My cold blooded 240..part 2
 

I posted earlier about my 81 240d running cold even in the summer. Now it barley makes it up to 60* after a long haul.
I put in a new mb T-stat and run a 50/50 mixture of coolant. I have checked the engine temps/ head temps with my infared heat gun and she does run cool..around 150* at best. My gauge appears to be fine.
btw.. I did put in a new bosch water pump a few weeks ago.. had a small drip from teh weep hole...................so my question is....

should I run cardboard in front of the radiator ?.........or
should I remove the fan and and fan shroud until spring ( and watch teh gauge) when temps get above 65* ambient?

EDITED: ALL THREE THREADS ARE NOW COMBINED INTO THIS THREAD

Could the viscous fan clutch be stuck? To much airflow will make over efficient cooling.

240s have a rigid
 

fan.

yes you may need some cardboard in cold weather. be careful with it though. on the highway you may overheat. start with a small piece.

tom w

I personally wouldn't panic about it running that temp. Give it a good italian tune up occasionally :) I would also see if you can get an after market thermo that runs a little hotter if you are really concerned.

Are you sure the stat is working and installed correctly (not backwards)? Can you feel hot coolant circulating to the radiator when the temp is less than 80C? If so, I would recheck the stat. You shouldn't need to block the radiator to run at the correct temp.

I dunno about a 240D, but my FSM states the minimum operating range for my 220D is 70*c, not 60*c.
Not getting up to full operating temp is not a good thing. You need the heat to get any condensation out of the oil, and for all the running tolerances to get to proper spec. The engine will wear faster and make less power when cold.
I definately would NOT do an italian tuneup unless the engine had been up to full operating temp for some time.

If you go to www.********.com, they have thermostats listed for your vehicle up to 195*F.
If it is interchangable, they also list Behr brand 87*c thermostat kits ('stat and o-ring) for my 220D.

Since you have one of those nifty temp guns (I'm jealous) you could use it to check when the thermostat opens. If you read hot coolant starting to enter the radiator hose when the engine is still pretty cold then you probably have a bad thermostat.

No clutch fan on my 240... direct drive

btt...

I put some cardboard in front of the radiator and drove 20 miles....

no change....whats up with that?

are you sure the temp
 

guage is working?

did you say your heater produces heat?

tom w

Yes gauge is right on according to the infared thermometer pointed on the head.... and yes I get lukewarm heat...not hot

i would suspect
 

the stat. i would prob remove it and check to be sure it is installed correctly and use a pan with boiling water to check its function. when installed, the flat disc goes down. easy to get wrong i have done it.

tom w

DID you happen to point
 

the IR thermo @ the oil cooler??

Perhaps the thermostat for the oil cooler is stuck open. Thats about the only thing that might explain it your issues. Its supposed to open @ about 95 on my 300d.

An improperly installed coolant thermostat wouln't really cause your issues.

Never knew there was a t- stat for the oil cooler... where is it located?.. on the cooler I assume ?

http://rbk3.com/mbz/tsm/MBZ18-120%20OIL%20THERMO.pdf

http://rbk3.com/mbz/tsm/MBZ18-005%20OIL%20SYS.pdf

It did on my 300D. Temp stayed at 60C or less, stat was installed backwards by PO. The stat may have also been failed, replaced it and car ran at 80C, even in very cold temps.