Engine Temp Too Hot Warning

[peterlee]

Hi all,
Apologies for disappearing for so long, busy in a new job... :P

Anyway, I wanted to ask if any of you have encountered your C5 overheating?
I've been getting a warning "STOP - Engine temp too hot...".

Seems to happen from cold start after about 10 mins of cruising with the air-con on at the first mark. After the warning comes on, I off the air-con as a precaution and rev a little, and the temp goes back to normal with no further recurrence. This problem has been happening regularly for the past 3 weeks...

What's the fix?

Cheers,
Peter

[Gadler]

Hi Peter

So far, I have had no serious problem with the cooling system of my 5+ yr old C5 despite being stuck in traffic jams (once for 9 hours on NS highway travelling from KL to Penang!) with air-con on.

My only instance of temp rising above normal was when the car was about a year old and the resistor that causes the radiator fan to run at slow speed (this happens whenever we turn on the air con) burned out so that the fan did not turn on until the temp was quite high and then the fan turned on at high speed (at high speed the resistor is by-passed). But the temp was never high enough to cause the warning message to flash (or maybe pre-facelift C5 did not have this message?)

So could it be that your slow speed resistor is shorted so that the rad fan is not on and you get the high temp warning before the fan cut in at high speed to lower the temp again?

[voyager]

my old C5 no problems with overheating.

my present one has the same symptoms as peter described (mine no need to switch on aircon also got), but only on cold start.

mine doesn't give the overheat warning, because it doesn't exceed the 3/4 mark. it goes down by itself without me having to rev it.

sorry for my very brief reply but i'm still overseas :-P internet access very limited :-P

[peterlee]

Hey Gadler!
That sounds like you may be right about the resistor!!

Sounds very logical because it only happens on cold start... I guess after that the high fan juz kicks in... I'll go down and check it out!

Thanks for the heads-up man!!

[Gadler]

One way to check if it is indeed the low speed fan is after you start the car from cold and with the a/c on, look from the front of the car to see if the cooling fan is on.

[peterlee]

Its never on actually... I checked before...

Good catch Gadler. I'll check with C&C later and update here.

[peterlee]

Update:

C&C has changed the fan, as the resistors and relays were incorporated into the fan.

But... the overheating still persists today. I will be monitoring over the next few days and then probably its back to troubleshoot again. :-\

Anymore ideas guys?

[lrrp77]

How about the engine temp sensor?

[peterlee]

Ah...! A final update... C&C seemed to have fixed the cold start overheating problem. :)

They changed the thermostat and coolant sensor (I mentioned the German C4 recall on this) and it seem to do the trick. No problems over the past couple of days. Now the low speed fan kicks in once the engine starts to warm up. Most likely it was the thermostat which caused the problem. So now you know the possible fix. ::)

The engineer who isolated the fault was Ah Kiat, another nice and friendly chap from C&C. Guess those having the same problem can look him up. One thing I like about C&C guys, they were patient and listened to my suspicions on what I thought the faults were and then did the troubleshooting without giving me the brush-off... :P

[voyager]

good to hear this :-)

so far, my cold-start-overheating seems to be under control, in that it's not reproducible every morning, and when it does occur, the needle does return to a normal operating temp once the fan kicks in.

:-)