Rallye Temp Gauge Interpretation - Is this right?

Wouldn't a needle this high concern you a tad in traffic? It looks like this is my setting when the car is at a relatively low temperature.

These are newly refaced and calibrated gauges so I am not sure what "normal" looks like. I also changed out the solid fan for a Heavy Duty clutch and Mopar fan so I REALLY don't know what normal looks like with this gauge.

When I got home, I put a laser on engine and things look pretty cool.

Outside Temperature 71 F
Radiator Center (taken from Front) 127 F
Top Hose 162 F
Bottom Hose 138 F (+/- 5% margin due to difficult reading)
Driver’s head (front) 191 F (+/- 5% margin due to difficult reading)
Passenger head (front) 190 F (+/- 5% margin due to difficult reading)

The factory gauge is "subjective" at best, I usually remove the temp sender temporary from the engine and install an actual thermal couple probe inside a compression fitting and read what the water temp actually is under actual running conditions

I hope when you installed a NEW sending unit, that you put NO sealant or Teflon tape around the threads

Dayclona, I think subjective is the best word for it! Now that I know a 70% reading reflects a fairly low temperature I can just make a mental note of that and carry on.

Once I get a warmer day and the needle raises even more I can take more laser readings.

Thanks again for the response and taking a few minutes to send me some ideas.

-Steve

Used an IR gun to check mine.

cnxt, you are awesome! I really appreciate the photos. This would suggest I have a terrible sensor.

What did you hit with the laser? The water pump housing, head, upper hose?

-Steve

340 engine, I checked several spots.
The top of radiator and thermostat housing were the most stable/repeatable readings.

Settled on the thermostat housing, heart of the matter right?

Just got this table today. For those old Mopar gauges, they read based on the resistance of the sender. For the temp gauge it looks like this:

C = 75 ohms
1/2 = 27 ohms
H = 10 ohms

I am replacing the sender this afternoon but I was wondering about the temp readings cnxt posted here; The external radiator and housing readings of 205 seems a little higher than many on this board like to see.

I have read many posts where people have said they like to see temperatures around 200 and that 210 is too high.

Is that because the external readings taken with a laser are a little higher than the actual internal temperature or running at <200 is unrealistic without a push fan?

Steve, I think your over thinking this. Run it for a bit on the road and check the temp of the stat housing. Under 210 after running hard on a hot day is OK. Depending on stat rating you're likely fine right now , assuming a160 stat.

ruderunner you are probably right.

It's 70 outside and I just ran about 15 minutes in stop-and-go traffic and the top hose (at the thermostat) got up to about 204 which is OK for now.

I changed out the sending unit and now at 205, the gauge reads at 90% so I guess I will keep shopping for sending units. This is the second one I tried from O'Reileys and I probably need to start looking for another brand.

Once I get the sending unit corrected I will take another good look at the timing. I think it may be jacked a little too high.

Just installed a new sender from NAPA and the gauge reads like it should now.

The Echlin ECH TS6178 is far more accurate than the BWD brand from O'Reillys.

Mission complete, problem solved thanks for the sanity check on the gauge readings.

-Steve

How about a pic, how close to mine?

Pretty close! Still letting the car warm up to get another picture but here is how mine looks right now.

Agree with Dayclona... get a "reliable" gauge to validate/understand/interpret what the dash gauge is telling you. A $10-15 parts store gauge will do it. See what the backup gauge tells you vs dash gauge and interpret accordingly.

On my setup, I run on the bottom line of the operating range while rolling on the dash gauge. Seems low. Backup gauge tells me it is right around stat temp of 180. All is well with the cooling system and engine. The (rebuilt) dash gauge + new sender just reads a bit low.

If you need to fine tune the gauge there's a small window on the back of the gauge that will adjust the pointer...Move the "teeth" a little at a time...Only do this if you've confirmed the reading through a secondary gauge or temp reader... I'll usually adjust to center the gauge at normal operating temp if needed just to match up the sender to the gauge

Quote:

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Pretty close! Still letting the car warm up to get another picture but here is how mine looks right now.

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I dunno, looks like the needle is postioned higher than cnxt's and at a lower temperature. Also appears when it hits 190 it will be in the same spot as your original photo.

Great photos, you Guys. Will definitely keep your pictures for reference when I get to this on mine.

I like ScreaminDriver's suggestion: for sure going to keep that one.