i posted this issue on vintage side,but no response.my temp gauge does not work,just stopped about a month ago.i know these cars have mechanical units.is sensor on top of thermostat housing or in drivers side engine block.what do i have to do to diagnose and repair.?

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95 e320,87 sdl,79 300sd

is the thermostat any good?

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hum.....
1987 300TD 311,000M Stolen. Presumed destroyed

i do not know,havent pulled it out,system was working fine then not.

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95 e320,87 sdl,79 300sd

First thing I'd do is check for electrical power at the sensor. If you don't have any (I suspect this) then you'll need to start chasing until you find what is probably an open circuit - I'd start with the grounds under the dash.

Was the gauge "flakey" just before it suddenly went out?

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daBenz - 1970 220D

where is sensor located in my car?thermostat housing or engine block

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95 e320,87 sdl,79 300sd

Apologies on my part - the temperature sender isn't electrical - I was thinking of a different vehicle. It does make the troubleshooting easier.

The sensor should be located in the head, left side just above the front corner of the injection pump, in the hole forward of the heater hose.

Troubleshooting:
1. Ensure coolant level is OK. Start and run cold engine with radiator cap off, make sure level doesn't drop as engine warms up.
2. Ensure thermostat is working.
3. Lower coolant level, then pull sensor. Wipe off and test with a lighter or a match - have someone else watch the gauge. Clean, if necessary, with fine emory cloth - just enough to get the gunk off.
4. Ensure sensor cavity in head is free of gunk.
5. Lightly tap back of gauge housing, behind the dash. The "last resort."

If this doesn't work then you'll need to replace the gauge assembly. Be very carefull so you don't pinch the tubing.

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daBenz - 1970 220D

thanks ill check .good info

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95 e320,87 sdl,79 300sd