I appreciate all your help in advance, this forum has been so useful to me.

Our dealers warranty runs out tomorrow, so time is of the essence, just figured my strongest hypothesis last night so now to post the details and seek all your wisdom.

I talked my mother (cash strapped pensioner) into buying a 2002 C180, I have had a few C240's and received nothing but good experiences. now I think there is a major problem.

Car runs great, there is an intermittent slight shudder on take off, warm or cold, we are not in winter mode (Auto box) so is starting in 1st.

Twice I have run it up a fairly steep hill (No more than 15 degree gradient) and the thing has died on me, the experience is exactly as an overheating engine ceasing up (Loss of power, very rough idle, won't go or change down, etc) this occurred just over the 100 degree mark on the temp gauge. pulled over, waited an hour, drove fine, engine did not over heat, no temp warnings, running at just a touch under the 100 mark.

Here is the trick, I notice the dealers transmission service centre has put an after market oil inter cooler on it (Quite large 10% of radiator surface area) but left the original one on, I asked why it was changed, was told the MB one leaked, OK, went home, compression test = no leak, called back, was told Oh it has a flow restriction, hooked water hose to it = no flow issue.

I am now suspect they put a larger inter cooler on it to mask a greater, more expensive issue the dealer did not wish to repair.

I disconnected the electric cooling fan and ran the motor to 120 degrees (I have good glycol mix and users book states should run OK up to 130) car drive great, no issues = rules out engine fault right ?, the temp warning has never, ever come on, I am certain the engine has never and does not overheat. of course, did not drive car far so as not to over heat motor, so transmission did not get hot.

I will run the car up a hill tonight to confirm if it is the transmission "over heating" even though it is extremely dangerous to break down up there on a single lane.

What could this be ? torque converter ? why would a larger inter cooler be necessary to fit ? (Am certain no issue with smaller, original MB unit) am certain someone is feeding me lies, would running the tranny 20 degrees lower mask a heat related fault ?

Have been to dealer twice for repair, each time engine light is reset, I know they are not resetting by disconnecting battery, but they won't tell me the codes either, I asked them what was the fault and what they did to fix it and am getting the run around, I am no mechanic, but I do know a few things about cars and have performed full engine break and re builds in the past, solving problems in manufacturing is my profession. can't say the dealer is trying one on as he is just sending to his mechanic.

Any help or insights / suggestions are gratefully welcomed, I strongly feel responsible for my mums purchase, I crawled all over the car for 4 hours and took it for a long test drive, all checked A OK, of course I never took it over a big hill on a hot day (Who would on a test drive)

VIN starts with WDC203, so from what I have read, it does not fall under the coolant getting into transmission oil issue, they certainly appear to be separate circuits.

Thank you

 

It sounds as though the transmission is reading a high temp issue & going into limp. The external cooler fitted to try & stop this. I smell a rat. Get hold of an OBDII scanner that can scan transmission codes. Post all stored codes here.

Demand the vehicle be taken back to standard & repaired to operate properly standard. Take no BS from dealers.

The temperatures you are quoting are in Celcius - Yes! They are miles too high. The thermostat opens at 87 deg C and that is pretty much coolant operating temperature.

 

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