My Ls400 1995 Rad Expansion Tank

[The-Acre]

1 hour ago, Malc said:

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

Weird, although it could still be thermostat related because they can stick and unstick. 

[Malc]

ok guys, just sailed thru the MOT at 231,581 miles

the water issue has been thoroughly investigated over several days by my indy ........... a slight insignificant potential weep at the bottom ( hose ) of the expansion tank, tightened and sound .......... he says many many O Rings that could have weeped during the hot hot period but he doesn't simply know, as it's not been leaking in the 5  days he's had the car and the trips done to see if the loss would repeat itself ......  it hasn't

He's been over everything except taking a peek at the waterpump ( renewed with the cambelt 2.5 yrs ago ) as the work involved is quite immense to get the covers off etc

Maybe a sticking thermostat at the time .........  the red coolant when it leaks would be a good tell tale sign of course  ........... he's put in some Coolant Seal

There was zero dilution with the red coolant even after my topping up about 1.5 gallons at the time ...... indicating evaporation rather than loss, evaporation coz the water only would have steamed away we're thinking, leaving the red constituent behind

So there we are, just keeping an eye on it all for the next few months before I get totally confident in her again !

Thank you guys for your great, as usual,  input

Malc

[brendangeorge]

On 10/8/2020 at 2:59 PM, royoftherovers said:

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

Hi John

I forgot to reply - I beg a thousand pardons.  It was a flat AUX bat so I showed my neighbour where to charge it.  All good now - Lexus MK could not be bothered to even call him back.

Bren

[royoftherovers]

16 minutes ago, brendangeorge said:

Hi John

I forgot to reply - I beg a thousand pardons.  It was a flat AUX bat so I showed my neighbour where to charge it.  All good now - Lexus MK could not be bothered to even call him back.

Bren

Thanks for replying Bren. As a result you are back in my squad to travel to play Mars away.  🙂

[Mikaelse]

On any "normal" car if you loose coolant and see no visible leaks on ground you suspect that you have a coolant leak into cylinders or to oil channeling. I have had both a few times on non lexus cars.  Best case due to defective head gasket OR much worse a cracket head which can happen if low coolant level is not noticed in time and head is overheated. 
I have been told these problems are very uncommon on our LS400.   
The airlock etc thing.  I have drained and filled most of the fluid at one time and did not follow prcedure and was wondering why I did not get same in as I drained out... After extensive adling and a little revving with full heat on etc. Found after looking in instructions that I could fill another liter at the fill hole on top of the engine. Solved.  Have no idea what would happen to that airpocket if left in there. 

 

[Malc]

All now appears to be sound as a bell and it must surely have been a sticking thermostat 

Malc

[ambermarine]

Malcolm

If that is your prognosis then replacing it should be the next step because it will likely stick again at the most inappropriate time.

[Malc]

2 hours ago, ambermarine said:

If that is your prognosis

well, not my prognosis, but probably yours actually 

My indy could find absolutely zero issues with anything at all causing my extraordinary loss of water ....  he had the car for 5 days, ran it out and about each day, checking the levels the following morning

checked everything he could and found nowt .....  he did say that there are a myriad of " O " rings in the system and it could have simply been one of those weeping during the extreme hot weather and the limited driving I was doing, facilitating the weep / leak ......  he didn't mention the thermostat other than heard me say about it from the posts here !

A conundrum for sure BUT nevertheless, all seems fine right now BUT of course the driving I'm doing in her is so so tiny at this time sadly

Malc