Definitiely something wrong.Car is running hot.

[Rocky]

Mine runs about the same as yous kamer.

[davis449]

You guys convinced me, I'm taking mine to the dealer to get the thermostat looked at. This would be the third thermostat, counting the one that originally came with the it, that's been replaced on this car.

[kameraguy]

So after some research it appears the OEM thermostat for a w202 is supposed to open only at approx 87 degrees.

So, if this is correct, shouldn't a w202 only run as hot as that before cooling down?

So maybe with this in mind, my car temps are ok (i'm still trying to reduce this further though), but for those running 95-100 or more....especially in "normal" driving situations...I still think this is not normal. Unless this indicates a w202 cooling system is not able to effectively cool the system. But since there are a few of us who don't see anything over 100...or even 90 for that matter....i'd still advice to have the car checked out.

Some things I found while researching this which may help someone who may not know already:

1) Coolant Cap....if it doesn't create a strong seal, the cooling system can't pressurize, so in essence you have a breach in the cooling system. Check that and replace if in doubt.

2) Make sure to use MB Antifreeze. Which i believe is also Zerex. Some MB owners report warmer temperatures unless using this stuff.

3) Ratio of coolant to water. The more water in the system, the more heat absorbing properties the system has. It seems this is one of the biggest variables which affects engine temps. So I suppose it depends on where you live, but make sure the ratio is correct. If in doubt, re-do it yourself. I believe there is a device to mesure the specific gravity of the coolant mixture to help determine if it is ideal or not.

4) Thermostat. My issue was defintely a bad t-stat. Seems to be an easy fix, so double check it.

5) Temperature sensor. Have this checked to see if it is functioning correctly.

6) Make sure you have EXACTLY the correct amount of coolant. Too little, or even too MUCH can cause cooling system issues. This must be exact for ideal operation. If you need to top-off, adding distilled water is preferred over more coolant as more water always helps with the cooling.

7) coolant color should be clear. i'm still confirming this, but I read online MB coolant is clear. If it's not, this is probably not MB coolant.

* if someone can confirm or correct me on this one i'd appreciate it.

8) Fan relay. Make sure your fans are working correctly. I reasd the ceramic sensor is also in a poor location which can easily be damaged. For example, a car wash may damage this sensor.

*if someone can confirm the location, i'd appreciate it. I read it was somewhere in the front bumper?

8) obviously check for any leaks.

9) fan belts. Make sure they are not loose or damaged.

10) fan clutch. Check to make sure this is indeed operating correctly.

11) Radiator. I suppose it stands to reason an older car with the OEM radiator loses it's ability to cool the engine over time. Whether it is a gradual issue which increases engine temp slowly over time, or if it is an abrupt change, i do not know. But I suppose in a worse case scenario this will need to be checked as well. With a car over 100K on the clock, might as well replace it and related hoses. It sure can't hurt and 100K is not a bad service life anyway. I will do this soon.



This is something i'm still looking into, but I hope the above may help others get an idea of what to look for if they have temperature issues. I'll add more info as i find it.

Edit: btw, I found some good info at mercedes shop related to engine temp issues. And i also found Duck Muck there. I guess that's where he is hanging out nowadays

[Recaro18]

so Kam, what did Zim actually replace on your car? i get paranoid specially on hot weather...and guess what, i'm moving to sacramento, so i need to know a way to get my temp to go down....

thanks

Ricky

[Renn 208]

MB coolant is clear, but not colorless, it's a super faint yellow, but is essentially clear when mixed in your coolant tank.

This is one of the ways that MB techs can tell if you've used anything other than MB Coolant. Put a drop of the green stuff in and you'll be flushing for days to get the green to disappear.

[speedybenz]

On my C43 I use very little anti-freeze, about 1/2 gallon of Halvoline stuff and the rest is water and then watter wetter.

I would like to find a thermostat that opens at say 75 degree C but haven't had any luck finding one.

Kam, could you send me your old thermo so I can see if the are other models out that will have the same phyical dimensions but maybe a lower opening temp.

Jeff

[kameraguy]

Ricky, Zim replaced my thermostat.

Jeff, i'll see if that thermostat is still in the shop. If not, i'll see if he can give me another broken t-stat for a w202.

I would definitely be interested in a cooler opening t-stat.

Are there any problems using a thermostat that opened at say 75 or 80 degrees? Would this also cause problems if the car ran between 80 and 75?

From what i'm seeing with my car, if it's true the t-stat opens at 87degrees, then this basically keeps my car hovering around 87 -91. So I suppose a t-stat which opens at 75-80 would theorhetically keep my car at 80-84-ish...

Would sound much better than how it is now.

Any reason MB chose to use 87 degrees?

