If everything else is working, what you describe could be the result of an issue with the head or gasket. (I know, that's pretty unlikely for an OM61x). Is there any pressure in the system when cold? Also, if the needle moves very rapidly, that indicates an electrical problem - NOT a temperature problem. It should take 15-30 seconds or longer to move from 95c to 105c. If it's only a second or two, time to check electrical connections...

Hi RW,

Same problem with my 83 300D. I did a drain and refill, no flush. Poured in real slow, ran the motor for a bit, poured in more. Took a couple of hours altogether but now that car stays rock like half way to the 100 mark. Used to always read high. Lots of other work was done on the car, axles, cleaning of electrical contacts and such and it was off the road all last winter. It has been running ok all summer heat wise. I don't know exactly what fixed it which sucks, but it is OK now.

I should have mentioned...I am not exhibiting the signs of a bad head gasket (no pressure when cold, no coolant loss, coolant stays the same color..)

It must be electrical, you are right. But where do I start. I did get some very good advice from a previous post, but all were beyond my skills as this requires taking the dash off. I want to take to an indy and explain to them what to do first so the clock does not tick, tock forever...

AC

__________________
'83 240D (W123) 321K miles
250KM Mileage Award
500KM Mileage Award

'84 300TD (W123) 215k miles
250K mileage award pending

No progress to report yet. Haven't had time to work on the car. Too busy with work that actually provides income. Planning on pulling the radiator to have it tested/flowchecked. Probably will put fluid in the fan clutch too. Will update as possible. RT

__________________
When all else fails, vote from the rooftops!
84' Mercedes Benz 300D Anthracite/black, 171K
03' Volkswagen Jetta TDI blue/black, 93K
93' Chevrolet C2500HD ExCab 6.5TD, Two-tone blue, 252K

Thank you...just so you know, we have the exact same symptoms and I have a 2 year old radiator with merc coolant only!

I would suggest you stop by your indy and have him take the temp with an IR non contact thermometer. This will tell you if the guage is reflecting the correct temp. If it is, you may be able to skip the radiator step and move to the electical or sensor or guage.

I will post my progress...

AC

__________________
'83 240D (W123) 321K miles
250KM Mileage Award
500KM Mileage Award

'84 300TD (W123) 215k miles
250K mileage award pending

acastell,
I have put a bottle of Toyota silicone fluid in the fan clutch. Initially I thought it helped but tonight she started running hot just like before with the ambient temps in the low 30's. The radiator is cool to the touch on shutdown, across the entire core. If it was that cool from a lack of flow there would be no flow at all and it would overheat all the time I would think? No access to a IR thermometer. The next step is to pull the radiator and have it tested but that will be next week at least. In the meantime I plan on trying another thermostat. Sensor will be replaced too. An oil sample is being sent tomorrow to see if there is any problems with coolant in the oil. Will update as it unfolds. RT

__________________
When all else fails, vote from the rooftops!
84' Mercedes Benz 300D Anthracite/black, 171K
03' Volkswagen Jetta TDI blue/black, 93K
93' Chevrolet C2500HD ExCab 6.5TD, Two-tone blue, 252K