IS220d Intermittent overheat and coolant issues

[CazzyG]

Hi Everyone, [ New member from Ireland, Already read pretty much 90% if not all posts related to this issue before joining ]

I have an issue which has startled me, I know my way around cars have done some descent work on different engines but this has left me speechless.

 

Issue:

Car drives smooth and effortlessly if cruising, Just finished a 500km round trip and car gauge only went into red when i was overtaking on harsh acceleration or about 20+ % incline along the motorway/road, Coolant seem to be boiling/pressurized at least as i feel the pressure release when opening the radiator cap. Some gurgling noise on the dash centre panel when heating is on high. Coolant seem to leak from overflow pipe and then blown all over. When topping it up only takes about 500ml roughly.

 

Fixes so far:

Change of Waterpump, Thermostat, Coolant flush, Serpentine belt, Radiator cap, Full service including brakes.

 

Potential Causes ????

? Headgasket -:

Having experienced failed headgasket before [Renault] where white smoke comes from exhaust, or overheating within few km and loss of cabin heat {The Lexus is not showing any of the following except cabin heat loss which is fixed by mostly topping up coolant or gear down into high revs which seem to get the heat going again [airlock maybe] }

 

? Carbon build up on top of pistons thereby causing pressure within piston and cyclinder head  {That's what  local mechanic claimed after changing everything, I didn't get the concept though; how this will cause intermittent overheating under load.

 

?Coolant temperature sensor   :- Wouldn't this delay thermostat opening then, if it's not working properly ?

 

The top hose always has some pressure as it is hard to press when the cap is on.

 

Any pointers are much appreciated.

 

Thank you 🙂