Question for those in the north....
 

My mechanic says I might not need or benefit from a new thermostat. Symptoms-- outside temps in the 60's, car will not heat the engine for more than 60 degrees tops....therefore the heater doesn't get hot enough to be of any use. He says it might not be a stuck open thermostat, and that replacement might not help. And that I might have to put cardboard or some such in front of the radiator daily (and adjust it as far as temps go on the temp guage while driving). Any of you guys in the northern areas have anything to say on this? First day off I shall replace the stat anyways, but if he is right, any other solution?

Regards

Run-em

I don't think there were any MB models that required cardboard blocking the radiator to get the motor up to temps in 60 degree weather.

What model are we talking about? There are thermostats that are not just open close valves but traffic controllers of sort.

I live in North Dakota where temps have gone down as low as -30F and wind chills down to -80F. I don't use a piece of cardboard. I replaced my thermostat and ran my Benz all winter. Soooo replace your thermostat, fllush your system, and use Mercedes coolant. I don't understand your mechanic's statement that a new thermostat "might not help". If he stands by that statement I would suggest that you get a different mechanic or at least get a second opinion. Better yet do the procedure yourself that way you know it's done right.

It probably IS a stuck open thermostat, which is the way it is supposed to fail. Replacing your failed thermostat will increase the heat from your heater, and make your engine run at the proper temperature too. Make sure you have the rubber seal around the t-stat. The old one can be as hard as a brick.

Though only driving my MB ('87 300TD) one NH winter, I certainly agree with the above. A new thermostat and MB coolant were some of my first purchases. I also checked the remainder of the cooling system (hoses, fans, radiator, mono-valve, etc.) before the cold set in. Mine generates great heat when called on to do so. Though not everyone agrees, and for specific reasons, I installed the block heater cord and used it. A properly running diesel may or may not need the heater yet I feel more confident with it. Contrary to a prior post about routing the cord, I actually did not cut a hole in the hood to have easy access to the plug end. :D

I also don't understand why your tech would tell you what (s)he said.

Hmmm, that is unusual, a mechanic that doesn't want to just throw parts in a car and see if it works. Is he just lazy, or aren't you paying him? ;) I live in Wisconsin with 80 below wind chills and have never used the cardboard technique. Although, hopefully this will be the first winter with my diesel benz, if I can get it running.

Just replace the $3 part and troubleshoot from their.

Glenn

Yes, find a new mechanic
 

The fact that the car does not warm up and the heater doesn't produce heat is usually a sign that either the thermostat is stuck open or has been removed. If it has been removed it could have been either because it was faulty and the PO took it out because he was too lazy to buy a new one or there was some other problem like overheating and removing it was a "free repair". Either way, you won't know until you at least try to fix it right by replacing the thermostat first and see what happens. As others have said here, there is no reason to use cardboard on a Mercedes.

Tell your mechanic.....
 

Mercedes are manufactured in Germany and from what others tell me, it gets pretty frosty there in the winter.

(He may be using what he has seen from Ford-Chevy-Dodge diesels, where the cooling system is set up for towing large loads. They need the cardboard.)

In fact, my MB puts out heat faster than any other vehicle I've ever owned. As others have recommended, changing of the thermostat should resolve this.

Yeah, new 'stat.
The cardboard technique is not for an engine that does not ever get up to temp. Cardvoard is called for more when you are going down the highway in winter and watch the temp needle slowly crawl up a bit above the normal operating temp, then swing down below operating temp as the thermostat opens. The inrush of frigid water from the radiator makes the 'stat slam shut and the temp again starts crawling upwards. This will repeat constantly, and over a wide temp range depending on ambient temperature.

I have thought about putting something over my oil cooler though. Since the oil doesn't have a thermostat, I don't know if the oil really gets up to temp in the colder weather now.

not stuck open
 

from my experience, when your thermostat is stuck open, your engine gets warmer. All of your coolant is constantly running through the block, not having a chance to cool away from the block. My car was running extremely hot. I pulled the thermostat and it was stuck open. I changed it and everything went back to normal. your thermostat needs to open and close to allow the coolant to cool. I'm thinking that your thermostat is opening up to early. Maybe it is the wrong thermostat. Either way, spend the 15 minutes and change the 10 dollar thermostat. Oh yeah, whats up with this carddboard mechanic.

???????

A thermostat is closed when temp. of the coolant is below a certain level. This helps the car reach op. temp. much sooner so it is more efficient. If your thermostat is stuck closed, your engine will overheat. The coolant sensor measures engine temp. - not radiator temp. If the thermostat is stuck open then the coolant does not reach the proper operating temperature. Therefore, the coolant going into the heater core is not hot enough to give much heat to the cabin.
Also, when the temp. of the engine is not hot enough it will allow all kinds of other problems - eventually. Premature rust in the exhaust system, condensation forming in the oil, etc.

I think your experience is atypical. I've run 240Ds and other cars without thermostats in order to diagnose problems and they run very cool, never getting up to operating temps and the heat from the heater is minimal. Running them without T-stats would be even more "open than open" as there is nothing to impede the flow of coolant through the block and radiator...I can't imagine why having a "stuck open" T-stat would result in a higher operating temp...makes no sense.

In fact, I'm pretty sure it does have a stat. Those Germans think of everything....

Your mechanic isn't a mechanic!

Your engine, as are all engines, are designed to run at a specific temperature. Running too cool could be detrimental, just as running too hot!

You cannot guage engine temperature properly with a cardboard cover over the radiator.

i t could be
 

that the stat is missing. any chance the mechanic removed it and doesnt want you to find out?

just trying to think of why he is talking of such strange ideas.

tom w