alwabel

I have IS 250 2012, heat start to reach H, I did change the heat sensor, Radiator, Cooling fan and nothing improve. after driving for 20-30 minutes heat going up to the High and within 25-30 seconds it is dropped to normal engine heat. COuldn't figure what is the problem, is it something to the engine cylinder block or something major, please any help is highly appricitaedThanks

Petet

Sassper

Sounds like air in the system, did you notice any changes before/after replacing the items you did? (sensor, radiator, fan, etc). Also 2nd on the thermostat, it could be the wrong part and have too strong of a spring rate

Petet

alwabel

Yes I did, but the same problem still exist, I started by replacing the sensor, then cooling fan (two Pcs), then thermostat, then the radiator, still the problem, run in normal heat for about 30 minutes then start to claim to very hot, when it almost reaches the limit (red line) 20-25 seconds and dropped to normal

alwabel

no change after any of these changes.
About the tmermostat, it is from Lexus agency

Mrfix

You said you changed the radiator and thermostat, Did you bleed your cooling system properly? You might also check to see if your thermostat is operating properly? It seems your coolant is being held in the engine and then released at some point and the temp drops to normal. It sounds like you either have air in your system or the thermostat is sticking.

alwabel

thanks, MrFix
I did bleed the coolant and replace it with a new one, not sure if there is any air?
I am trying now to change the relays, hope this will succeed again Thanks

EdgarLex

You should be "bleeding the coolant" after replacing it. Is this the way you did it? When you say you "bled" the coolant, what do you mean by this?

monkey92

iTrader: (3)

have you double checked the thermostat was placed in the right direction, I once installed mine backwards and it cause the car to over heat. Checked and installed it right and it fixed the problem .

Sassper

OP, I would wait and verify technique/check on what other people have mentioned before throwing more money at relays or whatever. No sense in replacing things that are working properly before checking the low-hanging fruit.

MikeFig82

iTrader: (13)

https://www.aa1car.com/library/overheat.htm

alwabel

yes and recheck again, yes

alwabel

Finally I found a crack in the engine block, cost me too much to change and repair