Gauge or Sending unit?

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ROSEDOGGYDOG

umop apisdn w,I
So I finally get my new ebay air intake on the SGT and took it out yesterday for a test run. During the run I noticed my water temp didn't quite get to the 1/4 mark. I was out for at least a good 15-20 minutes, the gauge itself gets power since its moving.

Could the sending unit really have gone bad or is it more likely that its something worse as in the instrument cluster needs to be replaced? I popped the plug wire off the sending it (damn little bugger) and it seems to be straight forward, needle plugs into sending unit and gets temp.

I picked up a Mr. Gasket radiator cap with temp. gauge and it went to 180 degrees while the dash gauge was just under the quarter mark.

Has anyone else had this same problem?
 
R

ROSEDOGGYDOG

umop apisdn w,I
Re: Gauge or Sending unit?

I've seen my gauge get to the half way mark before, now it won't even make to the 1/4 mark and I've let it sit there and idle for a good period.

My worst fear is that I'm going to have to replace the entire instrument cluster for one damn gauge. This happened once before when my oil pressure gauge went, I thought it was the sending unit but it was the gauge.
 
P

pinellas50

New Guy
Re: Gauge or Sending unit?

DaveP said:
That's where all three of my Sytys run: About the 3/16 mark with 180° thermostats. In cold weather right at 1/8th. In hot weather, traffic, A/C on Almost to the 1/4.

I think you're OK.
Click to expand...
Exactly what my truck does as well. Datamaster shows that my truck normally runs around 175 or so around the 1/8th mark.
 
R

ROSEDOGGYDOG

umop apisdn w,I
Re: Gauge or Sending unit?

Not one to stop pondering on a subject I decided to call my dealer mechanic. He told me to check the thermostat and that its most likely the problem. I guess I can go with that since its some maintance that should be done anyways.

I grabbed one at Pepboys today on my way home and I also picked up a new sending unit just in case but thats where the new question comes from.

The guy sold me something like this (of course their website sucks so I'm using pics from Schucks):
ts80071-1.jpg


What you can't see in that pic is inside it there are two pins!? and it looks nothing like the current sending unit I have in there currently. My sending unit looks like it has a hole in it for the one pin coming off my plug wire.

Now on Schucks website they have this "Standard Motor Products Fan Switch" that almost looks like the sending unit I have in there but I can't tell for sure with out looing into it.

ts253.jpg


Do you guys know what I am talking about? What would I do with two pins anyways?
 
sly dvl

sly dvl

Ya, it's got a Turbo
Re: Gauge or Sending unit?

The other pin in the sensor probably isn't used for the application. Mine has one wire but a 2 cavity connector.
If the plug fits, use it.
 
gkrcr882

gkrcr882

SyTyless......for now!
Re: Gauge or Sending unit?

Hmm, and here I thought my gauges were messed up since my temp gauge reads low too. Glad to hear its a common thing.
 
Tophatjimmy

Tophatjimmy

Syclone FNG
Re: Gauge or Sending unit?

thats a knock sensor if I'm not mistaken. I believe in the NA 4.3 Vortec they use that hole for the KS instead of a temp sensor. your water temp sensor should be up by the water neck.
 
R

ROSEDOGGYDOG

umop apisdn w,I
Re: Gauge or Sending unit?

Holy crap am I confused now, when I unplugged it the temp gauge did not even turn on.

Looks like more looking around tonight.
 
R

ROSEDOGGYDOG

umop apisdn w,I
Re: Gauge or Sending unit?

Wow you guys are right that is the knock sensor, I'd just naturally assumed thats where the water temp sending unit was at makes sense that it would be there.

So after looking it up I feel all dunce like on the internet... Thanks for the heads up I would have looked real stupid at the store.
 
S

socalblue

New member
Re: Gauge or Sending unit?

The temp.sending unit, used by the cluster gauge is different from the temp sensor used by the ECM. the prongs are faced differently, take a look one is perpendicular T the other is - - I THINK!!!!

The sending unit for the temp gauge cluster should be on the driver side by the headers. The temp sensor used for the ECM is the one on the manifold...I know my temp gauge doesn't work, because I have a separate mechanical temp gauge to compare off of...even after replacing the sending unit...I feel more secure with a mechanical one anyways.
 
R

ROSEDOGGYDOG

umop apisdn w,I
Re: Gauge or Sending unit?

DaveP said:
Is this a SyTy engine? It looks like a 93 CPI (L35) based on the valve cover color. If so, the temp sender is on the RIGHT head. Green wire.

That knock sensor and location is correct for a L35. There is another KS on the rear of the Pass cyl head. KS have BLUE wires.
Click to expand...

No, this is a 92 Sonoma GT stock engine. I found the temp sending unit #519 per GM diagram at parts counter, its just left of the thermostat. I changed the thermostat last night, didn't do anything to help but I gave it a shot.

Changing the temp sending unit looks to be fun. Got pull the belt tensioner off.
 
R

ROSEDOGGYDOG

umop apisdn w,I
Re: Gauge or Sending unit?

Right side being passanger side correct? I see the plug and wire will try to get to it tonight but the Lakers are playing so I may hold off till tomorrow.
 
R

ROSEDOGGYDOG

umop apisdn w,I
Re: Gauge or Sending unit?

Well the Lakers played like crap in the end so I jumped on the GT and had some sort of success.

I picked up a cheap electric water temp gauge on the way home and tapped the sending wire (just outside of the plug/sending unit) while connecting the negative terminal to the battery/ground. This brought my temp gauge back to life. As soon as I disconnected the ground wire it dropped again, touched and its back, disconnect and its gone. So I now can tell its a bad ground but what I want to know is can the sending unit be that bad ground?

While yes I have a new sending unit ready to be put in I'm curious to hear what you guys have to say first.

@ DaveP, thanks for that heads up!
 
R

ROSEDOGGYDOG

umop apisdn w,I
Re: Gauge or Sending unit?

Okay nevermind what I said in the last post (cept for that part thanking Dave). Ugh were to begin?

First I changed the temp sending unit easy enough, put new fluid in the system till it was full.

Then I let it idle and the temp basically rose to the same area just under the 1/4 mark, $20+ wasted on sending unit it looks like. I tried the grounding again but then that made my gauge read close to 260 and it wouldn't come down but yet the reading on my radiator cap was telling me 170-180ish and this was with the heater running. I took the ground off and then held my rpms at 3k for about half a minute and let off. Then my gauge actually hit the 1/4 mark and slightly went just past it and stayed there, checking against the cap gauge it read about 200.

So now I've come to the conclusion that between the first 1/4 is 100 degrees and the others are in 20 degree increments or I could be way off on this either way I'll have to do more spot checks in between but thats the way its looking. I had been under the impression that every 1/4 was repersenting 40 degrees.

I'm starting to feel better about this, thanks again DP and P50.
 
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