Temp Gauge on the motor. 8V71. Where??

[Chaz]

I want to put a temp gauge right on the motor so I have an "accurate" reading. Any suggestions on what kind or where?  (sorry, it's not a small block Chevy so I'm kinda lost!  )

  Tryin to keep cool,
        Chaz

[DavidInWilmNC]

I want to put a temp gauge right on the motor so I have an "accurate" reading. Any suggestions on what kind or where?  (sorry, it's not a small block Chevy so I'm kinda lost!  )

  Tryin to keep cool,
        Chaz

Hi Chaz,

Like you, I want a mechanical temp gauge for the engine.  I have the gauge, but it was never hooked up when the engine was rebuilt.  On my 8V-71, there are three places for senders to be mounted on the passenger side (right side?) thermostat housing facing the outside (away from the engine).  I haven't connected mine yet, but am in the process of finding a bushing to reduce the size down to that of the bulb. 

David

[Busted Knuckle]

Alot of coaches I have worked on over the yrs have had 2, 1 on each head or thermostat housing each! That way if you are experiencing problems, you can narrow it down to which head or radiator is likely the problem! FWIW! BK

[Chaz]

Hmmmm......
  The temp gauge holes (3) on my bus are on the drivers side. 2 Have single wires and 1 has 3 wires but they are all cut off. (Is the two singles for the up front gauge and indicator light?)  Can I use the 3 wire sending unit spot? Or should I use one of the single wire spots?

  And, should I use a mechanical or electric? The manual one will have all that excess wire/whatever. But, I want it accurate as I know the one up front isn't. (shows 210 when it's 185, I think. Checked radiator with infra-red gun)

Thanx,
      Chaz

[maria-n-skip]

Chaz,

   When you checked the radiator with a gun was it the top or bottom of the radiator.

   I'm just confused about something.

   I always was told mechanical is more accurate and dependable.  FWIW.


Skip

[Chaz]

Skip, that was the reason he (Jerry Lieber) checked it to see what the difference was from top to bottom. It was 185 on top and 155 on the bottom. So I guess that means the radiator was doing ok.
     Chaz

[roadrunnertex]

Per section 6 page 3 figure 3 - GMC Coach maintenance manual X-7564 P8M4905A & P8M4108A.
It shows two sending units.
The top one by the square casting which is the thermostat housing is the Overheat sending unit.Item #5
The lower one is the Temperature sending unit.Item #6.
Hope this helps.
Install a "Tee" fitting and put the mechanical gauge sending unit on one side and the electrical sending unit on the other side of the "tee".

[Chaz]

Thanx Tex!!!
  But I wonder what that third unit with the 3 wires coming off of it is? They are all cut off so I know it's not used.
  If it's not in the book, if I took a picture of it, do you think anyone would know?
   Thanx,
         Chaz

[Busted Knuckle]

Thanx Tex!!!
  But I wonder what that third unit with the 3 wires coming off of it is? They are all cut off so I know it's not used.
  If it's not in the book, if I took a picture of it, do you think anyone would know?
   Thanx,
         Chaz                         

Chaz please post a picture and I'm sure we can help! FWIW
  BK 

[Buffalo SpaceShip]

Chaz, here's a pic of my t-stat housing showing where they put my mech. gauge sender (top right). I can read the mech. gauge on the engine through the vent in the rear cap (aftermarket cap). It reads about 5 deg. less than the elec. one in the dash (which makes me drive more conservatively... I like that).

HTH,
Brian B.

[compedgemarine]

dont know if it helps but on my Eagle with a 6v92 the one in the head with three wires is part of the auto shut down system and is interconnected to a similar switch on the oil pressure block next to the oil pressure sender. the switches have three connections labeled C, NO, NC.
steve
1981 Eagle model 10

[Barn Owl]

Install a "Tee" fitting and put the mechanical gauge sending unit on one side and the electrical sending unit on the other side of the "tee". 

Wouldn't that put the sending units out of the coolant flow and give an inaccurate reading?

[Chaz]

Thanx Steve. I'll check that out.

Barn Owl, I was kinda wondering the same. I'm sure it would still work, but I would think the reading would be off a bit. And to the wrong side.
I think I can just go ahead and pull the 3 poled one out and use that spot. I'm just not sure about "electric or mechanical"? I would like to go mechanical, but I don't like all that excess cable or whatever you call it.

  Pondering,
     Chaz

[compedgemarine]

a good electric gauge with clean power is about as accurate as they anything now days. does your bus have the auto shutdown? is this the original motor? if not maybe some of the cut wires are left from the swap and it was easier to cut them and leave them than fix it right. my bus had a lot of broken insulation and chaffed wires so I got fed up and ripped it all out and built a new harness based on the wiring diagram in the manual so I eleminated all the stuff that no longer is used. makes tracking things alot easier.
Steve

[Chaz]

Thanx Steve.
  Sounds like you have more patience than a buzzard or are a gluton for punishment!!  That wiring thing would send me to the "nut house"!! SOONER!!!! LOLOL
  I don't know much about the history of my bus. So i don't know what is what. But I do have a 24v system and I'm not sure how an electrical gauge will work with that.
  I guess i could get around it some how, but maybe a mechanical would be easier and more accurate. 

  Thanx,
   Chaz