Tach cluster water temp gauge different?

Does the water temp gauge tend to read higher on the tach clusters than they do on the standard clusters? I recently swapped my regular speedo only cluster for a junkyard tach cluster, and everything works great, but on my old cluster, when fully warmed up, the water temperature gauge would read about 1/4 the way up. On the tach cluster, at normal operating temp the gauge reads a hair above the halfway point. Just wondering if this was normal, or maybe trucks with the tach cluster used a different temp sending unit (unlikely but possible I suppose)? Anyone else notice this?

Hmmm this would be interesting to find out.






_justin

Apparently, different resistance values of the sending unit would be slightly different on the gauge for standard type instrument cluster and for the tachometer-type cluster, and different still for Canada. I have no idea why. See

Actually, it depends on the gauge that's in the dash......if you could put 3 different non-tach dashes in your truck you would see that all three would read slightly different! I've swapped quite a few of these (never changing the sending unit) and they all read a little differently.....not much, but enough to notice. In other words, they're likely NOT a high quality, high precision instrument! They built them to be simple and last a long time I would think, otherwise they would have temperature marks or graduations on them!
Plus the fact that the dash tach temp. gauge and the regular dash temp. gauge are totally different in their mechanical movement, so a difference between the two will be apparent for sure.
I added a cheap SunPro temp. gauge in my red regular cab truck just so I would have a temperature "number" to go by and therefore it would be readily apparent if the temp. was running hotter than normal........gotta put it in an "A" pillar gauge pod one of these days!

Good to know. Are there any unused 1/8 NPT ports to use for a temp gauge sender? I know there is the big square pipe plug in the intake manifold, is that the only place to tap in without any drilling? If so, what size is that so I can get a 1/8 adapter? I have an extra water temp gauge that I have laying around, I might as well throw it in and put it in some kind of nondescript place so if my truck ever starts running hot or anything I can take a look at it and make sure its actually overheating, I am not a huge fan of having a ton of gauges visible.

Factory gauge sending unit location:


"Computer" temp sending unit location:


Where I put my aftermarket gauge sending unit:


What it reads at full operating temp with a 195 degree thermostat:

(around 150 to 165 degrees is the max I've seen so far)

Factory gauge at that temp - (non-tach equipped):

Cool, thank you for the pics. Do you know what diameter/thread pitch that plug in the manifold is?

Also, quick question in regards to the windshield wiper switch. What is supposed to happen when you pull on the lever, and what is supposed to happen when you push on it? When I pull my lever nothing happens, and when I push it the wipers run but no fluid comes out.

One of the included SAE adapters fit into the port I used (originally the thermo valve). I believe the plugs are also SAE pipe thread. The green computer sensor is a metric thread with a washer on it.

Sorry I don't remember which size adapter I used.

what does it mean when your mazda has been setting for a few days and you go to start it up and as soon as i turn the key the temperature gauge goes all the way pass hot and stays

Shorted sender or the wire is grounding out somewhere.
Easy to figure out if the sender went bad by just disconnecting the wire from it.
If the gauge drops to full cold, the sender is bad.