Just bought a 1993 190E-2.6 and have a question with regards to the indicated engine temperature. It has read around 75 deg C when warmed up since I've had it. Thinking this was a little too cold (and knowing the vehicle was getting less than the 30 mpg the guy who sold it to me said he was getting), I installed a new M-B thermostat (87 deg C) just this evening. Well, no change in the indicated temperature, so I'm thinking temperature guage or sending unit. Anyone see fault with my troubleshooting? If there was a faulty sending unit, could it impact engine performance?

 

The temp. reading on your gauge comes from a single pole sending unit that only provides your gauge with a temp. reading, not the computer. If in fact your car is running to cold, of which 75'C would be, than yes that would effect gas mileage and increase engine wear. If I remember correctly the ohm reading from the single pole sending unit should be around 60 ohms which would equal 80'C. This should give you a starting point to work from and your troubleshooting seems very accurate!!

 

Thanks for the info! I'll try to check out the sending unit today . . . but . . . yesterday while idling in a parking garage (I don't idle too much), the temperature actually made it to around 87 deg C, then cooled back to the 77 or so it has been running when I got back on the highway. This is odd behavior for someone who is used to American cars. Any thoughts? What temperatures do the rest of you observe on the road?

 

Mercedes uses a real time gauge and sensor, american and japanese cars use a sensor that has a dead spot in it to keep the gauge reading the same when the car is warmed up. Most mercedes cars tend to run on the hot side, around 90 when cruising and can creep up to around 105' and greater when sitting in traffic (idling). Around 107' the aux. fans will kick in and cool it back down to around 90'.

 

I have the same problem, except sometimes when I am idling the temperature rises to about 100'. When this happens, I have always been afraid of overheating, so I either shut off the car or start driving to cool it down. Is this really necessary if you say the aux. fan comes on at 105'? It is an 87 260e.

 

your temps. are fine at 100'C. It's a hard thing to get used to seeing such high temps. but it's normal for the benz's. The only time to get concerned is when you see temp. gauge nearing the 115' to 120' mark, then something is wrong because as soon as your aux. fans kick in around 105 to 110 it will lower the temp. of the engine.</P>

 

Ahhh thanks for that info on the high 100 running temp. I had a volvo and it never got that high..with my benz300 it woould creep up until she started cooling back down I'd start panicking hahah..glad to hear it is normal. My 300 always runs about 80-85, unless Im stuck in traffic. I've been pouring coolant in every day thinking it was thirsty.

 

I also have a 93 190E 2.3 and mine did the same thing, but my specialist told me it was normal - just watch for coolant drips - that was my lesson in a new water pump and $800.00 + later, I still think it runs to hot at times, but I know it is just the way it is - frustrating is when I loose what little get up and go I have in the car when it gets up there in temperature...

 

Turning the engine offwill get it hotter for a period of time. The coolant is no longer being cooled and circulated.If you're in traffic or intend to drive off momentarily, don't turn it off thinking it will cool down.</P>


I don't know if the MBs do this. Can't verify right now, maybe jetforeman knows?There's a cooling trick on the C5 Corvette when it's idling and hot. Turn on the air conditioner. It makes the auxilliary fans kick on. People who drag race these actually idle in the staging area with their A/C turned on to keep from overheating!</P>

 

your correct about the aux. fans coming on when the A/C is turned on, but unlike the vette for example, the aux. fans are turned on by pressure not by just selecting the A/C to on. When the system pressure reaches a prescribed amount the aux. fans will come on low speed, high speed is activated when the engine temps go above 107'C.