Thermostat
 

Can anyone tell me where to find the thermostat? I have an 89 300 se and the heat on the inside generally is only luke warm, but does not blow very hard. I have had the blower brushes replaced and the armature checks out ok. I pulled the mono valve the other day and the best I can tell there is no hole or cracks in it. I have noticed that the heat blowing on the driver's side is not as warm or as hard as the passenger side. Can anyone tell me what could be wrong? The car came from the east coast. Could a new thermostat help? Location?

i'm not sure if there are two thermostats but from what i know the thermostat is the metal semi-dome shaped thing that hose from the radiator attaches to

http://www.peachparts.com/images/300e_engine.jpg

from this pic....there is a red tag by the radiator....follow that hose from the radiator...curves a little to the left and attaches to a metal part.....that is the thermostat

hope i helped more than i confused

Is the temperature on the guage coming up to around 85 degrees C? If so, then your thermostat is not your problem. If the temp is not coming up, then the thermostat is near the front, drivers side of the engine.

To check the control valve, feel of the hose going to the valve and then the hose going away from it. If the hose going away is colder, then the problem could be the valve or the controls that actuate the valve.

Best of luck,

renyf1, Good picture of a clean engine, how do you or what do use to clean and detail your engine compartment?

enjoy your drive,timreid

How fast should the temp come up? I have a 92 400E and when its cold out and im driving, it hardly comes up at all. Im wondering if this is related to my starting problem.

Thanks...Peter

Timreid,

I actually "stole" the pic from the Mercedesshop.com's feature on the 300E cars :-)

Peter,

My temp comes on pretty quick depending the temp I set and in the auto mode. In about 5mins it gets pretty warm but most of the time what I do is select the defroster for the front and rear and once the main windows are clear just switch it on either Economy setting or heat from the botton vents only since I always have a jacket on.

Ren

no i mean the engine temp. Today, i drove about 20 miles in 56 degree weather and the engine temp. never rose above the little mark that comes after the 40 degree mark (55 degree?). However, whenever I stopped to get gas and left the car running, the temp. rose to just past the 55 mark but only by a hair. I think i need a tstat.

Peter,
You do need a thermostat, and do it ASAP. Cold-running engines dump excess gas into the cylinders and may cause excess wear, and, I think, may shorten the life of your catalytic converter.

Mine hits 80 degrees (which is the set point for my thermostat) within 5 miles of driving, even in subfreezing weather.

Could be worse
 

It could have failed closed, but at least you would know that right away:eek:

monovalve
 

what is the easiest way to test the monovalve to see if it is working properly? I know that if I start replacing items here and there, it will get expensive and maybe not correct the problem. Any suggestions?

Remove the electrical connector from the monovalve. That should lock it open. See if that improves cabin heat.

It doesn't tell if you the monovalve is stuck partway closed, though.

Sixto
91 300SE
87 300SDL
83 300SD