I have an issue that I cannot seem to solve. I'll lay it out here: Specs: 1958 Apache Chevy 350 with TH350 Tranny Original type gauges 1. I was driving one day and noticed that the temp gauge was showing extremely hot (over the far right "dot"). 2. I parked the truck and noted that the radiator was not boiling but didn't drive it again that day. 3. The next day, I drove the truck and had the same experience. So I replaced the thermostat to see if that was the issue. 4. Still the same experience. So I drained the radiator and refilled and had the same issue. 5. Next I rewired from the gauge to the temperature sending unit and hooked the hot side of the gauge directly to the battery. Same result. 5. Then I went to a local parts store and got a new sending unit. Same result. 6. Then I ordered a new gauge and installed it. Same result. 7. Next I bought a manual gauge and the truck operates at about 190 degrees consistently. So I know it's not overheating. 8. As a desperate measure, I bought a 12 volt to 6 volt resistor and put it on both the send and ignition side of gauge just to see if the voltage was the issue. Same result. I'm out of ideas here. It seems like the temperature sender is just not calibrated with the gauge somehow. The gauge shows the temperature heating up and cooling off but just shows it being hotter than it is. From what I can tell when my needle is over the last "dot" on the right of the gauge my truck is running about 190 degrees. The gauge I bought locally has a number of WT203. I purchased it at O'Reilly. So I'm wondering if it's not giving the correct resistance for the gauge. But what's puzzling about that is that the gauge worked for a while before messing up. So it seems like it wouldn't be the temperature sending unit since there has been two installed with the same result.
Do you have the right sending unit for the gauge. The sending units have built in resistince to work what ever gauge it was set for and temps are around for a set up in uses. Now that you are using 350 from 69-up with factory gauges form 55-59 you will have to play test them to find the right one for your needs, unless some one has got the same set up and done the work and know what one you need. Maybe some one will help here. good luck.
Hey. Thanks for the response. That was my thought early on. But I went to the local O'Reilly and went through their books and it appears it's the same part (WT203) for all motors from that time. Even the straight 6. I thought that perhaps the gauge wanted 6 volts rather than 12 so I hooked up the 6 volt resistor and got the same result. Killing me.
I had the same problem. I eventually figured out that the current from the gauge was causing the (NAPA) sender to heat up. I replace it with a Wells TU5 from Autozone, and it works.
Thanks a lot! Thanks for the help. This has been killing me. I will get the other part and try it out this weekend. Thanks again!
Helped Some I bought the TU5 at AutoZone and it actually did knock the gauge down about 25% from where it used to be. It still reads about 3/4 of the way to pegged at running temp, but it's definitely a step in the right direction. I found a place called Lectric Limited (lectriclimited.com) and they sell a unit that's supposed to be better than others. So I ordered one. We'll see.
I have had the same problem for several months, just haven't had time to dig into it. I'll post progress I discover, if any.
Success! OK. Here's what I got to work. I ordered a Send Unit from www.lectriclimited.com. Its part number is 01513321. I also ordered a Temperature Pigtail Kit which is basically just original wiring for the unit from the gauge to the unit. That kit number is 34620. Hooked everything up and it works! I had no idea that the sending units varied so much and ones that showed they were for a 58 Apache were not necessarily going to work. Ones I tried that didn't work for me were the WT203 from O'Reilly and the TU5 from AutoZone. To be fair, I never tried a unit from Classic Parts. At any rate, I hope my problems help others out there in the same boat.
Most of the parts stores like AutoZone, O'Reilly and the like simplify their inventories by listing the same part for several different applications that are close but not exactly the same. If it fits in the same hole, they figure it's close enough. I've had better luck with Napa, they were more expensive but the parts always seemed to work better and last longer. I've noticed that seems to be changing though, most guys will go for the cheaper part and they have to change with their market audience to be competitive. I'm glad you got it figured out! Bob
