Fsher21

Okay I have been having problem after problem with my temp switch in my block that is for the gauge. Unplugging the wire drops the gauge to 0, grounding it pegs it, like it should. The gauge appears to be in at a slight angle, but it went in like that finger tight for the most part and the last 2 sensors were the same. The head of the sensor is about 2-3mm off the block since I did not want to break it off.

Right now the current issue after all the issues I will mention below, is that my gauge is reading high. The gauge starts like normal, but before my engine reaches operating temp the gauge has already climbed past 210 and decides to sit steady at 230 or whatever the line is just before the red. It moves into the red a little when at temp but if I park it stays just below. This is with the same part number as below, but duralast brand from autozone.

Before all this, the first problem was my gauge wouldn't sit still at 210, it would almost get there, sit for a second, then drop down to around 150 in a few seconds and slowly climb back up, rinse and repeat.

Clever me said hey I can fix this! So I did, well tried. The new sensor's head was slightly bigger, enough that I needed the valve cover off to get it in. Part number is TU236 with the wells name. So I broke that sensor off flush leaving a hollowed out piece of brass behind, which I got out with a bolt extractor after 2 weeks of no gauge. Got a new sensor from a different place and installed it and we are back at the current problem.

Any ideas? Thanks

Turbo X_J

Maybe try a MOPAR sending unit?

Radi

What resistance (to ground) does the sensor measure at operating temp?
From what I can gather it should be roughly 900 ohms at 190 degrees for a '96, dropping to roughly 500 ohms at 230 deg.

Fsher21

Thanks! Will test after work. It got up to the red line after under a mile of driving and the engine wasnt hardly warm. I noticed the sensor nut thing is contacting my valve cover so would that affect the resistance throwing it off?

Radi

That may be your problem right there, if you are talking about the contact the sensor wire attaches to (on top) . Ground makes it read full-scale.
If it's the "nut" part that screws into the block- no problem- it's grounded on that end through the block anyway.

Fsher21

No it is the "nut" itself contacting. From the last 4 hours of researching I haven't come up with more than replacing the new sensor. Tested the resistance at 1,500 ohm or so with temp outside at 80 degrees and engine likely the same. I will get it up to temp and test it to see where it sits.

I was really suspecting the voltage regulator since it reduces the voltage going to/between the gas and temp gauge. My gas gauge and light currently have my going 180 miles/adding 13 gallons when it reads low. Not sure that is a problem or related anymore though.

Likely going to get another sensor and hope for the best. Sucks because I have to take the damn valve cover off every time i replace/screw up this damn thing.

edit: got the engine nice and warm and tested it twice, 115 ohm then 125 ohm about 15 mins later. Guess the valve cover is coming off AGAIN to make room for this new guy! If it doesn't work I'm stuck again.

Fsher21

Replaced the sensor while working to replace my rad. It is reading high, but I think it is because I have air in my system and I just havent fully purged it out yet. Doesn't explain why it was high before the rad replacement unless air was in the system then too? If my lower rad hose is empty, is that a sign of anything?

Wingnutz

I have been trying to troubleshoot a problem like this for the past couple weeks. Numbers aren't matching up. Do different sensors depending on different years have different resistances to temperatures?

freegdr

air cannot be a issue with open cooling systems only with closed renix systems ...

Fsher21

could the part autozone has be incorrect and the resistance is off? The issue persists but I just know if it moves into the red for more than a few seconds I will have a problem.

I was implying worst case scenario where i was getting exhaust pumped into my coolant causing a permanent hot air pocket under the sensor. Through all my troubleshooting regarding the issue a cracked head often came up.

freegdr

...

freegdr

a sign of exhaust getting into coolant is bubbles in over flow bottle while running is the temp reading high at all driving speeds plus stopped in traffic?

Fsher21

my temp gauge wouldn't sit still like it should. it wouldn't make it to 210 before dropping down to about 150 in under 3 seconds. It would then work back to just under 210 in about 6 seconds and repeat. The fluctuation would only tighten up after driving 30 minutes or more. I verified with a point and shoot temp reader that the temp was not doing that at the tstat housing and various other spots.

So I replaced it but broke off the first sensor in the head and didn't have it working for a few weeks. Put the same part number in again and it got up to just before the red line after only a few mins of driving and sat there even with the actual engine temp increasing. Used the warranty to replace that after verifying the resistance wasn't what it should be.

So that leave me where I am at now...Everything else working fine but the gauge. Only guess is the sender autozone stocks doesn't have the correct range, which throws the gauge off. Forgot to mention the first replacement sensor was the same part number as autozone but listed on a different parts site.

Fsher21

When I first start driving it and before the tstat opens, the temp does go into the red and drops to around 220 when the tstat opens. Then after that it builds to where it sits happily and works "normal" if it was the 210 line instead of the 230ish reading I see.

freegdr

id take it back try napa or bennet see if itcure the issue...