Been there done that and the stat is in correctly on my car
... removing the fan is the next step

Just 'cose it's new, don't mean it works !



.

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[http://languageandgrammar.com/2008/01/14/youve-got-problems-not-issues/ ]

"A liberal is someone who feels they owe a great debt to their fellow man, which debt he proposes to pay off with your money."

Marine diesels have an 'infinite' radiator.

Their thermostat keeps the engine at the correct temperature.

If you are sure that the gauge is correct, then the problem must still lie with the thermostat. It may not be shutting off as it should a lower temperatures, or there may be an internal leak around it.

Or, remove the fan and board up the radiator...

Yet again...removing the fan will warm your car up but it will not fix the actaul problem.

Take out your stat and check it in a pan of water while bringing it to a boil.

Then you know it is working

hopefully it won't come to that Might as well fix the problem instead. One thing's for sure - the engine generates a significant amount of waste heat. Even a 240D. That heat is transferred to the air surrounding it. Check your assumptions, at least one is incorrect. My 617 has an oil cooler, (I don't know if the 240 does) and if the oil thermostat fails, oil is pumped to the oil cooler even when it's cold. Could be an offbeat thing like that.

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'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.

This is a sad fact.

where’s the oil thermostat on a 240d? mine has an oil cooler

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Jason Green
1977 240D AUTOMATIC the Beast
1974 Super Beetle



Suppose you were an idiot. And suppose you were a member of Congress. But I repeat myself.
- Mark Twain, a Biography

Oil cooler literally cool after highway travel?
http://www.peachparts.com/shopforum/diesel-discussion/29095-oil-cooler-literally-cool-after-highway-travel.html#post156048

You need to take a look at your thermostat again. You can install a radiator the size of Kansas but the thermostat will keep the engine at the proper operating temperature.

Assuming that you installed the right thermostat and it was in the right orientation to the engine (spring toward engine), I'd change the temperature sender. They can go bad over time.

Also, check the wiring from the sender to the vehicle. If you ground the sender, the temperaure gauge should peg out on hot.

I have a OM616 turbo engine with 72F thermostat, even in low 20Fs, the vehicle quickly gets up to 80C and remains steady there, I am at 6000Ft elevation on top of that.

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99 Gurkha with OM616 IDI turbo

2015 Gurkha with OM616 DI turbo

2014 Rexton W with OM612 VGT

I cover my rad not only to stop air flowing through the radiator, but also onto the engine block. Even if the tstat is closed and no coolant flows through the rad, the blast of -30C air onto the block is more than enough to 'air cool' my diesel - preventing it from reaching 80C on the highway.

I also cover my oil cooler rad with cardboard. Even if it has its own built in tstat.. suppose it is not perfectly functioning and some oil sneaks by?

At about -4C, the cardboard comes out because the car now needs the airflow, and the rads and tstats all do their normal business and keep the engine at 80C.

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Cheers!
Scott McPhee

1987 300D

Strange, I've driven my 300D in -10F temperatures at highway speeds without the engine temperature ever getting below 80C, it just takes a little longer to warm up. I doubt these cars were designed to require cardboard to run correctly.

My 83 is like that also. Never drops below 80C no matter how cold it gets, highway or idling- no cover. The T-stat is whatever was in the car when I bought it, never taken it out to look at it- could very well be the original. I bought a 95C MotoRad T-stat from Autozone but never installed it since the current T-stat seems to be doing fine.

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

No matter what it calculates out theoretically, when it is 20 below, my mb diesels will not warm up enough to produce heat without adding some cardboard to the radiator. YOu have to be careful though if you forget it is there the car will over heat when the ambiant temp gets up to 20 and you are on the highway.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

240D 77, all manual , I installed a new motor in 2002, this was a complete motor from the dealer, the only issue that I had with the new motor was the thermostat, the shop struggled for months but could not get the thermostat to work as intended, tried different thermostats, burped the system, you name it, it just would not open.
Finally I gave up and have been driving the car without a thermostat for about 9 years. I live in Houston where summers last about 8 months, the winters are not brutally cold, I just place a cardboard in front of the radiator and get a decent heat in the cabin.

Vahe