Problem with Overheating

jax2006

Drive '03 Renault Megane

Overheats slightly when driving for bout 25 mins. Only just above the half way mark. Begins to get hotter when stopped in traffic or at lights. Never reaches the red. Then wen driving again it seems to cool very fast, maybe in ten or fifteen seconds. Cools back down to just above half way.

-coolant in reservoir lasts a few weeks from the max mark to min mark.
-engine sounds a bit more grumbly, i think
-fans do kick in, in fact one runs for a minute after the engine is off just cooling it down
-no coolant in the oil
-no oil in the coolant
-no extra smoke out the exhaust
-no change in how long the petrol lasts
-found a crack in the coolant reservoir could this be causing the overheating?

anybody have any ideas. really bugging me.

thanks for the help

testicle

Perfectly normal behaviour.

The crack in the coolant resevoir probably explains where your coolant goes.

jax2006

i dont think its normal mate because after a year of driving the car it seems to be only startin this now. could the crack be causing the overheating?

thanks for the reply

Hal1

Check for leaks under the coolant bottle and from the hoses etc. Other than that, maybe the water pump.

jax2006

Hal1 wrote: »

Check for leaks under the coolant bottle and from the hoses etc. Other than that, maybe the water pump.

coolant is leaking, should have mentioned that. leaves stains on the ground.

Muckie

Sounds like your engine has very little coolant, to keep it cool.
Maybe visit your local scrapyard or ring Renault
and get a replacement. Not a big job. Put on the new reservoir and
top up with coolant and your car will be motoring like normal.

COB MGV8

Does it still happen immediately after you have topped up the coolant ?

-If so, it could be that you have an airlock in the system somewhere - couple of different ways of sorting that out.

-Other possibility is that the crack is causing a drop in pressure leading to it running hot

- Just because there is no extra smoke from exhaust or there is no obvious water in oil , doesn't mean that the HG isn't gone (could be a small issue)

2qk4u

Could be the thermostat. Easy and cheap fix.

beachlife

-found a crack in the coolant reservoir could this be causing the overheating?
Yes...The cooling system is a sealed unit there by keeping the coolant under pressure the leak in the system can cause your problems.did a rover one recently and the same part was only 30 euro new ....give renault a buss the part might be cheap and it has to be done to test the rest of the system anyway......

metzengerstein

2qk4u wrote: »

Could be the thermostat. Easy and cheap fix.

you could be right there ,sounds like same problem i had for a while it kept overheating ,water and some coolant ,all over the place took out the thermostat and it solved the problem till i got a new one .

there is a simple way to test it if you take it out put it in boiling water and you should see if it opens and closes properly

itarumaa

The crack in the coolant resevoir means that the coolant system is not pressurised, so basically coolant just boils away,

pointless to change thermostat before you change the resevoir and remember also that resevoir cap is important as well, because it usually makes sure that system stays in correct pressure.

testicle

2qk4u wrote: »

Could be the thermostat. Easy and cheap fix.

It's not even going in to the red...

peasant

itarumaa wrote: »

The crack in the coolant resevoir means that the coolant system is not pressurised, so basically coolant just boils away,

pointless to change thermostat before you change the resevoir and remember also that resevoir cap is important as well, because it usually makes sure that system stays in correct pressure.

what the man said

jax2006

thanks for all the replies. i will change the reservoir first and see how we get from there. just hoping its nothing serious.
oh n does anyone know where the theromstat is situated in the renault megane, not in manual. thanks