Slight Overheating At Hihg Speed

[Jamalaya]

HI All,

I just did a 2 years service for my Lexus IS220D and also passed MOT.

However, I have noticed that the car very very slowly overheats when driving at 80-90 mph (OK I don't do this all the time :-) ). It goes up by a dash or 2 (on the dashboard meter) over a distance of 100-150 miles.

As soon as I go back to 70 it cools down immediately.

it will take sometime for the temperature to rise but it does rise.

I cannot see any leak, or white smoke. I slightly lose some coolant over a period of months (about 6 months). What should I be looking for?

Thanks.

Just to add, it sill does 42 mpg and I don't feel any difference in driving.

[james250]

Loosing some coolant over 6 months is most probably from overflow from the expansion bottle which is normal. I had a similar issue with my IS250 last year where a few times I noticed it raised a few times but never was able to replicate it but then on holiday it overheated rapidly causing coolant to boil. It turned out to be a faulty radiator pressure cap. I would check the pressure cap (obviously only open this when car is completely cooled down and no pressure remaining in the system). The other thing it could be is a faulty thermostat.

[Jamalaya]

Hi James250

Thanks for the reply. I actually (embarrassingly) made a mistake :-) . I checked the coolant last night , and it was way down, below half. So I topped it up and this morning I pushed the speed up to 90 mph and there was no change in temperature. I will check it again on my way back home. However, as you mentioned, I find myself topping it up every 6 months or so (or after a long distance drive 400 miles @70-80mph) . I'll check the pressure cap and the thermostat as well.

[Jamalaya]

Well I have been testing it for few days, no overheating at all :hocus-pokus:. One more thing I have , The car had a full 2 years service, and passed MOT just few days ago.

I have a "check MVS" (I think) warning light, with skidding icon on the right and an engine on the left. Again, the car is working like new. No loss of power whatsoever and still makes 42 mpg @ 75 mph from Swindon to Oxford (daily).

Taking the above into consideration what can cause this warning? (have been on for a month now). One upon a time I read somewhere on how to get rid of the warning but I cannot remember the sequence. Still I need to know possible causes. I will check with a mechanic later who can read the code.

Thanks for your time.

[ChumpusRex]

The check VSC light, skid light and engine light mean ANY error code related to the engine or emissions system.

The cause can be ANY engine fault, sensor fault, electrical fault or emissions fault; the lights can stay on for a few days after the fault has gone, depending on what the issue was.

The only way to narrow the issue is to get the codes read. However, a very common issue on the 220d is the EGR valve getting sooted up.