Coolant Temperature Sensor question

1976-1985: 230T, 230E, 230TE, 230CE, 280E, 280TE, 280CE, 240D, 300D, 300CD, 300TD,
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Dernburg Wagon
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Coolant Temperature Sensor question

Post by rjs1981 » Wed 15 Nov, 2017 9:48 am

Hey guys and gals,

I've been searching the forum for an answer to this, but can't seem to find one here or on the web. I've recently had a bit of trouble starting my 230e once it's warmed up. To go along with that, fuel consumption is uncommonly bad, and there are some mild temperature issues also. I'm going to start with the coolant temperature sensor, and believe these have two of them (?), one for the gauge and one for the computer.

My questions is, are both the sensors the same part number? Just don't want to order one for the gauges if they are in fact different.


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Re: Coolant Temperature Sensor question

Post by 230ew123 » Wed 22 Nov, 2017 4:00 pm

it may not necessarily be your coolant sensor assuming your cooling is in good nick and happy a solid at 83c (what does she sit at when warm?) may be something to do with your fuel delivery or ignition

I recall last summer something akin, went through with new starter (hi torque after market as the original is a dog to access), ignition coil, battery, leads, ngk iridium sparks, rotor in the distributor (common to wear), distributor cap (common to wear ((go bosch, beru is crap)), fuel pump..(check fuses and use copper ones not aluminium)

bit later, replaced the lower fuel filter, they wear and can leak at the seam which is just not cool dribbling petrol as you drive..easy to remove hard to reassemble without an extra long flex socket to reach through the plastic guard, bit of a dog of a job, lying on your back with petrol running down your arms, careful not to get it in your eyes..

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Tony From West Oz
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Re: Coolant Temperature Sensor question

Post by Tony From West Oz » Wed 22 Nov, 2017 10:46 pm

I had a look in the EPC and while I know there are 2 temperature sensors, I could only find one on the OM61x engine diagrams.
I believe that there is no reason for them to be different for the separate functions (Temperature Gauge and GP Relay temperature sensor) and it would be simple for MB to use the same type sensor for both functions.
It is simple to check:
With the engine cold, use a multimeter to measure the resistance from the terminal of the sensor to ground. They should read the same value +/- 10%
Repeat with a hot engine. They should still be the same as each other. If so, feel free to use one to test the other's function.

Life is a journey, with problems to solve, lessons to learn, but most of all, experiences to enjoy.

'83 W123 300D 325000km (Wife's car Josephine - sold).
'84 W123 300D replaced good OM617 912 with OM617 952 and enjoyed having good acceleration for the first time since first driving a 300D in 2002 - became engine and trans donor for 300CD Turbodiesel conversion. Now parted out.
'86 W124 300D sold (Wife's old car - sold )
'85 W123 300CD, 275 000km (Fatmobile) rebuilt turbodiesel from previous Fatmobile transplanted into 280CE (SOLD)
'99 W202 C250 Turbodiesel (my darling Wife's car - Sold)
'98 W202 C250 Turbodiesel (my car - Sold)
'06 Ssanyong Musso Crew Cab 2WD Ute (OM662 diesel and Auto Transmission)

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