Three senders - what is what - 85 300D - PeachParts Mercedes-Benz Forum

meltedpanda · #1 03-08-2008, 10:08 PM

Told you I would have lots of questions

3 senders I see
one on top of thermostat housing
One on the sie
One back on the exhaust manifold in front of banjo bolt attachment

So what are they and what one is the temp sender for the temp gauge.
Part numbers would be great!

tangofox007 · #2 03-08-2008, 10:14 PM

Quote:

Originally Posted by meltedpanda

One back on the exhaust manifold in front of banjo bolt attachment

If you meant to say "intake manifold," that would be the turbo overpressure protection switch.

Maybe you could let us know what "sie" means?

meltedpanda · #3 03-08-2008, 10:15 PM

sorry, been under the car all day, , one on top of the thermostat and one on the side

pawoSD · #4 03-08-2008, 11:41 PM

1. Thermostat housing - sensor for the climate control cutout (when the temp rises it allows the blower to come on when coolant is 38C or above)

2. On the side of the engine - This is the temperature sender for the engine, it feeds the gauge on the instrument cluster

3. On top of the intake manifold - I think this is the temperature sensor for the glow plug relay, the temp it senses determines how long the "glow light" on the dash comes on. I may be wrong....officially I don't know exactly what it is.

OlBrenner · #5 03-09-2008, 12:41 AM

Quote:

Originally Posted by pawoSD

1. Thermostat housing - sensor for the climate control cutout (when the temp rises it allows the blower to come on when coolant is 38C or above)

2. On the side of the engine - This is the temperature sender for the engine, it feeds the gauge on the instrument cluster

3. On top of the intake manifold - I think this is the temperature sensor for the glow plug relay, the temp it senses determines how long the "glow light" on the dash comes on. I may be wrong....officially I don't know exactly what it is.

3. As stated before is the sensor for the overboost, it's just a pressure switch.

Icefire · #6 03-09-2008, 12:51 AM

The way I interpreted the question he is talking about the 3 senders on the thermostat housing. (only 85s) have this, an 83 SD would have only one sender on the thermostat and a vacuum switch for the egr.

AFAIK the 3 sensors are for the egr control computer, the aux fan control, and blower fan cut in.

**Edit, the 300D's might only have 2 sendors on the theromstat housing.

The other posters are correct about the overboost sensor infront of the banjo.

mobetta · #7 03-09-2008, 01:30 AM

the temp sender for the gauge is on the side of the head, between the GP's.........

meltedpanda · #8 03-09-2008, 09:05 AM

OK thanks, so on manifold - boost sensor'
top of thermostat - temp cut out
side - temp sender to guage

yes this 85 has both senders on the thermostat housing
I do not see one in the block, but will look again,
anyone have a parts picture?

Brian Carlton · #9 03-09-2008, 10:18 AM

Quote:

Originally Posted by meltedpanda

OK thanks, so on manifold - boost sensor'
top of thermostat - temp cut out
side - temp sender to guage

yes this 85 has both senders on the thermostat housing
I do not see one in the block, but will look again,
anyone have a parts picture?

Take a look at the SD. It's got a temperature sensor on the driver's side of the head which is used for the temperature gauge. If the W123 does not have this, then one of the sending units in the thermostat housing will operate the gauge.

charmalu · #10 03-09-2008, 08:30 PM

The sender on the side of the thermostat has a wire that goes to a switch over valve behind the brake booster. pull the wire off the sender and ground it with a piece of wire. you will hear the switch over valve click. not sure what it was connected to, there is a rubber vac connector that had a line that went some where

before I improved on things

.

There are 2 sensors on the left side of the engine. one between #1 & #2 injector and the other between #2 & #3 injector. the first one is for the temp gauge, and second one I believe is for the glow plug relay.

the sensor on the top of the thermostat housing has a wire the goes over to the right side, and posibly to the EGR modual behind the right foot well kick panel.

Charlie ☺

meltedpanda · #11 03-10-2008, 09:24 AM

thanks!

tangofox007 · #12 03-10-2008, 10:02 AM

Quote:

Originally Posted by charmalu

The sender on the side of the thermostat has a wire that goes to a switch over valve behind the brake booster. pull the wire off the sender and ground it with a piece of wire. you will hear the switch over valve click.

Are you 100% sure about that?

pawoSD · #13 03-10-2008, 10:07 AM

The sender on the thermostat is merely a temperature switch. It grounds the connector at 38C to flip on the climate control blower. Simple as that. If it fails in the open position then your blower will not come on unless you ground the connector. This happened on our 300D. I could ground and un-ground the connector with the car off but climate control on, and could hear the relay in the CC clicking when I grounded it.

MBeige · #14 03-10-2008, 10:11 AM

Isn't the one from the thermostat housing for the auxiliary fan, to ensure it comes on when the coolant temp rises above a certain temperature (determined by the thermoswitch - which can be replaced with different versions)?

tangofox007 · #15 03-10-2008, 10:13 AM

Quote:

Originally Posted by MBeige

Isn't the one from the thermostat housing for the auxiliary fan, to ensure it comes on when the coolant temp rises above a certain temperature (determined by the thermoswitch - which can be replaced with different versions)?

No.