W202 C200 running hot?

[martin_a]

Ok, so I checked out some of the earlier posts on here and it seems that the viscous coupling could be a culprit or it sounds like it could be the impellar in the water pump. however, not being an expert I thought it best to double check.

Drove the car into work this morning and having hit the edinburgh traffic the needle rose to 3/4 way up the scale. That looks to me like well over 100. It didn't hit the red and did seem to come back down a bit when I turned up the heat on the fans but it got worryingly high for me.

I'm a tad annoyed as I just got the car and it sat and idled fine on the seller's drive for ages! Next day we're looking hot.

Any thoughts or advice?

m.

 

[panason1c]

Have you made the usual checks for head gasket failure?, 'mayonaise' on dipstick/oil filler cap, oil in coolant, etc, etc?

Try the so called 'carrot test' on the viscous fan, where you push a carrot into the spinning fan and if the carrot stops the fan it suggests the viscous coupling is u/s. (i know it sounds daft but other forum members say to do this)

The thermostat could also be suspect?

 

[martin_a]

I checked the oil, that seemed to be fine. Car was cold when I looked at it but there was oil on it so hadn't been wiped or anything from what I could tell.

Agree on thermostat actually. Easy to remove/check?

thanks!

m.

 

[panason1c]

Yes, easy to remove, not worth checking the old one really, better to just fit a new one and then you have eliminated that as a suspect once and for all.

 

[martin_a]

Grrr eurocarparts don't have them online. Beign a pain, any pointers on best place to buy? Can I bag one from Halfrauds?

 

[panason1c]

Try contacting europarts directly as sometimes they dont show a part as available online when they do actually stock and supply the item.

Otherwise, MB are not too expensive for a thermostat.

 

[martin_a]

email sent to MB Edinburgh.....

 

[martin_a]

Ok so just been out to check now it's cooled a bit.

Top hose from the expansion tank was flat so squeezed it back into shape.. However it wasn't like that yesterday so just a case of topping up?

Oil all looks clean and clear. In fact taking the oil cap off shows a fairly clean looking engine.

m.

 

[martin_a]

Ok MB want £30 for a themostat which seems pricey and £7 plus the VAT for a rad cap which doesn't.

I put water in, squeezed the hose a few times and it seemed to swallow the water ok. I got about half a litre in there I think.

Car was then ok for most of the journey home but the pause to back it onto the drive saw the temp start rising again. Still no puddles under the car though

Any thoughts?

m

 

[NW_Merc]

have you checked your thermostat is working? If you take it off the car and put it in hot water, the thermostat should open, if it doesnt then you know its the culprit.

 

[martin_a]

Thanks chap.

I've not been able to take the thermostat housing off yet, bit dark and I don't have any coolant to refill the system.

On the plus side, the top pipe is now still inflated so that's a small victory. However the bottom hose is cold which suggests something isn't right!

I just took pics of the radiator cap housing and the engine oil. The radiator does show some white marks but these don't seem oily, it's more like evaporation marks if that makes sense?

Oil still looking very clean.

So are we thinking thermostat most likely culprit given that the bottom hose is cold?

I hope so, having just got the car I have fingers crossed it's something simple.

m.

 

[Dec]

Just for your guidance and what is normal;

-After about 3 miles you get to just above 80c (83 to 85) that’s normal on the open road.

-If you’re stuck in traffic the needle will rise to about 100c (between 80c -120c)

-As soon as you get into free flowing traffic needle will slowly drop to normal = 80c

The bottom hose should be a lot cooler than the top hose as the air going through the radiator cools it down.
The top hose can suck flat a lot more than you might think, no one noticed because the don’t usually be looking under the bonnet that regularly.
To me, every thing that you have said so far sounds normal.

Dec

 

[grober]

The thermostat from MB will come in a new cast housing complete with new O ring. That's why its a bit more expensive.You could also try removing the fan +viscous coupling--- If its the large nut at the rear towards the engine side it will have a left hand thread 36 mm IIRC = FAN Spanner from Halfords. http://www.halfords.com/webapp/wcs/..._productId_214258_langId_-1_categoryId_165469
and carefully clean the bimetal strip on the front which activates the coupling fluid valve-- often get s clagged up with road dirt preventing it sensing the air passing thro the rad. WD40 AND AN OLD TOOTH BRUSH ARE IDEAL CLEANING AIDS. failing that a new viscous coupling may be required.

 

[martin_a]

Brilliant chaps.

The reason I was worried is that the C180 I had, brilliant car and the reason I bought another W202, never moved off 80 degrees, no matter what.

It only moved when the little hose from the bottom of the thermostat housing had perished. replacing that dropped a fair bit of fluid and it was a right sod for over heating until I got all the air back out.

This was certianly 3/4 of the way up the gauge which worried me a lot! I'm convinced it is something and nothing, I'll give her a run later and see how we go.

At least I'm less concerned now. Of course if it gets up towards red I'll be off for some bits and I think I'll look at the spanner too although the car is amazingly clean. It's only done 58,000 from new.

m.

 

[Ianswing]

my god,a full tank in the bottom shot !! you a lottery winner ? not seen that on mine for ages lol

 

[Beno]

Coolant hoses should not collapse it they do it indicates trapped air. When the car is up to temp the bottom hose will be cooler than the top but it will still be hot (Top hose approx 90 bottom approx 45) Thermostats can fail in a way which causes the engine to run hot although its rarer, I think your on the right track looking at that first, buy a genuine MB one worth it for the extra few quid.