Hot running

[richardlw]

OK guys - I'm a newbie but I've read through most of the threads on this topic.
Car is a 1997 C200 auto. Until the beginning of this year the water temperature NEVER went over 85 degrees whatever you did. Then it started to run up to about 90 degrees, maybe seeing 100 when stopped in traffic after a fast run.

Made it a priority at the annual service a couple of weeks ago. So, they changed the water pump (which leaked apparently although I never had to add water!) and that had no effect. So I went back and whinged.

The service manager went for a drive in quite warm weather and got the temperature up to 100 by sitting stationary whilst revving to 3000 rpm and then ascertained that the viscous coupling was u/s as the fan did not run any faster.
So they changed it and I went to Le Mans last week for the 24 Hours.

On the way down, three up and a bit of luggage, and on a very nice day, we saw 90/100 degrees all the way. Slowing down to around 70mph from no more than 85mph got the temp down to 90 but no less. Stuck in traffic in Le Mans we saw 110 and climbing and got a bit panicky (and annoyed) and parked up just in time. 5 hours later, in an underground car park, the temperature was still about 70 degrees. (God knows where it got to before it started to cool)

Driving round on days when the air temperature was 95+ degrees, the water would reach 90/100 even in clear air. Stuck in traffic on the same day saw about 110.

Driving round the Peripherique yesterday in heavy but moving traffic I had to put the heater on full and open the windows to keep the water below 120 and even back home down to two and a lot less luggage, we still had 90/100 degrees.

Went back to MB Bromley this morning and established that the viscous coupling still worked and the service manager though that this was all perfectly normal. They are keeping the car to check a few more things however.

My gut feeling is blocked rad (which stays touchable at all times!) or thermostat staying partially closed and restricting the flow. As I said at the beginning, the temperature was a rock solid 80 degrees. And the heater has been a lot less effective since this all began.

Questions. Is this behavious "normal" and what damage is likely to be done by such excessive temperatures in the block and the head? Does anyone have a view on what else might be causing the "problems"? Are all MB dealers as inept as MB Bromley (we are now on our 4th visit)?

I should add that my other car is air cooled and this is my wife's so, up to this point, I have taken very little interest in it.

Thanks in advance for your comments....

Richard Ling-Williams

 

[tom7035]

Hi Richard and welcome. More knowledgeable people than me will undoubtedly come in here but, assuming you were not having to add water, the first thing I would have done right at the start was replace the thermostat. In fact I still think this is the simple solution to your problem.
Having perused the forum as you say you will probably realise that Mercedes Dealerships (barring a tiny few) will replace the ash-trays, car mats and wiper blades to try to resolve most problems!
I'll hand you over now to the experts. Good luck, Tom.

 

[richardlw]

Thanks for that Tom.

You're right about the dealers. I couldn't believe going to collect the car after it had been serviced and being given a list of things that needed doing - what is the point of that when a simple phone call for permission or otherwise to do the work would have saved another visit.

The thermostat is the obvious culprit but why is that obvious only to us?

Richard Ling-Williams

 

[niva441]

Hi there, welcome to the forum.

I recently had a similar problem with my W202 C250TD.

The first thing the specialist did was to clear out debris between the radiator at the front of the engine bay. That made some improvement.

I also went to Le Mans and prior to that they replaced the viscous coupling, as they noted that it wasn't pulling hard. However mine has done over 200k miles and the specialist has only ever replaced these 4 times. Although it did run slightly warm at times down to Le Mans no real problem in the extreme temperatures.

 

[blassberg]

The thermostat is the obvious culprit but why is that obvious only to us?

1) thermostat - completely agree and easy to test
2) obvious to a dealer - no it's too cheap

 

[alexspurs61]

1) thermostat - completely agree and easy to test
2) obvious to a dealer - no it's too cheap

Just picking up on this - it's a similar theme.

Should be an easy one - do I have to drain the rad/all coolant if I'm changing the thermostat? I'm hoping it's just 'plug and play!

On an s210 2 litre petrol.

Cheers

 

[Stevie A]

You'll lose some coolant when changing the thermostat. I can't believe they changed a water pump that didn't even seem to be leaking.

 

[mioba]

this thread seems typical of dealers, and the mechanicss seem have no idea.

have to agree entirely, this is the thermostat.

personally, i would have removed the petcock and flushed the old coolant with a hose, refilled with distilled water and ran the engine to get the mixture flowing and drained - refilled 3 times, before adding coolant.

also wash your radiator, soapy water and a old paintbush - scrub v gently in the direction of the fins as they are very soft.

seems no one (well dealers) does coolant flushes anymore, just a check and correction - this will never remove the crud from the radiator.

this is the time to relpace the thermostat and whilst the rad is empty check the condition of the hoses too, any mushy feeling and they should be replaced.

ps dispose of old coolant properly, its highly toxic and smells sweet, so its attractive to animals, seal it and dispose of it properly.

 

[Stircrazy]

My water pump chucked it yesterday and water was ****ing out from the outlet pipe as fast as I could put it in, I took the car to my mates workshop and showed him the water ****ing out and he fitted a 2nd hand pump for £70.

I could have had it back by lunchtime but was busy and got it at 4 pm.

Easy.

Moral is find a good mechanic and point him in the right direction.

Makes everybody happy!