bat is low.  I may have a degree in Electrical engineering and 40 years experience but it is not hybrid or electric vehicle focused yet :).

The good news is the RX450h is very reliable - when the warrant runs out next I'd bet on one of Musk's creations being on my drive.

Bren

[Malc]

Then all I've done in putting maybe a good gallon into the expansion tank is just about OK until I can get down to my indy for it's annual service and MOT AND now the coolant to be completely changed and refilled properly ! AND a thermostat change too. I have advised him all your kind thoughts

Thank you

Nothing more I can personally do to get this right

The airblow hot / cold into the car these past few weeks just hasn't been right I know, and now I know why, a silly airlock developed hopefully

It's blowing ok temperatures now I think,  thankfully

Roll on another month

The MOT is due 8th December so 9th November is good enough I hope

Malc

[Malc]

Ok so today I ran her thru 18 miles of fast dual carriageway, traffic jams and roadworks along the A2 to Rochester Cathedral from home, and back along 14 miles of easy driving country lanes with no traffic

Checked the expansion tank etc at the Cathedral and then again when home

Nothing moved on the marked level and no signs of water anywhere

Maybe she's OK now and I feel comfortable taking her to my indy which is about an hour's drive next month

Fingers xd 

Malc

[Malc]

Am I going to go mad checking this expansion tank level ?

Just topped up to the full mark about a mug full, 350mls I think ............  after its cooled down from a gentle 30 mile country lane drive in the sunshine

But prior runs the level hadn't moved 

Malc

[Razor61]

23 minutes ago, Malc said:

Am I going to go mad checking this expansion tank level ?

I don’t think you are so long as you always check it when properly cold as a reference point, first thing in a morning normally. Cooled down isn’t the same as ‘cold’ in my opinion but I’m not an expert Lexus Technician. But if after a run and cooled down you need to put some coolant in then I suspect you are losing coolant somewhere.

[brendangeorge]

On 10/11/2020 at 4:56 PM, Razor61 said:

I don’t think you are so long as you always check it when properly cold as a reference point, first thing in a morning normally. Cooled down isn’t the same as ‘cold’ in my opinion but I’m not an expert Lexus Technician. But if after a run and cooled down you need to put some coolant in then I suspect you are losing coolant somewhere.

Hi Paul

That's the madness - I spent two weeks checking the level and topping up the tank, I put cardboard under the car etc. - nothing was leaking so I stopped.  There was no leak.

Bren

[Bluesman]

4 hours ago, brendangeorge said:

Hi Paul

That's the madness - I spent two weeks checking the level and topping up the tank, I put cardboard under the car etc. - nothing was leaking so I stopped.  There was no leak.

Bren

Maybe this could be of help.   http://www.lexls.com/tutorials/cooling/coolant.html

[Razor61]

9 hours ago, brendangeorge said:

There was no leak.

Hi Malc,

No ‘visible’ leak maybe but it seems to be disappearing somewhere. Do you think there is pressure in the cooling system after a run? One way to check without loosening the cap is to feel the hoses. No pressure usually means a leak somewhere in my limited experience.

[Razor61]

11 hours ago, brendangeorge said:

On 10/11/2020 at 4:56 PM, Razor61 said:

I don’t think you are so long as you always check it when properly cold as a reference point, first thing in a morning normally. Cooled down isn’t the same as ‘cold’ in my opinion but I’m not an expert Lexus Technician. But if after a run and cooled down you need to put some coolant in then I suspect you are losing coolant somewhere.

Hi Paul

That's the madness - I spent two weeks checking the level and topping up the tank, I put cardboard under the car etc. - nothing was leaking so I stopped.  There was no leak.

Bren

Sorry Bren, I can't read. I thought Malc had wrote this................as a side note, now it's getting colder I've noticed the heating on my LS400 starts to warm up then blows colder for a while then warms up again. It's like the thermostat opens and lets the cold water through from the rad etc. Maybe that is normal or I have an issue as well I must start checking the coolant level.....

[Malc]

2 hours ago, Razor61 said:

I must start checking the coolant level.....

on my Mk2 Ls400, that I bought at 8562 genuine miles all those years back ( and before it was written off ! ) the expansion tank was permanently at a very low level, nothing I could do to top it up permanently succeeded .......  so I left it " short "  ....... it never caused an issue !

so frustrating at the time 

Malc

[Malc]

ok Rad Expansion tank has been totally behaving itself of late .......  probably done about 150 miles in 10s, 20s, and 30s and some of it A249 and M2 hard driving too ( now I have the confidence in her back ) and zero change to the water level

I really don't understand it, it's bonkers

The car is however going to my indy on Monday for it's annual MOT and service AND a thorough investigation of this water issue 

Malc