Water Temp Sending Unit?

PNWorBUST72 · April 03, 2018, 05:59:50 PM

So I am having trouble determining which unit is the sending unit for my dash water temp gauge...

I am seeing two, almost identical sending units on the right side of the engine/Passenger side but MCI only shows one...

I know there is one for the engine compartment gauge, I will worry about that one later.

Is there a way to confirm what engine I have? I THINk its an 8v71...

eagle19952 · April 03, 2018, 06:26:18 PM

https://www.detroitdieselpartsdirect.com/documents/detroit-diesel-specs/detroit-diesel-model-number-high-res.jpg

https://www.detroitdieselpartsdirect.com/finding-your-detroit-diesel-engine-serial-number

chessie4905 · April 03, 2018, 06:47:19 PM

Key on, engine off...disconnect wire from sendi g unit, one at a time. Have someone watch dash for light or gage movement.

buswarrior · April 03, 2018, 07:15:55 PM

The auto shut down use its own sender or does it share?

Damned things...

Happy coaching!
Buswarrior

neoneddy · April 03, 2018, 09:00:45 PM

I have a 6v92 so it's different, but maybe this can help.

I was having mine shutdown at odd times. Turns out I had a loose wire on the temp sensing gauge that manages the shutdown.

For me that was the far right wire. If I grounded that wire it would shutdown.

Dave5Cs · April 03, 2018, 09:07:59 PM

Look on the face of the lower pulley it will be embossed there. Looks like an 8v71 but should say.
The water temps if like mine there is one on each side so you get an even reading and it is the one nearest to the rear doors. you might only have one on the passenger side.

PNWorBUST72 · April 04, 2018, 07:32:18 AM

This is as close as my short little arms can get but Detriot says it's not a valid number. I'm guessing it 8va192239...did they use paranthesis?

luvrbus · April 04, 2018, 08:31:01 AM

Should say 708x then the serial number the 7 stands for 71 series you are missing some numbers

gumpy · April 04, 2018, 10:07:41 AM

You have an 8V71NA engine.

It appears from the photo you have a safety system tempstat in both sides, and a temperature guage sending unit on the right side. This is how it should be.

It also appears you have a mechanical temperature sender in the bottom of the right side. Maybe that's for the rear guage?

bevans6 · April 04, 2018, 10:16:50 AM

There should be two "senders" (one is a sender, the other is a switch) in the right hand thermostat housing, and one switch in the left hand thermostat housing. The switches on my MCI 8V-71 have red domes under the terminal, and an ohm-meter reads open to ground. They (Gumpy calls them Tempstats) switch and ground out the terminal when they get too hot. The sender has no dome, and should read around 150 ohms to ground.

Brian

PNWorBUST72 · April 04, 2018, 12:35:42 PM

Thanks guys. Detroit still cannot confirm my engine serial number so they cant get me parts. Or the parts guy was too lazy too try. Luckily MCI had everything I needed so far.

I replaced the BLUE Sending unit on the right side, ordered the Alarmstat for the left.

Here is the Right side, I replaced the far right top one today, no clue what the left one is yet. The bottom one is for the gauge in the engine bay.

Here is the left side, the top is the Alarmstat and the bottom is....

luvrbus · April 04, 2018, 04:25:03 PM

Serial numbers are really not that important since those old engines have been changed and rebuilt over the years,that is a good serial number but not for a 1978 MCI that is a 1972 engine ,the 72 year model was from 164953 to 212755 the 1st 8v71 in 1973,your engine should have a serial number of 35xxxx or above if it was original in a 1978 MCI HTH

PNWorBUST72 · April 05, 2018, 02:16:34 PM

@gumpy

Any idea what the RED sensor is for? MCI doesnt list 2 of them and Detroit is useless.

buswarrior · April 05, 2018, 02:45:24 PM

Correction, the employee at the Detroit outlet you tried to deal with wasn't able to help a new guy looking for parts and answers...

Try a different dealer? One more likely to have an interest in 2 strokes? Marine, agricultural water pumps, the oil patch, still lots of 2 strokes in pockets...

Happy coaching!
Buswarrior

gumpy · April 06, 2018, 06:23:47 AM

Quote from: PNWorBUST72 on April 05, 2018, 02:16:34 PM
@gumpy

Any idea what the RED sensor is for? MCI doesnt list 2 of them and Detroit is useless.

I believe that is your alarmstat switch. The left one in the photo of the right side with the red dome under the terminal. The right one in that photo is the guage sender unit, I believe.

The one in the left side head is also an alarmstat switch.

Call C&J Bus Repair in Bloomington, MN. They'll have those in stock. cjbusrepair.com