water temp sensor

narita · Postby **narita** » Tue Nov 10, 2015 5:06 pm

Ok so i have a 1/8 npt vdo sensor and a asi 1/8 nptf hose adapter.

Will the npt to nptf require sealant and if so which is the safest to use as to not alter the temp readings from the sensor?

hks_kansei · Postby **hks_kansei** » Tue Nov 10, 2015 5:27 pm

Not sure if you need sealant, but frankly a little smear wont hurt.

No need to worry about the sealant being sensor safe with a water temp sensor, that only really applies to things like 02 sensors that can give weird readings with the fumes from the sealant.

Pretty much anything should work, as long as it can take the heat, and won't dissolve in water (i'm pretty sure all auto sealants are ok on both counts)

madjak · Postby **madjak** » Tue Nov 10, 2015 7:17 pm

Also thread tape works fairly well. I find it less messy than sealants.

narita · Postby **narita** » Tue Nov 10, 2015 11:00 pm

May be worth noting the sensor grounds through the adapter. So using any sealant will need to be carefully.

hks_kansei · Postby **hks_kansei** » Wed Nov 11, 2015 1:42 pm

narita wrote:May be worth noting the sensor grounds through the adapter. So using any sealant will need to be carefully.

ohhhh.....

In that case use nothing.

bartmanftw · Postby **bartmanftw** » Wed Nov 11, 2015 2:56 pm

narita wrote:May be worth noting the sensor grounds through the adapter. So using any sealant will need to be carefully.

But doesn't the housing sit between two coolant hoses? I'd use sealant and add a ground from the sensor housing the engine to get a good ground.

madjak · Postby **madjak** » Wed Nov 11, 2015 3:02 pm

I've found with using sealant or thread tape that there must still be enough contact on the threads to earth it. I've always used some sort of sealant as I hate leaks and never had a problem with earthing.

zossy1 · Postby **zossy1** » Wed Nov 11, 2015 3:32 pm

madjak wrote:I've found with using sealant or thread tape that there must still be enough contact on the threads to earth it. I've always used some sort of sealant as I hate leaks and never had a problem with earthing.

+1

sailaholic · Postby **sailaholic** » Wed Nov 11, 2015 6:54 pm

You should use an electrically isolating but heat conducting sealant on all exposed faces of the sensor. Otherwise the sensor will ground through the coolant and promote engine destroying electrolysis. I find hysol to give good results. http://www.loctite.com.au/3320_AUE_HTML ... 2643214337

The high strength epoxy is strong enough to resist the erosion fretting that can effect the sensor due to the high water flows. Smearing a bit of the left over on the joins between radiator hosing and sensor adapter will also prevent crevice corrosion on the adapter.

I've almost missed your trolling Narita. I see your stilling working on your subtlety. It's getting pretty good, this one was almost a logic puzzle.

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narita · Postby **narita** » Thu Nov 12, 2015 3:24 pm

Thanks.

Not trolling this time. The hose adapter has a seperate thread for the grounding wire. So the threads of the sensor need to be able to ground through the sensor.

sailaholic · Postby **sailaholic** » Thu Nov 12, 2015 11:44 pm

It the sensor truely needs to be grounded it can't be installed in a radiator hose with out providing a cable from the adapter to the body. Which isn't impossible just strongly recommended.

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hks_kansei · Postby **hks_kansei** » Fri Nov 13, 2015 9:00 am

sailaholic wrote:It the sensor truely needs to be grounded it can't be installed in a radiator hose with out providing a cable from the adapter to the body. Which isn't impossible just strongly recommended.