Also, I wonder if these t-stats are not consistent, explaining why we have so many variances of "normal" operating temperatures.

[kameraguy]

Originally posted by speedybenz
On my C43 I use very little anti-freeze, about 1/2 gallon of Halvoline stuff and the rest is water and then watter wetter.

I would like to find a thermostat that opens at say 75 degree C but haven't had any luck finding one.

Kam, could you send me your old thermo so I can see if the are other models out that will have the same phyical dimensions but maybe a lower opening temp.

Jeff

Jeff, with this mixture, is this applicable for the I6 cooling system?

Also, do you also experience engine temps above 85 on a regular basis? What has been the max sustained temp you've had during normal driving...not tracking

Renn...so your car runs over 100 degrees at times?!

[kameraguy]

Originally posted by oaktownc43
I checked with the mercedesshop parts and the stock factory thermostat on a 1999 C43 is 87C so the tempature must at least reach that at a minimum for it to even open. My car will go to about 100C max on a hot day and I have been told by very good mercedes techs that this is ok and normal.It has never gotten higher than 100C at any time so far. At speed it will go to approx 88C a little above thermostat rating.
Phillip
1999 C43

My bad Philip, I overlooked the fact you already confirmed 87degrees is the t-stat open temp.

100 degrees or higher.....for some reason that doesn't sit right with me. Maybe because i've seen my needle go all the way to 120. So if I see my needle go past 100....then what's considered "not" normal?? like, is 118 still normal? That's pretty damn close to red.

Also, had I not been worrying about my engine after it past 100...I could have easily overlooked it going all the way...

This is definitely personal opinion, but i'm sure you guys already know how freaked I get over problems which i could avoid, and for me, I want that temp needle registering as close to the middle as possible. And i'm not talking about "fixing" the needle so it only registers 80! I mean I would love the peace of mind knowing my engine is as close to 80 as possible. 85-90 I suppsoe can't be helped due to the OEM t-stat. But anything higher just gets under my skin.

[kameraguy]

Originally posted by Rocky
Mine runs about the same as yous kamer.

Thanks for the feedback Rocky. This makes me feel a bit better.

So is it not correct to want a cooler running engine, or is 90 degrees really just a fact of life.

But if we can find a way to reduce engine temps, that would be awesome. At the very least, there's gotta be a way to get those running around 100 or so even lower.

[kameraguy]

Question:

Any problems running a W202 without a thermostat?

I understand the car will take longer to warm up without it. Would this be a problem in itself if the engine is running cold? More fuel consumption, higher emmisions, etc?

But once it is warm, is the thermostat needed?

Would this theoretically keep the engine cooler once the 87 degree restriction is bypassed?

Just a thought.

[nokia8860]

Runing the part numbers you find that the thermostat 110 200 05 15 which opens at around 87C, I say around because there are +/- to it as its not that exact... hey its wax, the part is used for alot of different MB models. Which means then of course the selection in the aftermarket is alot more than just searching for a 93-00 202.

So basically if you lust for a 78C/174F thermosat then visit your local autoparts store and pick up a Beck/Arnley 1430578 for around 20 bucks. However, 78C might be a little to cold for most applications and you might be better off with Beck/Arnley 1430602 which opens up at 82C/180F.

Either way, if youre unhappy with your thermostat opening at 87C you do have other selections out there. Also keep in mind you can find other brands that make the replacement thermostat just ask the parts guy what are the cross part equiv of the ones mentioned above cuz maybe you like mr gasket, be cool, stants or whatever else.

Also make sure you change up your mixture with more water than coolant as this will help lower temps as well.

[Recaro18]

cool joey, i'll try that...

[kameraguy]

You the MAN Joey!!! I think that 82 degree thermostat sounds great. I will try and pick that up this week!


btw- someone told me their should be no problems running WITHOUT a thermostat. Is this true???

[nokia8860]

Originally posted by kameraguy
You the MAN Joey!!! I think that 82 degree thermostat sounds great. I will try and pick that up this week!


btw- someone told me their should be no problems running WITHOUT a thermostat. Is this true???

np man. i know you want a fridge. i answered the 2nd one via mail

[Denlasoul]

nokia:

you the man. looks like another mod to consider.

[CKlasse]

Do not take out your thermostat.. your engine will have hard time warming up... then ECM will stay in the open loop. Repetitious event like this will trigger your CEL.

Correct me if I am wrong anyone?

[CKlasse]

BTW Kameraguy... I was talking about your issue with few guys here. One tech had long experience working on his own S500. He tried all the simplest stuffs until finally he replaced the Radiator itself eventhough there is no apparent problems. Sure enough, his temp is back to normal.

Perhaps after all those things we looked at, its simply the radiator conduction is getting old.

