300d part ID
 

Can anyone ID this part? Also, please tell where it's located in the car. Is it in front of the driver or passenger?

I'm asking because my 300d seems to like to overheat when it's not blowing out hot air. I have checked the monovalve. It seems coolant might be clogged somewhere and this part might be bad.

Here's the seller's description of the part...

climate control module/actuator unit from an 83 MBZ 300D

It is the evil Climate Control Servo.

http://pointlessbanter.net/files/200...vil_monkey.gifhttp://www.thepartsbin.com/images/ca...300384-145.jpg

Suck it up baby, that is the dreaded ACC servo. The gods have cursed you.

Can you give me more information besides just the name? Why is it evil? Does it fail often? Must be an expensive part. Can it get clogged? Is it under the dashboard where it's hard to get to? I can see coolant hoses going into the dashboard. I'm assuming this is where it lives. My car makes grinding noises in front of the driver's seat when the hot air does finally blow.

If the car you are referring to is one of the ones in your signature, you do not have this part on your car. They were not installed after 1980(?). The noise you are hearing is something else.

Yup, if you have a monovalve (which you do in your 83) you don't have a servo which was an earlier design. That's not your problem (fortunately). What are you symptoms and what are you hearing?

You don't have the Evil Servo you lucky devil! Have you replaced the thermostat? That and the radiator are the usual overheat causes on the OM617's. (or an air pocket from a low coolant condition)

Thanks for all your replies. I'm still at a lost as to why my 85 300d is overheating.

I have posted this previously here: http://www.peachparts.com/shopforum/showthread.php?t=203337

Ok, this is what's happened since then.

I have drilled a couple of holes in the t-stat and the car has been running hot, but not overheat. The temp gets up to 110 C when the hot air is not blowing out.

When hot air does blow out, the temp is a normal 80 C. The hot air only kicks in occasionally, but most of the time, it just blows out cold air! My center vents do not blow out any air. When hot air does blow out, I hear a brief grinding noise in the gauge cluster area like something is opening.

I have also checked out the monovalve. It seems to be working when I tested with a 12v battery charger and the rubber diaphram is ok. I have also tried a different but used climate control module.

History of car's cooling:
1. Car does not show temp when I first bought it.
2. Replace t-stat, temp shows normal for a couple of months
3. Car had a couple overheating episode, coolant runs low, etc.
4. Flush out old coolant
5. Drilled holes in tstat, car now runs hot when no hot air blows out.

Can anyone tell me what's under the dash board besides the heater block? I'm thinking of removing the t-stat and bypassing the climate control all together and see if that helps.

Sounds like a blocked radiator to me.

Removing the t-stat is NOT an option. It must be there for the system to pump water in the right directions. Not using one can make things much worse.

24 - ac expansion valve
35 - ac climate control servo (1977-1980)
36 - Heater valve (230, 240d models)
37 - mono valve (300d, 81 and up)
38 - mono valve repair kit (plunger chamber and seal)
39 - aux water pump
45 - climate control amplifier

So it looks like my car doesn't have the ac cc servo. Thank goodness as this part is quite expensive. Anyone know what the climate control amplifier does? Does this part fail often?

Listen, quit worrying about your climate control system. It has nothing to do with your overheating, other than circulating your coolant through a longer path maybe providing some cooling. Focus on very wise advice such as the quote above.....;)

Your Radiator Is Clogged...
 

So go to the Mercedes dealer and buy TWO pounds of Citric Acid cleaning powder , then get two gallons of distilled water , drain your cooling system including removing the block drain plug (17MM hex ., right behind the exhaust manifold drop) , refill with plain water and add one cup of a non sudsing detergent like SHOUT etc. , drive it to work and back , drain this and flush with garden hose (block drain out too) , untill clean water coming out all holes , mix Citric Acid Powder with distilled water in a clean plastic bucket & fill cooling system , drive to work and back , drain cooling system including block drain , noting the incredible amout of black crap that comes out , flush with garden hose again and re-fill with 60/40 % mix of distilled water and either $pendy Ma 'Benz coolant -OR- ZEREX (same stuff) with 60 % of the mix being water .

This should help , if there's still a red dust coating the inside of the radiator hose after the Citric Acid flush , you have a sersious issue and the cleaner needs to stay in there longer .

Sometimes you can find Citric Acid Powder in baking supply stores , the radiator flush crap from the auto parts store is crap and WILL NOT do the job .

Have fun , it's a tedious job but do-able @ home and you'll prolly do a better job that the rushed , Flat Rate dealer mechanic will .