calling Barrie aka "the thermosensor meister" - PeachParts Mercedes-Benz Forum

jsmith · #1 04-24-2002, 02:45 PM

with the warmer, humid weather my external temp readout is fading in and out again. i figured it's time for some minor surgery on that thermosensor by the license plate. so i dug up those old threads and was pleasantly surprised to find part numbers for the replacement sensor. went on to the newark electronics site and ordered one (did i say one, i meant three!!! - but they wouldn't let me change my order after i submitted it

). the part came today and it wasn't exactly what i was expecting. i mean those leads are thin! so, a couple of questions:

- i have a 100W soldering gun and a 40w iron - use the iron right?
- the smallest shrink tubing i have is what's shown in the picture, should i butt it right up to the head?
- where can i get conductive paste / wax - is that readily available?

cheers

Ron Johnstone · #2 04-24-2002, 07:19 PM

Use the lowest wattage iron, put the shrink tubing right up to the head and later cover anything showing with good quality tape. BE SURE to put a heat sink, (a small alligator clip, a hemostat, whatever), on the leads to the thermistor before soldering and do it as fast as possible so you don't overheat it. Thermal compound can be purchased at any Radio Shack.
Good luck!

jsmith · #3 04-24-2002, 10:35 PM

is there a way to open up the old probe without damaging the tube? i was going to slit the tube covering and i was trying to get the tip off but wasn't successful. i remembered that i have some thermal paste that i used on a CPU - heatsink contact so i'll use that. RS just gave me the usual blank looks and i didn't feel like checking out their entire inventory (yet again)...

thanks

ps. a 356? cool! how about some pix?

Ron Johnstone · #4 04-25-2002, 12:04 PM

Don't know how to get an original out as I have only worked on already ripped apart ones.
RS calls it: "Heat Sink Grease", p/n 276-1372, $1.99. Your stuff will work just fine. In fact, my probe is just hanging in space behind the bumper.
My 356C is currently buried behind and under all the winter crap in the garage and is utterly filthy. I'm very ashamed as it is a very nice car.

jsmith · #5 05-02-2002, 08:18 AM

i dug this up because i was able to confirm that my reading starts to fade in and out when the weather is wet. the past few days when it was warm and dry, the reading was solid. regardless of whether it is fading in & out or solid, the reading is correct. could this be indicative of a corroded / loose connection somewhere? where exactly does the sensor cable hook up "behind the fuse box"? i don't want to slice open the temp probe and replace it only to find that it wasn't the problem...

jsmith · #6 05-07-2002, 09:44 AM

just replaced the thermistor. split the tube, excised the old one and soldered the new one in. it's still fading in and out - i suspect a bad connection at the harness junction. if only someone could tell me where it is (by the fusebox somewhere?)...

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