[nokia8860]

Originally posted by Denlasoul
nokia:

you the man. looks like another mod to consider.

sorry man but this is only for the inline 6. I will see what is available for the v6/v8 as they use a different type of thermostat.

[kameraguy]

Originally posted by CKlasse
BTW Kameraguy... I was talking about your issue with few guys here. One tech had long experience working on his own S500. He tried all the simplest stuffs until finally he replaced the Radiator itself eventhough there is no apparent problems. Sure enough, his temp is back to normal.

Perhaps after all those things we looked at, its simply the radiator conduction is getting old.

Thanks for the insight Cklasse. So before your friend replaced his radiator, can you confirm how "hot" it was running on average? And what it typically is at now? Like, after the radiator change, is his car typically dead even with 80 now? And if it does warmk up, what's the warmest it runs now?

If my car temperature doesn't get better after a re-mix of the coolant to water ratio, and possibly a new lower temp thermostat.....new radiator it is.

I know it's one of the costliest things to do in terms if the cooling system...but I suppose over 100K on the OEM is already a good service life. So hopefully if I replace it, I can expect at least another 100K more...

And Joey, your 190 runs PERFECT man. When you say it runs hot...nowhere near as hot as my car!!! That thing was dead even with 80 on the freeway...and you KNOW I was looking every minute!

[714guy]

Originally posted by kameraguy
Thanks for the insight Cklasse. So before your friend replaced his radiator, can you confirm how "hot" it was running on average? And what it typically is at now? Like, after the radiator change, is his car typically dead even with 80 now? And if it does warmk up, what's the warmest it runs now?

If my car temperature doesn't get better after a re-mix of the coolant to water ratio, and possibly a new lower temp thermostat.....new radiator it is.

I know it's one of the costliest things to do in terms if the cooling system...but I suppose over 100K on the OEM is already a good service life. So hopefully if I replace it, I can expect at least another 100K more...

And Joey, your 190 runs PERFECT man. When you say it runs hot...nowhere near as hot as my car!!! That thing was dead even with 80 on the freeway...and you KNOW I was looking every minute!

Kam

i heard over time you radiator gets cloged and isn't effiecent, most people only change it when its leaking. That could very well be the problem, I wonder if there is any way that you could flush it out and give it a real good cleaning instead of replacing the whole thing, b/c they dont look cheap at least ours don't.

[Eurosport]

i missed this thread
but
wholy shit that's expensive towing

mine runs idle to warmup to 80
then stuck in traffic 85-90
freeway 80 sometimes just below 80

i have noticed about 5 degrees lower than these numbers after i put in water wetter, BUT only first day after putting it in, after that back to normal so i guess it's not worth it

another thing to think about which definitely is a common problem is head gasket on these (from history of the car on star report i know mine has been changed by previous owner under warranty at 49k so it'll be good for a long time) but i just hope yours won't go out soon, running hot is a sign for that to happen
hopefully it was the thermostat
gl

[CKlasse]

Originally posted by kameraguy
Thanks for the insight Cklasse. So before your friend replaced his radiator, can you confirm how "hot" it was running on average? And what it typically is at now? Like, after the radiator change, is his car typically dead even with 80 now? And if it does warmk up, what's the warmest it runs now?

During highway or even city driving, his car was in the 85-90 range. In the traffic, it would go beyond 90. So, he replaced the thermostat and things got a lil better. Then, he noticed lil particles in his disposed coolant. That convinced him to buy a new radiator. Few bucks later... The S class is running perfect.

[Three Point 6]

Kam,

When I first got my C36 I did alot of research before I purchased & I remember a site where a Guy in the Phillipines bought a 'tropics' clutch for his fan which was a Sachs part#. He said it dropped running temps 10-15 degrees. It will lock up a little earlier and do its job. Oh yhea if your a horsepower junkie it will cause more parasitic drag and maybe more noise but I bet it solve your problem cheaper than a new radiator.

Check this site out. This gut apparently knows how to make a Benz run cool............

http://pages.prodigy.net/jforgione/MB_S500.html

[kameraguy]

Thanks for the link 3.6. I spent some time admiring his S500 coupe before remembering to check out his enginer cooling tips/products.

I am interested in his cool harness. Has anyone tried that? I guess it tricks the engine to turn on the fans earlier than usual. And the testimonials sound promising.

I'll drop him an e-mail to inquire about a w202 as I did not see our cars supported on the list.

The article on properly using WW was very interesting. No doubt this is a must-do as well. I nee done of those AF checkers!!

Well, my car has consistently run between 85-95 degrees...which still bugs me, but I am getting the picture this is "acceptible". But anything I can do to drop it down to no more than 87 degrees would be welcome.

Recaro, have you changed your thermostat yet?