engine too hot....

[daminder]

Hi Guys,

Recently my 190E overheated due to the temperature switch failing causing the cooling fan not to function.
During it's replacement the garage done a block/pressure test and thankfully confirmed the head gasket hadn't been damaged.

Ok, but this is my problem. I'm finding that the engine is running too hot...
The temperature gauge seems to go and down when moving and idling (as normal I suppose...) and there doesn't seem to be any coolant loss.

But, what i'm finding is that when its raining and the car is stationary in traffic, mine is the only car that starts to let off steam from the bonnet when the water hits it.

I know this is common sense and the law of physics, but it never seemed to happened before the overheating problem.

I've noticed this happen immediately even on short journeys and when I've lifted the bonnet it seems that the engine maybe getting too hot .

This is not only very embarassing as mine is the only car steaming, but I'm worried somethings seroiusly wrong.
Can someone  please help and advise???

Thanks

 

[sunil sood]

i had  a similar problem when my car used to overheat in traffic/idling conditions-it was cured by replacing the a cooling fan switch like in your case.
tne normal temp gauge behaviour should be just above the 80 mark once the car has warmed up and may rise to the middle of the 80 to 100 mark in traffic when the fan should cut in /out to maintain a steady temperature.
i too have notice the bonnet on my car does let off some steam in traffic but i do not think this abnormal -just the laws of physics-you will notice the inside of the bonnet is painted black-this absorbs heat from the engine and hence the some steam on the top of the bonnet.
so as long as the temp gauge does not climb above the 95 to 100 mark i think there should be no cause for concern.
perhaps other 190 owners will repond

 

[daminder]

Thanks for the reply Sunil,
Problem is,  this steam from the bonnet never happened before the overheating and to make matters worse my other cars (non mercs..) don't have this problem.
You say the bonnet is painted black well mine isn't - it's the same colour as the bodywork (cream). So it shouldn't absorb any heat....
And i think the temperature does go beyond 100, but eventually comes down a little.

Anxiously concerned.

Thanks mate

 

[Spike]

I would thoroughly check for leaks on the system when its really hot. It only takes a very small leak to lose pressure in the system which in turn will cause the car to overheat.

Most common thing is the resevoir cap itself which can lose pressure.

My car showed similar symptoms recently and it turned out that the thermostat housing had a tiny hairline fracture. The leak was so small that I wasnt losing water, just pressure.

As I say, get the engine nice and hot and look very closely for any signs of a leak.

 

[daminder]

thanks,

will try that.

However, can i therefore assume 100 % that the gasket hasn't blown??

 

[daminder]

thanks,

will try that.

However, can i therefore assume 100 % that the gasket hasn't blown??

 

[sunil sood]

daminder,

i mentioned in my previous post that the the inner aspect of the bonnet-(that is the one which faces the engine ) is painted black not the outer surface.

the causes of overheating are-

faulty thermostat,
failed cooling fan switch,
blocked radiator,
airlock insystem,
faulty expansion tank pressure/radiator cap(this includes it not being closed properly)
faulty cooling fan coupling itself,
faulty fuse that supplies the cooling fan

-i would as spike mentioned check the easy things first such as a leak search,cap,fuse,thermostsat.

 

[Geronimo]

Hi daminder,
Relax - don't worry about the steam. My bonnet steams in rain but old Geronimo never gives up! I,ve probably done about a thousand miles or more now on a new radiator and thermostat but not sorted out the faulty fan (it spins at same speed as engine speed, we at the forum have sussed its the thermo viscous clutch but I'll sort that in time) and its constantly going to 120 and always drops down to average temp - so like I said relax, these are fairly big powerful cars and are bound to get a bit warm, there also solid as a rock and will keep on ticking.
The inside of bonnet also has the remnants of a foam lining presumably to keep the heat in, I will be replacing this with a mirror film to reflect heat, it should also help light up the engine bay when working on it.